Fluoroalkylated α,β‐Unsaturated Imines: Efficient and Versatile Substrates for the Synthesis of Fluorinated Vinylogous β‐Amino Esters and 3,4‐Dihydropyridin‐2‐ones

A simple and efficient synthesis of vinylogous fluoroalkylated β‐amino mono‐ (4) and diester (9) derivatives by the regioselective 1,2‐addition of enolates derived from alkyl acetates or diethyl malonate to fluoroalkylated α,β‐unsaturated imines (1) is described. These fluorinated imines (1) were used as intermediates in the regioselective synthesis of fluorine‐containing trans‐3,4‐dihydropyridin‐2‐ones (6, 8a, 8b, 10) and 3,3‐spiro‐3,4‐dihydropyridin‐2‐ones (8c–h) by conjugate (1,4‐) addition of enolates derived from α‐mono‐ and α,α‐disubstituted esters. Fluoroalkylated β‐amino esters (4, 9) and 3,4‐dihydropyridin‐2‐ones (6, 8, 10) were also prepared by the olefination of enaminophosphonate 2with BuLi, addition of aldehydes and subsequent addition of the enolates derived from esters 3.