Cyclopolymerization substituent effects

The very high levels of head addition and the substituent effects reported in these studies are inconsistent with expectations based on knowledge of the reactions of small radicals (see 2.3) and are at odds with structures formed in the intermolecular step of cyclopolymerization of diallyl monomers (see 4.4.1.1) where overwhelming tail addition is seen. 

Propagation in cyclopolymerization may be substantially faster than for analogous monoene monomers.15" The various theories put forward to account for this observation are summarized in Butler s review.98 A recent theoretical study by Ttiziin et al.u3 looks at the effects of substituents on the rate of the cyclization step. 

Cyclopolymerization of 1,6-heptadiyne having bulky substituents was effectively carried out by the MoCls-based catalysts, and their optimized polymerization results are summarized in Table 6. ° In most cases, the polymer yields were quantitative. And the result-... 

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