The c/s-3-vinyl-4-piperidineacetic acid, known as meroquinine,1 was recently described as a synthetic 3.64 (s, 3 H, -OCtf3), 4.9-5.S (m, 3 H, CH=CH2), 7.37 (s, 5 H, phenyl); mass mje 287 (M+)]. This ester was utilized in the synthesis of ajmalicine and 19-epiajmalicine.411 (11) Correct analytical figures have been obtained for all compounds for which physical and spectral data are given.

A one-pot, three-step strategy for the regioselective semihydrogenation of dienes is described. This procedure uses 9-BBN-H as a temporary protective group for alkenes. Yields range from 55% to 95%, and the reaction is tolerant of a variety of common functional groups. Additionally, the final elimination step of the sequence can be replaced with a peroxide-mediated alkylborane oxidation, generating regioselectively semihydrogenated product alcohols.

Total Synthesis of Cinchona Alkaloids. 1.

Replacement of the final dehydroboration step by H2O2‐mediated oxidation allows regioselective formation of primary alcohols such as (XIII), (XV), and (XVII).

Eine stereospezifische Totalsynthese von Merochinen (X) wird beschrieben.