Radicals cyclotrimerization

Free radical initiated cyclotrimerization of allyl- and but-2-enyl-phosphine in the complexes (149 n = 1,2) yielded the macrocyclic P3 complexes (150 - 1,2), respectively <89IC28il>. Complex (149,... 

Terpolymers of tetrafluoroethylene, perfluoromethyl vinyl ether, and small amounts of a cross-linking termonomer, such as, for example, perfluoro(4-cyanobutyl vinyl ether), are free radically copolymerized in emulsion. Vulcanization occurs by cyclotrimerization of the cyano groups to s-triazine rings. The elastomer has a glass transition temperature of —12 C and a brittle temperature of —39° C. It is very resistant to weathering and possesses a good low-temperature flexibility. 

All three alkynes can be incorporated into a single molecule, making the reaction entirely intramolecular. This has been used in a synthesis of Cryptoacetalide 11.60 (Scheme 11.21). The triyne 11.58 was constructed by coupling a diyne 11.56 containing a carboxylic acid with an alkynol 11.57. A ruthenium catalyst was found to be most effective for the cyclotrimerization, combined with microwave heating. The synthesis was completed by deprotection and free-radical spiroketal formation. 

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