Second Encounter with Sulfur—Interaction of an Enamine and a Dithioketene Acetal

Second Encounter with Sulfur—Interaction of an Enamine and a Dithioketene Acetal 

Sulfur compounds are exceedingly interesting and useful systems. Their impressive versatility is the result of their complex chemistry, which any self-respecting organic chemist should be acquainted with. 

Although we have brushed lightly over some sulfur-related transformations in past problems, the next two exercises touch upon more central aspects of organosulfur chemistry that provide challenging mechanisms. 

This quality makes compound I labile towards a moderate carbon nucleophile such as that of an enamine. From the interaction of these two species. 

An equilibrium condition between V and VI, however, is also conceivable in the present case, owing to the thermodynamic instability implied in the gem-inal substitution of isopropyl and dimethylamino groupings. The persistence of VI in the reaction medium would give opportunity for a bimolecular interaction in the Michael mode with a second mole of substrate. The ensuing rare fragmentation that liberates the amine portion from VII looks more familiar if one draws it in parallel with the hydrolysis-decarboxylation of a /3-keto ester. 

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