[2+2] Photoadditions with chiral 2,5-cyclohexadienone synthons
摘要:
Three chiral 2,5-cyclohexadienone synthons bearing different chiral auxiliaries were examined in [2+2] photoadditions with cyclopentene. Regeneration of the 'masked' double bond in the adducts resulted in the preparation of optically active 5-4-6 adducts. The enantiomeric purity of each adduct was found to be >95% using comparative C-13 NMR analysis of the appropriate ketals. The asymmetry induced in the cycloaddition step of our methodology indicated that the facial selectivity was directly correlated to the degree of steric bulk of the chiral auxiliary oil the synthon. (C) 2002 Elsevier Science Ltd. All rights reserved.
[2+2] Photoadditions with chiral 2,5-cyclohexadienone synthons
摘要:
Three chiral 2,5-cyclohexadienone synthons bearing different chiral auxiliaries were examined in [2+2] photoadditions with cyclopentene. Regeneration of the 'masked' double bond in the adducts resulted in the preparation of optically active 5-4-6 adducts. The enantiomeric purity of each adduct was found to be >95% using comparative C-13 NMR analysis of the appropriate ketals. The asymmetry induced in the cycloaddition step of our methodology indicated that the facial selectivity was directly correlated to the degree of steric bulk of the chiral auxiliary oil the synthon. (C) 2002 Elsevier Science Ltd. All rights reserved.