Acetylene derivatives diynes

A 50-60%-soln. of N,N-diethylprop-2-ynylamine in hexane passed al 65° during ca. 40 min. through a KNHa-on-alumina catalyst N,N-diethylprop-l-ynyl-amine. Y 65%. F. e. s. A. J. Hubert and H. G. Viehe, Soc. (G) 1968, 228 enamines from 2-ethyleneamines s. Soc. (G) 1968, 2048 1,3-dienes from acetylene derivatives, also conjugated tetraenes from a,co-diynes, s. Ghem. Ind. 1968, 975. 

When colorless crystals of rac-s-trans-3,8-di-tert-butyl-l,5,6,10-tetraphenyl-deca-3,4,6,7-tetraene-l,9-diyne (123) were heated at 140 °C for 2 h, the ben-zodicylobutadiene derivative (126) was produced as green crystals. As shown in the sequence (Scheme 20), 123 is first isomerized to its s-ds-isomer (124), and intramolecular thermal reaction of the two allene moieties through a [2+2] conrotatory cyclization gives the intermediate 125, which upon further thermal reaction between acetylene moieties gives the final product 126 [19,22].This is another example of the crystal-to-crystal reaction. 

Parker, Raphael, and Wilkinson have investigated a synthetic approach to tropinone (124), which they call the acetylenic route (78). Reaction of hexa-1,5-diyne-l,6-dicarboxylate (145) with methylamine yields the pyrrolidine derivative (146), which by catalytic hydrogenation affords the diester 147 (79,50). 

We can narrow the difference from 10 kJmol-1 even further once it is remembered that in the comparison of meso-bisallene, 27, and (Z, Z)-diene, 29, there are two extra alkylallene and alkylolefin interactions for which a stabilization of ca 3 kJ mol-1 for the latter was already suggested. Admittedly, comparison with the corresponding 1,5-cyclooctadiyne suggests strain-derived anomalies. From the enthalpy of hydrogenation, and thus derived enthalpy of formation, of this diyne from W. R. Roth, H. Hopf and C. Horn, Chem. Ber., 127, 1781 (1994), we find 1/2S (bis-allene, bis-acetylene) equals ca — 80 kJ mol-1. We deduce that the discrepancy of this last 5 quantity from the others is due to strain in the cyclic diyne. 

Acetylene and its derivatives can be polymerized by chain growth in the presence of suitable transition metal catalysts to give high molecular weight (MW) polymers (Equations (l)-(4)). The monomers include acetylene, mono- and disubstituted acetylenes, and a,tv-diynes. The polymers possess carbon-carbon alternating double bonds along the main chain and exhibit unique properties (e.g., metallic conductivity) that are not expected with vinyl polymers. 

Perfluoroalkylcopper reagents couple with 1-iadoacetylenic derivatives to give the expected perfluoroalky(-substituted acetylenes [226] (equation 153) The coupling reaction is complicated by formation of the diyne from competitive exchange processes... 

Woodgate et al. [51] applied the C-H/acetylene coupling to the ortho-selective alkenylation of terpene derivatives (Eq. 27). The basic feature of this reaction is the same as the alkenylation reaction of Murai et al. The combination of acetophenone and diynes provides a new entry for the copolymerization of aromatic ketones with acetylenes. Weber et al. [50] studied extensive reactions of ruthenium-catalyzed C-H/acetylene coupling with respect to the step-growth copolymerization of aromatic ketones and acetylenes (Eq. 28). These coupling reactions provide a new route to the preparation of trisubstituted styrene derivatives. 

Diynes. A general method for preparation of 1,3-diynes, particularly terminal ones, involves palladium-catalyzed coupling of alkynylzinc derivatives with (E)-l-iodo-2-chloroethylene. This alkene is obtained in 83% yield by reaction of acetylene with iodine monochloride in 6 A HCI. Coupling results in a l -chloro-1,3-cnync (1), which is converted into a l-sodio-l,3-diyne (2), which in turn can be reduced or alkylated to give a 1,3-diyne. 

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