Treatment of meso-diols 3 and 6 with CCL and vinyl acetate without solvent produced the AE part of Aconitium alkaloids 2 and 7 in 68% and 75% yields, respectively, with > 96% e.e. Quantitative formations of their MTPA esters 4 and 8 were achieved by reaction with MTPA in the presence of DCC and DMAP in ClCH2CH2Cl.
Stereoselective total synthesis of (.+-.)-atisine via intramolecular double Michael reaction
6-dicarboxylate (6). The synthesis is composed of the following key steps: (1) formation of the azabicyclo [3.3.1] nonane by a double Mannich reaction, (2) enantioselective conversion by a lipase-catalyzed acylation, (3) stereoselective hydroboration in the presence of BF 3 .Et 2 O, and (4) construction of the bicyclo [2.2.2] octane ring system by an intramolecular double Michael reaction