Diacetylenes, synthesis

The conducting and physical properties can be modified by the use of 3-/4-substituents, or A-substituents in the case of pyrrole. The counter-ions can be incorporated into a side-chain (self-doping), as in the polymer of 3-(thien-3-yl)propanesulfonic acid. Oligo(thiophenes) are also useful in these applications and have been specifically synthesised up to 27 units long by palladium(0)-catalysed couplings or via the diacetylene synthesis (17.12.1.1). ... 

Oligo(thiophenes) are also useful in these applications and have been specifically synthesised up to 27 units long by palladium(0)-catalysed couplings or via the diacetylene synthesis (section 14.13.2.2). ... 

Various polymerization route with unique starting monomer [64] have been developed, e.g., topochemical poly(diacetylene) synthesis with pyrrole-, thiophene-, -Si-groups dienophilic addition of maleic imides, Diels-Alder polymers via cyclopentadienone derivatives. 

Bloor, D., and R. R. Chance (eds.) Poly diacetylenes Synthesis, Structure, and Electronic Properties, Martinus Nijhoff, Leiden, The Netherlands, 1985. 

Because diacetylene is unstable, a stable diacetylene derivative, 1-methoxybut-l-en-3-yne (65CB98), is often employed in the synthesis of pyrroles. The reaction with ammonia proceeds under conditions of heterogeneous catalysis (a mixture of reagent vapors is passed through a catalyst-containing reactor heated to 150°C), approaching a yield of 50-70% but with primary aromatic amines, the yield drops to 20%. 

The synthesis can be conducted both in solution and without solvents. The reaction in solvent (e.g., methanol, ethanol, dioxane, dimethylformamide) is recommended for volatile 1,3-diynes and amines in this case the pyrroles are purer and the yield is higher. With disubstituted diacetylenes, ammonia and primary alkyl- and arylamines produce 1,2,3-trisubstituted pyrroles under the same conditions (65CB98 71MI1). Since disubstituted diacetylenes are readily obtained by oxidative coupling of acetylenes (98MI2), this reaction provides a preparative route to a wide range of pyrroles. 

The reaction of diacetylene or its monosubstituted homologs with guanidine in the presence of an equimolar amount of sodium ethylate (80°C, EtOH, 14 h) leads to 2-amino-4-alkylpyrimidines (33) (70ZOR1347 71ZOR14). Their structures were proved by comparison of their properties (as well as those of their picrates) with those of authentic samples obtained by independent synthesis. 

The synthesis of thiophene from diacetylene was first performed by Schulte (62CB1943), who used sodium sulfide in aqueous alcohol (pH 8-10), the yield being no more than 20%. 

By using a cocatalyst of Pd-Cu, aryl-alkenyl halides couple efficiently widi alkynes to generate die disubstituted alkynes (Scheme 9.6).8 This coupling reaction has been applied to die synthesis of polyphenyleneethynylenes by Yamamoto et al. in 1984 (Scheme 9.7).9a Due to the ready availability of diacetylenes and the mild coupling condition, this strategy has been widely used for die preparation of many poly(aryleneethynylene)s.9... 

In late 1995, a team led by Vollhardt and Youngs reported their work on the strained PAM/PDM hybrid 80 [55]. Whereas the synthesis of 80 was not remarkable [Eq. (2)1, the solid-state behavior of the molecule was. X-ray crystallography revealed that the macrocycle was moderately strained, with the monoynes bent inward toward the center of the macrocycle by 3.9 -11.5° and the diyne unit bent outward by 8.6-11.2°. More importantly, crystal packing revealed that the diyne moieties were aligned in the prerequisite fashion for topochemical diacetylene polymerization to occur. Indeed, irradiation of crystals of 80 produced a violet... 

Acetylene- and Diacetylene-Expanded Cycloalkanes and Rotanes. 201 1 -42 de Meijere A, Kozhushkov SI, Khlebnikov AF (2000) Bicyclopropylidene - A Unique Tetra-substituted Alkene and a Versatile Cj-Building Block. 207 89-147 de Meijere A, Kozhushkov SI, Hadjiaraoglou LP (2000) Alkyl 2-Chloro-2-cyclopropylidene-acetates - Remarkably Versatile Building Blocks for Organic Synthesis. 207 149-227 Dennig J (2003) Gene Transfer in Eukaryotic Cells Using Activated Dendrimers. 228 227-236 de Raadt A, Fechter MH (2001) Miscellaneous. 215 327-345 Desreux JF, see Jacques V (2002) 221 123-164... 

Whiting Researches on Acetylenic Compounds. Part XXXIV. Further Studies on the Synthesis of Diacetylenic Glycols. J. Chem. Soc. [London] 1952, 1998. 

Sundar and Keller have reported the synthesis of linear boron-silicon-diacetylene polymers (31) (Fig. 21) using phenylboron dichloride (PBD) as the source for boron.50 The compositions of the thermally stable boron-silicon-diacetylene copolymers 31a-d are summarized in Figure 21. These polymers were observed to possess exceptional thermooxidative stabilities. 

The synthesis of block polymers of diacetylene-silarylene and diacetylene-carboranylenesiloxane polymers (99a-e) (Fig. 61) by the polycondensation reaction of 1,4-dilithiobutadiyne with l,4-bis(dimethylchlorosilyl) benzene and/or l,7-bis(tetramethylchlorodisiloxane)-m-carborane have been reported by Sundar and Keller.129 These polymers are a hybrid between the carboranylenesiloxane and silarylene-siloxane polymers and have high char yields (up to 85%) at 1000°C in N2 and in air, reflecting the thermal stabilizing effects of the carborane and aromatic units in the polymeric backbone. 

A general synthesis of dibenzo-annelated dithieno[3,Z-b Z, 3 - thiophene 18 has been reported from bis(o-hydro-xyl)diacetylenes. This cyclization constructs a fused tricyclic skeleton in one pot. The subsequent dechalconization with copper powder produces a series of thiophene and selenophene-based heterocenes (Scheme 64) <20050L5301>. 

A more general synthesis of selenophene derivatives, starting from diacetylenes and sodium hydrogen selenide, was investigated by Curtis.48 In the synthesis of new tetraphenylporphyrin molecules containing heteroatoms other than nitrogen, Ulman et al.49 used in principle the method of Curtis for the synthesis of the starting material (17). 

The cobalt-catalyzed cooligomerization of diynes with nitriles allows a simple one-step synthesis222 of condensed pyridine derivatives including difficultly accessible 5,6,7,8-tetrahydroisoquinolines223 The synthesis is a versatile one in that pyridines condensed with five- and seven-membered carbocyclic rings can also be achieved in moderate yield in similar fashion. Additional attractive features of this simple synthesis are the formation of condensed isoquinolines by the use of functionalized nitriles and the pronounced regioselectivity observed when dissymmetrical diacetylenes are employed (Scheme 148).222... 

Saulnier expanded this reaction to an elegant synthesis of indolo[2,3-a]carbazole 355, featuring a polyannulation from the diacetylene as shown [315]. 

Only two general methods have been developed for the synthesis of the macrocyclic annulenes.9 The first of these, developed by Sondheimer and co-workers, involves the oxidative coupling of a suitable terminal diacetylene to a macrocyclic polyacetylene of required ring size, using typically cupric acetate in pyridine. The cyclic compound is then transformed to a dehydroannulene, usually by prototropic rearrangement effected by potassium i-butoxide. Finally, partial catalytic hydrogenation of the triple bonds to double bonds leads to the annulene. 

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