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Influence of the Bridgehead Substituent on the Stereoselective Leuckart Reaction of 2‐Norbornanones − Skeletal Rearrangement versus Structural Retention
Author(s) -
García Martínez Antonio,
Teso Vilar Enrique,
García Fraile Amelia,
MartínezRuiz Paloma
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200108)2001:15<2805::aid-ejoc2805>3.0.co;2-g
Subject(s) - chemistry , norbornane , 2 norbornyl cation , substituent , enantiopure drug , stereochemistry , intramolecular force , stereoselectivity , formamides , medicinal chemistry , organic chemistry , enantioselective synthesis , formamide , catalysis
The synthesis of chiral amine norbornane derivatives has been achieved by means of the Leuckart reaction of various 2‐norbornanones. We propose an ionic mechanism for this process in which the formation of a 2‐formylamino‐2‐norbornyl cation is the common initial step. The reaction pathway and the isolated products are strongly dependent on the nature of the bridgehead substituents; hydrogen and alkyl groups yield only enantiopure 2‐norbornyl formamides with structural retention, whereas O ‐acyl or N ‐acyl groups favour a pinacol‐type skeleton rearrangement through a cascade of Wagner−Meerwein rearrangements and intramolecular transamidations.