2010
DOI: 10.1021/ja100951u
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Zirconium(IV)- and Hafnium(IV)-Catalyzed Highly Enantioselective Epoxidation of Homoallylic and Bishomoallylic Alcohols

Abstract: In this report, zirconium(IV) and hafnium(IV)-bishydroxamic acid complexes were utilized in the highly enantioselective epoxidation of homoallylic alcohols and bishomoallylic alcohols, which used to be quite difficult substrates for other types of asymmetric epoxidation reactions. The performance of the catalyst was improved by adding polar additive and molecular sieves. For homoallylic alcohols, the reaction could provide epoxy alcohols in up to 81% yield and up to 98% ee, while for bishomoallylic alcohols, u… Show more

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Cited by 74 publications
(46 citation statements)
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“…2 Methods based on transition metals that allow for the use of directing groups (e.g., allylic alcohol bearing substrates) have achieved high levels of enantioselectivity and have served as benchmarks as the field has strived for expanded substrate scope. More remote directing groups, 3 and metal-free based catalysts 411 have also proven effective for various classes of olefins. So, too, have directing group-free processes proven to be of great importance.…”
Section: Introductionmentioning
confidence: 99%
“…2 Methods based on transition metals that allow for the use of directing groups (e.g., allylic alcohol bearing substrates) have achieved high levels of enantioselectivity and have served as benchmarks as the field has strived for expanded substrate scope. More remote directing groups, 3 and metal-free based catalysts 411 have also proven effective for various classes of olefins. So, too, have directing group-free processes proven to be of great importance.…”
Section: Introductionmentioning
confidence: 99%
“…Lastly, to our knowledge, supported Hf(IV) catalysts (Hf-SiO 2 ) have not been reported for epoxidation, though homogeneous studies show similar selectivities to Ti analogues. [35][36][37] Beyond individual catalyst studies, there are few head-to-head comparisons of different supported metal oxides for epoxidation. In the 70s, Sheldon benchmarked several homogeneous and SiO 2 -supported catalysts for olefin epoxidation with alkyl hydroperoxides and found high activity and selectivity with Ti(IV) and Mo(VI), the latter of which poorly performed when supported due to significant leaching.…”
mentioning
confidence: 99%
“…It was our additional surprise to recognize the outstanding enantioselectivities of tert -allylic and homoallylic alcohols, which had never been observed for titanium or vanadium metal catalyst. 51,61 …”
Section: Catalytic Asymmetric Oxidationmentioning
confidence: 99%