942129-37-5Relevant articles and documents
Practical, general, and systematic method for optical resolution of gem-dihalo- and monohalocyclopropanecarboxylic acids utilizing chiral 1,1′-binaphtholmonomethyl ethers: Application to the synthesis of three chiral pesticides
Yasukochi, Hiroaki,Atago, Takayuki,Tanaka, Akihiro,Nakatsuji, Hidefumi,Yoshida, Eri,Kakehi, Akikazu,Nishii, Yoshinori,Tanabe, Yoo
experimental part, p. 540 - 547 (2008/10/09)
We performed an efficient practical and systematic optical resolution method for gem-dihalo- and monohalocyclopropanecarboxylic acids 1 and 5 utilizing chiral 1,1′-binaphthol monomethyl ether (R)-2 as the key auxiliary. Direct esterification of 1 with (R)-2 gave two 1R- and 1S-diastereomeric esters 3 with marked different Rf values, both of which were easily separated using simple column chromatography. Monodehalogenation of separated chiral esters 3 using t-BuMgCl and cat. Co(dppe)2Cl2 gave two 1,2-trans- and 1,2-cis-diastereomers 4 with markedly different Rf values, both of which were similarly separated using simple column chromatography. The obtained diastereomers 3 and 4 were easily hydrolyzed to the desired enantiopure acids 1 (>99%) and 5 (>99%), respectively, with recovery of (R)-2, both in good to excellent yields. Utilizing the present method, important chiral agrochemicals, carpropamid 6 and fencyclate 7, were readily synthesized. Pyrethroid 9 with three asymmetric centers was efficiently synthesized in a much better yield compared with the reported method. The Royal Society of Chemistry 2008.
