Highly stereoselective radical carbonylations of gem-dihalocyclopropane derivatives with CO.
A couple of radical carbonylations of gem-dihalocyclopropanes 1 using CO and Bu3SnH (formylation) or Bu3Sn(CH2CH=CH2) (allylacylation) successfully proceeded to give trans and cis adducts (2 and 3) with good to excellent stereoselectivity (trans/cis = >99/1-75/25 or 17/83-1/99). The formylation of 2,3-cis-disubstituted 1,1-dihalocyclopropanes enhanced trans selectivity (trans/cis = >99/1-95/5), whereas both 2,3-cis-disubstituted and 2-monosubstituted 1,1-dihalocyclopropanes underwent allylacylation with nearly complete trans selectivity (trans/cis = >99/1). Inherently less reactive gem-dichloro- and bromochlorocyclopropanes than gem-dibromocyclopropanes served as favorable substrates. [reaction: see text].
Nishii
Yoshinori
Y
Department of Chemistry, Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan. nishii@shinshu-u.ac.jp
Nagano
Takao
T
Gotoh
Hideki
H
Nagase
Ryohei
R
Motoyoshiya
Jiro
J
Aoyama
Hiromu
H
Tanabe
Yoo
Y