Benzene, 1,2-diethynyl

Benzene, o-dibenzoyl-isoindole synthesis from, 4, 330 Benzene, diethynyl-polymerization, 1, 295 polymers... 

A-Substituted polypyrazoles can also be obtained by using A-alkylhydrazines, and it should be noted that these polymers consist of a random mixture of head-to-head and head-to-tail structures. Other syntheses of polypyrazoles have been described in the literature. Thus polyphenylene pyrazoles (742) and (743) occurred when m- or p-diethynyl-benzene (DEB) reacted with 1,3-dipoles such as sydnones or bis(nitrilimines) (Scheme 64). 

Previously developed methodology <1996CHEC-II(8)889, B-1984MI1> was applied to the construction of bis-2-spiro-l-boraadamantane 65 in 16% overall yield starting from triallylborane and fra r-l,4-diethynyl-l,4-dimethoxycyclohexane 73 (Scheme 29). The product was purified by chromatography, and the crystals formed incorporated two molecules of benzene for each molecule of 65. The benzene was removed under high vacuum. 

The bromine atoms in 2,5-dibromo-l,3,4-thiadiazole 54 undergo a palladium-catalyzed Stille reaction with the organostannyl derivative 55 (Equation 7) <1998CEJ2211>. The thiadiazole 54 was co-polymerized with diethynyl benzene 56 (Equation 8) and diethynyl pyrrole in a Sonogashira cross-coupling reaction <2005MM4687>. 

A paper by Meijer et al. described the synthesis and electronic properties of a series of PPE-PPV hybrid oligomers. The approach is shown in Scheme 11 [70]. Starting from a brominated stilbene, reaction with a series of diethynyl-benzenes furnished pentameric PE-PV hybrids in yields around 80%. The materials are used as emitters in LEDs and other electrooptical devices. It was noted that fibrous aggregates formed upon melting and recooling of thin films of these pentameric PE-PV hybrids. 

In their early contribution, Griitzmacher and Lohmann identified diethynyl-benzene (65) instead of 1,3-didehydronaphthalene (51) as the pyrolysis product of 1,3-dinitro- and 1,3-dibromonaphthalene, based on the high ionization potential measured (8.96 0.02 eV). Obviously, a rearrangement analogous to the ring opening of m-benzyne takes place for the annellated derivative as well (Schemes 16.10 and 16.18). 

Polycarbosilanes with the structure [SiR2—C=C—Z—C=C] (R2SiI 2,3,4,5-tetraphenyl-l-sila-2,4-cyclopentadiene Z 1,4-benzene, 4,4 -biphenyl, 9,10-anthracene, 2,7-fluorene and 2,6-pyridine, 6,6 -bipyridine, 2,5-thiophene, 2,6-p-dimethylaminonitrobenzene, 2,6-p-nitroaniline, 2,6-p-nitrophenol and 2,7-fluoren-9-one) were prepared by the reaction of l,l-diethynyl-2,3,4,5-tetraphenyl-l-sila-2,4-cyclopentadiene with the appropriate (hetero)aromatic dibromide or diiodide in the presence of [(PPh3)2PdCl2] and Cul182 (equation 69). 

Of particular interest to the formation of polymers is the fact that many bistetracyclones have been synthesized by this method (17, 18). The reaction of bistetracyclones X, XV, and XVI with m- and p-diethynyl-benzene (XVII and XVIII) in toluene at 225°C. for 24 hours, afforded the phenylated polyphenyls XIX and XX in quantitative conversions (16,19,22). 

The polymerization of the bispyrones XXX and XXXI with p-diethynyl-benzene (XVIII) in toluene at 225°-300°C. for 20-48 hours produced both soluble and insoluble fractions of polymers XXXII and XXXIII (Reactions 21 and 22). The soluble portions were only relatively low molecular weight ( [17] = 0.1). These materials did show the same excellent thermal stability as exhibited by the polyphenyls of type XIX and XX. 

The dibenzo derivative of a cyclic acetylenic silane 96 was synthesized by mono-deprotonation of 1,2-diethynyl-benzene with 1 equiv of lithium hexamethyldisilazide (LiHMDS) followed by treatment with 0.5equiv of dichlor-odiphenylsilane (formation of 95). A repeat of the deprotonation step, followed by silylation cycle, gave 96 in 77% yield after column chromatography (Scheme 19). One-step preparation of 96 using 2 equiv of base and 2 equiv of the silylation agent also yielded the desired product, however, the yield was 50% of those of the previous method... 

Preparation of Poly[3-Diethynyl Benzene-co-(tris-(3-Ethynyl-Phenyl) Trimesate)]... 

In transformations analogous to those in equation (39), Rh(PPr3)2 fragments have been attached to the alkynyl substituents of 1,3,5-triethynylbenzene and various diethynyl-benzenes and naphthalenes, and converted to vinylidenes as illustrated in (56) and (57). ... 

Decarbonylation (2, 451 3, 327-329 4, 559). 1,3-Diynes (2) can be prepared from diethynyl ketones (1) by treatment with 1 eq. of trisftriphenylphos-phine)chlororhodium in refluxing benzene (15 hr.) or refluxing xylene (1-4 hr.). 

A luminescence study of the solid-state photopolymerization of p-diethynyl-benzene,58 the photopolymerization of epoxides,57 other photochemical poly-... 

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