1.3- Dienes acetylene derivs.

Ebdon and coworkers22 "232 have reported telechelic synthesis by a process that involves copolymerizing butadiene or acetylene derivatives to form polymers with internal unsaturation. Ozonolysis of these polymers yields di-end functional polymers. The a,o>dicarboxy1ic acid telechelic was prepared from poly(S-s tot-B) (Scheme 7.19). Precautions were necessary to stop degradation of the PS chains during ozonolysis. 28 The presence of pendant carboxylic acid groups, formed by ozonolysis of 1,2-diene units, was not reported. 

Markl et al.92 have obtained heterocyclohexa-2,5-dienes (51), by cycloaddition of arylphosphines, arylarsines, and dialkylstannanes with acetylene derivatives in the presence of 18-crown-6 and benzene. The technique is superior to the conventional free radical method (benzene, AIBN) or to the method employing a strong base (BuLi, THF, or NH2Na,NH3). 

Reaction of the metal substituted acetylene derivative 328 with diphenylcarbodiimide affords the [2+4] cycloadduct 329 In this unusual reaction diphenylcarbodiimide reacts as the diene, involving one of the aromatic double bonds, and the metal substituted acetylene derivative reacts as the dienophile. 

See also acetylenic compounds, alkylmetals, alkynes, azides, boranes, CYANO COMPOUNDS, DIENES, HALOACETYLENE DERIVATIVES, HALOGEN OXIDES, METAL ACETYLIDES, METAL EULMINATES, OXIDES OF NITROGEN... 

The synthesis of (5S,15S)-diHETE is shown in Scheme 4.16 and makes use of Pd-Cu coupling of a terminal acetylene to trans vinyl bromides (48 + 50 —> 51 and 51 + 49 — 52) to obtain eneynes. The acetylenes are reduced by catalytic hydrogenation to give the requisite cis-trans dienes. Acetylenes 46 and 47 bear the suitable optically active secondary alcohols for the (5S)and (155)-alcohol functions in the natural product and are derived from chiral reductions of the corresponding ketones. ... 

Hexafluoroacetone azine reacts with two equivalents of terminal olefins (71JCS(C)2404) and with acetylene derivatives (75TL1125), forming 1,5-diazabicy-clo[3.3.0]octenes and l,5-diazabicyclo[3.3.0]octa-2,6-dienes 27, respectively (Scheme 27). The cycloaddition involves two [3 + 2] processes. The structure of azamethineimine is confirmed by X-ray analysis data (74AGE475). 

Disubstituted quinolines of type 21 were obtained from acetylenic ketones 2 as a result of a condensation reaction with 2-amino thiophenol 19 followed by sulfur extrusion (entry f). Acetylenic ketones have also been employed as dienophiles in Carbonyl-Alkyne-Exchange (CAE) reactions with dienes 22 (derived from 2,2-dialkyl-2,3-dihydro-4//-pyran-4-ones )(entry g) or 24 (entry h) to yield aromatic compounds 23 and 25 in a highly regioselective way. 

Dienes from 1,2,3-trienes via reductive carboxylation Synthesis of acetylene derivatives from 1,2,3-trienes Reductive alkylation... 

CM-l,2-Ethylene-l,2-disilanes from acetylene derivs. A soln. of tolan in benzene-d added to 2 eqs. r/5-bis(dimethylphenylsilyl)bis(methyldiphenylphosphine)platinum, and allowed to react at room temp, for 15 min - Z-l,2-bis(dimethylphenylsilyl)-l,2-diphenylethene. Y 79%. F.e. and 1,2-disilylation of unactivated ethylene derivs., also 1,4-disilylation of 1,3-dienes, s. T. Kobayashi et al., Chem. Letters 1989, 467-70. 

Diene synthesis with 5-vinyl-2,3-dihydro-1,4-dioxins Phenolether ring from acetylene derivs. via 2,3,4a,7-tetrahydro-1,4-benzodioxins... 

Intramolecular diene synthesis with acetylene derivs. 

Phosphonic acid esters from chlorophosphites— 1,3-Dienes from acetylene derivatives s. 19, 725... 

Isoxazoles from nitrile oxides and acetylene derivatives—Diene syntheses s, 18, 758 isoxazoles from stable sterically hindered nitrile oxides s. G. Grund-mann and J. M. Dean, J. Org. Ghem. 30, 2809 (1965) reactions with cyanogen di-N-oxide s. G. Grundmann et al., A. 687, 191 (1965)... 

Without additional reagents 1,4-Dienes by aiiylie addition of ethylene derivatives to active acetylene derivatives... 

Mercuric acetate/sodium tetrahydridoborate Oxymercuration-demercuration s. 22, 143 improved yields with mercuric trifluoroacetate, Markownikoff monohydration of dienes, s. J. Org. Chem. 37, 1941 (1972) ketones from acetylene derivs. s. G. Chandra, D. Devaprabhakara, and M. S. Muthana, Current Sci. 40, 400 (1971)... 

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