Mechanistic Analysis of Azine <i>N</i>-Oxide Direct Arylation: Evidence for a Critical Role of Acetate in the Pd(OAc)<sub>2</sub> Precatalyst
作者:Ho-Yan Sun、Serge I. Gorelsky、David R. Stuart、Louis-Charles Campeau、Keith Fagnou
DOI:10.1021/jo101821r
日期:2010.12.3
direct arylation of pyridineN-oxides are presented. The order of each reaction component is determined to provide a general mechanistic picture. The C−H bond cleaving step is examined in further detail through computational studies, and the calculated results are in support of an inner-sphere concerted metalation−deprotonation (CMD) pathway. Competition experiments were conducted with N-oxides of varying
The present invention provides a compound which is useful as a PGI
2
receptor agonist, and a pharmaceutical composition.
The present invention is directed to a pharmaceutical composition comprising a compound represented by the following formula [1]:
1
(R
1
and R
2
are the same or different and each represents optionally substituted aryl, Y represents N or CH, Z represents N or CH, A represents NH, NR
5
, O, S, or ethylene, R
5
represents alkyl, D represents alkylene or alkenylene, E represents phenylene or single bond, G represents O, S, or CH
2
, R
3
and R
4
are the same or different and each represents hydrogen or alkyl, Q represents carboxy, alkoxycarbonyl, tetrazolyl, carbamoyl, or N-(alkylsulfonyl)carbamoyl), or a pharmaceutically acceptable salt thereof as an active ingredient.
A series of prostacyclin receptor agonists was prepared by modifying the central heteroaromatic ring of lead compound 2, and a docking study was performed to investigate their structure-activity relationships by using a homology-modeled structure of the prostacyclin receptor. Compound 2 and its derivatives could be docked to the prostacyclin receptor in two ways depending on the position of the nitrogen atom within the heteroaromatic ring. Furthermore, hydrogen bonding between the nitrogen atom in the heteroaromatic ring and the hydroxyl group of Ser20 or Tyr75 of the receptor appears to be important for the potent expression of biological activity. (c) 2007 Published by Elsevier Ltd.