Part I. Synthesis of 1,3,3-trinitroazetidine via the oxidative nitration of N-p-tosyl-3-azetidinone oxime, and Part II. Synthesis and conformational studies of urea-based calix(4)arenes

Part I. The synthesis of 1,3,3-trinitroazetidine 1 has been accomplished. Alkylation of p-toluenesulfonamide with the tert-butyldimethylsilyl ethers of 1,3-dihalo-2-propanols in the presence of K{dollar}sb2{dollar}CO{dollar}sb3{dollar} afforded the tert-butyldimethylsilyl ethers of 3-azetidinol. Cleavage of N-(p-toluenesulfonyl)-3-(t-butyldimethylsiloxy)azetidine with acetic acid gave N-(p-toluene-sulfonyl)-3-azetidinol 42. Subsequent oxidation with CrO{dollar}sb3{dollar}/HOAc gave N-(p-toluenesulfonyl)-3-azetidinone 24. Treatment of the ketone with hydroxylamine hydrochloride afforded N-(p-toluenesulfonyl)-3-azetidinone oxime 7. In the final step this oxime was allowed to react with 99% HNO{dollar}sb3{dollar} to simultaneously nitrolyze the p-toluenesulfonyl group and oxidize the oxime moiety to produce 1,3,3-trinitroazetidine 1.; Part II. The reaction of 1,3- and 1,4-bis(bromomethyl)benzene with the dianion of the 5-tert-butyltetrahydro-1,3,5-triazine 2(1H)one and 2-imidazolidone has been used to synthesize a series of 16- and 18-membered ring calixarene analogs which incorporate the cyclic urea units. The structures and conformations of these novel macrocyclic ring systems have been investigated in the solid state by x-ray crystallography and in solution by various NMR methods. The results indicate important conformational equilibria dominated by species having syn and anti alignments of the urea carbonyl groups. The interconversion of these conformers likely occurs by carbonyl group through the annulus rotation. AM1 semi-empirical molecular orbital geometry optimizations are consistent with these findings.