pH-Controlled Selective Protection of Polyaza Macrocycles
作者:Zoltan Kovacs、A. Dean Sherry
DOI:10.1055/s-1997-1418
日期:1997.7
Piperazine (1), tetraazacyclododecane 3 and pentaazacyclopentadecane 4 react with chloroformates in acid solution to give the selectively protected carbamate derivatives 1a, 3a-d, and 4a. The benzyloxycarbonyl derivatives 3d and 4a were alkylated with tert-butyl bromoacetate and removal of the benzyloxycarbonyl protection by catalytic hydrogenation afforded tert-butyl esters 5b and 6b in good yields.