Ralph William Turner

Syntheses of 3,7-dimethylpentadecan-2-ols from intermediates formed from co-oligomerisation reactions of butadiene with diethyl malonate and acetaldehyde

Abstract The products of the reaction of butadiene with diethyl malonate catalysed by a palladium complex and of butadiene with acetaldehyde catalysed by a nickel(0) complex have been used in two syntheses of 3,7-dimethylpentadecan-2-ol.

The Diels–Alder reaction of furan and phenylsulphonylpropadiene. The simple base induced rearrangement of 3-methylene-2-endo-phenylsulphonyl-7-oxabicyclo[2.2.1]hept-5-ene

The Diels–Alder reaction of furan and phenylsulphonylpropadiene gives predominantly the 7-oxabicyclo[2.2.1]heptane (1), whose hydrogenation products (3) and (4)provide a simple entry to the synthesis of substituted cyclohexenols.

Cycloaddition reactions of allyliron complexes: synthesis of cyclopentanoid derivatives such as (±)-sarkomycin

A cycloaddition reaction between dimethyl 2-cyanofumarate and (σ-3-methoxyallyl)(η5-cyclopentadineyl)dicarbonyliron has yielded a cyclopentanoid derivative which has been used in a synthesis of sarkomycin; a precursor to brefeldin A has also been prepared from the same intermediate.

A versatile synthesis of carbapenems from substituted dihydropyrans

Abstract Dihydropyrans (1) are converted by hydrolysis and reduction to δ-lactones (3), and then to azetidinones (5) which are key intermediates for the synthesis of carbapenems.

A novel Diels-Alder approach to carbapenems

Abstract An inverse electron demand hetero-Diels-Alder reaction between 2-acylaminomethylene-3-oxobutanoic acid derivatives (5) and ketene acetals (6) yields crystalline dihydropyrans, which are versatile intermediates in the synthesis of carbapenems.

Metal-assisted cycloadditions. Part 3. Reactions of dicarbonyl(η5-cyclopentadienyl)(η1-2-methoxyallyl)iron with electron-deficient olefins and acetylenes

Dicarbonyl(η5-cyclopentadienyl)(η1-2-methoxyailyl)iron (3) has been treated with a number of tetra-, tri-, and disubstituted electron-deficient olefins and acetylenes. A mixture of cyclic and linear products has been formed from reaction of complex (3) with trimethyl ethylenetricarboxylate and diethyl 1 -cyanoethylene-1,2-dicarboxylate, with exclusive formation of the cyclopentyl-Fp adduct from ethyl 3,3- and 2,3-dicyanoacrylates. Reaction of complex (3) with tetramethyl ethylenetetracarboxylate, its tetraethyl analogue, diethyl methylenemalonate, t-butylcyanoketen, and dimethyl acetylenedicarboxylate has given, on the other hand, only linear adducts arising from H-transfer. Demetallation of the (η1-3,3-dicyano-4-ethoxycarbonyl-1-methoxycyclopentyl)-Fp complex (6b) with ceric ammonium nitrate and carbon monoxide has given a mixture of the corresponding cyclopentanone dimethyl acetal and olefin derivatives.

Acid-induced broadening of 1H N.M.R. signals in the 6-hydroxychroman and 5-hydroxydihydrobenzofuran series

Acids at least as strong as trichloroacetic acid induce line broadening in the 1H n.m.r. spectra of 6-hydroxychroman and 5-hydroxy-2,3-dihydrobenzofuran derivatives. The effect is specific for derivatives of hydroquinone although it is weak in the absence of the heterocyclic rings. The dihydrofuran ring confers greater sensitivity than the dihydropyran ring. A second heterocyclic ring increases the sensitivity greatly. Nuclear (aromatic) methyl groups increase the sensitivity but acyl groups remove it. The effect is attributed to the formation of traces of cation radicals and is destroyed by bases or water. It varies in the same way as hyperfine coupling constants where these are known for the cation radical species. It can be used to simplify complex spectra because only protons very close to the carbon or oxygen atoms of the hydroquinone nucleus are affected strongly; conversely, it can be used for diagnostic purposes. The syntheses of some oxygen heterocycles needed for the survey are discussed briefly.

Stereoselective routes to functionalised hexa-2,4-dienals from cyclobutenes

6-Substituted (2Z),(4E)- and (2E),(4E)-hexa-2,4-dienals have been prepared from a cyclobutene derivative via stereoselective electrocyclic ring-opening and isomerisation processes.