A Convenient Method for the Synthesis of Stable α‐Fluoro Enamines of Nucleobases

Abstract

Abstract Treatment of a whole set of nucleic acid bases and related derivatives 4 , 9 and 10 with electron‐deficient hexafluoropropene or 1,1,3,3,3‐pentafluoropropene in the presence of sodium hydride gave the corresponding N 1 and N 9 stable fluorinated enamines with high regioselectivity. This alkylation is a result of a Michael type addition–elimination process and gave the desired products 2a – 10a and 2b – 10b as E / Z mixtures. Unexpectedly, treatment of 2b with tert‐ butyllithium and subsequently with [D 4 ]methanol gave different results for E and Z stereoisomers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)