The thia-Michael addition reactionh as been demonstrated to be ah ighly powerful tool in organic synthesis. Indeed, the influential natureo ft his reactionh as been wellestablished in the fields of medicinal chemistry,c atalysis, drug discovery,a nd materials science. The emergence of numerous synthetic strategies that take advantage of thia-Michael addition reactions of electron-deficienta lkenes has unleashed countless opportunities for the design and synthesis of diverse biologically relevant organosulfurc ompounds. However,d espite myriad potential synthetic applications, there has not been anye xclusive reviewso ft he thia-Michael addition reaction. Therefore, this Focus Review plots the journeyo ft he thia-Michael addition reaction in organic synthesis, and is categorized according to catalyzed and catalyst-free thia-Michael addition reactions. Figure 1. Summary of the applicationsoft hia-Michael adducts.[a] Dr.Scheme1.Catalyzed pathways for the thia-Michael addition reaction.EW-G = electron-withdrawing group.Scheme2.Acetic-acid-catalyzed thia-Michael additionr eaction proposed by Allen et al. [24] AsianJ.O rg.Scheme3.Indium-bromide-catalyzed thia-Michael addition reaction.Scheme4.Thia-Michael addition reaction followed by a1 ,2-addition of TMSCN in one pot. TMSCN = trimethylsilyl cyanide.Scheme5.Bi III -catalyzedt hia-Michael additionreactiono fa,b-unsaturated carbonyl compounds. Tf = trifluoromethanesulfonyl.Scheme6.Bismuth-triflate-catalyzed synthesis of bis-thioether compounds. Bn = benzyl.Scheme7.Iron-/copper-catalyzed thia-Michael additionr eaction.Scheme8.VO(OTf) 2 -mediated synthesis of b-mercapto ketones. Np = naphthyl.Scheme9.Substrate scope for the synthesis of 3-sulfanyl-substituted 1-(arylamino)-pyrrolidine-2,5-diones.Scheme10. Regio-and enantioselective addition at the d position of conjugated systems.Scheme11. Mechanistic modelf or the enantioselective d addition of at hiol to an a,b,g,d-unsaturated dienone,catalyzed by achiral Fe III Àsalenc omplex.Scheme12. Chemoselectivesynthesis of 2-amino-3,1-benzothiazines (15) and 3,4-dihydroquinazoline-2-thiones (16)byu sing ortho-aminocinnamate (13)a nd isothiocyanates 14.Scheme13. Reactionmechanism for the chemoselective synthesis of 2amino-3,1-benzothiazines (15)and 3,4-dihydroquinazoline-2-thiones (16).Scheme14. ZrCl 4 -assisted three-component reactionf or the synthesiso fbaryl-b-mercapto ketones.Scheme15. LiF-nanocube-mediated thia-Michael addition reaction.Scheme57. Ni II -catalyzed enantioselective synthesiso f2-aryl-3-nitrothiochroman-4-ols.Scheme58. Te ntative reaction mechanism for the Ni II -catalyzed asymmetric synthesis of 2-aryl-3-nitrothiochroman-4-ols.Scheme59. Pepsin-catalyzed synthesis of functionalized chiral dihydrothiophenes.Scheme69. Mechanistic aspects of the stereoselectives ynthesis of tetrahydrothioxanthenones.Scheme70. Enantioselectivesynthesis of methyl 2-((R)-2-nitro-1-(aryl/heteroaryl)ethylthio)acetatesa nd thiomorpholin-3-ones.Scheme71. Water-accelerated thia-Michael additionr eaction proposedb y Chakraborti and co-work...