Unexpected effect of protecting group and solvent on the stereoselectivity of m-CPBA epoxidation of diprotected cis-4,5-dihydroxycyclohexenes
摘要:
The stereoselectivity of m-CPBA epoxidation of diprotected cis-4,5-dihydroxycyclohexenes has been studied as a function of protecting group. solvent and in one example, epoxidising reagent. Three different ways of obtaining high levels of trans diastereoselectivity have been uncovered. In addition, the results suggest that bulky silyl protecting groups (eg triethylsilyl and tert-butyldimethylsilyl) can, in CH2Cl2, behave as moderate cis-directors via hydrogen bonding to m-CPBA. (C) 1998 Elsevier Science Ltd. All rights reserved.
Optimisation of enantioselectivity for the chiral base-mediated rearrangement of bis-protected meso-4,5-dihydroxycyclohexene oxides: asymmetric synthesis of 4-deoxyconduritols and conduritol F
作者:Simon E de Sousa、Peter O'Brien、Christopher D Pilgram
DOI:10.1016/s0040-4020(02)00370-8
日期:2002.6
based on diastereoselective epoxidation of a cyclohexene followed by chiral lithium amide-mediated epoxide rearrangement has been used to synthesise an allylic alcoholbuildingblock of >95% ee. The key step is the enantioselective rearrangement of a bis-protected meso-4,5-dihydroxycyclohexene oxide. A range of protecting groups and chiral base structures were surveyed in order to find the optimum protocol
Unexpected effect of protecting group and solvent on the stereoselectivity of m-CPBA epoxidation of diprotected cis-4,5-dihydroxycyclohexenes
作者:Simon E. de Sousa、Alex Kee、Peter O'Brien、Simon T. Watson
DOI:10.1016/s0040-4039(98)02319-3
日期:1999.1
The stereoselectivity of m-CPBA epoxidation of diprotected cis-4,5-dihydroxycyclohexenes has been studied as a function of protecting group. solvent and in one example, epoxidising reagent. Three different ways of obtaining high levels of trans diastereoselectivity have been uncovered. In addition, the results suggest that bulky silyl protecting groups (eg triethylsilyl and tert-butyldimethylsilyl) can, in CH2Cl2, behave as moderate cis-directors via hydrogen bonding to m-CPBA. (C) 1998 Elsevier Science Ltd. All rights reserved.