De SR, Kumar G, Jat JL, Birudaraju S, Lu B, Manne R, Puli N, Adebesin AM, Falck JR. Regio- and stereoselective monoepoxidation of dienes using methyltrioxorhenium: synthesis of allylic epoxides.
J Org Chem 2014;
79:10323-33. [PMID:
25321319 PMCID:
PMC4227570 DOI:
10.1021/jo501958d]
[Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
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Methyltrioxorhenium
(MTO) complexed with pyridine was shown to
be a highly effective catalyst for the regioselective monoepoxidation
of conjugated di- and trienes using 30% H2O2 at or below room temperature. The resultant allylic epoxides, and
the triols derived from them, are versatile synthetic intermediates
as well as substructures present in many bioactive natural products.
The site of epoxidation was dependent upon olefin substitution, olefin
geometry (Z vs E), and the presence
of electron-withdrawing substituents on adjacent carbons. For 1-acyl(silyl)oxypenta-2,4-dienes,
epoxidation of the distal olefin was generally favored in contrast
to the adjacent regioselectivity characteristic of Sharpless, peracid,
and other directed epoxidations of hydroxylated dienes.
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