N-benzyloxycarbonylaziridine in the syntheses of 2-aminoethyl armed lariats and selectively N-protected polyazacrown ethers

Abstract

The 15- and 18-membered mono- and bi-bracchial N-aminoethylene armed lariats 6, 7 and 8 have been synthesized by alkylations of parent azacrowns using N-benzyloxycarbonylaziridine 2 and subsequent removal of Z-protecting groups by catalytic hydrogenolysis. Extraction experiments with M⁺-picrates (M⁺= Li⁺, Na⁺, K⁺ and Cs⁺) showed medium efficacy of 6, 7 and 8 and only slight selectivity of 6 for Cs⁺. The syntheses of selectively N-protected polyazacrowns 10-benzyl-1,4-dioxa-7,10,13-triazacyclopentadecane 12, 10,19-dibenzyl-1,4,13,16-tetraoxa-7,10,19,22-tetraazacyclotetracosane 16 and 4,16-dibenzyl-1,10-dioxa-4,7,13,16-tetraazacyclooctadecane 21 exemplify the application of N-benzyloxycarbonylaziridine 2 as a suitable building block for preparations of selectively N-protected polyaza-macrocycles.