Hydrogen Borrowing Catalysis with Secondary Alcohols: A New Route for the Generation of β‑Branched Carbonyl Compounds

A hydrogen borrowing reaction employing secondary alcohols and Ph* (Me5C6) ketones to give β-branched carbonyl products is described (21 examples). This new C–C bond forming process requires low loadings of [Cp*IrCl2]2, relatively low temperatures, and up to 2.0 equiv of the secondary alcohol. Subst...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2017-02, Vol.139 (7), p.2577-2580
Main Authors: Akhtar, Wasim M, Cheong, Choon Boon, Frost, James R, Christensen, Kirsten E, Stevenson, Neil G, Donohoe, Timothy J
Format: Article
Language:English
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Summary:A hydrogen borrowing reaction employing secondary alcohols and Ph* (Me5C6) ketones to give β-branched carbonyl products is described (21 examples). This new C–C bond forming process requires low loadings of [Cp*IrCl2]2, relatively low temperatures, and up to 2.0 equiv of the secondary alcohol. Substrate-induced diastereoselectivity was observed, and this represents the first example of a diastereoselective enolate hydrogen borrowing alkylation. By utilizing the Ph* group, the β-branched products could be straightforwardly cleaved to the corresponding esters or amides using a retro-Friedel–Crafts reaction. Finally, this protocol was applied to the synthesis of fragrance compound (±)-3-methyl-5-phenylpentanol.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.6b12840