A Study On The Reaction Of Methyl 6-chloro-2-oxobicyclo[3.1.0]hexane-6-carboxylate With Amines

The ring opening of cyclopropane and its derivatives introduces an important method for building functionalized carbocyclic and heterocyclic skeletons.Thus,it becomes a hot research subject.Our group has made much progress in the ring opening of cyclopropanes and has successfully constructed five-membered ring,six-membered ring,seven-membered ring structures and so on.We then continue our research on the ring opening of methyl 6-chloro-2-oxobicyclo[3.1.0]hexane-6-carboxylate.(1)First of all,we explored the reaction of methyl6-chloro-2-oxobicyclo[3.1.0]hexane-6-carboxylate with amines at the absence of any additives,giving predominant formation of substituted diphenylamines or methyl benzoates when arylamines and aliphatic amine participated in the reaction respectively.We found it was carried out well at high temperature and gave excellent yields.We chose toluene and 120℃ as optimal reaction condition.(2)Then,we were intrigued to study the reaction between methyl6-chloro-2-oxobicyclo[3.1.0]hexane-6-carboxylate and glycine methyl ester hydrochloride,the reaction reacted well under the same conditions.We then chose some amino acid ester hydrochlorides as substrates to test the scope of the reaction.(3)Finally,we chose aromatic hydrazine hydrochlorides as substrates,studying its reaction with methyl 6-chloro-2-oxobicyclo[3.1.0]hexane-6-carboxylate.Surprisingly,we afforded products of asymmetric azobenzenes instead of hydrazobenzenes which might be due to the oxidation of oxygen in air.Thus,we proposed a rational mechanism.We also found that methyl 6-chloro-2-oxobicyclo[3.1.0]hexane-6-carboxylate can even react well with aromatic hydrazide under thermal conditions.