A series of three (E)-2-alkylidene-1,4-di-p-tosyl-1,2,3,4-tetrahydro-quinoxaline compounds

The three title quinoxaline derivatives, (E)-2-(4-methylbenzylidene)-1,4-di -p-tosyl-1,2,3,4-tetrahydroquinoxaline, C30H28N2O4S2, (II), (E)-2-(4-methox ybenzylidene)-1,4-di-p-tosyl-1,2,3,4-tetrahydroquinoxaline, C30H28N2O4S2, ( III), and (E)-2-(3-chlorobenzylidene)-1,4-di-p-tosyl-1,2,3,4-tetrahydro-qui noxaline, C29H25ClN2O4S2, (IV), were synthesized by palladium-catalyzed het ero-annulation. The E configuration of the exocyclic double bond in the thr ee compounds has been established by the present X-ray study. The saturated part of the quinoxaline moiety in all three compounds assumes a distorted chair conformation. The numerical descriptors indicate a high degree of iso structurality between compounds (II) and (III), but no isostructurality wit h compound (IV).