Chloro-5-hexyne

A. 6-Chloro-2-hexyne. A 2-1., three-necked, round-bottomed fiask is equipped with a low-temperature condenser (Note 1), a gas inlet, and a... 

Gas chromatographic analysis at 79° using a flame detector in conjunction with a 183 x 0.32 cm. stainless-steel column containing Dow-Corning 550 fluid on silanized support gave peaks for l-bromo-3-chloropropane (6.5 minutes) and 6-chloro-2-hexyne (9.3 minutes) whose areas were shown to be proportional to the mole fractions. The latter were determined by integration of the expanded (50 Hz sweep width)... 

In contrast to the behavior of 3-hexyne in trifluoroacetic acid, addition of HCl in acetic acid yields essentially rra s-3-chloro-3-hexene (48%) and 3-hexanone (52%) as products, with less than 1% of the cis chloride (31,42,43). The 3-hexanone has been shown to arise from an intermediate vinyl acetate. The kinetics are complicated, but they seem to be of first order in substrate and second order in HCl. Added tetramethylammonium chloride increases the rate of product formation and changes the product composition to >95% trans-3-chloro-3-hexene and <5% 3-hexanone. A termolecular electrophilic addition via an intermediate such as 14 has been proposed (31,42) to account for these data. 

Many examples exist for Pd-catalyzed cross-couplings of alkenylzirconocenes with simple carbocyclic aryl or alkenyl halides, whereas few precedents are seen for the coupling of alkenylzirconocenes with heteroaryl halides. Undheim and coworkers reported a Pd-catalyzed cross-coupling of 2,4-dichloropyrimidine with alkenylzirconocene [50]. Hydrozirconation of hexyne readily took place at room temperature with zirconocene chloride hydride in benzene. The resulting hexenylzirconocene chloride (76) was then coupled with 2,4-dichloropyrimidine at the more electrophilic 4 position, giving rise to 2-chloro-4-[( )-l-hexenyl]pyrimidine (77). 

Although this alkylation of alkali chloroacetylide is completely analogous to the alkylations described in the previous experiments, the procedure for the preparation of 1-chloro-l-hexyne warrants a brief explanation. 

Presence of a certain type of functional groups in alkynes does not interfere with silylformylation. For example, the chlorine atom in 5-chloro-l-pentyne 44 and the cyano group in 5-cyano-l-pentyne 46 do not affect the silylformylation to give 45 and 47 respectively (Equations (10) and (11)). 4-Bromo-l-butyne and 6-bromo-l-hexyne also give the corresponding silylformylation products." ... 

To a large bottle are added 116.5 gm (1.0 mole) of 3-chloro-l-hexyne, 20.0 gm (0.20 mole) of cuprous chloride, 16.0 gm (0.30 mole) of ammonium chloride, 10 ml of concentrated hydrochloric acid, 50 ml of water, and 0.6 gm of copper bronze. The bottle is sealed and shaken at room temperature for 14 days. The organic layer is separated, dried over potassium carbonate, and fractionally distilled through a glass-helix-packed column to afford 61.0 gm (52%) of nearly pure l-chloro-l,2-hexadiene, b.p. 54°-57°C (50 mm), p5 1.4567-1.4680, 9.3 gm (8%) of 3-chloro-l-hexyne, and some polymeric material. Shorter periods of reaction give lower yields. The product is purified as described for bromopropadiene. 

The stereoselective synthesis of the title compounds has been achieved. Thexylborane on reaction with 2 molar equivalents of 1-iodo-l-alkyne at 0 °C proceeds to near completion (88% for 1-iodo-l-hexyne) to form fully substituted organoborane (33), which upon treatment with 2 molar equivalents of sodium methoxide at 0 °C readily produces trans-1,2,3-butatrienes (Eq. 102) 157). The same reaction, however, with either 1-chloro or 1-bromo-l-alkynes is sluggish to form the thexyl-l-halo-l-alkenyl-borane31). 

For 6-chloro-l-phenyl-l-hexyne (X = Cl, > 0 002m), isomerization to the allene is promoted at the cathode and subsequent stepwise reduction (equation 79) to three... 

C6H80S furfuryl methyl sulfide 1438-91-1 449.15 39.021 2 7491 C6H9CI 6-chloro-1-hexyne 10297-06-0 395.42 33.934 2... 

C7H12 4-methyl-2-hexyne 20198-49-6 15.874 131.007 1.2 11588 C7H13CI trans-1-chloro-1-heptene 53268-67-0 16.856 148.858 1,2... 

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