Copper-Catalyzed Asymmetric N−H Insertion Reactions: Couplings of Diazo Compounds with Carbamates to Generate α-Amino Acids
摘要:
A Cu/chiral bipyridine catalyst has been developed for the asymmetric insertion of alpha-diazocarbonyl compounds into the N-H bonds of carbamates to generate an array of easily deprotected arylglycines in good ee. With respect to the reaction partners, as well as the ligand, this process complements the only other report of highly enantioselective N-H insertion reactions.
Organocatalytic Methods for Chemoselective <i>O</i>-<i>tert</i>-Butoxycarbonylation of Phenols and Their Regeneration from the <i>O</i>-<i>t</i>-Boc Derivatives
作者:Sunay V. Chankeshwara、Rajesh Chebolu、Asit K. Chakraborti
DOI:10.1021/jo8013325
日期:2008.11.7
without any side reactions (bromination, addition of CBr3 to a double bond, and formation of symmetrical diaryl carbonates, cycliccarbonates, or carbonic-carbonic anhydrides). The parent phenols are regenerated from the O-t-Boc derivatives by the catalyst system CBr4-PPh3 without affecting other protecting groups (aryl alkyl ether, alkyl ester, and thioacetal) or competitive side reaction such as bromination
Screening of a compound library against endothelin receptors (ET(A) and ET(B)) revealed PD 102566 (compound 1) as an ET(A) selective antagonist. Synthesis,and structure-activity relationships (SAR) of a series of analogs are described. Copyright (C) 1996 Elsevier Science Ltd