Improved Titanium Tetrachloride Procedure for Enamine Synthesis. II. Scope of the Reaction.

Uncovering Reaction Pathways of 1-Aminocyclohexenes with [(1-Alkynyl)carbene]tungsten Complexes Leading to Cyclopentadienes and Dihydropyrroles

“…We assume that both reaction paths are initiated by π-cyclization of the (3Z)-1-tungsta-1,3,5-hexatriene unit of a "semi-open" isomer (3E,3ЈZ)-14aϪc to give first a cyclopentadiene derivative P, from which in- 1,1,1,1,1-Pentacarbonyl-4-[(1-diethylamino-3,4- 1,148.3,143.5,139.8 and 133.7 (each C q ,C1Ј,C4,C4aЈ,C8aЈ,142.7 (CH,C3),129.5,128.6,128.2,127.5,and diethyl(3,amine [20] (2b) (201 mg, 1.00 mmol) were treated as described above in n-pentane solution 127. (1) (482 mg, 1.00 mmol) and (3,4-dihydronaphthalen-1-yl)dipropylamine (2c) [20] (229 mg, (3E)-4b:…”

“…13 C NMR (CDCl 3 ): δ ϭ 147.7 (CH, C2Ј), 144.9 (C q , C9b), 141.8 (C q , i-C Ph), 137.4 (C q , C5a), 130.4 (C q , C9a), 128.7, 127.6, 127.5, 126.4, 126.2, 126.0, and 121.9 (2:2 205.0, 204.8, 204.5, 198.9, 197.7, and 197.6 yl-4,5,6,7-tetrahydroinden-3a-yl)diethylamine (12b), (3-Ethyloxy- 1, and 17.6 [31.7, 25.0, and oxy-3-phenyl-2-propyn-1-ylidene)tungsten (1) (121 mg, 0.25 mmol) 19.7] (each CH 2 , C3ϪC5), 13.6 and 13.4 [15.7 and 13.3] {15.6 and in 1 mL of CDCl 3 was added to (cyclohex-1-enyl)diethylamine 14.6} (2Ј-OCH 2 CH 3 and 2ЈЈ-OCH 2 CH 3 ). Ϫ IR (diffuse reflection): (7b) [20] (38 mg, 0.25 mmol) in an NMR tube at 0°C to give an ν ϭ 2061. 2, 1924.2, 1911.2 cm Ϫ1 .…”

“…75 [a] ine (2a) [3] [20] (173 mg, 1.00 mmol) in n-pentane (4 mL) was stirred at 0°C for 14 h. A precipitate of compound 3a [341 mg, 52%, R f ϭ Scheme 7. Indenes and spiro-tetrahydropyrroles by cyclization of dinuclear complexes 14:…”

“…C 45.14, H 3.52, N 1.25; found C 44.46, H 3.20, N 1.48. 7.01 (3 m, ratio 2:1:2 H, Ph), 7.23 (s, 1 H, 3-H) in 1 mL of CDCl 3 was added to (cyclohex-1-enyl)dipropylamine (7c) [20] (45 mg 294.4 (WϭC2Ј),205.4,204.7,198.6,and 197.7 [1:1:4:4, with compound 7c was performed in chloroform instead of dichloromethane, a protonated aminocyclopentadiene 13c was obtrans-and cis-CO, 2 W(CO) 5 ], 153.8 (C q , C4Ј), 152.6 (C q , C1), 146.8 (C q , C4ЈЈ), 146.7 (CH, C3ЈЈ), 145.3 (C q , i-C 4Ј-Ph), 143.7 tained, from which compound 12c could be generated by treatment with NaOH/H 2 O. Formation of compound 13c as the sole product (CH, C3Ј), 141.3 (C q , i-C 4ЈЈ-Ph), 129.…”

Exploring organic synthetic experimental procedures

“…By this modified procedure, almost quantitative yield could be obtained within a few minutes. It was, however, found that the relative amounts of TiC1Jcarbonyl compound and amine/carbonyl compound which should be used for achiving a rapid enamine formation were highly dependent on the structure of the carbonyl compound [30,32]. In the example shown below, the synthesis of enamine from methyl isobutyl ketone and morpholine was studied by a central composite design.…”