Stable carbocations. 244. Use of 2-thienyl, 2-furyl, 5-ethyl-2-furyl, and protonated 4-acetylphenyl substituents in carbon-13 NMR chemical shift correlations
作者:George A. Olah、Arthur L. Berrier、G. K. Surya Prakash
DOI:10.1021/jo00141a019
日期:1982.9
Synthesis of a renewable hydroperoxide from (+)-norcamphor: influence of steric modifications of the bicyclic framework on asymmetric sulfoxidation
A renewable tertiary hydroperoxide has been efficiently synthesized in 83% overall yield starting from commercially available (+)-endo-2-norborneol. This oxygen donor, derived from (+)-norcamphor, when employed in Ti(O i-Pr)(4)-catalyzed sulfoxidations, proved to be considerably more reactive when compared to a previously reported camphor-derived hydroperoxide. Reduced steric hindrance of the new oxidant lowered the level of asymmetric induction achieved in the oxidation, but stereo-convergent kinetic resolution has been exploited to improve enantioselectivity. Excellent recovery (95%) of the tertiary alcohol at the end of the sulfoxidation provides a highly advantageous chiral resource saving protocol. (C) 2004 Elsevier Ltd. All rights reserved.