The stereochemical course of addition of allyltrimethylsilane to protected l-alaninals and l-serinals in the presence of Lewis acids. Total synthesis of cis-(2R,3S)-3-hydroxyproline
作者:D. Gryko、P. Prokopowicz、J. Jurczak
DOI:10.1016/s0957-4166(02)00255-0
日期:2002.6
l-alaninals and l-serinals was investigated and high levels of asymmetric induction were achieved. Stereochemical models for rationalisation of the results obtained are proposed. cis-(2R,3S)-3-Hydroxyproline was synthesised starting from N-Cbz,O-TBS-l-serinal, in which the crucial step involves addition of allyltrimethylsilane to the aldehyde in the presence of SnCl4.
A Novel BF3.cntdot.OEt2-Catalyzed [3 + 2] Annulation of N-Cbz-.alpha.-Amino Aldehydes with Allyltrimethylsilane. Highly Stereoselective Synthesis of Cis-2,3,5-Trisubstituted Pyrrolidines
In the presence of BF3.OEt(2) (0.2 molar equiv), the reactions (-10 degrees C, CH2Cl2) of N-Cbz-alpha-amino aldehydes with allyltrimethylsilane produced pyrrolidines in good yields (70-80%), with high all-cis stereoselectivity at the C12, C-3, and C-5 positions, along with small amounts of the expected homoallylic alcohols.