Octa-l,7-diyne

Bis(l-boraadamant-2-yl)methane and -ethane <1998IZV728, 2000IZV501, B-2003MI94> are available via allylboron-acetylene condensation from hepta-l,6-diyne and octa-l,7-diyne, respectively. 

Condensation of triallylborane with octa-l,7-diyne (130-140 °C, 3 h) followed by treatment with methanol afforded a mixture of stereoisomeric l,4-bis(3-methoxy-3-borabicyclo[3.3.1]non-6-en-7-yl)butanes 66a and 66b (Scheme 26). Hydroboration of the latter with H3B-THF in THF and heating under reflux for 2 h gave rise to a mixture of racemic bis-l-boraadamantanes 67a and meso-ioim 67b in 94% overall yield. Pure racemate 67a was isolated by crystallization from the reaction mixture (THF) and converted to the pyridine complex 64 whose structure was established by X-ray diffraction analysis. 

Complexes 68 (mp 173 °C) and 69 (mp 114°C) were prepared starting from the reaction between trimethallyl-borane and octa-l,7-diyne (Scheme 27) . 

Octa-l,7-diyne, Nona-1,8-diyne, and Deca-l -diyne... 

Likewise, a,co-diynes can be used in this cycloaddition for instance, octa-l,7-diyne 176 affords the 5,6,7,8-tetrahydroisoquinoline 177 with nitriles ... 

Dien-4-ynes 136 (R -R = alkyl) are produced from propargylic carbonates 135 and terminal alkynes in the presence of a palladium-phosphine complex and copper(I) iodide. The linear co-dimerization of terminal acetylenes and 1,3-dienes is catalyzed by ruthenium(cyclooctadiene)(cyclooctatriene)(trialkylphosphine) (alkyl = Et, Bu or octyl) thus 1-hexyne and methyl penta-2,4-dienoate give a mixture of the eneynes 137 and 138. Coupling of octa-l,7-diyne (139) with the acetylenic bromo acid 140 in aqueous THF-methanol containing butylamine, hydroxylamine hydrochloride and copper(I) chloride gave a mixture of the triynyl acids 141 and 142. ... 

The heat of hydrogenation of octa-l,7-diyne might be expected to be twice that of 1-butyne, which is in effect one half of the molecule. The difference is only 0-6 kcal/mole. The heat of hydrogenation of hexa-l,5-diyne —139-4) compares closely with that found for octa-l,7-diyne, as might reasonably be anticipated. Also, the heat of hydrogenation of dodeca-3,9-diyne (—131 15) is close to that estimated for two moles of 3-hexyne, (ca. —131 6). In octa-l,7-diyne, hexa-l,6-diyne, and dodeca-... 

A mixture of propargyl bromide and tetrahydrofuran added during 45 min. with ice-cooling below 30° to Al and a trace of HgClg in the same solvent, stirring continued 1 hr. at 25-30°, 1,2-dichloro-1,2-diethoxy ethane and tetrahydrofuran added in one portion at 0°, and kept ca. 2 hrs. at 40-50° -> 4,5-diethoxy octa-l,7-diyne. Y 87%. Also the dimethoxy analog s. H.-J. Kabbe, E. Truscheit, and K. Eiter, A. 68A, 14 (1965). 

Octa-l,7-diyne treated with CO2 (initial pressure 50 kgcm - at room temp.) in THF at 100° in the presence of 10 mol.% of Ni(0)-catalyst (prepared from Ni(cod)2 2 eqs. l-(2 -pyridyl)-2-(di-A -butylphosphino)ethane) for 20 h - 5,6,7,8-tetrahydro-3/f-2-benzopyran-3-one. Y 68%. Such functionalized tert. phosphines with hard ligand components owe their effectiveness to intramolecular coordination of the pyridyl group to the Ni-atom in a 6-membered chelate. Trialkylphosphine ligands were not effective for terminally unsubst. acetylenes. F.e. and effect on regioselectivity s. T. Tsuda et al., J. Chem. Soc. Chem. Commun. 1989, 9-10 review of syntheses based on pyridine coordination s. P. Tomasik, L. Brzozka, Wiadom. Chem. 41, 741-57 (1987). 

Higher-order Cycloaddition Reactions. Recently, Rigby and coworkers observed another product during their studies on the three component cycloaddition reactions using tethered alkynes. Thus, a photochemically promoted reaction between thiepin chromium complex 1 and excess octa-l,7-diyne 10 gave pentacycle 12 in 45% yield. Likewise, nonadiene 11 provided pentacycle 13 in 38% yield (eq 4). ... 

With terminal alkynes, a mixture of 2,3,6- and 2,4,6-trisubstituted pyridines is obtained, in which the symmetrical products 183 predominate. Likewise, a,ci)-diynes can take part in this cycloaddition for instance, octa-l,7-diyne (184) affords the 5,6,7,8-tetrahydroisoquinoline 185 with nitriles ... 

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