Synthesis of 2,3,5-triaryl-4-trifluoromethyl thiophenes

Recent Advances in the Synthesis of Thiophene Derivatives by Cyclization of Functionalized Alkynes

“…An interesting approach to regioisomeric 2,3,5-triaryl-4-trifluoromethylthiphenes 107 and 108 , based on 1,3-dipolar cycloaddition between 1-aryl-3,3,3-trifluoro-1-propynes 105 and 1,3-dithiolium-4-olates 106 (1:1 molar ratio), was developed some years ago (Scheme 31) [109]. Reactions were carried out in xylenes at 120 °C for 20–32 h [110].…”

“…Synthesis of 2,3,5-triaryl-4-trifluoromethylthiophenes 107 and 108 from 1-aryl-3,3,3-trifluoro-1-propynes 105 and 1,3-dithiolium-4-olates 106 [110]. …”

Intramolecular alkyne–dithiolium cycloaddition: a joint experimental and DFT mechanistic study

“…38 Rather than the expected DTF dimerization products, the reaction surprisingly produced a major product (4) that features a unique tricyclic indenothiophene motif. The newly formed rings (B and C) in 4 are supposedly constructed through an intramolecular cycloaddition process, 39,40 while the sp 3 benzylic carbon of the B ring hints at a protonation step taking place on the vinylic carbon adjacent to the dithiole group of 3 at the initial stage of the reaction. [41][42][43] Mechanistically, two plausible reaction pathways can be proposed to account for the reaction outcome.…”

“…From IM-1 the reaction can possibly proceed through two approaches based on commonly known organic reaction mechanisms. The rst reaction pathway is a concerted 1,3-dipolar cycloaddition 39,40 that directly leads to a cage-shaped intermediate IM-3 with the backbones of B and C rings assembled simultaneously. The second one is a stepwise pathway, in which the alkynyl group attacks the carbocation of dithiolium ring via an alkyne Prinstype cyclization [44][45][46][47][48][49] at rst.…”

Strain‐Promoted 1,3‐Dithiolium‐4‐olates–Alkyne Cycloaddition

“…First reported in 1964, [11] 1,3-dithiolium-4-olates (DTOs) are essentially known to undergo thermal 1,3-dipolar cycloadditions in the presence of activated alkynes,followed by aretro-Diels-Alder reaction to deliver substituted thiophenes. [12] This thermal process has received limited attention, probably because of the poor regioselectivity,the limited scope,and the drastic reaction conditions required to assemble the thiophene unit. Their reactivity with activated alkenes such as fulvenes, [13] azirines, [14] maleimides, [15] and acenaphthylene [16] has also been sporadically reported.…”