Enantioselective Epoxidation of Nonconjugated <i>cis</i>-Olefins by Chiral Dioxirane
作者:Christopher P. Burke、Yian Shi
DOI:10.1021/ol901724v
日期:2009.11.19
A variety of nonconjugated cis-olefins has been enantioselectively epoxidized with chiral ketones 2, and up to 92% ee has been obtained. The two prochiral faces of an olefin are likely stereodifferentiated by the relative hydrophobicity of the olefin substituents and/or allylic oxygen functionality.
Gleason-type chiralauxiliaries were used for the synthesis of a novel class of sulfonium salts, obtained via methylation of the sulfide with Meerwein's salt. The salts were reacted with aldehydes under basic conditions to provide epoxy amides, which were reduced to their corresponding epoxy alcohols in excellent enantiomeric excesses. Interestingly, it was feasible to synthesize both enantiomeric
Development and application of versatile bis-hydroxamic acids for catalytic asymmetric oxidation
作者:Allan U. Barlan、Wei Zhang、Hisashi Yamamoto
DOI:10.1016/j.tet.2007.03.071
日期:2007.7
preliminary results of our new designed C(2)-symmetric bis-hydroxamic acid (BHA) ligands and the application of the new ligands for vanadium-catalyzed asymmetric epoxidation of allylic alcohols as well as homoallylic alcohols. From this success we demonstrate the versatile nature of BHA in the molybdenum catalyzed asymmetric oxidation of unfunctionalized olefins and sulfides.
Tungsten-Catalyzed Asymmetric Epoxidation of Allylic and Homoallylic Alcohols with Hydrogen Peroxide
作者:Chuan Wang、Hisashi Yamamoto
DOI:10.1021/ja411379e
日期:2014.1.29
A simple, efficient, and environmentally friendly asymmetricepoxidation of primary, secondary, tertiary allylic, and homoallylic alcohols has been accomplished. This process was promoted by a tungsten–bishydroxamic acid complex at room temperature with the use of aqueous 30% H2O2 as oxidant, yielding the products in 84–98% ee.
伯、仲、叔烯丙醇和高烯丙醇的简单、高效和环境友好的不对称环氧化已经完成。该过程在室温下由钨-双异羟肟酸配合物促进,使用 30% H2O2 水溶液作为氧化剂,产生 84-98% ee 的产物。
Stereospecific Synthesis of α‐Hydroxy‐Cyclopropylboronates from Allylic Epoxides
Herein, we report a catalytic and stereospecific method for the preparation of enantioenriched α‐hydroxy cyclopropylboronates with control in four contiguous stereocenters. The reaction involves the borylation of readily available allylic epoxides using an inexpensive Cu(I) salt and a commercially available phosphine ligand. High diastereocontrol is achieved and different diastereomers can be selectively