pH-Controlled Selective Protection of Polyaza Macrocycles
- 1 July 1997
- journal article
- research article
- Published by Georg Thieme Verlag KG in Synthesis
- Vol. 1997 (07) , 759-763
- https://doi.org/10.1055/s-1997-1418
Abstract
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.Keywords
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