Synthesis of highly enantiomerically enriched amines by the diastereoselective addition of triorganozincates to N-(tert-butanesulfinyl)imines
作者:Raquel Almansa、David Guijarro、Miguel Yus
DOI:10.1016/j.tetasy.2008.10.012
日期:2008.11
different from the ones observed with the corresponding Grignardreagents, which allows, in several cases, the preparation of both enantiomers of an amine from the same imine substrate. When mixed triorganozincates are used, one can take advantage of the slow transfer rate of the methyl group to use it as a non-transferable one. Both aromatic and aliphatic aldimines, as well as activated ketimines, are good
Asymmetric synthesis of α- and β-amino acids by diastereoselective addition of triorganozincates to N-(tert-butanesulfinyl)imines
作者:Raquel Almansa、Juan F. Collados、David Guijarro、Miguel Yus
DOI:10.1016/j.tetasy.2010.03.046
日期:2010.6
The diastereoselective addition of triorganozincates to (R)-N-(tert-butanesulfinyl)imines has been used as a key step to achieve the synthesis of highly enantiomerically enriched N-protected alpha- and beta-amino acids. Desulfinylation of the addition products followed by benzoylation of the nitrogen atom of the obtained primary amines and oxidation of one of the substituents on the carbon atom connected to the nitrogen complete the sequence. Using the same configuration in the sulfinyl chiral auxiliary, alpha-amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. alpha,alpha-Disubstituted alpha-amino esters with high enantiomeric purity can also be prepared when a-imino esters are the starting substrates. (C) 2010 Elsevier Ltd. All rights reserved.