title: Cyclization of Hindered Fluorinated Dichloro(5- and 6-)alkenyl Radicals. Structural Effects of Olefins on the Selective Formation of 5-exo and 6-endo Cyclization Products.
abstract: Reaction of 3-butenyl radicals generated by photolysis of variously substituted Barton esters (both open-chain 1a-d and cyclohexyl 1e-h) with CF(2)=CCl(2) gave a mixture of cyclized products (cyclopentanes 6 and 8 and cyclohexanes 7 and 9) as well as noncyclized products (4and 5) in various ratios depending on the substitution pattern at the olefinic moiety. The product ratios of [cyclization (6 + 7 + 8 + 9):noncyclization (5)] for 1 with more alkyl substituents on the CC double bond were greater than those for 1 with fewer substituents. The products ratio of [5-exo (6 + 8):6-endo (7 + 9)] was influenced by a steric effect. Photoreaction of Barton ester 2 with CF(2)=CCl(2) gave a mixture of cyclohexanes 16 and 17 as well as noncyclized 14 and 15. Dehydrochlorination of decalins 7g and 7h followed by oxidation of sulfide and [2,3]sigmatropic rearrangement of the allyl sulfoxide gave octahydronaphthalenones 23 and 27, respectively.
authors.affiliation: Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-01, Japan, and National Industrial Research Institute of Nagoya, Hirate-cho, Kita-ku, Nagoya 462, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Okano
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Ishihara
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Takakura
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Tsuge
authors.forename: Shoji
authors.initials: S
authors.lastname: Eguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kimoto