Pd-catalyzed reductive cleavage of NN bond in dibenzyl-1-alkylhydrazine-1,2-dicarboxylates with PMHS: application to a formal enantioselective synthesis of (R)-sitagliptin
摘要:
An environmentally benign approach involving Pd-catalyzed reductive N-N bond cleavage in dibenzyl-1-alkylhydrazine-1,2-dicarboxylates leading to the synthesis of N-(tert-butoxy)carbamates under very mild conditions has been described. PMHS serves as an inexpensive source of hydride in MeOH/deionized H2O medium. This protocol has been successfully applied in the formal synthesis of (R)-sitagliptin, an anti-diabetic drug. (C) 2015 Elsevier Ltd. All rights reserved.
A series of secondary amine–thiourea catalysts derived from l-proline and chiral diamine were prepared and successfully applied to the highly effective and enantioselectiveα-amination of unmodified aldehydes with various azodicarboxylates in excellent yields (up to 99%) and enantioselectivities (up to 99% ee) within a few minutes.