Quinazolines. Part XIX. Reduction of 2-amino-5,6,7,8-tetrahydroquinazoline-4-carboxylic acid and 1,2,5,6,7,8-hexahydro-2-oxoquinazoline-4-carboxylic acid

Abstract

2-Oxocyclohexylglyoxylic acid condensed with guanidine carbonate and urea to yield, respectively, 2-amino-5,6,7,8-tetrahydroquinazoline-4-carboxylic acid (1) and 1,2,5,6,7,8-hexahydro-2-oxoquinazoline-4-carboxylic acid (2), and not the isomeric indoles (6) and (7). Catalytic reduction of the carboxylic acids (and their methyl esters) gave the 3,4(or 1,4)-dihydro-derivatives [(8) and (12)], which rearranged to the 3,8a(or 1,8a)-dihydroisomers in the presence of acid. 1,4,5,6,7,7a-Hexahydro-3-hydroxyindol-2-one (15) and its 1-benzyl derivative (16) were prepared for spectral comparison. The former compound was further reduced with sodium borohydride to 3-hydroxy-cis-perhydroindol-2-one (17).