Reaktionen der Trialkylsilyl‐trifluormethansulfonate, XII. Aldol‐Additionsreaktionen mit 2,6‐Bis(trimethylsiloxy)thiophen‐Synthese bicyclischer γ‐Lactone

Reactions of Trialkylsilyl Trifluoromethanesulfonates, XII. — Aldol‐Type Reactions with 2,6‐Bis(trimethylsiloxy)thiophene Synthesis of Bicyclic γ‐Lactones In the presence of trimethylsilyl triflate ( 2 ) aromatic aldehydes 4 react with 2,6‐bis(trimethylsiloxy)thiophene ( 3 ) to yield the 3,4‐disubstituted thiosuccinic anhydrides 5 . By hydrolysis of the products 5 in the presence of lead acetate the diaryl‐substituted cis ‐bislactones 8 are obtained. Dialkyl‐substituted cis ‐bislactones 10 are formed in a aldol addition of aliphatic aldehydes 9 to 3 catalysed by zinc chloride and subsequent hydrolysis of the intermediates. The synthesis of 3,4‐bis(dialkoxyalkyl)thiosuccinic anhydrides 7 is achieved by the reaction of 3 with carboxylic acid orthoesters 6 catalysed by 2 .