Titanium‐Catalyzed Intermolecular Hydrothiomethylation of Alkenes

A catalyst screening for six different α‐alkylation reactions of methyl sulfides with unsaturated substrates performed in hermetically sealable and inexpensive 42‐well aluminum reactor blocks is described. As a result, a new titanium‐catalyzed hydrothiomethylation reaction of alkenes, which takes place under C─H bond activation at the α‐carbon atom of simple methyl sulfides, is presented. The best catalyst is prepared in situ from the readily available titanium catalyst precursor Ti(CH 2 SiMe 3 ) 4 , a formamidinato ligand precursor, and the Lewis acid [Ph 3 C][B(C 6 F 5 ) 4 ]. Although selected 1,2‐disubstituted alkenes, for example, cyclohexene and cyclopentene, undergo successful hydrothiomethylation reactions, the best results are obtained with monosubstituted 1‐alkenes. In these cases, the reactions take place with excellent regioselectivity and give branched hydrothiomethylation products exclusively (23 examples). When dimethyl sulfide is used as a substrate, either the monohydrothiomethylation product or the dihydrothiomethylation product can be obtained with very good selectivity.