With 1,3-Butadiynes

Disodium telluride and diacetylenes react in methanol to give tellurophenes. With 1,3-butadiyne, tellurophene is obtained. l-Organo-l,3-butadiynes yield 2-organotellurophenes. l,4-Diorgano-l,3-butadiynes produce 2,5-diorganotellurophenes. The yields of these reactions generally do not exceed 50%. 

When the reactions were carried out with methanol-OD, perdeuterotellurophenes were obtained  

Similarly, but generally on a smaller scale, the following tellurophenes were prepared  

The difficult to handle and dangerous 1,3-butadiyne, which is a gas at 20°, must be generated and used in the rather elaborate apparatus described above. Non-gaseous butadiynes are easier to handle, and can be prepared separately and dropped to the sodium telluride solution after dissolution in an organic solvent  

A synthesis which is more convenient for the small-scale preparation of tellurophene employs sodium telluride, formed by the reduction of tellurium with sodium formalde-hydesulfoxylate in aqueous sodium hydroxide, and 1,4-bis[trimethylsilyl]-l, 3-butadiyne  

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Figure 10.6. Products obtained from permethyltitanocene and permethylzirconocene with 1,3-butadiynes.

Schwarz and coworkers115 used 1,2,3-butatriene, along with 1,3-butadiyne, as a precursor for the generation of neutral 1,2,3-butatrienylidene in a neutralization/reionization mass spectrometric sequence (C4H4 - C4H2- - C4H2 - C4H2+ ). 

Depending on the nature of the Cp ligands, the metal, the stoichiometry, and the reaction conditions, very different complexes have been obtained by treatment of (25-28) with 1,3-butadiynes. For instance, the formation of (29) and (30) results of cleavage of the C-C bond of the alkynes. The coupling of two alkyne units in the coordination sphere of the metal gives (31). ... 

ARSENIC PENTAFLUORIDE (7784-36-3) A noncombustible, corrosive gas. Contact with moisture, water, steam, or acids causes decomposition and forms hydrogen fluoride and arsenic pentoxide. Incompatible with reducing agents, alkalis, organic or siliceous materials. Violent reaction with 1,3-butadiyne (also a gas, CAS registry number 460-12-8). Attacks glass and metals in the presence of moisture. 

Hydrazine hydrate reacts with 1,3-butadiyne moieties in competition with the carbonyl groups. Therefore, tosylhydrazine is employed for the selective reaction with the latter. The sodium salts of the resulting tosylhydrazones are heated to give the diazo compounds 16,18, and 20 [8, 10]. As some of the 1,3-butadiyne derivatives in Table 11-2 undergo spontaneous polymerization in the solid state (see Section 11.4.1), they have to be kept in solution. 1,3-butadiyne units are also known to react with diazo groups [11] and therefore the diazo compounds such as 16, 18, and 20 must be kept refrigerated. 

H. Higuchi, T. Ishikura, K. Miyabayashi, M. Miyake and K. Yamamoto, Synthesis and properties of orientational isomers of hybridized dihexylbithiophene-octaethylporphyrin connected with 1,3-butadiyne linkages. Tetrahedron Lett, 40, 9091-9095 (1999). 

Another type of stimulus-responsive supramolecular polymer was produced using the complementary affinity of a bisporphyrin (Figure 7.20). The bispor-phyrin units were connected with 1,3-butadiyne units to produce homoditopic tet-rakisporphyrin 23. The iterative self-assanbly of 23 gave rise to supramolecular nanometric polymeric assemblies. An electron-deficient aromatic guest can aggressively bind within the bisporphyrin cleft, causing the supramolecular polymeric assemblies to dissociate. 

Fu X, Chen J, Li G et al (2009) Diverse reactivity of zirconacyclocumulenes derived from eouphng of benz5mezirconocenes with 1,3-butadiynes towards aeyl cyanides synthesis of indeno[2,l-b]p5uroles or [3] cumulenones. Angew Chem Int Ed 48 5500-5504... 

The above mentioned coupling procedures were also used to prepare a large variety of nonconjugated and conjugated systems with 1,3-butadiyne units as building blocks that are summarized in various reviews [1, 2, 28, 29]. 

Herein we mention that Pd-catalyzed coupling reactions between alkynes are also available to generate symmetrical 1,3-butadiyne units [21b, 22]. So far they have not been applied to the preparation of cyclic systems with 1,3-butadiyne units. 

Scheme 3.5 Generation of [Cp(PPh3)2Ru=(C)4H2] (4) by reaction of [RuCI(Cp)(PPh3)2] with butadiyne and addition of HNPh2 across the C3-C4 bond of the chain.

Scheme 3.6 Formation of the butatrienylidene complex 10 by reaction of [RuCl2(dppm)2] with butadiyne.

As with butadiyne, the sodium salts of the polyynes 79 which are present in the reaction mixture after dehydrohalogenation can be alkylated or condensed with carbonyl compounds. The resulting derivatives are more stable and can usually be obtained in somewhat higher yields than the parent polyynes, but the improvement is only slight in the pentaacetylene case, where, for example, the dimethyl derivative, CHsCC QsCHj, is obtained in 3% yield . 

The reaction of phenol with butadiyne gives amorphous condensation products" , but aminophenols add in the presence of KOH in DMSO-dioxane giving cis- and ria/i.T-aminophenoxybutenynes (99)" . 

Primary and secondary aliphatic amines react readily with butadiyne under mild conditions and without the necessity of added catalyst. A wide variety of secondary amines has been used including, for example, dimethyl-, diethyl-, di- -butyl- and diallylamine, as well as the heterocyclic derivatives pyrrolidine, piperidine and morpholine. The product in each case is the corresponding l-(A, A -dialkylamino)-l-buten-3-yne 1291 2-135... 

The photocycloaddition chemistry of pyridines substituted with electron-donor and electron-acceptor groups at the 2- and 3- positions continues to be exploited. The results of irradiation of such pyridines in the presence of 2-cyanofuran have now been described. The yields of the (47r+47r) cycloadducts (29) and (30), the pyridine dimer (31) and the transposition isomer (32) are dependent on the level of methyl substitution on the heteroarene and are given in Scheme 2. Other photocycloadditions to heteroarenes reported within the year include the reactions of benzodithiophene (33) with butadiyne derivatives and dimethyl acetylene dicarboxylate, giving low yields of (34) and (35) respectively, the latter from photorearrangement of the primary adduct (36). The (271+471) photocycloaddition of indoles (37) to cyclohexa-1,3-dienes (38) is sensitized by the aromatic ketones (39), and yields (14-46%) of the exo and endo isomers of the adduct (40) in ratios which are dependent on the substituents on the addends. 

Chart 7.1. Examples of cyclophanes with butadiyne units. 

Chart 7.4. [3]Catenate 51, Cavitands 52 and 53 with butadiyne units. 

Exploded phospha[f2]pericyclines (38, n = 3-6) with butadiyne linkages have been prepared by Markl et al., both by a one-pot approach and by stepwise... 

The reaction of l,4-bis(trimethylsilyl)-l,3-butadiyne (174) with disilanes, followed by treatment with methylmagnesium bromide, produces i,l,4,4-tetra(-trimethylsilyl)-l,2,3-butatriene (175) as a major product[96]. The reaction of octaethyltetrasilylane (176) with DMAD proceeds by ring insertion to give the six-membered ring compounds 177 and 178[97], The l-sila-4-stannacyclohexa-2,5-diene 181 was obtained by a two-step reaction of two alkynes with the disilanylstannane 179 via the l-sila-2-stannacyclobutane 180[98],... 

It seems quite obvious that the thiophenes are related to the polyacetylenes which they accompany. This viewpoint has recently been illustrated by the formation of thiophenes from polyacetylenes and hydrogen sulfide under almost biological conditions. In a recent lecture summary, the preparation of terthienyl, junipal, and (241) from 1,4-disubstituted butadiynes and hydrogen sulfide is claimed. A large number of bithienyls have been prepared and their nemato-dicidal activity investigated. All the compounds with strong activity were found to be derivatives of 2,2 -bithienyl. ... 

The composition of the mixture of products of different structures depends on the diacetylene diazomethane ratio (68LA124). With a 1 1 ratio of butadiyne and diazomethane, 3(5)-ethynylpyrazole dominates (55%). The yields of isomeric 3- and 5-ethynyl-l-methylpyrazoles are 8 and 11%, respectively. The double excess of diazomethane leads mainly to a mixture of N-methylated isomers (81%), 10% of 3(5)-ethynylpyrazole, and a small amount (3%) of bipyrazole (68LA124) (Scheme 3). 

Thus, 1,4-dibenzoyl- 1,3-butadiyne with diazomethane forms 3(5)-benzoylethy-nylpyrazole (yield 59%) (68LA124). In a similar way, the reaction of 2,7-dimethyl-octadiyne-2,7-diol with diazomethane leads to 4-[3-(l-hydroxy-l-methylethyl)-l//-pyrazol-4-yl]-2-methylbut-3-yn-2-ol in 64% yield (58CB1841) (Scheme 7). 

Note that 1,4-substituted butadiynes with diazomethane can form two isomers. Kuznetsov and co-workers have considered this problem in detail and established that diphenyldiacetylene with diazomethane forms, in standard conditions (ether, 0°C, 9 days), only one of the two possible regioisomers 4-phenyl-3(5)-phenylethynylpyrazole (yield 86%) (93ZOB1107). The cyclization of derivatives of phenoxy-2,4-hexadiyn-6-oles with diazomethane leads to only one isomer of alkynylpyrazole (76MI1 77MI1) (Scheme 8). 

Similarly, the cross-coupling of N-protected 4-ethynylpyrazole with 1-(1-ethoxyethyl)-4-iodo- l//-pyrazole leads only to disubstituted butadiyne (2001 UP 1) (Scheme 50). 

It was found [99JCS(PI )3713] that, in all cases, the formation of the deiodinated products 38 and 39 was accompanied by formation of the diynes 40 which were isolated in 60-90% yield. The authors believed that the mechanism of deiodination may be represented as an interaction ofbis(triphenylphosphine)phenylethynyl-palladium(II) hydride with the 4-iodopyrazole, giving rise to the bisftriphenylphos-phine)phenylethynyl palladium(II) iodide complex which, due to the reductive elimination of 1 -iodoalkyne and subsequent addition of alk-1 -yne, converts into the initial palladium complex. Furthermore, the interaction of 1-iodoalkynes with the initial alkyne in the presence of Cul and EtsN (the Cadiot-Chodkiewicz reaction) results in the formation of the observed disubstituted butadiynes 40 (Scheme 51). 

Would you expect a conjugated diyne such as 1,3-butadiyne to undergo Diels-Alder reaction with a dienophile Explain. 

In contrast, the trimer 89 with ethyne and butadiyne links stabilizes the thermodynamically disfavored endo transition state, and the endo adduct 86 is rapidly and almost exclusively formed. 

When the acyclic dehydrohexamer 156 was oxidatively cyclized, an increased yield (49%) of the butadiyne-expanded [6]rotane 166 was observed, but the yield of the expanded [12]rotane 171 with a Cgo inner ring suffered from the fact that the corresponding acyclic dehydrododecamer 159 slowly decomposed in the syringe pump [48]. 

The oxidative coupling, however, normally provides better results, as was demonstrated by the reasonably efficient cyclization of 179 to the homoconjugated 16-membered macrocycle 180 (14% yield) with alternating ethyne and butadiyne units (Scheme 34) the alternative Cadiot-Chodkiewicz coupling of the bisterminal diyne 38 and the dibromotriyne 177 gave only a 2.6% yield of 180 [4]. 

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