Acyclic Diyne Metathesis

Acyclic diperoxyketals, 14 287 18 457 Acyclic diyne metathesis (ADIMET), 26 951 Acyclic monoterpenes, aroma chemicals, 3 237... 

Bunz UHF (2003) In Grubbs RH (ed) Handbook of metathesis. WUey-VCH, 3 354-370 Acyclic diyne metathesis utilizing in situ transition metal catalysts an efficient access to alkyne-bridged polymers... 

An alternative method to make PAEs is the acyclic diyne metathesis (ADIMET) shown in Scheme 2. It is the reaction of a dipropynylarene with Mo(CO)6 and 4-chlorophenol or a similarly acidic phenol. The reaction is performed at elevated temperatures (130-150 °C) and works well for almost any hydrocarbon monomer. The reaction mixture probably forms a Schrock-type molybdenum carbyne intermediate as the active catalyst. Table 5 shows PAEs that have been prepared utilizing ADIMET with these in situ catalysts . Functional groups (with the exception of double bonds) are not well tolerated, but dialkyl PPEs are obtained with a high degree of polymerization. The progress in this field has been documented in several reviews (Table 1, entries 2-4). Recently, a second generation of ADIMET catalyst has been developed that allows... 

Scheme 2 Synthesis of PAEs by acyclic diyne metathesis (ADIMET).

The acyclic diyne metathesis polymerization of dodeca-2,10-diyne is catalysed by W(=CEt)(OCMe3)3 see equation 73. But-2-yne is eliminated and the product is an off-white insoluble powder with the same Tm as the polymer prepared from cyclooctyne (Section XII.B)7. 

This contribution describes the synthesis and properties of organic alkyne-bridged materials that have been made by alkyne metathesis or by Acyclic Diyne Metathesis (AD I MET). This review covers mostly poly(aryleneethynylene)s made at the author s laboratory in South Carolina. A comprehensive review covering poly(aryleneethynylene)s listing important contributions in adjacent areas has appeared [1, 2]. This chapter discusses the synthesis and properties of dialkyl-poly(paraphenyleneethynylene)s (dialkyl-PPEs) in relation to the concept of ADIMET with simple catalyst systems. 

PPEs by Acyclic Diyne Metathesis (ADIMET) Utilizing Schrock s Tungsten Carbyne Complex 11... 

Alkyne metathesis is generally restricted to internal alkynes, and is driven to completion by the evolution of gaseous 2-butyne. Representative examples of alkyne cross-metathesis are depicted in Scheme 33, and include (i) dimerization of alkynylbenzoic acid derivative 287, (ii) alkyne cross-metathesis of 289 and bis(trimethylsilyl)acetylene, (iii) cross-metathesis of enyne 291 and various alkynes and metathesis dimerization of 291, and (iv) formation of high molecular weight alkyne-containing polymers through acyclic diyne metathesis (ADIMET) polymerization of acyclic diynes (e.g., 293) " using the molybdenum hexacarbonyl/2-chlorophe-nol system. 

Bunz, U.H.F., Mangel, T., and Mullen, K. (1997) Acyclic diyne metathesis (ADIMET), an efficient route to poly(phenylene)ethynylenes (PPEs) and nonconjugated polyalkynylenes of high molecular weight. Angew. Chem. Int. Ed., 36, 506-509. 

ACYCLIC DIYNE METATHESIS CONDENSATION, ADIMET, AND RING CLOSING REACTIONS OF DIYNES... 

In 1995, we started to study acyclic diyne metathesis condensation of nonconjugated diynes with the catalyst ( BuO)3W=C Bu which catalyzes metathesis of disubstituted alkynes but not of 1-alkynes. Therefore we tested diynes with methyl or ethyl endgroups for Acyclic Diyne Metathesis (ADIMET). W2( BuO)6 was used as catalyst which is easier to synthesize. Figure 4. 

One year after our first publication on the ADIMET reactions which we had developed for conjugated and nonconjugated acyclic diyne metathesis Fiirstner et al. reported on the use of our technique for interesting syntheses of substituted cycloalkynes with Z-configuration by RCM [13]. 

We found that methyl or ethyl substituted diynes give Acyclic Diyne Metathesis Condensation (ADIMET) which is similar to the Acyclic Diene Metathesis (ADMET) of dienes. The catalysts we used for ADIMET reactions are the Schrock type carbyne complex ( BuO)3W=C Bu or W2( BuO)6. For ADIMET reactions we used no or only small amonts of solvent. With higher amounts of solvents Ring Closure Metathesis (RCM) of diynes occured. 

Acyclic diyne metathesis (ADIMET) is the method of choice for the preparation of PPEs. After the first successful attempts with a tungsten carbyne complex [148],... 

Scheme 11.19. Acyclic diyne metathesis for the formation of OPEs and PPEs.

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