The first asymmetric [2,3]-sigmatropicrearrangement of achiral allylic amines has been realized by quaternization of the amines with an enantiomerically pure diazaborolidine and subsequent treatment with Et3N. The resultant homoallylic amines were obtained in good yields and excellent ee's. The observed diastereo- and enantioselectivities were rationalized by invoking a kinetically controlled process
Intramolecular radical hydrosilylation — the first radical 5-endo-dig cyclisationElectronic supplementary information (ESI) available: experimental data. See http://www.rsc.org/suppdata/cc/b2/b204879e/
作者:Stephan Amrein、Armido Studer
DOI:10.1039/b204879e
日期:2002.7.11
Intramolecularradical hydrosilylations using allyloxy- and propargyloxycyclohexadienylsilanes comprising 5-endo-trig as well as 5-endo-dig processes are presented.
The first catalytic enantioselective allylic substitution reaction with alkylboron compounds has been achieved. The reaction between alkyl-9-BBN reagents and primary allylic chlorides proceeded with excellent γ-selectivities and high enantioselectivities under catalysis of a Cu(I)-DTBM-SEGPHOS system. The protocol produces terminal alkenes with an allylic stereogenic center branched with functionalized
A variety of trialkylsilylvinylcyclopropanes were prepared by two different routes: (a) Cyclopropanation of 1-alkenylsilanes and (b) the reactions of 1-bromocyclopropyllithium with trimethylsilyl chloride. Radical induced ringopeningreaction of these cyclopropanes were examined. 1-Dimethylphenylsilyl-2-vinylcyclopropane or 3-methyl-1-trialkylsilyl-2-vinylcyclopropane provided the corresponding homoallylic
1-Trialkylsilyl-2-vinylcyclopropane or 3-methyl-1-trialkylsilyl-2-vinylcyclopropane provided the corresponding homoallylic silane exclusively upon treatment with PhSH, Ph3SnH, or C6F13I. On the other hand, 3-phenyl-1-trimethylsilyl-2-vinylcyclopropane or 3-acetyl-1-trimethylsilyl-2-vinylcyclopropane gave allylic silane selectively.