Diastereoselective Aldol Reactions of (Z)-N-[Bis(methylthio)methylene]-α,β-didehydroglutamates
摘要:
In the reaction of the enolates of (Z)-N-[bis(methylthio)methylene]-alpha,beta-didehydroglutamates with aldehydes, the retroaldolization process is faster than the aldol reaction, thus inhibiting the obtainment of the desired targets 6. However, in the presence of TMS-Cl as trapping agent, the equilibrium can be deplaced and the aldols 6 are obtained in the form of their TMS-derivatives 8. In the presence of BF3 or TBAF, either the syn or the anti adducts can be selectively obtained with good yields and diastereoselectivities.
Reaction of N-[bis(methylthio)methylene]glycinates with electron deficient alkynes. Synthesis of (Z)-α,β-didehydroglutamic acid derivatives
作者:Carlos Alvarez-Ibarra、Aurelio G Csákÿ、Elena Martín Ortega、M Jesús de la Morena、M Luz Quiroga
DOI:10.1016/s0040-4039(97)00913-1
日期:1997.6
The addition of either the alkaline enolates of the glycinates 1 or their naked enolates to electron defficient alkynes allows for the synthesis of substituted (Z)-alpha,beta-didehydroglutamic acid derivatives 7 via a Michael addition/1,3-prototropic rearrangement sequence. (C) 1997 Elsevier Science Ltd.