Unusual behaviour of bis[omega-hydroxyalkyl]-1,8,4,5-naphthalenetetracarboxylic bisimides in bisimide-lactam ring contraction: experimental and theoretical study

A series of novel [omega -hydroxyalkyl]-1,8,4,5-naphthalenetetracarboxylic bisimides has been synthesised and tested in the bisimide-lactam ring conta ction reaction. It was found that N,N ' -bis[omega -hydroxyalkyl]-1,8,4,5-n aphthalenetetracarboxylic bisimides with short methylene spacer show unusua lly low reactivity in bisimide-lactam ring contraction reaction common for six-membered bisimides. The molecular modelling results shows that the reas on for such a behaviour is deprotonation of one of the hydroxy groups of bi simides destabilising tetrahedral intermediate - the key intermediate in th e ring contraction reaction. (C) 2001 Elsevier Science B.V. All rights rese rved.