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
摘要:
Reaction of 3-butenyl radicals generated by photolysis of variously substituted Barton esters (both open-chain 1a-d and cyclohexyl 1e-h) with CF2=CCl2 gave a mixture of cyclized products (cyclopentanes 6 and 8 and cyelohexanes 7 and 9) as well as noncyclized products (4 and 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 CF2-CCl2 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.
BARTON, DEREK H. R.;SARMA, JADAB C., TETRAHEDRON LETT., 31,(1990) N4, C. 1965-1968
作者:BARTON, DEREK H. R.、SARMA, JADAB C.
DOI:——
日期:——
MAILLARD B.; KHARRAT A.; GARDRAT C., NEW J. CHEM., 11,(1987) N 1, 7-13
作者:MAILLARD B.、 KHARRAT A.、 GARDRAT C.
DOI:——
日期:——
Further studies on carbon-carbon bond formation based on the radical reactions of acyl derivatives of N-hydroxy-2-thiopyridone
作者:Derek H.R. Barton、Jadab C. Sarma
DOI:10.1016/s0040-4039(00)88890-5
日期:1990.1
By careful exclusion of oxygen, carbon radicals, generated from the W lamp photolysis of O-acyl derivatives of N-hydroxy-2-thiopyridone, can be added efficiently to methylvinyl ketone. Extension to the radical from pent-4-enoic acid provides another synthesis of cyclopentane derivatives. Analogous additions with other electrophilic olefins are also reported.
Cyclization of Hindered Fluorinated Dichloro(5- and 6-)alkenyl Radicals. Structural Effects of Olefins on the Selective Formation of 5-<i>exo</i> and 6-<i>endo</i> Cyclization Products
Reaction of 3-butenyl radicals generated by photolysis of variously substituted Barton esters (both open-chain 1a-d and cyclohexyl 1e-h) with CF2=CCl2 gave a mixture of cyclized products (cyclopentanes 6 and 8 and cyelohexanes 7 and 9) as well as noncyclized products (4 and 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 CF2-CCl2 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.