A. Fesenko, Ludmila A. Trafimova, D. V. Albov
Mar 11, 2015
Citations
0
Influential Citations
9
Citations
Journal
Tetrahedron Letters
Abstract
A five-step synthesis of 4-(1-mesyloxyethyl)-6-methyl-5-tosyl-1,2,3,4-tetrahydropyrimidin-2-one via amidoalkylation has been developed. Reactions of this compound with C-, O-, S-, and N-nucleophiles led to the highly diastereoselective formation of polysubstituted 2,3,4,5-tetrahydro-1H-1,3-diazepin-2-ones as a result of ring expansion. The diastereoselectivity of the reactions depended on the nucleophile used and changed from cis to trans. The results obtained were explained by the formation of a bicyclic cyclopropane intermediate followed by cleavage of the zero bridge and stereoselective addition of the nucleophile to the resulting dihydro-1H-1,3-diazepin-2-one under kinetic control. The prepared cis-4-alkoxy-5-methyldiazepines reacted with alcohols under acidic conditions to give thermodynamically more stable trans-isomers. When harsh acidic conditions were used, ring contraction of 4-alkoxydiazepines to give 1-carbamoyl-1H-pyrroles was observed.