despite the recent advances in the fields of both C–H and C–C bond activation. Herein, we report a palladium-catalyzed migrative carbofluorination of saturated amides enabled by the activation of both the C(sp3)–H and the Cquaternary–Cσ bonds. In this transformation, the α-quaternary carbon of Weinreb amides is converted to α-tertiary fluoride with concurrent migration of an aryl or an amido group from
Intermediates useful for the preparation of antihistaminic piperidine derivatives
申请人:Merrell Pharmaceuticals, Inc.
公开号:US06348597B2
公开(公告)日:2002-02-19
The present invention is related to a novel intermediates and processes which are useful in the preparation of certain antihistaminic piperidine derivatives of the formula
wherein
W represents —C(═O)— or —CH(OH)—;
R1 represents hydrogen or hydroxy;
R2 represents hydrogen;
R1 and R2 taken together form a second bond between the carbon atoms bearing R1 and R2;
n is an integer of from 1 to 5;
m is an integer 0 or 1;
R3 is —COOH or —COOalkyl wherein the alkyl moiety has from 1 to 6 carbon atoms and is straight or branched each of A is hydrogen or hydroxy; and pharmaceutically acceptable salts and individual optical isomers thereof,
with the proviso that where R1 and R2 are taken together to form a second bond between the carbon atoms bearing R1 and R2 or where R1 represented hydroxy, m is an integer 0.
A new bio-inspired approach is reported for amide and peptide synthesis using α-amino esters that possess a potential activating group (PAG) at the ester residue. To activate the ester functionality under mild metal-free conditions, we exploited the facile dearomatization of phenols with hypervalent iodine(III) reagents. Using a pyridine–hydrogen fluoride complex, highly reactive acyl fluoride intermediates