Diels-Alder reactions of [alpha], [beta]-unsaturated sulfinate esters for the preparation of poly hydroxy/mercapto compounds

Alberico, Dino
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University of Guelph

This thesis examines the reactivity of ethyl ('E')- and ('Z')-2-carbomethoxyethenesulfinates (24) in Diels-Alder chemistry with a variety of dienes including cyclopentadiene, furan, anthracene, 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene. Experiments were conducted under both thermal, and Lewis acid catalyzed conditions. In most cases, Lewis acid catalyzed reactions proceeded faster and demonstrated greater selectivity. Steric evaluations of ('E')-24 with cyclopentadiene were conducted in an effort to improve 'endo:exo' selectivity. Increasing the size of the sulfinate ester functionality lead to increased S-'exo' selectivity, as expected. Increasing the size of the carboxylic ester functionality resulted in the opposite expected selectivity. Attempts to create bis sulfinate containing dienophiles will also be reported. An evaluation of the cycloadducts as a synthetic approach to poly hydroxy/mercapto compounds is also discussed. The cycloadducts were subjected to a number of different reduction conditions employing LiAlH4 and DIBAL. In some cases, benzyl bromide was added to trap the thiolate resulting in the sulfide.

Diels-Alder, Cycloadducts, Lewis acid catalyzed conditions, Thermal, Sulfinate ester functionality