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Allenyl Enolates – A New Class of Chiral Ambident Nucleophiles, 5 . Ireland–Claisen Rearrangements of Allenic Silyl Ketene Acetals
Author(s) -
Becker Markus,
Krause Norbert
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970413
Subject(s) - ketene , silylation , electrophile , chemistry , nucleophile , regioselectivity , sigmatropic reaction , claisen rearrangement , selectivity , medicinal chemistry , conjugate , organic chemistry , stereochemistry , catalysis , mathematical analysis , mathematics
Allenic silyl ketene acetals 3 formed by conjugate 1,6‐addition of organocuprates to 2‐propen‐1‐yl and 2‐buten‐1‐yl 2‐en‐4‐ynoates 1 and regioselective enolate capture with silyl electrophiles readily undergo [3,3]‐Ireland‐Claisen rearrangements to the 2‐substituted methyl 3,4‐dienoates 4 . The simple diastereoselection of the formation of 4b could be improved by variation of the silylating agent as well as the addition of bases. in the case of product 4c , the sigmatropic rearrangement also takes place with good diastereofacial selectivity, i.e., with axis‐to‐center chirality transfer.