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Enantioselective Synthesis of Quaternary Δ 4 ‐ and Δ 5 ‐Dehydroprolines Based on a Two‐Step Formal [3+2] Cycloaddition of α‐Aryl and α‐Alkyl Isocyano(thio)acetates with Vinyl Ketones
Author(s) -
Odriozola Amaiur,
Oiarbide Mikel,
Palomo Claudio
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201703526
Subject(s) - stereocenter , thio , enantioselective synthesis , bifunctional , aryl , chemistry , alkyl , squaramide , conjugate , catalysis , medicinal chemistry , organic chemistry , organocatalysis , mathematical analysis , mathematics
A divergent synthesis of optically active quaternary Δ 4 ‐ and Δ 5 ‐dehydro prolines is developed based on the first catalytic enantioselective conjugate addition of α‐substituted isocyano(thio)acetates to vinyl ketones that is general for both α‐aryl and α‐alkyl isocyano(thio)acetates. The new tetrasubstituted C−N stereocenter is formed without the need of any metal salt due to a bifunctional tertiary amine/squaramide catalyst, featuring a bulky polyaryl sidearm and an unusually short squaramide diamide H⋅⋅⋅H interatomic distance in the solid state.