Microwave-assisted reactions of $\alpha$-diazoketones with hetaryl and ferrocenyl thioketones

Differently substituted hetaryl thioketones react with less reactive diazoketones under MW irradiation in toluene solution. After only 2 min, the reactions were complete and, depending on the type of the used diazoketone, α,β-unsaturated ketones, acyl substituted thiiranes or 1,3-oxathiols were obtained as final products. In the case of azibenzil and di(thiophen-2-yl) thioketone, a new type of 1,5-dipolar electrocyclization of the intermediate thiocarbonyl ylide involving a thiophene ring led to a fused sulfur heterocycle. In contrast to hetaryl thioketones, the ferrocenyl analogues decompose under MW irradiation. Alternatively they react with diazopropanone and 2-diazo-1-phenylethanone in boiling THF in the presence of LiClO4 to give α,β-unsaturated ketones as sole products. In these cases, the reactions require long reaction times