Remarkable Synthesis of 2-(Z)-6-(E)-4H-[1,4]-Thiazepin-5-ones by Zwitterionic Rhodium-Catalyzed Chemo- and Regioselective Cyclohydrocarbonylative Ring Expansion of Acetylenic Thiazoles

Abstract

Cyclohydrocarbonylative ring expansion of acetylenic thiazoles in the presence of CO, H(2), and catalytic quantities of the zwitterionic rhodium complex (eta(6)-C(6)H(5)BPh(3))(-)Rh(+)(1,5-COD) and triphenyl phosphite affords thiazepinones in 61 to 90% yields. This novel transformation of a 5- to a 7-membered heterocycle is readily applied to acetylenic thiazoles containing hydro, alkyl, alkyl halide, vinyl, and benzo substitutents in positions 4 and 5 of the thiazole ring in addition to alkyl-, ether-, ester-, vinyl-, and aryl-substituted alkynes at position 2.

Synthesis of Multi‐Substituted 2‐Iminopyridine by Conjugate Addition of Ethyl Cyanoacetate Derivatives to Alkynyl Imines

“…13 C NMR spectra were recorded with a JEOL EX-270 (67.8 MHz) or JNM α-500 spectrometer (126 MHz). Chemical sifts are reported in δ units, parts per million from the central peak of CDCl 3 (δ = 77.0 ppm) as the internal reference.…”

“…Ethyl cyanoacetate derivatives 1b [11] and 1c, [12] alkynyl imines 2d, [7a] 2e [7a] and 2f [7a] and alkynylthiazole 8 were prepared according to the literature. [13] A solution of ammonia in dichloromethane was prepared by extracting ammonia from aqueous ammonia with dichloromethane and drying with sodium sulfate. All reactions were carried out under argon.…”

“…1 H NMR (500 MHz, CDCl 3 ): δ = 8.02 (s,1 H),2 H),2 H),4 H),4 H),2 H),3.94 (q,J = 7.2 Hz,2 H),3.85 (s,3 H), 0.92 (t, J = 7.2 Hz, 3 H) ppm. 13 C NMR (126 MHz, CDCl 3 ): δ = 165. 2, 159.5, 143.7, 138.5, 130.5, 128.4, 128.1, 127.4, 127.1, 126.6, 114.9, 108.0, 60.2, 55.5, 13.7 = 3431, 2930, 2838, 1719, 1622, 1559, 1511, 1442, 1368, 1308, 1256, 1201, 1080, 1128, 1074, 1024, 900, 837, 799, 766, 737, 704, 603 = 164.8, 160.6, 159.4, 146.5, 143.7, 135.7, 135.5, 134.8, 129.5, 128.3, 128.0, 127.5, 126.0, 114.8, 107.8, 60.3, 55.5, 29.3, 24.8, 22.3, 21.5, 14.3 = 3314, 2928, 1710, 1619, 1559, 1507, 1459, 1416, 1367, 1296, 1223, 1173, 1071, 1035, 833, 797, 736, 710 cm -1 .…”

“…1 H NMR (500 MHz, CDCl 3 ): δ = 8.00 (s,1 H),2 H),3 H),2 H),2 H),4.25 (q,J = 7.2 Hz,2 H),3.83 (s,3 H),2 H),2 H),1.31 (t,J = 7.2 Hz,3 H),2 H),0.73 (t,J = 7.3 Hz,3 H) ppm. 13 C NMR (126 MHz, CDCl 3 ): δ = 165. 2, 160.5, 159.4, 145.5, 144.3, 135.9, 134.8, 130.1, 129.9, 129.1, 128.1, 128.0, 114.8, 107.0, 60.3, 55.5, 32.4 30.9, 22.8, 14.3, 13.6 = 3433, 3058, 2959, 1705, 1633, 1562, 1505, 1414, 1365, 1312, 1284, 1248, 1218, 1175, 1132, 1029, 903, 852, 767, 701 1, 159.7, 144.2, 142.3, 139.0, 134.7, 128.3, 127.7, 127.6, 127.1, 116.0, 115.1, 107.8, 60.1, 55.5, 33.5, 13.7 = 3304, 3074, 2930, 2837, 1715, 1629, 1564, 1510, 1414, 1366, 1286, 1247, 1170, 1122, 1030, 913, 838, 783, 734 8, 159.6, 158.7, 146.5, 142.6, 136.1, 135.7, 134.1, 128.3, 125.3, 123.9, 115.9, 115.1, 107.2, 60.1, 55.5, 33.3, 29.4, 25.0, 22.7, 21.9, 14.4 = 3451, 3048, 2977, 2925, 1650, 1587, 1490, 1442, 1397, 1372, 1305, 1265, 1214, 1148, 1036, 980, 908, 829, 768 2, 157.8, 152.9, 143.6, 140.8, 127.8, 127.7, 126.7, 124.8, 115.1, 113.9, 99.6, 60.0, 14.9, 13.3 = 3442, 2931, 2856, 2198, 1716, 1621, 1553, 1509, 1446, 1378, 1300, 1253, 1227, 1174, 1140, 1079, 1022, 919, 835, 783 9, 159.8, 159.0, 143.9, 137.8, 136.0, 132.2, 130.1, 128.0, 126.2, 125.6, 119.6, 117.4, 115.1, 103.3, 79.5, 74.7, 61.1, 55.6, 28.9, 27.9, 25.7, 25.0, 22.6, 21.8, 21.1, 15.3 …”

Zwitterionic Relatives of Cationic Platinum Group Metal Complexes: Applications in Stoichiometric and Catalytic σ‐Bond Activation

“…Compound 3 displayed exceptionally high regioselectivity in the hydroformylation of vinylarenes and vinyl ethers to branched aldehydes; under appropriate conditions, p-isobutylstyrene (5) afforded quantitatively 2-(4-isobutylphenyl)propanal (6; Scheme 1), which can be exploited as a synthetic intermediate en route to the non-steriodal anti-inflammatory agent ibuprofen. Subsequent reports by Alper and co-workers, as well as other groups, [62][63][64][65][66][67][68][69] documented the utility of 3 and related phenylborate zwitterions in a diversity of substrate transformations involving the breaking and/or forming of EÀH and EÀC s bonds, including (Scheme 2) alkene and alkyne hydroformylation, [37, 39, 42-44, 48, 54-56, 62, 63, 69] the germyl-and silylformylation (silylhydroformylation) of alkynes, [46,49,50,53,67,68] the reductive carbonylation of alkenes, [38] the carbonylation and/or cyclization of allylic amines and bromides, [41,47] hydrocarbonylation and silylcarbonylation reactions, [57,60,61,64] the hydroaminomethylation and hydroaminovinylation of alkenes, [58,59,65,66] ketone hydrosilylation, [40] and imine hydrogenation. [51] Compound 3 and related zwitterions have also M. Stradiotto et al…”