Alkynylthioimidazolium Salts: Efficient Reagents for the Synthesis of Alkynyl Sulfides by Electrophilic Thioalkynylation

Abstract

The efficient synthesis of a series of alkynylthioimidazolium salts through reaction of organozinc compounds with dibromo(imidazolium)sulfuranes is reported. Addition of Grignard reagents to these new species provided a highly modular, clean, and scalable access to a broad variety of alkynyl sulfides in good-to-excellent yields. The utility of this protocol was showcased by the preparation of alkynyl sulfides, which are particularly difficult to obtain or simply unavailable through the existing methodologies. In addition, the synthetic method was extended to the preparation of alkynyl selenides.

Polymorphism of bis(1,3-benzothiazol-2-yl) trithiocarbonate

“…This S1Á Á ÁS3 distance of 3.106 (1) Å , which is considerably shorter than the sum of van der Waals radii (3.78 Å ; Alvarez, 2013), indicates possible attractive chalcogenic interactions. Comparable T-shaped geometries around sulfur were observed by our group for dihalosulfuranes (Talavera et al, 2015;Peñ a et al, 2017;Averesch et al, 2019), where the interaction is even more pronounced because of the electronically depleted sulfur atoms.…”

Two‐Step Synthesis of Unsymmetrical Diaryl Sulfides by Electrophilic Thiolation of Non‐functionalized (Hetero)arenes

“…In the solid state the Se center of 54 features an acute angle (C4−Se1−C1, 99.82°) if compared with those of 14 and 17 , which probably derives from the decreased tendency towards hybridization of the heavier atoms in a group. A short contact between F1 and Se1 was additionally observed (3.209(1) Å); this is surely a consequence of the high electrophilicity of the selenium atom in this compound …”

“…With this selection of arylthioimidazolium salts in hand, we started a preliminary exploration to identify possible nucleophiles that could attack at the sulfur atom of these molecules and promote the release of the N‐heterocyclic carbene, with the concomitant formation of the desired diaryl‐, alkenyl(aryl)‐, or alkyl(aryl)sulfide. After some screening (see the Supporting Information for the optimization details), it was gratifying to find that a variety of Grignard reagents were suitable for that transformation, and afforded in satisfactory yields a complete set of structurally differentiated thioethers containing aryl‐, heteroaryl‐, alkenyl‐ and/or alkyl‐substituents directly attached to the sulfur atom 18 – 49 (Scheme ) . As standard conditions, 1.5 equivalents of the desired organo‐magnesium reagent in THF were used; note however that if acidic protons were present in the initial imidazolium thioether, such as in the case of unprotected pyrrole 29 or indole ring 32 , then additional equivalents of the organometallic nucleophile were employed.…”

A Route to Alkynyl Sulfides and Asymmetric Disulfides from Sodium Arylsulfiniate

“…(苯乙炔基)(4-三氟甲基苯基)硫醚(3j) [16] 137.39,130.92,128.12,127.71,127.53,125.53,125.08,124.79,123.36 (q,J＝271.3 Hz,1C),121.38,98.48,72.56;19 F NMR (470 MHz, CDCl 3 ) δ: -62.40; GC-MS (EI) m/z: 278.…”