From the study of the reactivity of γ,δ-ethylenic epoxides in the presence of lithium amides in non polar medium (ether, hexane, benzene) the normal behaviour of these compounds is found (β-elimination). In HMPT as a solvent, a total change of reactivity is possible; γ-elimination takes place and leads to the formation of 1-hydroxyalkyl-2-vinyl cyclopropanes in high yield. Nevertheless this cyclization
readily react with ethereal H2O2 in the presence of catalytic amounts of Na2MoO4-gly or MoO2(acac)2, affording the C═C trans hydroxylation–hydroperoxylation products in good yields with high regio- and stereoselectivity. Use of enantiomers of cyclic substrates resulted in corresponding enantiopure diol-tert-hydroperoxides. The possibility of further conversion of the diol-tert-hydroperoxides into triols
在催化量的Na 2 MoO 4 -gly或MoO 2(acac)2的存在下,一系列烯丙醇易于与醚H 2 O 2反应,从而以高收率提供C═C反羟基化-氢过氧化产物具有高区域选择性和立体选择性。使用环状底物的对映异构体产生相应的对映体纯的二醇-叔氢过氧化物。还举例说明了将二醇-叔氢过氧化物进一步转化为具有包含季中心的分离的叔-过氧基团的三醇或线性结构单元的可能性。
A sequential Claisen/ring-closing metathesis approach to the synthesis of spirocyclic cyclopentanes and cyclohexanes
作者:Patrick Beaulieu、William W. Ogilvie
DOI:10.1016/j.tetlet.2003.09.190
日期:2003.12
A new method for the formation of spirocycles is described using a sequential Ireland-Claisen/Metathesis strategy to construct spirocyclic systems. Optimization of the Ireland-Claisen conditions provides the key metathesis substrates. The metathesis reactions were highly regioselective by virtue of steric hindrance in the substrate olefins. (C) 2003 Elsevier Ltd. All rights reserved.
APPARU M.; BARRELLE M., TETRAHEDRON, 1978, 34, NO 11, 1691-1697
作者:APPARU M.、 BARRELLE M.
DOI:——
日期:——
Stereoselective aziridination of cyclic allylic alcohols using chloramine-T
作者:Susannah C. Coote、Peter O'Brien、Adrian C. Whitwood
DOI:10.1039/b811137e
日期:——
TsNClNa and t-BuSO(2)NClNa, BusNClNa) has been explored. The stereoselectivity of these reactions was highly dependent on the structure of the allylic alcohol and the chloramine salt. Generally, mixtures of cis- and trans-hydroxy aziridines were obtained, in which the major diastereomer was the cis-hydroxy aziridine, whilst complete cis-diastereoselectivity was observed in the aziridination of 1,3-disubstituted