The mansucript is an update to the earlier Science of Synthesis contribution describing methods for the in situ generation of thiocarbonyl ylides and Corey-Chaykovski reagents (sulfonium and sulfoxonium methanides). Whereas thiocarbonyl ylides react as electron rich 1,3-dipoles, Corey-Chaykovski reagents act as methylidene transferring agents. The most relevant application of thiocarbonyl ylides relates to the synthesis of tetrahydrothiophene (thiolane) and 1,3-dithiolane derivatives via [3+2] cycloadditions with electron deficient C,C and C=S dipolarophiles, respectively. In the recent decade, Corey-Chaykovsky reagents were widely applied for cyclopropanation, epoxidation, aziridination as well as for diverse heterocyclization reactions. In all cases, asymmetric versions of the applied protocols is of great interest.