Quinazolines. Part XVI. A stereospecific cis-addition of the elements of nitromethane across a tetrasubstituted ethylenic double bond

Abstract

The fusion of 3,4,5,6,7,8-hexahydroquinazolin-2(1H)-one with nitroacetic acid at ca. 60° gave a high yield of 8a-nitromethyl-cis-octahydroquinazolin-2(1H)-one. The stereochemistry of this product was deduced by ¹H n.m.r. spectroscopy and by conversion, via the aminomethyl and bromomethyl derivatives, into 8a-methyl-cis-octahydroquinazolin-2(1H)-one. An authentic sample of the latter was prepared from methyl cis-2-chlorocarbonyl-trans-2-methylcyclohexanecarboxylate. A Schmidt reaction gave the cis-2-amino-derivative, which was converted via the 1-carbohydrazide into cis-2-aminomethyl-1-methylcyclohexylamine, which was cyclised with phosgene. A Hofmann reaction with methyl cis-2-carbamoyl-trans-2-methylcyclohexanecarboxylate, however, gave cis-2-amino-1-methylcyclohexanecarboxylic acid, which was converted into 4a-methyl-cis-octahydroquinazolin-2(1H)-one.