Article ID Journal Published Year Pages File Type
1348149 Tetrahedron: Asymmetry 2006 6 Pages PDF
Abstract

The Sharpless asymmetric epoxidation of (+)-zerumbol, itself obtained by the reduction of zerumbone 1 gave only all-erythro bisepoxide 3 which has five stereogenic centers. Chiral monoepoxide 4, which decomposed easily under acidic or high-temperature conditions, could also be obtained. The reaction mechanism was revealed to be diastereoselective but non-enantioselective monoepoxidation at the 2,3-position, which proceeded quantitatively followed by a second epoxidation at the 10,11-position, and also proceeded extremely enantioselectively giving an efficient kinetic resolution. Novel asymmetric diepoxydihydroxyzerumbol 6 and triepoxyzerumbol 7 each with seven stereogenic centers were formed with complete diastereoselectivity by dihydroxylation and epoxidation of bisepoxyzerumbol, respectively.

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(1S,2S,3S)-2,3-Epoxy-2,6,9,9-tetramethyl-6,10-cycloundecadien-l-olC15H24O2Ee = 89% [Capillary GC with chiral column (CPCD)][α]D23.5=+19.9 (c 1.16, EtOH)Source of chirality: asymmetric epoxidation of allylic alcoholAbsolute configuration: 1S,2S,3S

(1R,2R,3R,6S,7S,10S,11S)-6,7-Dihydroxy-2,3-10,11-bisepoxy-2,6,9,9-tetramethylcycloundecan-l-olC15H26O5Ee = 99% [1H and 13C NMR][α]D23.5=-2.6 (c 1.07, EtOH)Source of chirality: asymmetric dihydroxylation of chiral olefinAbsolute configuration: 1R,2R,3R,6S,7S,10S,11S

(1R,2R,3R,6S,7S,10S,11S)-2,3,-6,7-10,11-Triepoxy-2,6,9,9-tetramethylcycloundecan-1-o1C15H24O4Ee = >99% [1H and 13C NMR][α]D23.5=-4.5 (c 0.101, EtOH)Source of chirality: asymmetric epoxidation of chiral olefinAbsolute configuration: 1R,2R,3R,6S,7S,10S,11S

Related Topics
Physical Sciences and Engineering Chemistry Inorganic Chemistry
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