1670-94-6Relevant articles and documents
Synthesis of the Imidazoindole-spirolactone Ring System by Oxidative Double Cyclization. A Synthetic Approach to Tryptoquivalines
Nakagawa, Masako,Sodeoka, Mikiko,Yamaguchi, Keiichi,Hino, Tohru
, p. 1373 - 1384 (2007/10/02)
Imidazoindole-spirolactone 13, the principal ring system of tryptoquivalines, was succesfully synthesized by a new method via oxidative double cyclization of 1-(N-alkoxycarbonylalanyl)-3-indolepropionic acids (5) with N-bromosuccinimide, which were synthesized by acylation of benzyl 3-indolepropionate (10) with N-alkoxycarbonyl alanine p-nitrophenyl ester (12).The use of KF, 18-crown-6 and (iso-Pr)2NEt in acetonitrile lead to high yields of benzyl 1-(N-methoxycarbonyl-α-methylalanyl)-3-indolepropionates (4).The removal of the protecting group of 13c provided 2.The mechanisms of these reactions are discussed.Keywords - tryptoquivaline; imidazoindole-spirolactone; 1-(N-alkoxycarbonylalanyl)-3-indolepropionic acid; oxidative double cyclization; N-bromosuccinimide; acylation.