Rhodium(II)-Catalyzed Annulative Coupling of β-Ketothioamides with α-Diazo Compounds: Access to Highly Functionalized Thiazolidin-4-ones and Thiazolines

Abstract

An operationally simple and efficient one-pot protocol for the synthesis of highly functionalized thiazolidin-4ones and thiazolines has been devised via Rh(OAc) 2 -catalyzed annulative coupling of β-ketothioamides with diazo compounds under mild reaction conditions for the first time. This double functionalization of diazo compounds proceeds via selective Salkylation followed by intramolecular N-cyclization enabling the formation of C−S and C−N bonds at moderate temperature. Notably, the products possess Z-stereochemistry with regard to the exocyclic CC double bond at the 2-position of the ring. Further, the synthetic utility of the strategy has been revealed to access 2,3-dihydrobenzo[d]thiazoles. Remarkably, atom economy and tolerance of a wide range of functional groups are added characteristics to this strategy.

Pyridine vs DABCO vs TBAB in Annulations of δ-Acetoxy Allenoates with Thioamides Leading to Dihydrothiophene, Thiopyran, and Thiazole Scaffolds

“…Following the general procedure, the reaction of 1a (44.6 mg, 0.20 mmol) with 2d (70.6 mg, 0.24 mmol), pyridine (3.2 mg, 0.20 mmol) and K 2 CO 3 (55.3 mg, 0.4 mmol) afforded 3ad as a gummy liquid. Yield 69.5 mg (76%); 1 H NMR (500 MHz, CDCl 3 ) δ 10.22 (s, 1H), 7.24 (d, J = 7.5 Hz, 2H), 7.20−7.14 (m, 6H), 7.06−7.04 (m, 1H), 6.95 (dd, J = 15.5, 9.0 Hz, 1H), 5.78 (d,J = 15.5 Hz,1H), 4.20 (d, J = 1.5 Hz, 1H), 4.11 (q, J = 7.0 Hz, 2H), 3.94 (q, J = 7.0 Hz, 2H), 3.83 (d, J = 9.0 Hz, 1H), 1.19 (t, J = 7.0 Hz, 3H), 0.98 (t, J = 7.0 Hz, 3H); 13 C{ 1 H} NMR (125 MHz, CDCl 3 ) δ 166. 8, 166.2, 161.1, 145.8, 141.6, 140.1, 132.9, 129.4, 128.8, 128.5, 125.0, 121.7, 121.6, 95.5, 60.9, 59.5, 55.6, 54.8, 14.3 9 , 14.3 6 ; IR (neat) ν max 3248, 2979, 2928, 1716, 1643, 1593, 1565, 1461, 1410, 1367, 1238, 1156, 1030, 1H), 1.30 (t, J = 7.0 Hz, 3H), 1.06 (t, J = 7.0 Hz, 3H); 13 C{ 1 H} NMR (125 MHz, CDCl 3 ) δ 166.…”

Recent Advances in Retained and Dehydrogenative Dual Functionalization Chemistry

“…Singh and co-workers recently reported a Rh(II)-catalyzed annulative coupling reaction of β-ketothioamides (29) with αdiazo compounds (30) to obtain corresponding thiazolidinones (31) (Scheme 9). [13] The annulative coupling reaction proceeds through the generation of rhodium carbenoid species (29-A) from Rh(OAc) 2 and 30 via the extrusion of nitrogen. Addition of a thiocarbonyl group in 29 provides sulfonium ylide intermediates (29-B), and the subsequent proton transfer of 29-B generates N,S-acetals (29-C).…”

Synthesis and application of novel urea–benzoic acid functionalized magnetic nanoparticles for the synthesis of 2,3-disubstituted thiazolidin-4-ones and hexahydroquinolines

“…Nitrogen/sulfur-containing heterocycles with innumerable advantages in agricultural industry and medicinal chemistry are lucrative molecules for any researchers which are involved. 49–52 In this instance, thiazolidine-4-one derivatives as magic example of sulfur-containing heterocycles, have decisive roles in many functional materials, pharmaceuticals and natural products. 53–56 Alternatively, extensive applications of thiazolidines as antiinflammatory, 57 cardiovascular, 58 anticancer, 59 antimicrobial, 60 antioxidant, 61 antimycobacterial, 62 COX-1 inhibitor 63 and antiviral activities 64 are privileged property of these materials (Scheme 1).…”