Intermolecular Pauson−Khand Reactions of Cyclopropene:  A General Synthesis of Cyclopentanones

Abstract

[reaction: see text] The Pauson-Khand reaction of cyclopropene with a variety of terminal alkynes has been studied. The best reaction conditions involve NMO activation in CH(2)Cl(2) at -35 degrees C. In this way, 3-substituted-bicyclo[3.1.0]hex-3-en-2-ones have been obtained in good to excellent yields. As a synthetic application, several types of substituted cyclopentenones have been prepared from these cycloadducts by protocols involving conjugate addition and reductive ring opening.

Rhodium‐Catalyzed Hydrosilylation Reaction of N‐Sulfonyl‐1,2,3‐triazoles with Triphenylsilane: Access to Diverse Compounds

“…Optimization of conditions for rhodium-catalyzed hydrosilylation reaction of 4-p-tolyl-1-tosyl-1H-1,2,3-triazole (1b) with trialkylsilane (2), which leads to 2-(trialkylsilyl)-2-p-tolyl-N-tosylethanimine (IIb), and synthesis of (E)-2-(trialkylsilyl)-2-p-tolyl-N-tosylethenamine (3b) and 2-(trialkylsilyl)-2-p-tolyl-N-tosylethanamine (4b). H, 13 C NMR and mass spectrometry (see Supporting Information for the details). However, IIba was not stable under acidic, basic, and neutral aqueous conditions, so the following two procedures were carried out (Reactions A and B).…”

“…We attempted detriphenylsilylation of 4 in the presence of tetra-n-butylammonium fluoride (TBAF) and NaOH according to known conditions. [13] As shown in Scheme 4, the deprotection of 4a or 4b was successfully performed in mixed solvent of THF and water at 60°C, and corresponding arylethylamine derivatives 6a and 6b were obtained in 87 and 83 % yields, respectively. Therefore, the rhodium-catalyzed hydrosilylation method provides access to diverse compounds.…”

“…3, 136.8, 136.4, 135.9, 134.1, 133.1, 132.9, 130.3, 130.06, 130.02, 129.5, 128.0, 126.9, 117.4, 21.8 4, 136.4, 133.5, 133.3, 133.2, 130.0, 129.4, 129.3, 128.8, 127.9, 127.1, 126.9, 119.3 9, 137.4, 137.1, 136.4, 133.7, 133.3, 129.9, 129.3, 128.9, 127.9, 127.5, 127.1, 118.6, 34.4, 23.8 43-7.38 (m, 3 H), 7.36-7.27 (m, 12 H), 7.20-7.16 (m, 3 H) 4, 137.5, 136.5, 133.8, 133.3, 131.4, 129.9, 129.3, 129.1, 128.9, 127.9, 127.1, 118.7, 114.5, 55.9 08-7.97 (m, 3 H), 7.78-7.65 (m, 3 H), 7.41-7.35 (m, 3 H), 7.28-7.19 (m, 12 H), 7.19-7.13 (m, 3 H), 6.70-6.63 (m, 3 H), 6.56 (d, J = 12.4 Hz, 1 H) ppm. 13 C NMR (CDCl 3 , 150 MHz): δ = 137. 4, 136.5, 136.4, 135.1, 133.5, 133.1, 132.3, 129.8, 129.5, 129.3, 129.2, 128.8, 128.4, 128.2, 128.0, 127.9, 127.1, 121.9, 5, 136.5, 133.2, 133.0, 129.9, 129.4, 129.0, 128.0, 127.2, 117.8, 41.6 45-7.40 (m, 3 H), 7.40-7.27 (m, 17 H), 7.20-7.13 (m, 3 H), 6.80 (d, J = 7.6 Hz, 2 H), 6.39 (d, J = 11.7 Hz, 1 H), 6.31 (d, J = 11.7 Hz, 1 H), 4.24 (s, 2 H) ppm.…”

“…4, 136.5, 136.4, 135.1, 133.5, 133.1, 132.3, 129.8, 129.5, 129.3, 129.2, 128.8, 128.4, 128.2, 128.0, 127.9, 127.1, 121.9, 5, 136.5, 133.2, 133.0, 129.9, 129.4, 129.0, 128.0, 127.2, 117.8, 41.6 45-7.40 (m, 3 H), 7.40-7.27 (m, 17 H), 7.20-7.13 (m, 3 H), 6.80 (d, J = 7.6 Hz, 2 H), 6.39 (d, J = 11.7 Hz, 1 H), 6.31 (d, J = 11.7 Hz, 1 H), 4.24 (s, 2 H) ppm. 13 C NMR (CDCl 3 , 150 MHz): δ = 137. 5, 136.5, 133.5, 133.2, 130.8, 129.8, 129.22, 129.17, 129.09, 128.98, 128.4, 127.9, 127.1, 116.1, 60 5, 137.3, 136.5, 133.09, 133.07, 132.7, 132.6, 129.9, 129.3, 128.8, 127.9, 127.7, 127.2, 120 13 C NMR (CDCl 3 , 100 MHz): δ = 143.…”

“…4, 142.5, 137.1, 136.3, 134.9, 132.6, 129.9, 129.7, 129.3, 128.3, 128.0, 127.4, 45.3, 3 5 3 H),14 H),6.63 (d,J = 8.7 Hz,2 H),6.53 (d,J = 8.7 Hz,2 H),4.32 (dd,J = 8.7, J = 2.3 Hz, 1 H), 3.74 (s, 3 H), 3.74-3.63 (m, 1 H), 3.32 (dt, J = 12.8, J = 2.3 Hz, 1 H), 3.00 (dd, J = 12.8, J = 3.7 Hz, 1 H), 2.42 (s, 3 H) ppm. 13 C NMR (CDCl 3 , 100 MHz): δ = 158. 2, 143.3, 137.0, 136.3, 132.5, 130.3, 130.0, 129.7, 129.6, 128.0, 127.3, 114.2, 55.3, 45.3, 34.5, 21.6 = 159.8, 143.4, 139.6, 136.9, 136.3, 132.4, 130.0, 129.7, 129.6, 128.0, 127.3, 122.1, 113.4, 113.2, 54.8, 45.3, 35.9, 21.7 13 C NMR (CDCl 3 , 100 MHz): δ = 157.…”