Premium
Asymmetric 1,3‐Dipolar Cycloadditions of N ‐Benzyl and N ‐Diphenylmethyl Nitrones and α,β‐Unsaturated Aldehydes Catalyzed by Bis‐Titanium Chiral Lewis Acids
Author(s) -
Hashimoto Takuya,
Omote Masato,
Hato Yoshio,
Kano Taichi,
Maruoka Keiji
Publication year - 2008
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200700344
Subject(s) - methacrolein , nitrone , chemistry , chiral lewis acid , lewis acids and bases , cycloaddition , reactivity (psychology) , regioselectivity , substituent , titanium , stereoselectivity , 1,3 dipolar cycloaddition , catalysis , medicinal chemistry , enantioselective synthesis , stereochemistry , organic chemistry , polymerization , polymer , medicine , alternative medicine , pathology , methacrylic acid
Bis‐titanium chiral Lewis acids that contain two oxygen‐bridged titanium centers were successfully applied to the asymmetric 1,3‐dipolar cycloaddition of nitrones and α,β‐unsaturated aldehydes. The introduction of the diphenylmethyl group as the N substituent on the nitrones, with the aim of destabilizing the nitrone–Lewis acid complex, led to the drastic enhancement of not only the reactivity but also the enantioselectivity. By employing this approach, 1,3‐dipolar cycloadditions of nitrones and the rather unreactive methacrolein were facilitated to give cycloadducts that bear one all‐carbon quaternary center with unique regioselectivity and excellent stereoselectivity.