Diastereoselective 1,3-dipolar cycloaddition of Sm(III)-azomethine ylides to α,β-unsaturated esters
作者:Carlos Alvarez-Ibarra、Aurelio G. Csákÿ、M. Martínez、M.Luz Quiroga
DOI:10.1016/0040-4039(96)01402-5
日期:1996.9
Sm(III)-Azomethineylides were generated by fragmentation of the iminodithiocarbonates 1 with SmI2 in THF. 1,3-Dipolarcycloaddition of these species with α,β-unsaturatedesters 3 afforded the highly functionalized 2-methylthio-Δ1-pyrrolines 4 with good yields and diastereoselectivities.
Diastereoselective reduction of α-acyl-N-[Bis(methylthio)methylene]alaninates and phenylalaninates: Synthesis of α,α-disubstituted β-hydroxy α-amino esters
作者:Carlos Alvarez-Ibarra、Aurelio G Csákÿ、M Luz Quiroga、Dolores Ramírez
DOI:10.1016/s0040-4020(96)01121-0
日期:1997.2
Chemoselective reduction of the carbonyl group in α-acyl-N-[Bis(methylthio)methylene]-alaninates 1a-c and phenylalaninates 1d,e allowed for the diastereoselective synthesis of both the syn and the anti isomers of the corresponding N-protected α,α-disubstituted β-hydroxy-α-amino esters 2. The stereochemistry of the process was tuned by switching between chelation-controlled and non-chelation-controlled