Direct Catalytic <i>N</i>‐Alkylation of α‐Amino Acid Esters and Amides Using Alcohols with High Retention of Stereochemistry
Tao Yan, Ben L. Feringa, Katalin Barta
Abstract
The direct functionalization of naturally abundant chiral scaffolds such as α-amino acid esters or amides with widely abundant alcohols, without any racemization, is a demanding transformation that is of central importance for the synthesis of bio-active compounds. Herein a robust and general method was developed for the direct N-alkylation of α-amino acid esters and amides with alcohols. This powerful ruthenium-catalyzed methodology is atom-economic, base-free, and allowed for excellent retention of stereochemical integrity. The use of diphenylphosphate as additive was crucial for significantly enhancing reactivity and product selectivity. Notably, the only by-product was water and both substrates could be potentially derived from renewable resources.