[2+2] cycloadditions of keteniminium salts with resin bound alkenes, Part A, and permanganate oxidations of 1,5-dienes, Part B

Keily, John Fraser (2002) [2+2] cycloadditions of keteniminium salts with resin bound alkenes, Part A, and permanganate oxidations of 1,5-dienes, Part B. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The solid-phase synthesis of cyclobutanones and cyclobutyliminium salts was carried out employing the [2+2] cycloaddition between resin bound olefins and keteniminium salts, generated from tertiary amides. The substrate molecules were tethered to carboxylic acid functionalised polystyrene resin via an ester linkage, from which cyclobutanones, cyclobutanols and cyclobutylamines were isolated by transesterification, and by reductive cleavages.

Grignard addition to a cyclobutanone successfully resulted in the methylated product, whilst Beckmann rearrangement and Baeyer-Villiger oxidation allowed for the preparation of γ-lactams and γ-lactones respectively. Finally an unusual photochemically induced ring expansion/addition was carried out successfully with a resin bound cyclobutanone and imidazole to furnish the 2-imidazoyltetrahydrofuran.

The permanganate promoted oxidative cyclisation of geranyl benzoate was carried out under phase-transfer conditions. The reaction was optimised to give product THF diol in good yield (70%), then the optimised conditions were applied to cis- and electron deficient olefins. Our focus turned to the asymmetric oxidative cyclisation of phenone dienes using a chiral phase-transfer catalyst (CPTC). Asymmetric oxidation was optimised to give reasonable yields (47-50%) and good asymmetric induction (75%). Approaches towards the synthesis of Annonaceous acetogenins were investigated. Key bifuranyl-5-ones were prepared employing the permanganate oxidative cyclisation of 1,5,9-trienes.

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