C-alkylation of chiral tropane- and homotropane-derived enamines.

David M Hodgson, Andrew Charlton, Robert S Paton, Amber L Thompson

Index: J. Org. Chem. 78(4) , 1508-18, (2013)

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Abstract

The synthesis and alkylation of chiral, nonracemic tropane- and homotropane-derived enamines is examined as an approach to enantioenriched α-alkylated aldehydes. The two bicyclic N auxiliaries, which differ by a single methylene group, give opposite senses of asymmetric induction on alkylation with EtI and provide modestly enantioenriched 2-ethylhexanal (following hydrolysis of the alkylated iminium). The observed stereoselectivity is supported by density functional studies of ethylation for both enamines.