Phosphinoyl Radical-Initiated 1,2-Bifunctional Thiocyanodiphenylphosphinoylation of Alkenes

Abstract

1,2-Bifuctional thiocyanodiphenylphosphinoylation of alkenes is established through the phosphinoyl radical addition followed by Cu-catalyzed thiocyanation. This one-pot reaction is applicable to a range of aromatic, aliphatic, and cyclic alkenes to afford thiocyanodiphenylphosphinoylated compounds in satisfactory yields.

Copper‐Catalyzed Remote Direct Thiocyanation of Alkyl C(sp3)−H Bonds

“…Examination of the solvent effect showed that CHCl 3 was the best, with a substantial increase of yield to 78%; other solvents, including CH 2 Cl 2 , CH 3 CN, 1,4dioxane and PhCl, only gave inferior results (entries [10][11][12][13][14]. Further changing the reaction temperature to 90°C, 30°C or room temperature gave only unsatisfactory yields (entries [15][16][17], demonstrating the vital thermal effect. In addition, control experiments confirmed that no thiocyanation took place in the absence of the copper catalyst (entry 18), implying the essential role of the catalyst.…”

“…[14,15] Subsequent intramolecular 1,5-HAT of B affords the carbon-centered radical D. Meanwhile, the strong affinity of F and Si [19] would deliver intermediate E, via ligand transfer of C with TMSNCS. [16] After this, there are at least two possible pathways to the final product. For pathway I, radical rebound with D gives rise to R[Cu(III)L n ]SCN F. The final reductive elimination forms the remote C(sp 3 )À H thiocyanation product 2, along with the regeneration of the Cu(I) catalyst.…”

“…However, to date, the corresponding thiocyanation of N-fluoro aliphatic sulfonamides δ-C(sp 3 )À H has not been realized. To continue our interest in this field, we set out to examine the coppercatalyzed δ-C(sp 3 )À H thiocyanation of N-fluoro aliphatic sulfonamides using commercially available trimethylsilyl isothiocyanate (TMSNCS) [16] as coupling partners. By successfully overcoming intrinsically competing side reactions such as direct fluorination [17] and the formation of nitrogen-containing heterocycles, [14d] our protocol allows a variety of alkyl thiocyanates to be synthesized with up to 78% yield, under mild conditions, accompanied by high regioselectivity and good functional group tolerance.…”

Ag/Pyridine Co-Mediated Oxidative Arylthiocyanation of Activated Alkenes

“…In contrast, the 1,2-difunctionalization of alkenes comprising a cascade thiocyanation and β-functionalization is more appealing from a synthetic perspective because of its high economy of steps and atoms. In recent years, many metal-free and transition-metal-catalyzed transformations such as thiocyanooxygenation [ 24 , 25 , 26 , 27 ], dithiocyanation [ 28 , 29 ], thiocyanophosphinoylation [ 30 ], thiotrifluoromethylation [ 31 ], and thiocyanoamination [ 32 ] have been developed ( Scheme 1 ). In spite of these significant advances, arylthiocyanation of alkenes via 1,2-difunctionalization remains relatively unexplored.…”

Electrochemical Oxidative C–H Thiocyanation or Selenocyanation of Imidazopyridines and Arenes

“…8 Consequently, increasing efforts have been devoted to developing new methods to introduce SCN groups onto organic molecules. A series of thiocyanating reagents, 9 including N-thiocyanatophthalimide, 10 N-thiocyanatosuccinimide, 11 N-thiocyanatosaccharin, 12 N-thiocyanatodibenzenesulfonimide, 13 aroyl isothiocyanates, 14 trimethylsilyl isothiocyanate, 15 and various thiocyanate salts (NH 4 SCN, KSCN, NaSCN) have been used for this purpose. Among these reagents, the cheap and readily available thiocyanate salts have been favored in recent years.…”