C«H. 1-Butyne

Dimethyl-1-butyne (0.92 mL, 0.62 g, 7.52 mmol) is added to a solution of l methoxy(phenyl)carbene]pentacarbonylchromium (1.56 g, 5.00 nimbi) in tert-butyl methyl etoer (25 mL), and the resulting mixture is stirred at 45 °C under argon for 2 h. Concentration under reduced pressure and column chromatography... 

A solution of 0.22 or 0.25 mol (for propyne and butyne, respectively, note 1) of butyllithium in ca. 175 or 155 ml (respectively) of hexane is placed into the flask. After cooling to below -10 C, THF (130 ml) is added. Subsequently, a cold (-30 C) mixture of 0.10 mol of propyne or 1-butyne (Chap. IX, exp 1) and 30 ml of THF is added over 10 min in a number of portions, while keeping the temperature of the reaction mixture below -20 C. The cooling bath is then removed and the temperature allowed to rise A white or yellow suspension is gradually formed in the case of propyne and 1-butyne, respectively. The dimetallations are completed by warming the suspensions for an additional 1 or 1.5 h, respectively, at 35-40 C. 

The magnitude of the rate constants, their observed pressure dependence, and the products of the reactions are consistent with the mechanism involving the initial addition of OH to the triple bond. For example, the OH-l-butyne reaction at 298 K is about a factor of three faster than the reaction with n-butane (see Table 6.2), despite the fact that it has fewer abstractable hydrogens and the = C — H bond is much stronger than a primary -C-H bond ( 125 vs 100 kcal mol -1). In addition, a pressure dependence is not consistent with a simple hydrogen atom abstraction (see Chapter 5.A.2). 

CsHuN, Ethanamine, A-ethyl-A-methyl-tungsten complex, 26 40, 42 C6HF5, Benzene, pentafluoro-gold complexes, 26 86-90 C H4I2, Benzene, 1,2-diido-iridium complex, 26 125 CJT, Phenyl platinum complex, 26 136 C,H,N, Pyridine osmium complex, 26 291 OHtS, Benzenethiol osmium complex, 26 304 QH7P, Phosphine, phenyl-cobalt-iron complex, 26 353 QH 1-Butyne, 3,3-dimethyl-mercury-molybdenum-ruthenium complex, 26 329-335 C6H 4P, Phosphine, triethyl-platinum complex, 26 126 platinum complexes, 26 135-140 CsHisPO, Triethyl phosphite iron complex, 26 61... 

A solution, was prepared from 23 g of cyclopropylacetylene (0.348 mol) in 250 mL of THF by dropwise addition of 116 mL of a 3.0 M solution of ethylmagnesium bromide in ether (0.348 mol) over 1 h. This solution was maintained at 0°C for 1 h, then at 40°C for 3 h. To this solution, recooled to 0°C, 15.56 g of l-(2-amino-5-chlorophenyl)-2,2,2-trifluoromethylethanone (0.0696 mol), was added as a solid, portionwise over 5 min. The reaction mixture was allowed to stir at 0°C for 1.5 hours. The reaction was quenched at 0°C by dropwise addition of 700 mL of saturated aqueous ammonium chloride solution. The mixture was extracted with 2 times 400 mL portions of ethyl acetate, the combined organic phases were washed with brine and dried over MgS04. Removal of the drying agent and solvents left a yellow solid. This material was recrystallized from boiling hexanes (100 mL final volume) to afford 14.67 g of 2-(2-amino-5-chlorophenyl)-4-cyclopropyl-l,l,l-trifluoro-3-butyn-2-ol. A second crop (2.1 g) was obtained from concentrating the mother liquors. M.p. 153°-154°C. 

Transfer the supernatant, from step 2, by cannula, to the CuCN/LiBr solution at -20°C. Stir the solution for 15 min, and then warm to 0°C. Add 1,4-dichloro-2-butyne (1.84 g, 15 mmol). Stir the solution for 30 min, and then at room temperature for 1 h. 

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