- X=Y-ZH SYSTEMS AS POTENTIAL 1,3-DIPOLES. PART 11. STEREOCHEMISTRY OF 1,3-DIPOLES GENERATED BY THE DECARBOXYLATIVE ROUTE TO AZOMETHINE YLIDES
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The decarboxylative reaction of aryl aldehydes with cyclic secondary α-amino acids or primary α-amino acids in the presence of N-methyl- or N-phenyl-maleimide leads, via an intermediate azomethine ylide, to mixtures of bicyclic pyrrolidine cycloadducts in good yield.Cyclic secondary α-amino acids, where the carboxylic group is non-benzylic, give cycloadducts arising from a stereospecifically generated anti-dipole.Acyclic α-amino acids, and cyclic secondary α-amino acids with the carboxylic group located at a benzylic site, give rise to cycloadducts derived from both anti- and syn-configurations of the intermediate azomethine ylides.The reactions show little discrimination between endo- and exo-transition states for the cycloadditions.
- Grigg, Ronald,Surendrakumar, Sivagnanasundram,Thianpatanagul, Sunit,Vipond, David
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p. 2693 - 2702
(2007/10/02)
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