CYCLOPROPANEDIAMINES .4. SYNTHESIS AND H- 1-NMR SPECTRA OF PURE DIASTEREOMERS OF 1,2-CYCLOPROPANEDIAMINES AND 1,2-CYCLOPROPANEDIAMMONIUM DIBROMIDES

The efficient preparation of pure diastereomers of N,N'-(1,2-cycloprop anediyl)diurethanes 16-18 and -diammonium dibromides 4, 19, and 20 is reported. Curtius rearrangement of cis- and trans-1,2-cyclopropandicar boxylic dihydrazides 14 yields di(O-benzyl) diurethanes 16 on a 10-100 g scale. The cis-1,2-cyclopropanedicarboxylic dihydrazides cis-14 ten d to form bicyclic products. Thus, from cis-14a a small amount of 22a is obtained besides the diurethane cis-16a. Cyclisation is the main re action in the case of cis-1,2-dimethyl-1,2-cyclopropanedicarboxylic hy drazide (cis-14e) which affords the bicyclic products 22e and 24, but no diurethane. The 1,2-dimethyl-1,2-cyclopropanedicarboxylic acid (27) reacts with diphenyl phosphorazidate to produce the monobenzyl ester 29. The diurethanes 16 are methylated (--> 17) and benzylated (--> 18) at both nitrogen atoms. The benzyloxycarbonyl group is removed from t he diurethanes 16-18 by the action of hydrogen bromide in acetic acid to yield the 1,2-cyclopropanediammonium dibromides 4, 19, and 20. The H-1-NMR spectra are analysed and the results are employed as criteria for the configurations.