Synthesis of dithioacetals via gold-catalysed hydrothiolation of vinyl sulfides

The synthesis of unsymmetrical dithioacetals based on gold catalysis is described. Although many approaches to the preparation of symmetrical dithioacetals have been developed, the methods to access unsymmetrical ones remain limited. In this regard, we report a mild synthetic method with a broad substrate scope. Screening of various gold catalysts identified a catalyst, which allows the hydrothiolation of both activated and unactivated vinyl sulfides with high efficiency. Moreover, the reaction displays broad compatibility for both aryl and aliphatic thiols.

t BuOLi-promoted terminal alkyne functionalizations by aliphatic thiols and alcohols

Selective radical addition to terminal alkynes is always a difficult task to achieve because it gives a mixture of stereo- and regioisomers. Herein we describe the selective addition of aliphatic thiols or alcohols to N-phenylpropiolamides (terminal alkynes) using lithium tert-butoxide (^tBuOLi) in ethanol as a promoter. Mechanistically, it has been shown that the reaction proceeded through the generation of a thiyl radical intermediate, and the amide group in N-phenylpropiolamide could help in the activation of the alkyne, which led to thioacetalization via the formation of a (Z)-selective anti-Markovnikov vinyl sulfide. The (Z)-selectivity during the formation of vinyl sulfides was controlled by an intramolecular sulfur⋯oxygen interaction.

Direct synthesis of 1,3-dithiolanes from terminal alkynes via visible light photoredox catalysis

AA visible light-mediated, metal-free, regioselective dihydrothionation of terminal aromatic as well as heteroaromatic alkynes has been achieved by using Eosin Y as a photoredox catalyst at room temperature. The protocol...

Alcohol-mediated direct dithioacetalization of alkynes with 2-chloro-1,3-dithiane for the synthesis of Markovnikov dithianes

An alcohol-mediated dithioacetalization process that gains direct access to the corresponding Markovnikov-selective 1,3-dithianes using unactivated alkynes and nonthiolic/odorless 2-chloro-1,3-dithiane in a highly efficient manner has been developed. This methodology has the advantage of having mild reaction conditions, and the dithioacetalization process gives good to excellent yields with high Markovnikov-selectivity.

Metal Catalysis in Thiolation and Selenation Reactions of Alkynes Leading to Chalcogen-Substituted Alkenes and Dienes

This review covers recent achievements in metal-catalyzed Z-H and Z-Z (Z=S, Se) bond addition to the triple bonds of alkynes-a convenient and atom-efficient way to carbon-element bond formation. Various catalytic systems (both homogeneous and heterogeneous) developed to date to obtain mono- and bis-chalcogen-substituted alkenes or dienes, as well as carbonyl compounds or heterocycles, starting from simple and available alkynes and chalcogenols or dichalcogenides are described. The right choice of metal and ligands allows us to perform these transformations with high selectivities under mild reaction conditions, thus tolerating unprotected functional groups in substrates and broadening ways of further modification of the products. The main aim of the review is to show the potential of the catalytic methods developed in synthetic organic chemistry. Thus, emphasis is made on the scope of reactions, types of products that can be selectively formed, convenience, and scalability of the catalytic procedures. A brief mechanistic description is also given to introduce new readers to the topic.

Theoretical investigation of the mechanism of gold(i)-catalyzed hydrothiolation of alkynes and alkenes with phenthiol

The mechanisms of gold-catalyzed hydrothiolation of alkynes and alkenes with phenthiol have been investigated using density functional theory calculations.