The epoxidation of electron-deficient olefins using hydrogen peroxide in a strong alkaline solution and is generally known as the Weitz–Scheffer epoxidation. Occasionally, it is also referred to as the Weitz–Scheffer reaction. The asymmetric Weitz–Scheffer epoxidation has been widely used in organic...
The preparatively useful feature of this asymmetric epoxidation is the fact that opposite senses of enantioselectivity are observed with the same optically active hydroperoxide and the same prochiral enone substrate. Thus, whereas KOH in CH 3 CN affords the (α S ,β R ) - epoxide 3a from ...
zxnhys 药物化学 11 Bibliography:Wang, Z. (2010). Weitz‐Scheffer Epoxidation. In Comprehensive Organic Name Reactions and Reagents, Z. Wang (Ed.).doi:10.1002/9780470638859.conrr663 4楼2020-10-10 16:11 收起回复 登录百度帐号 下次自动登录 忘记密码? 扫二维码下载贴吧客户端 下载贴吧APP看高清直播...
The asymmetric Weitz−Scheffer epoxidation of the isoflavones 3, mediated by the cinchonine- and cinchonidine-derived phase-transfer catalysts (PTCs) 1, affords the enantiomerically enriched isoflavone epoxides 4 with ee values of up to 98% in nearly quantitative yields. With the appropriately configu...
The epoxidation of 2-substituted naphthoquinones with t-BuOOH in an aqueous buffer solution containing a small amount (up to 5 % molar equiv) of bovine serum albumin (BSA) gives the corresponding epoxides with enantiomeric excess (e.e.) up to 100 %. The enantioselectivity is very sensitive ...
Diastereoselective Weitz-Scheffer epoxidation of levoglucosenone for the synthesis of isolevoglucosenone and derivativesLevoglucosenoneEpoxideDiastereoselectiveHydroperoxideIsolevoglucosenoneHigh-yielding epoxidation conditions for the cellulose pyrolysis product (-)-levoglucosenone (LGO) and 3-aryl derivatives of...
The enantioselective epoxidation of the α,β-enones 1 with the optically active hydroperoxides (-)-(S)-2, catalyzed by the bases KOH or DBU, affords the enantiomerically enriched oxo epoxides 3 in high yields and with good enantioselectivities (up to 90% ee for KOH and up to 72% ee ...
Bortolini, O
Colonna S,Gaggero N,Manfredi A, et al.Asymmetric Weitz-Scheffer epoxidation promoted by bovine serum albumin. Part III. Highly stereoselective synthesis of optically active epoxynaphthoquinones. Tetrahedron . 1988Colonna, S., and Manfredi, A., 1986, Catalytic asymmetric Weitz-Scheffer reaction in the...
Examines the asymmetric Weitz--Scheffer epoxidation of isoflavones with hydroperoxides. Enantiomers of the isoflavone epoxides; Mechanisms on the asymmetric oxygen-transfer process; Importance of the phase-transfer catalyst structure.AdamWaldemarRaoParaselli...