Hepta-l,6-diynes

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. 

The THF adduct 70 (mp 147 °C) and pyridine adduct 71 (mp 178°C) of bis-l-boraadamantane with one CH2 bridge were synthesized by hydroboration-cyclization of the bis-bicycle 72, available from hepta-l,6-diyne (Scheme 28) . 

The structure of CuCl(hepta-l,6-diyne) consists of Cl-Cu-Cl chains cross-linked by the diyne. Compound CuCI(but-2-yne) is tetrameric, and has a puckered CU4CI4 ring with the copper atoms on the perpendiular bisectors of the triple bonds. Unlike the C=C bond in Zeise s salt, the C=C bond in the alkyne complex is coplanar with the copper and two adjacent chlorine atoms (58). 

Similar reactions of 3,3,5,5-tetramethyl-3,5-disila-hepta-l,6-diyne (60), 3,3,6,6-tetramethyl-3,6-disilaoc-ta-l,7-diyne (61), 3,3,5,5-tetramethyl-4-oxa-3,5-disila-hepta-l,6-diyne (62), and 3,3,4,4,5,5-hexamethyl-3,4,5-trisilahepta-l,6-diyne (63) with the WCl catalyst afford repeating ring-containing polyenes (64-67),... 

Diethyl hepta-l,6-diyne-l,7-dicarboxylate refluxed 3 hrs. with a soln. of excess methylamine in ethanol 2,6-di(ethoxycarbonylmethylene)-l-methylpiperidine. Y 83-90%. F. e. s. W. Parker, R. A. Raphael, and D. I. Wilkinson, Soc. 1959, 2433. N-Heterocyclics from ketenes s. 13, 682... 

Other ir-conjugated polymers, for example, poly(p-phenylene sulfide) [31,32], poly(hepta-l,6-diyne) [33], poly(4,4 -biphenylene) [34], and poly-(p-phenylene vinylene) [35], can be doped with iodine or AsFs, and the electrical conductivities of these doped polymers are significantly high. 

Dimethyl-l-butyne, 2408 1,8-Diphenyloctatetrayne, 3788 Hepta-l,3,5-triyne, 2641 l-Heptene-4,6-diyne, 2707... 

In this general area quite efficient intramolecular examples have been described as well (Scheme 6). A thorough examination of the intermediates and likely mechanisms associated with this system has been published. In particular, it has been found that the type of metallacycle formed depends on the length of the chain separating the two alkyne units in the diyne. Efficient intramolecular cycloaddition to a bicy-clic metallacycle occurs only from 1,6- and 1,7-diynes. The poor results on attempted cyclization of 1,5-diynes to give highly strained bicyclo[3.2.0]hepta-l,4-dien-3-ones result from resistance towards closure of the strained four-membered ring upon metallacycle formation. ... 

Maretina, LA. (2011) Novel data on cycloaromatization of systems, containing (Z)-hex-3-en-l,5-diyne and (Z)-hepta-l,2,4-triene-6-yne units, in Modem Problems of Organic Chemistry, (ed. R.R. Kostikov), St. Petersburg University Press, St Petersburg, pp. 375-410 (Rus), pp. 349-380 (Eng). 

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