Rhodium-Catalyzed Intermolecular [2 + 2] Cycloaddition of Terminal Alkynes with Electron-Deficient Alkenes

Abstract

The first catalytic intermolecular [2 + 2] cycloaddition of terminal alkynes with electron-deficient alkenes is reported. The reaction proceeds with an 8-quinolinolato rhodium/phosphine catalyst system to give cyclobutenes from various substrates having polar functional groups in high yields with complete regioselectivity.

Functionalized 1,3‐Diaminotruxillic Acids by Pd‐Mediated C–H Activation and [2+2]‐Photocycloaddition of 5(4H)‐Oxazolones

“…Despite the above, access to cyclobutanes by methods other than [2+2]‐photocycloaddition are scarce and in many cases they do not allow complex structures to be built. In addition, the selectivity of [2+2]‐photocycloadditions in solid state is good, provided that the topochemical Schmidt′s conditions are fulfilled, but they usually show a low selectivity in solution . Therefore, the synthesis in solution of cyclobutanes with well‐defined stereochemistry remains a significant challenge.…”

Rhodium-Catalyzed Dimerization of Arylacetylenes and Addition of Malonates­ to 1,3-Enynes

“…IR (KBr): 2961w, 2939w, 2908w, 2840w, 1654m, 1604m, 1559w, 1507s, 1289m, 1248s, 1180m, 1030s, 899m, 837s = 55.30, 55.33, 87.5, 90.5, 113.7, 114.0, 115.3, 118.1, 127.3, 130.0, 130.1, 133.1, 159.7, 159 2955w, 1732s, 1617m, 1434w, 1418w, 1327s, 1271m, 1251m, 1229w, 1167s, 1109s, 1068s, 1017m, 967w, 908w, 857w, 842m, 828m cm -1 . 13 One-Pot Rhodium-and Palladium-Catalyzed Reaction between Phenylacetylene (1a) and Malonate 5b; Dimethyl 2-(2,4-Diphenylbuta-2,3-dienyl)-2-methylmalonate (7) In a glovebox, Pd(OAc) 2 (1.1 mg, 0.005 mmol, 1 mol%), TDMPP (2.2 mg, 0.005 mmol, 1 mol%), toluene (0.5 mL), and phenylacetylene (1a; 51 mg, 0.5 mmol, 1 equiv) were added into a 10 mL Schlenk tube in this order. The solution was stirred for 1 h, after which a solution of 2 (8.9 mg, 0.025 mmol, 5 mol%) and P(p-anis) 3 (17.8 mg, 0.05 mmol, 20 mol%) in toluene (0.5 mL), CsF (76.0 mg, 0.5 mmol, 1 equiv), and 5b (365 mg, 2.5 mmol, 5 equiv) were added.…”

“…Our group has recently reported anti-Markovnikov addition of alcohols, 11 secondary amines 12 as well as the [2+2] cycloaddition of electron-deficient alkenes 13 to terminal alkynes catalyzed by 8-quinolinolato rhodium complex systems. During the course of these studies, the formation of alkyne oligomers as by-products was observed.…”

“…Dimethyl 2,4-Bis(4-fluorophenyl)cyclopent-3-ene-1,1-dicarboxylate (6d) Yield: 12 mg (34%); white solid; mp 138 °C. IR (KBr):3059w, 3000w, 2951w, 2843w, 1728s, 1602w, 1510s, 1507s, 1437m, 1302w, 1280s, 1257m, 1217w, 1201m, 1181m, 1165s, 1104m, 1060m, 964w, 951w, 939w, 826m, 788w cm -1 13. C NMR (CDCl 3 ): δ = 40.8, 52.1, 53.1, 56.4, 64.9, 114.9 (d, J C,F = 20.7 Hz), 115.4 (d, J = 21.6 Hz), 125.6, 127.5 (d, J = 8.5 Hz), 130.6 (d, J C,F = 7.5 Hz), 131.0 (d, J C,F = 3.8 Hz), 134.7 (d, J C,F = 2.8 Hz), 139.4, 162.1 (d, J C,F = 246.2 Hz), 162.5 (d, J C,F = 248.0 Hz), 169.6, 172.2.…”

Zirconocene catalyzed diastereoselective carbometalation of cyclobutenes

“…It should be emphasized that all starting cyclobutenes 1 were prepared by a rhodium-catalyzed intermolecular [2 + 2] cycloaddition of terminal alkynes with electron-deficient alkenes. 15 …”