Karl Hale

Karl Hale
Queen's University Belfast | QUB · School of Chemistry and Chemical Engineering

Doctor of Philosophy

About

112
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Publications

Publications (112)
Article
Full-text available
Here we provide definitive EPR evidence for the existence of α-triphenylstannylvinyl radicals in the low temperature O-directed free radical hydrostannation of dialkyl propargylic alcohols with Ph3SnH/cat. Et3B and O2 in PhMe. Isotropic hyperfine splitting patterns and spectral simulations confirm the assignments made. In the case of the α-tripheny...
Article
Full-text available
Porphyrins feature prominently in nature, be it as enzymatic cofactors, electron and exciton shuffles, as photoactive dyes, or as signaling substances. Their involvement in the generation, storage and use of oxygen is pivotal to life, while their photochemical properties are central to the biochemical functioning of plants. When complexed to metals...
Preprint
p>(-)-Agelastatin A (AA) in 1,2-propanediol (3-deoxy-DL-glycerol) elicits a dose-dependent decrease in OPN mRNA expression in canine Duchenne Muscular Dystrophy (DMD) myoblasts at doses ranging from 0.01 nM-30 nM. When intraperitoneally administered in the same vehicle to mdx mice at 2.5 mg/kg/day for two weeks, and at 1.5 mg/kg/day twice-weekly fo...
Article
Full-text available
O-Directed free radical hydrostannation of the β-cyclopropyl propargyl alcohol 57 with stannanes and cat. Et3B in THF/H2O or PhMe/MeOH failed to deliver any of the expected products of α-stannylvinyl cation capture. Instead only α-stannyl-β-cyclopropylvinyl radical intermediates were detected, which underwent fast H-atom abstraction and/or cyclopro...
Article
Full-text available
O-directed hydrostannation of β-cyclopropyl propargyl alcohol 22 with stannanes and cat. Et 3 B in THF/H 2 O or PhMe/MeOH fails to deliver any detectable products of α-stannylvinyl cation capture.
Preprint
O-Directed free radical hydrostannation of a β-cyclopropyl propargylic alcohol probe with stannanes and cat. Et<sub>3</sub>B in THF/H<sub>2</sub>O, or PhMe/MeOH, failed to deliver any detectable products of α-stannylvinyl cation capture. Instead only α-stannyl-β-cyclopropylvinyl radical intermediates could be detected, which underwent fast H-atom a...
Article
Full-text available
In this Personal Account, we will give an overview of the room temperature O‐directed free radical hydrostannation reaction of propargylically‐oxygenated dialkyl acetylenes with Ph3SnH and catalytic Et3B/O2 in PhMe. We will show how this excellent reaction evolved, and how it has since been used to stereoselectively construct the complex trisubstit...
Article
A new synthesis of (+)-brefeldin A is reported via Padwa allenylsulfone [3 + 2]-cycloadditive elimination. Cycloadduct 13 was initially elaborated into iodide 27, which, following treatment with Zn, gave aldehyde 28 whose C(9) stereocenter was epimerized. Further elaboration into enoate 38 and Julia-Kocienski olefination with 5 subsequently afforde...
Article
A unified total synthesis of the GRP78-downregulator (+)-prunustatin A and the immunosuppressant (+)-SW-163A based upon [1 + 1 + 1 + 1]-fragment condensation and macrolactonization between O(4) and C(5) is herein described. Sharpless asymmetric dihydroxylation was used to set the C(2) stereocenter present in both targets. In like fashion, coupling...
Article
A convenient asymmetric total synthesis of the potent HIF-1 inhibitory antitumor natural product, (-)- or (+)-(8R)-mycothiazole (1), is described. Not only does our synthesis confirm the 2006 structural reassignment made by Crews ( Crews , P. , et al. J. Nat. Prod. 2006 , 69 , 145 ), it revises the [α]D data previously reported for this molecule in...
Article
In this paper, an unambiguous synthetic strategy is reported for the preparation of enantiomerically pure cis-5-halo-piperazic acid derivatives in single diastereoisomer form. Contrary to the recent report by Shin et al. (Ref. 6), in which it is claimed that the Ph3P and N-chlorosuccinimide (NCS)-mediated chlorination of (3R,5S)-trans-N(1),N(2)-di-...
Article
Rules for predicting anionic SN2 displacement viability in furanose and furanoside sulfonates are presented.
Article
A new synthetic protocol for the hydroxymethylation of terminal acetylenes is described that involves stoichiometric Carreira alkynylation with solid paraformaldehyde (HO[CH2O]nH) in PhMe at 60 °C. Significantly, the method can be successfully applied on acetylenes that possess base-sensitive ester functionality and heterocyclic rings that readily...
Article
The original 1967 Richardson-Hough rules for predicting SN2 displacement viability in carbohydrate sulfonate derivatives with external nucleophiles have now been updated. Not only do the original rules still hold, but the newly updated rules rationalize why O-triflates (trifluoromethanesulfonate esters) frequently allow many seemingly "disallowed"...
Article
Stereochemical evidence is presented to demonstrate that (-)-inthomycin C has (3R)- and not (3S)-stereochemistry. Careful reappraisal of the previously published work2-5 now indicates that the Hatakeyama, Hale, Ryu, and Taylor teams all have synthesized (-)-(3R)-inthomycin C. The newly measured [α]D of pure (-)-(3R)-inthomycin C (98% ee) is -7.9 (c...
Article
An asymmetric total synthesis of the mast cell inhibitor (+)-monanchorin is reported in which a Sharpless AD on 11 and a cyclic sulfate ring opening with an azide feature as key steps. After further manipulation, a novel guanidine-controlled ester reduction provided the guanidine-hemiaminal 25 which underwent Wittig olefination to give 27. Hydrogen...
Article
A new pathway to (+)-inthomycin C is reported that exploits an O-directed free radical hydrostannation reaction on (-)-12 and a Stille cross-coupling as key steps. Significantly, the latter process was effected on 19 where a gauche-pentane repulsive interaction could interfere. Our stereochemical studies on the alkynol (-)-12 and the enyne (+)-7 co...
Article
Full-text available
Herein a new double O-directed free radical hydrostannation reaction is reported on the structurally complex dialkyldiyne 11. Through our use of a conformation-restraining acetal to help prevent stereocenter-compromising 1,5-H-atom abstraction reactions by vinyl radical intermediates, the two vinylstannanes of 10 were concurrently constructed with...
Article
A new method for ketone enolate C-acylation is described which utilizes alkyl pentafluorophenylcarbonates, thiocarbonates, and thionocarbonates as the reactive acylating agents, and MgBr(2)·Et(2)O, DMAP, and i-Pr(2)NEt as the reagents for enolization. A wide range of ketones have been observed to undergo clean C-acylation via this protocol.
Article
A new formal total synthesis of (-)-echinosporin has been developed based upon the Padwa [3 + 2]-cycloadditive elimination reaction of allenylsulfone 4 with the D-glucose-derived enone 14 which provides cycloadduct 12.
Article
Ein chemisches Vermächtnis: Nach langer Entwicklungszeit gelang es Keck und Mitarbeitern kürzlich, eine kurze und effiziente Totalsynthese des komplexen Naturstoffs Bryostatin 1 (siehe Struktur) zu realisieren. Die Schlüsselschritte der Synthese werden vorgestellt, ebenso wie einige herausragende neue Reaktionen, die im Verlauf des Projekts eingefü...
Article
A chemical legacy: Keck and his team have chemically pursued the bryostatin 1 structure with great vigor in recent years and, in late 2010, they finally completed their quest of developing a short and efficient total synthesis of this complex natural product (see structure). The present Highlight provides a brief but nevertheless detailed overview...
Article
Kutznerides 2 and 8 of the cyclic hexadepsipeptide family of antifungal natural products from the soil actinomycete Kutzneria sp. 744 contain two sets of chlorinated residues, a 6,7-dichlorohexahydropyrroloindole moiety derived from dichlorotryptophan and a 5-chloropiperazate moiety, as well as a methylcyclopropylglycine residue that may arise from...
Article
Herein we describe our application of the O-directed free radical hydrostannation of disubstituted alkylacetylenes (with Ph3SnH and Et3B) to the (+)-pumiliotoxin B total synthesis problem. Specifically, we report on the use of this method in the synthesis of the Overman alkyne 8, and thereby demonstrate the great utility of this process in a comple...
Article
A convenient new asymmetric synthesis of both enantiomers of erythro-3-hydroxyleucine is described. The key steps involve Sharpless asymmetric dihydroxylation (AD) of α,β-unsaturated ester 3, cyclic sulphate formation from the resulting diol, SN2 reaction with sodium azide, deesterification with aqueous sodium hydroxide, and hydrogenolysis. Utilisi...
Article
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.
Article
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.
Article
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.
Article
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.
Article
A reasonably efficient [2 + 2 + 2] fragment condensation strategy has been developed for assembling the cyclodepsipeptide sector of GE3 that involves 5−7. A Carpino HATU-mediated macrolactamization was used to close the 19-membered cyclodepsipeptide ring.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
In this Focus Review, we give an overview of various bryostatin total syntheses. We also discuss the synthesis of various bryostatin analogues and their biological activity. Work reviewed includes that of Masamune, Evans, Nishiyama and Yamamura, Hale and Manaviazar, Trost, Wender, Keck, Burke, Thomas, and Krische. Our coverage is primarily for the...
Article
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.
Article
Herein we describe our asymmetric total syntheses of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin. We also demonstrate that molecules of this class powerfully inhibit beta-catenin/TCF4- and E2F-mediated gene transcription within malignant human colon cancer cells at low drug concentrations.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
Asymmetric total syntheses of (+)-azinothricin and (+)-kettapeptin have been completed through a common new pathway that exploits a highly chemoselective coupling reaction between the fully elaborated cyclodepsipeptide 5 and the glycal activated esters 3 and 4 at the final stages of both respective syntheses.
Article
The synthesis of three potent new antitumor agents is described: the A83586C-citropeptin hybrid (1), the A83586C-GE3 hybrid (2), and l-Pro-A83586C (3). Significantly, compounds 1 and 2 function as highly potent inhibitors of beta-catenin/TCF4 signaling within cancer cells, while simultaneously downregulating osteopontin (Opn) expression. A83586C an...
Article
Full-text available
Effective inhibitors of osteopontin (OPN)-mediated neoplastic transformation and metastasis are still lacking. (-)-Agelastatin A is a naturally occurring oroidin alkaloid with powerful antitumor effects that, in many cases, are superior to cisplatin in vitro. In this regard, past comparative assaying of the two agents against a range of human tumor...
Article
In this chapter, we present a detailed account of our asymmetric synthesis of (+)-eremantholide A. Key steps in the final route were the Evans’ asymmetric aldol reaction that was used to set the C(7) and C(8)-stereocenters of the target, the Sharpless asymmetric epoxidation, which was employed to introduce C(6), and the Piancatelli TEMPO/BAIB regio...
Article
A new enantioselective synthesis of Masamune's AB fragment (1) for bryostatin 7 is described. Key steps in the new route include a Meerwein-Ponndorf-Verley reduction to set the O(7) stereocenter and an alkylative union between the dithiane 6 and iodide 5 to construct the C(9)-C(10) bond. Because we have previously published a synthesis of Masamune'...
Article
[reaction: see text] The O-directed hydrostannation of various propargyloxy substrates is reported with Ph(3)SnH/Et(3)B.
Article
[reaction: see text] Allylically oxygenated vinyl alpha-triphenylstannanes such as 22 can be readily converted into vinyl iodides and thereafter stereodefined trisubstituted alkenes with retention of configuration.
Article
[reaction: see text] The free-radical hydrostannation of 1 with Ph(3)SnH and catalytic Et(3)B in PhMe has been mechanistically probed. At high Ph(3)SnH concentrations, the O-directed hydrostannation pathway dominates, and 2 is formed with good selectivity (ca. 11.1:1). Substantially lower stannane/substrate concentrations increase the amount of tan...
Article
[reaction: see text] A new total synthesis of (-)-agelastatin A (1) has been achieved from the chiral oxazolidinone (-)-3. Although enone transposition was problematic when the Michael ring closure of 2 was attempted with strong base, the desired cyclization could be effected with Hunig's base after the pyrrole nucleus was brominated. Subsequent re...
Article
[reaction: see text] An enantiospecific total synthesis of Weinreb's advanced intermediate 2 for (-)-agelastatin A has been achieved from the Hough-Richardson aziridine 8. Noteworthy reactions in our sequence include the highly regioselective trans-diaxial ring-opening of 8 with azide ion to set up the vicinal diamido functionality present within (...
Article
[structure: see text] The synthesis of two truncated bryostatin analogues 2 and 3 is described. High-field NMR measurements on the C-ring analogue 3 in C(2)H(3)CN containing 25% (2)H(2)O have shown that it binds to the CRD2 of human PKC-alpha at virtually the same position as phorbol-13-acetate (PA) and bryostatin 1 (1). NMR titration studies have...
Article
[reaction: see text] The "Southern Hemisphere" intermediate 2, used by Masamune and co-workers for their asymmetric total synthesis of bryostatin 7 (1), has been synthesized from (E)-1,4-hexadiene (11) by a 24-step pathway that has a longest linear sequence of only 20 steps. This is the shortest synthesis of 2 so far recorded, and moreover, it is f...
Article
A mimetic of the A83586C cyclodepsipeptide has been synthesised via a three-segment coupling protocol involving dipeptides 9, 8 and 7; in contrast to our previous synthesis of A83586C, where the HATU-mediated macrolactamisation proceeded in 25% yield, the corresponding macro-lactamisation of seco-amino acid 18 occurred in ca. 78% yield.
Article
This review summarises the main developments that have occurred in bryostatin chemistry over the period 1982 to 2001 and has 117 references.
Article
[reaction: see text] A reasonably efficient [2 + 2 + 2] fragment condensation strategy has been developed for assembling the cyclodepsipeptide sector of GE3 that involves 5-7. A Carpino HATU-mediated macrolactamization was used to close the 19-membered cyclodepsipeptide ring.
Article
[reaction: see text] A biosynthetic proposal for ring formation in the antitumor agent halichomycin is presented in which macrocyclization of the putative prehalichomycin intermediate 1 is the first step. Compound 2 then undergoes dehydration to the alpha-keto N-acylimine 3 followed by tandem nucleophilic addition of the C(16)-hydroxyl to form the...
Article
[reaction--see text] An 18-step asymmetric synthesis of the bryostatin 1 "southern hemisphere" fragment (1) has been developed. Key steps include an aldol reaction between 6 and 7 and a dehydration to establish the (E)-exocyclic alkene in 2 and a stereoselective Luche reduction and protection with TESOTf to access 1.
Article
[reaction: see text]. An efficient [2 + 2 + 2]-fragment condensation strategy is described for obtaining the cyclodepsipeptide core of verucopeptin. The 19-membered macrocycle was established through a Carpino HATU mediated macrolactamization, which proceeded in good yield under high-dilution conditions.
Article
Full-text available
After a brief summary of our asymmetric total syntheses of A83586C and 4-epi-A83586C, we will go on to describe some of our synthetic work on the monamycins, and our most recent total synthesis studies on the bryostatin antitumor macrolides.
Article
A completely stereocontrolled asymmetric synthesis of an advanced B-ring synthon for the bryostatin family of antitumor agents is reported. Noteworthy features of our synthesis include the Smith-Tietze bis-alkylation reaction between 12 and 13 en route to C(2)-symmetrical ketone 10 and the totally stereoselective conversion of 10 into triol 18 via...
Article
The first enantiospecific total synthesis of (3S,5S)-hydroxypiperazic acid 1 is described. The synthesis begins from D-mannitol and exploits a tandem electrophilic hydrazination/nucleophilic cyclisation reaction to assemble the hexahydropyridazine ring system.
Article
Protected linear hexapeptide 2 undergoes a remarkably facile C(4)-epimerisation when macrolactamisation is attempted with BOP [benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate] and DMAP in CH2Cl2 under conditions of high-dilution; compound 6 is isolated in 51% yield from this reaction. In order to confirm its structure, 6 was...
Article
The first asymmetric total synthesis of antitumour antibiotic A83586C has been accomplished.
Article
In this paper, we describe a new synthetic pathway to ketopyranose 5,6-glycals. We also demonstrate the utility of these derivatives for preparing C(6)-functionalised ketopyranosides.
Article
Protected pentapeptide 9 has been converted to hexapeptide 3 and this chemoselectively coupled to activated ester 2 to give 1 after glycal hydration during SiO2 flash chromatography.
Article
An asymmeric synthesis of the activated esters 20 and 21 is reported. Both molecules equate with the C(28)–C(47) region of A83586C, and contain functionality appropriate for future unification with the hexapeptide unit. A useful new reaction is described for converting a methyl ester directly into a thioethyl or HOBT ester that operates under very...
Article
In response to a recent literature report by Decicco and Leathers (Ref. 13), the work of Hale, Delisser, and Manaviazar (1992) on the asymmetric synthesis of (3R)- and (3S)-piperazic acids has been reinvestigated, and the originally claimed product yields fully substantiated. The claims made in reference 13 about the proportions of cyclised product...
Chapter
For more than half a century, organic chemists have sought to control the stereochemistry of reactions involving chiral enolates for the purpose of constructing single diastereoisomers of moleeules in enantiomerically pure form; yet, it is only since the early 1980s that significant progress has been made on this topic. In this short chapter, we at...
Article
A unified synthetic strategy to the northern halves of antibiotics A83586C and citropeptin is reported.
Article
Calculations have been carried out on model systems with two potentially rate determining step on a single reaction path. Taking the ratio of the diastereoisomers as P, the mazima found on plots of ln P vs. 1/T are shown to derive from the intersection of a line characteristic of one rate-determining step and a second line characteristic of the tra...
Article
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.
Article
A maximum in a plot of In P vs. 1/T does not necessarily imply that the values of ΔΔH‡ for the two possible rate determining steps are of opposite sign.
Article
A convenient new asymmetric synthesis of both enantiomers of erythro-3-hydroxyleucine is described. The key steps involve Sharpless asymmetric dihydroxylation (AD) of α,β-unsaturated ester 3, cyclic sulphate formation from the resulting diol, SN2 reaction with sodium azide, deesterification with aqueous sodium hydroxide, and hydrogenolysis. Utilisi...
Article
A range of 5,6-glycals have been prepared from methyl β-D-fructopyranoside and their chemistry investigated.
Article
A formal total synthesis of the potent immunosuppressant FK506 (1) has been achieved via a concise construction of the Merck advanced intermediate (−)-2. Key features of the successful strategy include stereocontrolled σ-bond installation of the trisubstituted olefin moieties and an efficient coupling of the C(24)-C(34) dithiane (−)-10 with the C(1...
Article
The Sharpless asymmetric dihydroxylation (AD) reaction has been examined on a number of 1,1-disubstituted allyl alcohol derivatives. In the majority of substrates studied, the product diols had ee's in the 11–91% range and had absolute stereochemistry opposite to that predicted using the Sharpless steric model.
Chapter
Synthetic carbohydrate chemistry has undergone a renaissance in the last decade, and the purpose of this chapter is to highlight some of the more significant advances that have taken place in the area. All aspects of the subject are reviewed annually in the Royal Society of Chemistry publication Specialist Periodical Reports: Carbohydrate Chemistry...
Article
A convenient asymmetric synthesis of both (3R)- and (3S)-piperazic acids has been developed that is based on electrophilic hydrazination of a chiral bromovaleryl carboximide enolate with di-tert-butyl azodicarboxylate, followed by subsequent intramolecular SN2 displacement of the bromide by the resulting substituted aza anion. The diastereoselectiv...
Chapter
This chapter reviews thiophenes and methods of their preparation. A useful method for the preparation of 2,3-disubstituted thiophenes is based on the nucleophilic ring opening of 2-ethoxycarbonylcyclopropyl-(triphenyl)phosphonium tetrafluoroborate with various alkali-metal thiocarboxylates in tetra hydro furan (THF). Initially this reaction leads t...
Chapter
In this chapter, the synthetic chemistry literature on steroidal alkaloids is reviewed for the period from 1985 till 1998. The collectives are selective and no attempt to document the vast number of new steroidal alkaloids is characterized over this timeframe. The buxus alkaloids are extensively investigated, but a very little effort is expended on...

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