Tandem Cross-Coupling of Alkynyl Sulfides and Alkynyl Sulfoxides/[3,3]-Sulfonium Rearrangement to Construct Tetrasubstituted Furans

Abstract

In the presence of boron trifluoride, a variety of alkynyl sulfides and alkynyl sulfoxides undergo tandem cross-coupling/[3,3]-sulfonium rearrangement followed by 5-exo-dig heterocyclization. The strategy provides concise access to novel tetrasubstituted furans in good to high yields with 100% atom-economy efficiency. Further derivatization of the resultant furans was feasible by utilizing the incorporated alkylthio groups.

Sulfur in Waste‐Free Sustainable Synthesis: Advancing Carbon–Carbon Coupling Techniques

“…More complex cationic cascades are catalyzed by hard Lewis acids (such as BF 3 ), which activate alkynyl sulfides and trigger the formal [3+2] cycloaddition of alkynyl sulfides and alkynyl sulfoxides with the migration of the thiyl moiety (Scheme 12c). [110] In addition to effective stabilization of cationic intermediates, alkynyl sulfides are excellent traps for electrophilic radicals and are capable of maintaining a halogen transfer radical addition chain reaction (Scheme 13a). [111,112] Under photocatalytic reaction conditions, 1,5-HAT-mediated halogen transfer allows for a more complex radical cascade (Scheme 13b).…”

“…Among the uncommon reactivity of alkynyl sulfides, cobalt‐catalyzed [4+2] cycloaddition reactions (Scheme 12a) [107,108] and soft Lewis acid (such as Ag + cations)‐promoted [3+2] cycloaddition reactions with migration of the aryl substituent attached to S (Scheme 12b) [109] stand out. More complex cationic cascades are catalyzed by hard Lewis acids (such as BF 3 ), which activate alkynyl sulfides and trigger the formal [3+2] cycloaddition of alkynyl sulfides and alkynyl sulfoxides with the migration of the thiyl moiety (Scheme 12c) [110] …”

Organic Base-Facilitated Thiol–Thioalkyne Reaction with Exclusive Regio- and Stereoselectivity

“…28 was prepared as a colorless oil according to general procedure A in 87% yield (169.1 mg; elute: PE/EA = 2:1, R f = 0.5): 1 (Z)-4-((1-(Phenylthio)hex-1-en-2-yl)thio)phenol (29). 29 was prepared as a colorless oil according to general procedure A in 93% yield (147.2 mg; elute: PE/EA = 10:1, R f = 0.3): 1 H NMR (400 MHz, CDCl 3 ): δ 7.42−7.40 (m, 2H), 7.35−7.31 (m, 4H), 7.25−7.22 (m, 1H), 6.81−6.78 (m, 2H), 6.38 (s, 1H), 5.11 (s, 1H), 2.17 (t, J = 4.0 Hz, 2H), 1.79 (s, 1H), 1.48−1.44 (m, 1H), 1.29−1.20 (m, 2H), 0.83 (t, J = 8.0 Hz, 3H); 13 (35). 35 was prepared as a colorless oil according to general procedure A in 93% yield (145.3 (37).…”

“…Thioalkynes are one type of electron-rich internal alkynes exhibiting unique reactivities in a variety of transformations, such as hydrosilylation, − hydroboration, cycloaddition with different partners, − etc. One emblematic instance is the annulation of thioalkynes with organic azides under mild iridium catalysis, which displays regiospecificity in the generation of fully substituted 1,2,3-triazoles .…”

Regio- and stereospecific thiol-thioalkyne reaction facilitated by organic base

“…[12][13][14] Introduction of electronwithdrawing groups (EWG) could lead  addition in a nucleophilic manner, howbeit achieving stereospecificity, which has demonstrated to be critical in determining material behaviours, [15][16][17] is still an issue (Scheme 1b). [18][19][20][21][22] Thioalkynes are one type of electron-rich internal alkynes exhibiting specific reactivity in a variety of transformations, 23 such as hydrosilylation, [24][25][26] hydroboration, 27 and cycloaddition with different partners, [28][29][30][31][32][33][34][35][36] etc. One emblematic instance is the annulation of thioalkynes with organic azides under mild iridium catalysis, which displays regiospecificity in the generation of fully substituted 1,2,3-triazoles.…”