# Titanium‐Catalyzed Intermolecular Hydrothiomethylation of Alkenes

## TL;DR

A new titanium-catalyzed reaction adds methyl sulfide groups to alkenes with high selectivity, using a cost-effective reactor system.

## Contribution

A novel titanium-catalyzed hydrothiomethylation reaction of alkenes under C─H bond activation is developed.

## Key findings

- The reaction shows excellent regioselectivity for monosubstituted 1-alkenes, producing branched products exclusively.
- Dimethyl sulfide can yield either monohydrothiomethylation or dihydrothiomethylation products with high selectivity.
- The method uses a 42-well aluminum reactor block to study air- and moisture-sensitive titanium catalysts efficiently.

## Abstract

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(CH2SiMe3)4, a formamidinato ligand precursor, and the Lewis acid [Ph3C][B(C6F5)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.

Hermetically sealable, inexpensive 42‐well aluminum reactor blocks are used to explore new reactivities of air‐ and moisture‐sensitive titanium catalysts. As a result, methyl sulfides undergo efficient α‐alkylation with alkenes in the presence of a titanium catalyst precursor, a formamidinato ligand, and a Lewis acid, yielding branched hydrothiomethylation products with excellent regioselectivity. Graphical design by Melissa Schlüschen.