The ever-increasing interest in the chemistry of five-membered heterocyclic compounds is due to their paramount importance in such essentialf ields as pharmacology, medicine, biology,o rganic synthesis of fine chemicals, agricultural chemistry,a nd the chemical industry.T his Review summarizesa nd highlights methodsf or the synthesis of five-membered O-, N-, and S-heterocycles based on transformations of a,b-enals. Over the last decade, these reactions, which often differ from the processes involving other a,bunsaturated carbonyl compounds in methodology andr esults, have been gathering momentum. Many of the catalytic and technological novelties discussed in the review,s uch as asymmetricm etal-and organocatalysis, multiple catalysts, one-pot multicomponent reactions proceeding through domino,c ascade, or tandem reactions, andm icrowave activation, promote the formation of diverset arget products, the structures of which becomes clear from the mechanistic schemesg iven in the review.T he mechanisms discussed reflect great advances in the chemo-, regio-, and stereoselectivity of the reactions with participation of a,b-alkenals, achieved in the last 15 years, which allowsn ew five-membered heteroarenes and related compounds (pyrroles, dihydropyrroles, pyrrolidines,f urans, thiophenes) to be synthesized.