Enamine chemistry—XIX: Preparation and alkylation of cyclic and non-cyclic enamino-thiones

Enamino-thiones of the general type ArC(S)CH:CHNR₂,3(Ar=phenyl p-methoxyphenyl and p-bromophenyl NR₂= pyrrolidinyl piperidinol were prepared by reacting the corresponding enaminones 2 with 2,4-bis-(4-methoxyphenyl) 1,3,2,4-dithiadiphosphetane 2,4-disultide 1. The compounds 3 were reacted with methyl iodide and ethyl iodide to give exclusively S-alkylated iminium iodides 4 and 5, in quantitative overall yields N phenyl-2,3,5,6,7,8-hexahydro-4-qumolinethione, 8, and 2-methyl-N phenyl-2, 3,5,6,7,8-hexahydro-4-quinolmethione 9, were alkylated with methyl iodide ethyl iodide and benzyl bromide giving S-alkylated hexahvdro quinolinium halides. 10 and 11, respectively in high yields. The stereochemistry of the compounds of types 4 and 5 is discussed in detail.