corresponding pyridylmagnesium chlorides at room temperature by treatment with iPrMgCl. The resulting Grignard reagents were quenched by various electrophiles to afford functionalized pyridines. The brominemagnesium exchange of some dibromopyridines was also studied.
o-Chloro- and o-bromophenyl phenylsulfoxides and (3-bromo-4-pyridyl) phenylsulfoxide were treated with Grignard reagents to generate benzyne (or 3,4-pyridyne) in THF. The o-iodophenyl derivative, on the other hand, gave mainly o-(arylsulfinyl)phenyl Grignard reagent.
Bromine–magnesium exchange using iPrMgCl in THF at roomtemperature on 2-, 3- and 4-bromopyridines allowed the synthesis of various functionalized pyridines. The methodology was successfully used for the synthesis of 4-azaxanthone. Moreover, single exchange reactions observed on 2,6-, 3,5-, 2,3- and 2,5-dibromopyridines, with complete regioselectivity in the case of 2,3- and 2,5-dibromopyridines, afforded
Synthesis and biological evaluation of heteroarenes as reduced cysteine replacements are described. Of the heteroaryl groups examined with respect to FT inhibitor FTI-276 (1), pyridyl was the replacement found to be most effective. Substitutions at C4 of the pyridyl moiety did not affect the in vitro activity. Compound 9a was found to have moderate in vivo bioavailability.
A New Strategy for Deprotonative Functionalization of Aromatics: Transformations with Excellent Chemoselectivity and Unique Regioselectivities Using <i>t</i>-Bu-P4 Base
作者:Tatsushi Imahori、Yoshinori Kondo
DOI:10.1021/ja0342300
日期:2003.7.1
A new strategy for deprotonative functionalization of aromatics using t-Bu-P4 base has been developed, and highly chemoselective transformations have been achieved with unique regioselectivities.