An Efficient Catalytic Asymmetric Epoxidation Method
作者:Zhi-Xian Wang、Yong Tu、Michael Frohn、Jian-Rong Zhang、Yian Shi
DOI:10.1021/ja972272g
日期:1997.11.1
This article describes a highly effective catalyticasymmetricepoxidation method for olefins using potassium peroxomonosulfate (Oxone, Dupont) as oxidant and a fructose-derived ketone (1) as catalyst. High enantioselectivies have been obtained for trans-disubstituted and trisubstituted olefins which can bear functional groups such as tributylsilyl ether, acetal, chloride, and ester. The enantiomeric
A Mild and Efficient Epoxidation of Olefins Using <i>in Situ</i> Generated Dimethyldioxirane at High pH
作者:Michael Frohn、Zhi-Xian Wang、Yian Shi
DOI:10.1021/jo980604+
日期:1998.9.1
Silicon-directed acid ring-opening of allyltrimethylsilane oxide. X-ray structures of 3-triisopropylsilyl-2-(2,4-dinitrobenzoyloxy)-1-propanol and 3-triisopropylsilyl-2-(2,4,6-trinitrobenzoyloxy)-1-propanol
作者:Fatmir Badali、William Issa、Brett Pool、Jonathan M. White
DOI:10.1016/s0022-328x(98)01002-x
日期:1999.3
Allyltrimethylsilane oxide 5 undergoes regiospecific ring-opening with carboxylic acids in chloroform to give the hydroxy esters 6a-e. In polar solvents competing elimination results in the formation of allyl alcohol. Allyltriisopropylsilane oxide 17 undergoes analogous reactions as 5 in chloroform but does not undergo elimination in methanol or acetone. The X-ray structures of 18b and 18c reveal significant lengthening of the C-O (ester) bond (a remarkable 1.502(2) Angstrom for 18c), these structural effects are due to strong sigma(C-Si)-sigma*(C-O) interactions, particularly for 18c. (C) 1999 Elsevier Science S.A. All rights reserved.