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DOI: 10.1055/s-0030-1257969
Multifunctional Catalysts: Thiourea Amine Acid Salts
R. P. Singh, B. M. Foxman, L. Deng*
Brandeis University, Waltham, USA
Publication History
Publication Date:
23 August 2010 (online)

Significance
An efficient asymmetric vinylogous aldol reaction of 2-trimethylsiloxy furans and aldehydes catalyzed by a chiral organic salt is reported by the authors. This organic salt is generated by mixing the thiourea amine and trifluoroacetic acid in a 1:1 ratio. Under the optimized conditions (10 mol% catalyst, in chloroform or ether), the corresponding vinylogous aldol products (butenolides) can be obtained in good yields with high stereoselectivity (dr up to 96:4 and er up to 97.5:2.5). This organic salt catalyzed reaction showed a broad substrate scope: Aryl, alkenyl, and alkylaldehydes together with 5-substituted-2-trimethylsilyloxy furans can all be tolerated.