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Synthetic Applications of Enantioselective Protonation and Case Study for (S)-alpha-damascone

Charles Fehr, Harvey Randall

Chem Biodivers. 2008 Jun;5(6):942-57.

PMID: 18618390

Abstract:

Among the fragrance compounds synthesized by enantioselective protonation, (S)-alpha-damascone, (R)-muscone, and (S,S)-Vulcanolide are the most prominent ones. (S)-alpha-damascone has been prepared by four different procedures: from the magnesium enolate, from the lithium enolate, from the enol, and from the corresponding thiol ester. We now present a new, industrially viable protocol for the addition of allyl magnesium chloride to the 'cyclogeranoketene' by a Barbier reaction, followed by protonation of the ensuing magnesium enolate by an aggregate formed from (-)-N-isopropylephedrine, lithium isopropylate, and acetic acid, furnishing (S)-alpha-damascone in 91% yield and with 71% ee.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP43052875 Alpha-Damascone Alpha-Damascone 43052-87-5 Price
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