A versatile method for introducing a functionalized side chain into enamines 9a and l l a is described. This procedure provides an easy access to 16-deethyl-vincamines 16, 17 and 16-deethyl-apovincamines 18 -21.Vinca alkaloids, like (+)-vincamine (l), ( + )-apovincamine (2), and the unnatural (+)-ethyl ester 3 (Cavinton@) are biologically useful compounds as cerebral vasodilatory agents'). As their 16-deethyl derivatives have been found to display similar pharmaceutical activities') the synthesis of these derivatives has intensively been in~estigated~,~). Bromovincamines such as the 10-bromo and the 11-bromo derivatives have also been described to display increasing vigilance and psychostimulant effects5). In connection with our studies on the synthesis of Vinca alkaloids we have taken an interest in the synthesis of 16-deethyl-and lO-bromo-16-deethyl derivatives.a-Hydroxyimino ester 4 has been found to be a key intermediate in the synthesis of the eburnane alkaloids (+)-vincamine, ( -)-vincamone, and ( + )-apovincamine6). Therefore, we have searched for a stereoselective synthesis of a common intermediate of the deethyl derivatives 5 and 6, and in contrast to the "traditional route''4d) we have investigated the feasibility of the direct introduction of the side chain.As starting material the Schut enamine') 9a has been chosen, which is alkylated with ethyl bromopyruvate oxime *) (12) to give the corresponding iminium bromide 13 in 84% yield. Bromination of 9a, performed under conditions de-*) In this publication all the compounds with stereocenters are racemates.scribed earlier') in connection with Wenkert's enamine 10a, leads regioselectively to the desired 9-bromoiminium bromide 11 bin 65% yield. Alkylation of l l a with ethyl bromopyruvate oxime (12) in the presence of triethylamine givesBr-CH2-C-CO2C2H5