Peter Brownbridge

Chemistry of 2,5-bis(trimethylsiloxy) furans. I: Preparation and diels-alder reactions

A number of substituted 2,5-bis (trimethylsioloxy) furans were prepared from the corresponding succinic anhydrides, and were found to be reactive dienes for the Diels-Alder reaction with electron - withdrawing dienophiles, giving p-quinones and hydroquinones.

Chemistry of 2,5-bis(trimethylsiloxy)furans. II: Reactions with carbonyl compounds and the synthesis of 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane-4,8-diones☆

Abstract 2,5-Bis(trimethylsiloxy)furan reacted with a number of substituted benzaldehydes under activation of titanium tetrachloride to give 2,6-diaryl- 3,7-dioxabicyclo[3.3.0]octane-4,8-diones.

Amidinosulphenylation of alkenes

Abstract Phenylsulphenamides react chemoselectively with an alkene and a nitrile in the presence of trifluoromethanesulphonic acid to give N -(β-phenylthioalkyl) amidines; in the absence of nitrile an amine is formed. Regioselective 1,2-difunctionalization of alkenes with a nitrogen nucleophile and an alkylthio1−3 or alkylseleno1,4 group has attracted a good deal of interest recently, because it presents a simple answer to the lack of nitrogen electrophiles capable of attacking a weak nucleophile such as an alkene.5 Reductive or oxidative elimination of the RS(e) group leads to overall addition to or substitution at the alkene by the nitrogen nucleophile (“N”) respectively (Scheme 1).

Chemistry of 2,5-bis(trimethylsiloxy)furans. III: Synthesis of γ-hydroxybutenolides

Abstract γ-Hydrobutenolides were obtained from the reaction of substituted 2,5- bis(trimethylsiloxy)furans with aldehydes and ketones using titanium tetrachloride activation. Similarly, α,β-unsaturated carbonyl compounds reacted as a Michael receptor with the title compounds to give γ-hydroxybutenolides.

Reaction of electrophiles with 1,3-bis(trimethylsiloxy)-1-methoxybuta-1,3-diene, a dianion equivalent of methyl acetoacetate

The title compound reacts with a number of electrophiles with a different reactivity from that of the dianion of methyl acetoacetate.

A simple route to the 8-oxabicyclo[3.2.1]octyl and 9-oxabicyclo[3.3.1]nonyl systems. Synthesis of the 8-oxa analog of cocaine.☆

Abstract In the presence of titanium tetrachloride, 1,3-bis(trimethylsiloxy)-1-methoxybuta-1,3-diene condenses with hexane-2,5-dione or 2,5-dimethoxytetrahydrofuran to give the 8-oxabicyclo[3.2.1]octyl compounds 3 and 6 respectively, and with 2,6-dimethoxytetrahydropyran to give the 9-oxabicyclo [3.3.1]nonyl derivative 8 . Compound 6 is converted to a compound ( 9 ) which is the 8-oxa analog of cocaine.

Extended enolate ions from γ-phenylthio-crotonate esters

Abstract Substituted γ-phenylthio-crotonate esters (7) can be made by [1,2] and [1,3] PhS shifts: they form extended enolate anions which react with electrophiles at the carbon atom α to the carbonyl group and γ to sulphur.

Reactions of α- or γ.phenylthio substituted extended enolate anions derived from esters

The title anions are alkylated and acylated (α series only) exclusively at the α position. The α-phenylthio products give γ-phenylthio compounds by the [1,3]PhS shift and the PhS group may be removed from the products in a number of ways.

Biomimetic synthesis of sclerin

A general synthesis of 3-hydroxy-homophthalates is developed and applied to the synthesis of sclerin (1), a developed and applied to the synthesis of sclerin (1), a compound possessing plant-growth activity; the critical step in the synthesis of (1) can be considered as the controlled condensation of a dicarbonyl unit with a tricarbonyl unit, in analogy to the biogensis of polyketides.

Rearrangements of 2-phenylthioethanols with alkenyl, alkynyl, ester, and other functionalised alkyl substituents at the migration origin: synthesis of γ-phenylthiocrotonate esters

The effects of functional groups near the migration origin in [1,2] and [1,3] PhS shifts are explored: an α-CO2R group prevents migration, α or β vinyl groups have only steric effects, alkynyl or CO2Et groups encourage rearrangement and provide routes to γ-phenylthio unsaturated esters and ketones.