Fluorinated allenes: the syntheses of 1-fluoropropadiene, 1,1-difluoropropadiene and 1,1-difluoro-3-methyl-1,2-butadiene
作者:William R. Dolbier、Conrad R. Burkholder、Carlos A. Piedrahita
DOI:10.1016/s0022-1139(00)82289-7
日期:1982.7
Improved syntheses of 1-fluoropropadiene and 1,1-difluoropropadiene are presented as is the synthesis of a third reactive allene, 1,1-difluoro-3- methyl-1,2-butadiene. Gram quantities of these highly reactivefluorinated allenes may be prepared conveniently in high yield and purity. All three are reactivedienophiles and cycloadd regiospecifically using their non- fluorine-substituted double bonds.
Carbene chemistry. Part 13 [1]. Preparation of sole fluoroallenes by a carbene route, and the reaction of allenes with halogenocarbenes
作者:Michael J. Bunegar、Roy Fields、Robert N. Haszeldine
DOI:10.1016/s0022-1139(00)85226-4
日期:1980.6
Fluoroallene and 1, 3-difluoroallene are prepared in good overall yield by the addition of dichlorocarbene to vinyl fluoride and 1, 2-difluoroethylene respectively, followed by pyrolysis of the dichlorocyclopropanes and treatment of the resulting dichloropropenes with zinc. Pyrolysis of 1, 1-dichloro-2-fluorocyclopropane over zinc gives fluoroallene directly.
1,3-Dipolarcycloadditions of diazoalkanes, nitrones and nitrileoxides occur with high regioselectivity to 1,1-difluoroallene and fluoroallene, and with variable syn or anti π-facial diastereoselectivity with regard to additions to the latter. The roles of steric effects, frontier molecular orbital effects, electrostatic interactions and other factors which may be involved in determining the observed