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Publications (355)
Addition of Grignard- or other organometallic reagents to 3-halocyclohex-2-en-1-ones bearing an alkyl or aryl group at C-5, followed by mild acid treatment and exposure to DBU at room temperature, generates meta-substituted phenols in which the newly introduced meta substituent originates from the Grignard reagent. The range of effective organometa...
Piperazinedione 13, representing the BC rings of the anti-prostate cancer fungal metabolite MPC1001, was prepared by a route in which a sulfur-stabilized carbanion derived from 22 cyclizes onto the terminal ester of the pendant chain attached to N(1). Another model, 14, was synthesized by cyclization of an α-ketoamide nitrogen onto an ester; 14 rep...
Intramolecular conjugate displacement (ICD) reactions, developed by the Clive group, form carbocycles and polycyclic amines by intramolecular nucleophilic attack on a Michael acceptor with an allylic leaving group. Quantum mechanical investigations with density functional theory show that ICDs involve a stepwise addition, forming an intermediate st...
The title silyloxymethanethiols (II) and (IV) act as nucleophilic reagents for the introduction of a protected bivalent sulfur.
Conjugate addition of Me3SiMe2SiLi to cycloalk-2-en-1-ones, ketalization, Tamao-Fleming oxidation (Bu4NF, then H2O2, KHCO3), TPAP oxidation and acid hydrolysis generates 2-methyl cycloalkane-1,3-diones. Ketalization is needed in order to prevent addition of Me3Si(-) to the carbonyl. The pentamethyldisilanyl group has advantages over other silicon u...
A new family of routes to substituted phenols has been developed. 2-Bromo-3-methoxycyclohex-2-en-1-ones are readily deprotonated at C-6 and the resulting anions react smoothly with a variety of electrophiles; treatment with DBU in PhMe at room temperature then results in efficient aromatization to benzene derivatives of regiochemically defined subs...
N-Boc (S)-proline was converted into (2S)-2-[(phenylselanyl)methyl]pyrrolidine which was alkylated on nitrogen with 2-bromo-1-(4-methoxyphenyl)ethan-1-one. Reaction with vinyllithium, 6-exo-trigonal radical cyclization (Bu3SnH, AIBN, PhMe, 110 degC), dehydration (P2O5, H3PO4) and demethylation (BBr3) gave (+)-ipalbidine with ee >99%.
2-Bromo-3-methoxycyclohex-2-en-1-ones are readily alkylated at C-6 with reactive halides, and then treatment with DBU (2 equiv) in PhMe at room temperature results in smooth loss of bromide and aromatization to resorcinol (deltamonomethyl ethers of defined substitution pattern.
Several differently substituted 1,3-bipyrroles are prepared by this method and subsequent modifications.
A general method is described for the synthesis of 1,3'-bipyrroles. The route involves constructing a pyrrole ring on the nitrogen of a substituted 1H-pyrrole, so as to generate the 1,3'-bipyrrole. In this approach the nitrogen of the starting pyrrole was alkylated with a special Michael acceptor having an allylic leaving group, and the product was...
Intramolecular conjugate displacement (ICD), the process illustrated in eqn (1), has been applied to the Morita-Baylis-Hillman adducts formed from (5S)-5-(l-menthyloxy)-2(5H)-furanone and aldehydes that are substituted in the γ- or δ-position by geminal phenylthio groups. When the initial Morita-Baylis-Hillman alcohols are acetylated and oxidized t...
An advanced intermediate related to the structures of CP-225,917 and CP-263,114 was constructed by a sequence based on the use of Grob-like fragmentation, intramolecular conjugate displacement and [2,3]-Wittig rearrangement. A variant of the [2,3]-Wittig rearrangement was developed.
(Ethylthio)methanol
Paraformaldehyde
Ethanethiol
(1,1‐Dimethylethyl)[(ethylthio)methoxy]dimethylsilane
Chloro(1,1‐dimethylethyl)dimethylsilane
Triethylamine
(Chloromethoxy)(1,1‐dimethylethyl)dimethylsilane
Sulfuryl chloride
Sodium p ‐toluenesulfinate monohydrate
Sulfur
4‐Methylbenzenesulfonothioic acid, sodium salt
S ‐[[[(1,1‐Dimethyl‐ethyl)dimethy...
A detailed account is given of adventures experienced in the total synthesis of the marine alkaloid halichlorine. The successful approach involved constructing the quaternary asymmetric center at an early stage. The five-membered ring was formed by 5-exo-trig radical cyclization and the unsaturated six-membered ring by a process that formally repre...
The first synthesis of marinopyrrole B, which is highly active against methicillin-resistant Staphylococcus aureus, is described. The route involved constructing a pyrrole ring on the nitrogen of a 3-bromo-4,5-dichloropyrrole by N-alkylation with a special Michael acceptor having an allylic leaving group; the second pyrrole ring was then formed by...
Piperazine-2,5-diones are formed by Dieckmann cyclization (NaH, THF) of substructures of the type CH(2)-N(R)C(O)CH(2)N(R')CO(2)Ph in which the terminal methylene (CH(2)) that is adjacent to nitrogen closes onto the carbonyl group of the phenyl carbamate unit at the other end of the chain. R and R' are alkyl groups, and the terminal methylene is act...
A tricyclic epidithiodiketopiperazine was prepared having structural features related to the antitumor antibiotic MPC1001. The method is based on the use of the sulfenylating agent p-MeC6H4S(O2)SCH2OSiMe2Bu-t to introduce two protected sulfur atoms in a sequential and stereocontrolled manner. Fluoride-induced deprotection to remove the CH2OSiMe2Bu-...
Intramolecular conjugate displacement (ICD) has been applied to the Morita-Baylis-Hillman adducts formed from (5S)-5-(l-menthyloxy)-2(5H)-furanone and aldehydes that carry a protected β- or γ-amino group. DIBAL-H reduction of the resulting ICD products releases optically pure six- or seven-membered cyclic amines having a stereogenic center α to nit...
Protection of various aromatic and aliphatic thiols is achieved using 2,6-lutidine or proton sponge as a base.
Aromatic and aliphatic thiols can be protected by reaction with t-BuMe(2)SiOCH(2)Cl in DMF in the presence of a base (2,6-lutidine or proton sponge); the resulting t-BuMe(2)SiOCH(2)SR or t-BuMe(2)SiOCH(2)SAr are deprotected by sequential treatment with Bu(4)NF and I(2) to give symmetrical disulfides. Another mode of deprotection involves reaction w...
Additionally, synthesis of an azepine derivative is described.
Synthetic studies related to CP-225,917 are described, including the preparation of the fully oxygenated tetracyclic central core 3.Key words: CP-225,917, siloxy-Cope rearrangement, Cope rearrangement, strain-assisted rearrangement, furan, ruthenium dioxide, bridgehead olefin.
Δ4-Olefinic alcohols react with phenylselenenyl chloride to produce tetrahydrofurans with a phenylseleno-group trans and β to the ether oxygen. The [4.3.0] and [3.3.0] oxabicyclic systems produced have cis ring fusion as in 5 and 7.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Reaction of acetylides with aldehydes to form but-2-yne-1,4-diols, followed by triple bond reduction and oxidation of the hydroxyl groups, gives 1,4-diketones; these react with vinyllithium, and the resulting diols undergo ring-closing metathesis to form 2-cyclohexene-1,4-diols. Dehydration, usually by acid treatment, then gives benzenes carrying s...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Baylis-Hillman alcohols derived from methyl acrylate or acrylonitrile and carrying an N-Boc group β to the hydroxyl (CH(OH)CHNBoc) can be converted into unusual seven-membered heterocycles containing both nitrogen and sulfur by O-acylation (AcCl or EtOCOCl), N-deprotection (CF(3)CO(2)H), and reaction with CS(2). In a modification of this process, w...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
(S)-Pyroglutamic acid was converted into the (phenylthio)acetylene 14, which undergoes radical cyclization to the 7-azabicyclo[2.2.1]heptane 15. Ozonolysis then affords ketone 4, a synthetic precursor of (-)-epibatidine.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
D-Glucose was converted into the propargylsilane aldehyde 3, which underwent ring closure with retention of silicon, in the presence of camphorsulfonic acid, to give 5, and this was elaborated, via ketone 22, into 2, which had previously been transformed into D-myo-inositol-1,4,5-tris(dihydrogenphosphate). A crucial step in the synthesis is the ste...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Glyoxylic acid diphenylhydrazone (2, Y = NPh2) and the corresponding O-benzyloxime (2, Y = OBn) are easily esterified in high yield by β-bromo alcohols, and the resulting esters undergo radical cyclization to α-(2,2-diphenylhydrazino) or α-(benzyloxyamino) lactones on treatment with tributyltin hydride; the initial radical can be formed by homolysi...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
(Figure presented) 4-Hydroxy-3,4-dihydro-2H-pyridine-1-carboxylic acid benzyl esters, which are readily prepared from serine and terminal acetylenes, undergo Claisen rearrangement to piperidine derivatives when heated with butyl vinyl ether in the presence of Hg(OAc) 2 and Et 3N. This route to optically pure piperidines having substituents α to nit...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
AbstractA proper choice of methoxy and methoxymethyl groups for protection of the hydroxyls of polyoxygenated naphthalenes allows selective oxidation of either ring of the naphthalene structure with ammonium cerium(IV) nitrate; for example, 9 can be converted into 10, and 11 into 12.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
4-Chloro-, 4-bromo- and 4-iodoserotonin derivatives were synthesized from 4-halo-5-oxyindoles, themselves derived from coumarins. Synthesis of the 4-iodoserotonins involved conjugate addition of an allyl group to a 5-iodocoumarin, followed by conversion of the allyl group into an aminoethyl unit. One of the iodoserotonin derivatives was converted i...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
2',3'-Dimesylates of 5'-protected nucleosides are converted into the corresponding 2',3'-didehydro-2',3'-dideoxy compounds by treatment with telluride dianion in the form of the sodium or lithium salt. The method is well-suited to the preparation of unsaturated nucleosides that can be converted into compounds that are believed to be useful in the t...
Optically pure gamma-lactones fused onto a cyclohexenone are available by a radical-based method for desymmetrizing 4-hydroxy-2,5-cyclohexadienones.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Enone 5, derived by chemical degradation of compactin (1), was elaborated into the semisynthetic analogue 4, which is an inhibitor of cholesterol biosynthesis in rat liver microsomes.
Readily accessible 3-alkoxycarbonyl-6-hydroxy-5-halocoumarins can be converted into 4-halo-5-hydroxyindoles by a sequence whose essential steps are conjugate reduction or conjugate addition, decarboxylation, lactone opening with ammonia, phenolic oxygen protection, Hofmann rearrangement to an N-Boc ethylamine, oxidation to a quinone and deprotectio...
The total synthesis of the marine alkaloid halichlorine is described, based on an approach that involves constructing the fully substituted asymmetric center at an early stage. The five-membered ring is formed by 5-exo-trig radical cyclization and the unsaturated six-membered ring by a process that formally represents a sequential combination of co...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A detailed study has been made of a method of ring closure categorized as an all-carbon intramolecular conjugate displacement (ICD). This reaction involves intramolecular addition of a carbanion, which is stabilized by at least one electron-withdrawing group, to a Michael acceptor which has a leaving group in an allylic position. The process formal...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Esters, acids and acid chlorides can be converted via the intermediacy of their corresponding Weinreb amides into benzene derivatives that incorporate the original carbonyl carbon as part of the benzene ring. The process involves treatment of the derived Weinreb amides with 3-butenylmagnesium bromide and an allylic Grignard reagent, followed by rin...
trans-4-Hydroxy-L-proline was converted into a tricyclic compound representing three contiguous rings of the anticancer antibiotic MPC1001. The tricyclic model contains the dihydrooxepin and diketopiperazine subunits, as well as one of the sulfur atoms of the natural product. The diketopiperazine unit was formed by a new method that involves cycliz...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.