Improvement in the synthesis of (Z)-organylthioenynes via hydrothiolation of buta-1,3-diynes: a comparative study using NaOH or TBAOH as base

First synthesis of (difluoroiodomethyl)thiophenes through double iodation of 2-(difluoromethylene)but-3-yn-1-yl benzyl sulfides

The Sonogashira cross-coupling of 2-bromo-3,3-difluoroallyl benzyl sulfide with various terminal acetylenes afforded the corresponding 2-(difluoromethylene)but-3-yn-1-yl benzyl sulfides in acceptable to good yields. Subsequent double iodation of the enyne sulfides in a mixed solvent (CHCl3/EtOH = 50/1) provided promising 4-(difluoroiodomethyl)-3-iodo-2-substituted thiophenes in good to excellent yields.

Catalytic Hydrofunctionalization Reactions of 1,3-Diynes

Metal-catalyzed hydrofunctionalization reactions of alkynes, i.e., the addition of Y–H units (Y = heteroatom or carbon) across the carbon–carbon triple bond, have attracted enormous attention for decades since they allow the straightforward and atom-economic access to a wide variety of functionalized olefins and, in its intramolecular version, to relevant heterocyclic and carbocyclic compounds. Despite conjugated 1,3-diynes being considered key building blocks in synthetic organic chemistry, this particular class of alkynes has been much less employed in hydrofunctionalization reactions when compared to terminal or internal monoynes. The presence of two C≡C bonds in conjugated 1,3-diynes adds to the classical regio- and stereocontrol issues associated with the alkyne hydrofunctionalization processes’ other problems, such as the possibility to undergo 1,2-, 3,4-, or 1,4-monoadditions as well as double addition reactions, thus increasing the number of potential products that can be formed. In this review article, metal-catalyzed hydrofunctionalization reactions of these challenging substrates are comprehensively discussed.

Hydroelementation of diynes

This review highlights the hydroelementation reactions of conjugated and separated diynes, which depending on the process conditions, catalytic system, as well as the type of reagents, leads to the formation of various products: enynes, dienes, allenes, polymers, or cyclic compounds. The presence of two triple bonds in the diyne structure makes these compounds important reagents but selective product formation is often difficult owing to problems associated with maintaining appropriate reaction regio- and stereoselectivity. Herein we review this topic to gain knowledge on the reactivity of diynes and to systematise the range of information relating to their use in hydroelementation reactions. The review is divided according to the addition of the E-H (E = Mg, B, Al, Si, Ge, Sn, N, P, O, S, Se, Te) bond to the triple bond(s) in the diyne, as well as to the type of the reagent used, and the product formed. Not only are the hydroelementation reactions comprehensively discussed, but the synthetic potential of the obtained products is also presented. The majority of published research is included within this review, illustrating the potential as well as limitations of these processes, with the intent to showcase the power of these transformations and the obtained products in synthesis and materials chemistry.

Highly regio- and stereoselective synthesis of bis-sulfanyl substituted conjugated dienes by copper–palladium cooperative catalysis

An efficient one-pot method for the synthesis of (Z,Z)-isomers of 1,4-bis(sulfanyl)-1,4-diaryl-1,3-butadienes by the cooperative catalysis of Cu(Xantphos)I/Pd(OAc)₂ and a base has been developed.

A concerted addition mechanism in [Hmim]Br-triggered thiol–ene reactions: a typical “ionic liquid effect” revealed by DFT and experimental studies

The π⁺–π and H-bond interactions between [Hmim]Br and substrates promote a special one-step addition mechanism in thiol–ene reactions.

Modifiable diyne-based covalent organic framework: a versatile platform for in situ multipurpose functionalization

A COF material (TCD) containing diynes as both building blocks and active sites was prepared by microwave irradiation and employed as a versatile platform for the preparation of diverse functional materials.

A new microwave-assisted thionation-heterocyclization process leading to benzo[c]thiophene-1(3H)-thione and 1H-isothiochromene-1-thione derivatives

The first example of a MW-assisted tandem thionation/S-cyclization process, leading to benzothiophenethione and isothiochromenethione derivatives, is reported.

Metal-free synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles from 1,3-diyne-indole derivatives employing two successive hydroaminations

The uncatalyzed synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles derived from 1,3-diyne indoles was successfully carried out in PEG 400. The scope and limitations of the reaction were studied.

Recent advances in the synthesis of thiophene derivatives by cyclization of functionalized alkynes

This review is intended to highlight some recent and particularly interesting examples of the synthesis of thiophene derivatives by heterocyclization of readily available S-containing alkyne substrates.