Asymmetric Tandem Conjugate Addition–Aldol Condensation with N‐Acryloyloxazolidines Derived from 2‐Phenylglycinol. Issue 1 (8th December 2016)

• Record Type: Journal Article
• Authors: Zelocualtecatl‐Montiel, Iván; García‐Álvarez, Fernando; Juárez, Jorge R.; Orea, Laura; Gnecco, Dino; Mendoza, Angel; Chemla, Fabrice; Ferreira, Franck; Jackowski, Olivier; Aparicio, David M.; Perez‐Luna, Alejandro; Terán, Joel L.
• Is Part Of: Asian journal of organic chemistry. Volume 6:Issue 1(2017)
• Page Start: 67
• Page End: 70
• Publication Date: 2016-12-08
• Subjects: aldol reaction -- radical-polar mechanism -- diastereoselectivity -- domino reactions -- chiral oxazolidines; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; 547.005
• DOI: 10.1002/ajoc.201600501
• Languages: English
• ISSNs: 2193-5807

Abstract

Abstract: The tandem 1, 4‐addition–aldol condensation reaction of diethylzinc, α, β‐unsaturated chiral enantiopure oxazolidines derived from 2‐phenylglycinol, and carbonyl compounds is disclosed. The reaction proceeds through a radical‐polar crossover mechanism involving the aldol condensation of a trisubstituted zinc enolate through a Zimmerman–Traxler transition state. Installation of a 2‐pyridine moiety at the hemiaminal position of the chiral auxiliary allows obtaining both excellent asymmetric induction and diastereoselectivity (up to >90 % de ). The developed protocol is suitable for aromatic and aliphatic aldehydes, as well as ketones. Abstract : Zimmerman–Traxler is never getting old ! A three‐component tandem 1, 4‐addition–aldol condensation of diethylzinc, chiral N ‐acryloyloxazolidine derived from ( R )‐(−)‐2‐phenylgycinol and 2‐pyridine carboxaldehyde, and carbonyl derivatives in aerobic medium is presented. The procedure allows both excellent asymmetric induction and simple diastereoselectivity, is appropriate for aromatic and aliphatic aldehydes, and symmetrical and unsymmetrical ketones. The chiral auxiliary was cleanly removed under reductive conditions affording the corresponding 1, 3‐diols.