David Grayson

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• PhD
• Professor Emeritus at Trinity College Dublin

Phenyl benzenethiosulfinate reacts with enolate anions derived from ketones to give α-phenylsulfinyl ketones directly, together with minor amounts of α-phenylsulfanyl ketones. These are easily separated by forming the water-soluble sodium salts of the sulfinyl compounds. Grignard reagents also react with phenyl benzenethiosulfinate, to give mixture...

Guanidine is one of the most versatile functional groups in chemistry; compounds containing this system have found application in a diversity of biological activities, and in this chapter, the advances in the field of the synthesis of guanidines are presented. First, the preparation of acyclic guanidines involving the reaction of an amine with an a...

Abstract The use of 2-chloro-4,6-dimethoxypyrimdine as a tool for the syntheses of substituted guanidines is presented. This method, that we had previously shown to be very useful for aromatic amines, introduces an atom economical, cost effective and environmentally safe method for the installation of the guanidine functionality in aliphatic primar...

Target compound (VI) is prepared in 81% overall yield via a 3-step sequence comprising esterification, stereoselective reduction, and base-catalyzed intramolecular cyclization.

A novel method for the synthesis of arylguanidines (II) (13 examples), which offers an inexpensive and environmentally friendly alternative to classical routes, is developed.

The reaction of anions of phosphonates (I) with aldehydes gives Stobbe-like products (III) via intervention of a presumed intermediate lactone.

(E)-3-Bromo-1-phenylsulfonylprop-1-ene and (E)-3-iodo-1-phenylsulfonylprop-1-ene both form allylic organozinc reagents that react with aromatic aldehydes to give mainly 4-aryl-4-hydroxy-1-phenylsulfonylbut-1-enes. In contrast, reactions of the same organozinc species with 2-methylpropanal or 3-methylbutanal gave mixtures of diastereoisomeric 4-hydr...

(1S,5R,7R)-10,10-Dimethyl-4-oxa-3-thiatricyclo[5.2.1.01,5]decane 3,3-dioxideC10H16O3SEe = 100%[α]D27 = −3.7 (c 0.33, CCl4)Source of chirality: homochiral templateAbsolute configuration: (1S,5R,7R)

A novel method for the synthesis of aryl‐substituted guanidines in good overall yields is presented; it consists of the acidic cleavage of 2‐(arylamino)‐4,6‐dimethoxypyrimidines, which were prepared by coupling aryl bromides with 2‐amino‐4,6‐dimethoxypyrimidine. This methodology introduces a new means of protection for the guanidine functionality....

Considering the biological and chemical relevance of guanidine containing derivatives, we have devised a novel and efficient two-step synthesis of 2-arylamino-1,4,5,6-tetrahydropyrimidines. We have found that the coupling of aryl bromides with 2-aminopyrimidine is a very effective method for the high yielding synthesis of 2-arylaminopyrimidines. Mo...

Some camphor-derived vinyl sulfones bearing an oxygen functionality at the allylic position have been synthesised and their nucleophilic epoxidation reactions under Meth-Cohn conditions have been explored. The γ-oxygenated camphor-derived vinyl sulfones underwent mildly diastereoselective nucleophilic epoxidation reactions, affording the derived su...

Some camphor-derived chiral allylic and benzylic sulfones in which the sulfonyl group is located at the C-10, C-9 or C-8 methyl groups of (+)-camphor were synthesized. The C-9 and C-8 substituted sulfones were obtained via Wagner–Meerwein rearrangements of the bicyclic camphor framework. On treatment with LDA, the C-10 and C-8 substituted sulfones...

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.

A remarkably concise, chromatography-free route to the parent compound of the paullone family of cyclin-dependent kinase (CDK) inhibitors is reported. A similar strategy allowed the synthesis of the hitherto missing 9-azapaullone and its protonated, N-oxidised and N-alkylated derivatives. Screening studies identified an active and strongly selectiv...

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 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.

The generation of camphor-10-sulfonyl iodide in situ under halosulfonylation conditions or exposure of camphor-10-sulfonyl chloride to copper(II) chloride under Asscher–Vofsi conditions leads unexpectedly to the formation of 10-iodocamphor or 10-chlorocamphor, respectively. Additionally, convenient syntheses of 10-bromocamphor and 10-chlorocamphor...

Reactions of ethyl (2S)-lactate with various amines affords lactamides that are reduced with borane-methyl Sulfide in the presence of boron trifluoride etherate to generate enantiomerically pure P-amino alcohols in good yield.

Carbon–nitrogen whiskers have been prepared by pyrolysis of 1,2-diaminopropane at 950 °C or of allylamine at 900 °C followed by quenching. They are scrolls of carbon film typically 250 nm thick and up to 1 mm long with about five layers in a structure like a “cigare russe” or “brandy snap”, about 50 μm in diameter. Approximately 8 wt% of nitrogen i...

For Abstract see ChemInform Abstract in Full Text.

The mechanism by which dihydro-5-(3'-trifluoroacetoxypropyl)-2(3H)-furanone is formed when 3-(tetrahydro-2'-furyl)propanoic-trifluoroacetic mixed anhydride is treated with an acidic catalyst is defined, and routes to some potentially useful butanolide synthons are described.

(E)-3-Chloro-1-phenylsulfonylprop-1-ene and its iodo- and bromo-analogues, (Z)-1-iodo-3-phenylsulfonylprop-1-ene and (Z)-1-bromo-3-phenylsulfonylprop-1-ene, have each been successfully converted into lithiated carbanions which react regioselectively with aromatic aldehydes to give gamma-alkylated products whose nature depends upon the halogen subst...

The reaction of (−)-camphorquinone with excess moist bromine gives (−)-(1S,5S)-1-bromomethyl-3,3-dibromo-8,8-dimethyl-7-oxabicyclo[3.2.1]octane-2,6-dione rather than 1-bromomethyl-3,5-dibromo-8,8-dimethyl-7-oxabicyclo[3.2.1]octane-2,6-dione as has been reported in the literature. The controlled reaction of moist bromine with (−)-camphorquinone lead...

For Abstract see ChemInform Abstract in Full Text.

Stability testing of morphine sulfate formulated with nonpareil sugar seeds (consisting of sucrose and starch) and fumaric acid revealed the formation of the three impurities 5-(hydroxymethyl)-2-furfural, 10-hydroxymorphine and 10-oxomorphine. 5-(Hydroxymethyl)-2-furfural was isolated via semipreparative HPLC utilizing volatile mobile phase constit...

For Abstract see ChemInform Abstract in Full Text.

(E)-3-Phenylsulfonylprop-2-enenitrile reacts with sulfur-, oxygen- and carbon-based nucleophiles to yield (E)-configured β-substituted α,β-unsaturated nitriles via a regiospecific addition-elimination sequence.

Reaction of menthylmagnesium chloride with pyridine-2-carbaldehyde gives a mixture of four isomeric chiral menthyl- and neomenthyl-substituted pyridylcarbinols which were fully characterised by a combination of spectroscopic and X-ray crystallographic methods. All of these alcohols catalyse the addition of diethylzinc to benzaldehyde, but with disa...

(E)-3-Phenylsulfonylprop-2-enenitrile undergoes facile Diels–Alder reactions, moderate regioselectivity being observed with several unsymmetrical dienes. Danishefsky's diene and furfuryl alcohol react regioselectively. The cycloadducts formed with cyclopentadiene and with anthracene undergo base-catalysed elimination of benzenesulfinic acid to yiel...

(Z)-1,4-Dihydroxyalk-2-enes react with dicyclohexylcarbodiimide in the presence of catalytic amounts of copper(I) chloride to give O-alkyl monoisoureas which cyclise to give 2-substituted-2,5-dihydrofurans and dicyclohexylurea when they are treated with trifluoroacetic acid. Alkane-1,4-diols likewise give O-alkyl monoisoureas which cyclise to yield...

(E)-3-Phenylsulfonylprop-2-enenitrile undergoes facile Diels-Alder reactions, moderate regioselectivity being observed with several unsymmetrical dienes. Danishefsky's diene and furfuryl alcohol react regioselectively. The cycloadducts formed with cyclopentadiene and with anthracene undergo base-catalysed elimination of benzenesulfinic acid to yiel...

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.

β-Cyano-α-methylcycloalkanones are regiospecifically nitrosated at the α-position by pentyl nitrite in methanolic sodium methoxide to give fused isoxazolo-lactams via a pathway probably involving sequential cycloalkanone cleavage, isoxazole formation and lactamisation. The chemistry of some new compounds derived from the hydrocyanation products of...

Covering: mid-1997 to mid-1999. Previous review: Nat. Prod. Rep., 1998, 15, 439.

5-(Tetrahydro-2-furyl)pentanoic trifluoroacetic anhydride reacts in the presence of trifluoroacetic acid to yield 6-trifluoroacetoxy-9-nonanolide together with (E)-non-5-en-9-olide; treatment of the same mixed anhydride with titanium(IV) chloride gives 6-chloro-9-nonanolide, and its reaction with trifluoroacetic acid in the presence of sodium iodid...

5-Substituted furan-2-(3H)-ones are formed when mixed 3-(tetrahydro-2-furyl)propanoic trifluoroacetic anhydrides are treated with acid catalysts.

This chapter outlines the developments in the chemistry of acyclic and monocyclic monoterpenoids that have taken place between 1973 and 1992. A representative overview is provided and reactions related to general applications are discussed. The chapter also explores biotransformation reactions, the conversion of acyclic monoterpenoids into cyclic s...

The oxo acids (I) react with the appropriate aldehydes in the presence of pyridine to give the unsaturated ketones (III) including the compound (IIIc), a major constituent of the marine sponge Plakortis zygompha.

3-Oxobutanoic acid reacts with aliphatic aldehydes in the presence of pyridine to give α,β-unsaturated methyl ketones in good yields. Analogous results were obtained with a series of other β-oxo acids. Synthesis of (E)-7-methyloct-4-en-3-one, a major constituent of the marine sponge Plakortis zygompha, has been carried out using this methodology. A...

Gemäß Formelschema wird das symmetrische Cyclooctadion (VIIa) synthetisiert, ausdem die Fusicoccin H-Fragmente (VIII) und (XI) zugänglich sind.

The symmetrical cyclo-octanedione (4) has been synthesized and its stereochemistry determined; cyclisation of the derived triketone (5) led to the functionalised becyclo[6.3.0]undecene (12) which embodies the B/C ring system of the fusicoccin structure, and regiospecific alkylation of (4) with 4-iodobutyl benzoate to give (13) was followed by appro...

In Nacharbeitung einer 1928 erschienenen Veröffentlichung von Pillay und Simonsen wird nach dort angegebener Vorschrift aus (+)-Car-3-en (I) das Diol (II) dargestellt, wobei zusätzlich, vermutlich über das Epoxid (IV), das Cyclohexadien (III) (86:14) erhalten wird.

Reaction of (+)-car-3-ene with hydrogen peroxide in acetic acid and alkaline hydrolysis of the product gives (+)-carane-3β,4α-diol (1) and 1-acetyl-3,3-dimethylcyclohexa-1,4-diene (4). Lengthy treatment of (1) with hot, dilute sulphuric acid gives principally p-cymene (7) and (±)-carvenone (8). Shorter treatment of the diol (1) with acid gives (–)-...

Reaction of dibromocarbene with 4,4-dimethoxycyclohexene (7) affords 3,3-dimethoxy-7,7-dibromobicyclo-[4.1.0]heptane (8), which with lithium dimethylcuprate(II) and methyl iodide, and treatment of the product with acid, yields 7,7-dimethylbicyclo[4.1.0]heptan-3-one, ±(2). In the absence of methyl iodide, 7-exo-methyl-bicyclo[4.1.0]heptan-3-one, ±(1...

Epoxidation of (+)-car-3-ene (1) with acetonitrile–hydrogen peroxide afforded, besides (+)-3α,4α-epoxycarane (2), minor amounts of (+)-3α,4α-epoxycaran-2-one (3), (–)-3α,4α-epoxycaran-5-one (4), (–)-3α,4α-epoxycaran-2α-ol (5), and (+)-3α,4α-epoxycaran-5α-ol (6). Reduction of the epoxy-alcohol (5) with lithium aluminium hydride gave (–)-carane-2α,3α...

Reaktion der Titelverbindung (I) mit ätherischer HCl liefert ein Gemisch der Chlorcaranole (H) und (III).

The reaction of (+)-3α,4α-epoxycarane (2) with ethereal hydrogen chloride affords a mixture of (–)-3β-chlorocaran-4α-ol (1a; X = Cl) and (+)-4β-chlorocaran-3α-ol (4). The acetate of the former can be converted into (+)-4α-acetoxycaran-3α-ol (6a) by heating with 1,4-diazabicyclo[2.2.2]octane in dimethylformamide. Treatment of the epoxide (2) with hy...

Oxidation of β-diketones (R1CO·CR2R3·COR4) with alkaline hydrogen peroxide affords two types of acid depending upon the nature of R2 and R3. Where both of these are H, the products are R1CO2H, R4CO2H, and formic acid, which suffers further oxidation. Where R2 is alkyl, the products are R1CO2H, R2CO2H, R4CO2H, and R1R2CH·CO2H and/or R2R4CH·CO2H. Whe...

Coproporphyrinogen-III (1) is shown to be converted biochemically into protoporphyrin-IX (4) with loss of one hydrogen atom from each propionate residue on rings A and B and the 3H-tracer results are consistent with a stereospecific process.

Bei Behandlung von (-)-trans-Pinocarveol oder (+)-oz-2,3-Epoxypinan mit ätherischem HBr entsteht ein Reaktionsgemisch mit dem (-)-Bicycloheptan (I) als Hauptprodukt.

Der Bromalkohol (I) reagiert mit Silberacetat in Essigsäure zu Trimethylcyclopentenyl-acetaldehyd (IIa), der mit Lithiumaluminiumhydrid zum Alkohol (IIb) reduziert wird.

Die Oxidation des (+)-Carens (I) mit tert.-Butylchromat liefert das (-)-Carenon (II) (50% des Produktgemisches) sowie das (-)-Carendion (III), das Hydroxycymen (IV) und das (+)-Carenon (V) (je etwa 11,5%), ferner m- und p-Methyl-α-methylstyrol (7,7%) und andere Nebenprodukte (7,6%).

(+)-cis-3-(2-Hydroxyethyl)-2,2,5-trimethyl-cyclopentanone and its racemic form are synthesised from (+)-α-2,3-epoxypinane or (–)-trans-pinocarveol, and (±)-2,2,5-trimethyl-1-oxocyclopentane-3-carboxylic acid, respectively; treatment with base of the chloroketone, derived from the (+)-hydroxyketone, affords (+)-fenchone, while pyrolysis of the (+)-a...

Treatment of (+)-α-2,3-epoxypinane or (–)-trans-pinocarveol with hydrogen bromide gives a mixture in which (–)-2-endo-bromo-6-exo-hydroxy-1,3,3-trimethylbicyclo[2,2,1]heptane is the major product. With silver acetate this affords (–)-2,2,4-trimethylcyclopent-3-enylacetaldehyde, which gives (–)-4-(2-hydroxyethyl)-1,3,3-trimethylcyclopentene on reduc...

Oxidation of (+)-car-3-ene (III) with t-butyl chromate affords (–)-car-3-en-5-one (I), (–)-car-3-ene-2,5-dione (IV), 8-hydroxy-m-cymene (V), and (+)-car-3-en-2-one (VI), the first in good yield. Photolysis of (–)-car-3-en-5-one (I) in ethanol yields 3-isopropyl-5-methylphenol (VII), (+)-2α,4α,6α,9α,11α,13αH-1α,5,5,8α,12,12-hexamethylpentacyclo[7,5,...

Car-3-en (I) reagiert mit N-Brom-succinimid zu dem Addukt (II) in stereospezifischer Reaktion; dieses wird durch tert.-Butylat glatt zum (-)-β-3,4-Epoxy-caran (III) dehydrobromiert.

Die Oxydation der Titelverbindung (I) mit Chromtrioxid in Aceton, in Aceton mit Na-acetat bzw. in Pyridin liefert die neutralen Produkte (II) bis (XII), die ebenfalls bei der Oxydation von (I) mit Permanganat jedoch mit anderen relativen Ausbeuten entstehen.

Chemistry summer schools for 17-18 year old school students in the UK were run by Bristol ChemLabS, a Centre for Excellence in Teaching and Learning in Chemistry at the University of Bristol. Students attending were all studying Chemistry at post-16 level (A level in the UK) and experienced not only new practical techniques but also lectures on cut...

Oxidation of (+)-car-3-ene with chromium trioxide affords a range of neutral oxidation products similar to that obtained when permanganate is the oxidant. 8-Hydroxy-m-cymene is the major product when ‘unbuffered’ chromium trioxide in acetone is used. (+)-Car-3-en-2-one is formed only in traces. The ketol, (+)-3β-hydroxy-trans-caran-4-one, also a pr...

Using a combination of physical and chemical methods the conformational preferences of the cis-caranols have been deduced and their configurations confirmed.