Aldol Reactions of Ketone Donors with Aryl Trifluoromethyl Ketone Acceptors Catalyzed by 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) for Concise Access to Aryl- and Trifluoromethyl- Substituted Tertiary Alcohols

Molecules bearing aryl- and trifluoromethyl-substituted tertiary alcohol moieties are important as bioactive molecules, enantiomer-discriminating reagents, and their synthons and building blocks. To concisely synthesize these molecules, we have developed aldol reactions of ketone donors with aryl trifluoromethyl ketone acceptors catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The reactions were relatively fast, and the products were obtained in good to high yields under mild conditions. The CC bonds of the aldol reactions formed in perfect regioselectivities at the methyl group of the alkyl methyl ketones, at the γ-position of the β-keto esters, and at the methyl group of the β-methyl-substituted cyclic enones. For the aldol products from the reactions of β-keto esters, the enantiomerically pure forms were obtained by resolution of the enamines of the aldol products with a homochiral amine. Our methods provide a concise, fast access to molecules with tetrasubstituted carbon centers with trifluoromethyl-substituted alcohol moieties.