Conversion of stereoisomeric 2-amino-1-carbamoylcyclohexane-5,5-dicarboxylates into 6-amino-3-azabicyclo[3.3.1]nona-2,4-dione-1-carboxylates

Abstract

The separation of cis- and trans-2-amino-r-1-carbamoylcyclohexane-5,5-dicarboxylates 2 and 3 as 2-N-benzyloxycarbonyl (15, 16) and 2-N-benzoyl- (17, 18) derivatives is described. A dipeptide containing suitably protected L-phenylalanine and cis-2-amino-1-carbamoylcyclohexane (2) was also prepared. Moreover, cis- (17) and trans- (18) benzamido isomers were converted into ethyl t-6- (23) and c-6- (24) benzamido-r-1-carboxylate-3-azabicyclo[3.3.1]nona-2,4-dione, respectively. Similarly, ethyl c-6- phthalimido-r-1-carboxylate-3-azabicyclo[3.3.1]nona-2,4-dione (25) was obtained from diethyl t-2-phthalimido-r-1-carbamoylcyclohexane-5,5-dicarboxylate (22).