Acyclic Diyne Metathesis (ADIMET), an Efficient Route to Poly(phenylene)ethynylenes (PPEs) and Nonconjugated Polyalkynylenes of High Molecular Weight

Abstract

Conjugated and nonconjugated diynes can be readily converted to poly(phenylene)‐ethynylene derivatives and polyalkynylenes by acyclic diyne metathesis. The catalyst for these condensation reactions is [(tBuO)3 WCtBu], and they proceed with cleavage of volatile alkynes such as 2‐butyne and 3‐hexyne. The chain lengths of the polymers are controlled by reaction temperature and pressure.

Alkyne Metathesis: Catalysts and Synthetic Applications

“…[4] Weiss and co-workers first reported the synthesis of PPEs by alkyne metathesis (Scheme 25). [90] Catalyzed by tungsten alkylidyne 9 at 80 8C, ADIMET of 2,5-dihexyl-1,4-dipropynylbenzene monomer 94 provided PPE 95 in good yield, and the degree of polymerization (P n ) reached almost 100 repeating units. The NMR and mass spectra of 95 confirmed the presence of propynyl endgroups.…”

Shape-Persistent, Nano-Sized Macrocycles

“…Bunz reported random macrocyclization through alkyne metathesis [99] of the symmetrical monomer 68 (Scheme 25). [27,28,100] The 30-membered cyclic hexamers 5cϪf were isolated from the raw mixture in yields of 0.5Ϫ6%. Finally, Oda reported the synthesis of 30-membered phenylacetylene macrocycles 5g and 5h by a strategy in which the aldehyde-functionalized precursors 69 or 70 were cyclized to provide 39a and 39b by means of a twofold McMurry-type coupling reaction (Scheme 26).…”

Semiconducting Poly(arylene ethylene)s

“…This approach has, by and large, been developed and practiced by Bunz and involves the reaction shown in Equation 6.2, which liberates 2-butyne as a byproduct [11]. Alkyne metathesis catalysts can tolerate some functional groups and have also attracted recent interest in catalytic transformations for small molecule synthesis [12].…”