Solvent-free synthesis of -acylated -thioenaminones

-Acylated -thioenaminones compounds are intermediates that may be conveniently prepared from enaminones using montmorillonite as solid support at 40ºC.1 Herein, these compounds were prepared from an alternative green route. Reactions of enaminones 1a-e with phenyl isothiocyanate 2 under solvent-free condition at room temperature afforded a mixture of regioisomeric -acylated -thioenaminones 3a-e. This was confirmed by 1H NMR with the presence of the signals corresponding for both Z and E isomers in the 3:1 proportion. Under the same condition only one stereoisomer was obtained for the compounds 3f,g. As can be seen in Scheme 1, compounds 3a,b,e,f,g were obtained from enaminones with group R1 = H, nbutyl and CH2CH2OH in good yields and compounds 3c,d were obtained from enaminones with group R1 = Ph in poor yields.