Fluoride ion-catalyzed generation and carbonyl addition of α-halo carbanions derived from α-halo organosilicon compounds
作者:Makoto Fujita、Michio Obayashi、Tamejiro Hiyama
DOI:10.1016/s0040-4020(01)86661-8
日期:1988.1
The title carbanion species are generated from the corresponding α-haloorganosilicon compounds by the action of a catalytic amount of tris(diethylamino)sulfonium difluorotrimethylsilicate and are found to undergo addition to aldehyde carbonyl efficiently at ambient temperature. The synthetic potential of the reaction is demonstrated by application to the synthesis of some insecticides.
Anchimeric assistance by and migration of the vinyl group in reactions of sterically hindered organosilicon compounds of the type (Me<sub>3</sub>Si)<sub>2</sub>C(SiMe<sub>2</sub>CHCH<sub>2</sub>)(SiR<sub>2</sub>X)
作者:G. Adefikayo Ayoko、Colin Eaborn
DOI:10.1039/p29870001047
日期:——
The compound VsiSiMe2I [Vsi =(Me3Si)2C(SiMe2CHCH2)](1) is very similar in reactivity to (Me3Si)3CSiMe2I (2) in reactions with methanol and with alkali-metal salts in MeOH or MeCN, but (1) is much the more reactive towards electrophiles which induce rate-determining ionization of the Si–I bond, viz. CF3CH2OH (the factor f is > 500), CF3CO2H (f > 1 800), AgBF4 in CH2Cl2(f ca. 150), or AgSCN in CH2Cl2(f
1,3-Migration of chloride and azide substituents within organosilicon cations, and anchimeric assistance by the azido group
作者:Colin Eaborn、Paul D. Lickiss、Sabah T. Najim、M.Novella Romanelli
DOI:10.1016/0022-328x(86)80420-x
日期:1986.11
product in each being a mixture of (Me3Si)2C(SiEt2Cl)(SiMe2F) and (Me3Si)2C(SiEt2F)(SiMe2Cl), and analogous migration of N3 occurs in the corresponding reaction of (Me3Si)2C-(SiEt2N3)(SiMe2Br). Anchimericassistance by the N3 group facilitates the solvolysis of (Me3Si)2C(SiMe2N3)(SiMe2Br).
rotational barrier of the methylene bonds is extraordinary low. Therefore, in contrast to other bis(methylene)phosphoranes, the endo- and exo-Tms groups are indistinguishable on the NMR time scale even at −100°C. The analogous ferrocenylbis(imino)phosphorane Fc-P(=NTms)2 (9), can only be isolated in its dimeric form. The conditions, which are necessary for the formation of (9) from the corresponding
1,3-Migration of a phenyl group via a silicocation
作者:Colin Eaborn、Paul D. Lickiss、Sabah T. Najim、Wlodzimierz A. Stańczyk
DOI:10.1039/c39870001461
日期:——
(Me3Si)2C(SiMe2Ph)(SiEt2l) with AgBF4 in Et2O has been shown to give a ca. 2 : 3 ratio of the unrearranged (Me3Si)2C(SiMe2Ph)(SiEt2F) and the rearranged (Me3Si)2C(SiMe2F)(SiEt2Ph); the reaction is thought to proceed via a Ph-bridged cation (II).