Intermolecular catalytic asymmetric alkylations

As stated in the previous section, an extensive effort has been devoted to the development of intermolecular catalytic enantioselective a-alkylation reactions of aldehydes. In 2008, Nicewicz and MacMillan [147] accomplished the direct asymmetric a-alkylation of aldehydes with a-bromo carbonyl compounds (Scheme 8.36) via merging two types of catalysis, photoredox [148] and organo-catalysis. A variety of aliphatic aldehydes and electron-deficient a-bromo carbonyl compounds can be used, affording a-alkylated aldehydes in excellent yields (up to 93%) with outstanding enantioselectivities (up to 99% ee) in a relatively short reaction time. Furthermore, this alkylation protocol represents a technically simple... 

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