Highly Enantioselective Phase-Transfer Catalytic α-Alkylation of α-tert-Butoxycarbonyllactams: Construction of β-Quaternary Chiral Pyrrolidine and Piperidine Systems

Title
Highly Enantioselective Phase-Transfer Catalytic α-Alkylation of α-tert-Butoxycarbonyllactams: Construction of β-Quaternary Chiral Pyrrolidine and Piperidine Systems
Authors
박요한이영주홍석창김미현이명모김택수이재균제상섭박홍근
Keywords
α-tert-butoxycarbonyllactams; phasetransfer catalytic α-alkylation; β-quaternary chiral piperidines; β-quaternary chiral pyrrolidines
Issue Date
2011-12
Publisher
Advanced synthesis & catalysis
Citation
VOL 353, NO 18, 3313-3318
Abstract
A new enantioselective α-alkylation of α-tert-butoxycarbonyllactams for the construction of β-quaternary chiral pyrrolidine and piperidine core systems is reported. α-Alkylations of N-methyl-α-tert-butoxycarbonylbutyrolactam and N-diphenylmethyl-α-tert-butoxycarbonylvalerolactam under phase-transfer catalytic conditions (solid potassium hydroxide, toluene, −40 °C) in the presence of (S,S)-3,4,5-trifluorophenyl-3,3′,5,5′-tetrahydro-2,6-bis(3,4,5-trifluorophenyl)-4,4′-spirobi[4H-dinaphth[2,1-c:1′,2′-e]azepinium] bromide [(S,S)-NAS Br] (5 mol%) afforded the corresponding α-alkyl-α-tert-butoxycarbonyllactams in very high chemical (up to 99%) and optical yields (up to 98% ee). Our new catalytic systems provide attractive synthetic methods for pyrrolidine- and piperidine-based alkaloids and chiral intermediates with β-quaternary carbon centers.
URI
http://pubs.kist.re.kr/handle/201004/42045
ISSN
16154150
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KIST Publication > Article
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