The Unstabilized 5-Hexenyl Radicals

The first proposal of intramolecular addition of 5-hexenyl radicals was independently reported in 1957 by Marvel and by Butler. They polymerized 1,6-dienes and, finding that the products were devoid of unsaturation, assumed that the initially produced radicals had cyclized their work will be discussed in a later section. Also to be discussed is the pioneering work of Friedlander who, in 1958, reported the cyclization of diallyl ethers and diallyl thioethers under free radical conditions. 

The products of interest were 1-hexene (AH) (6%), methylcyclopentane (Cy5) (47%), cyclohexane (Cy6) (1%), and cyclohexene (trace). Since galvinoxyl suppressed the formation of methylcyclopentane almost completely, it was concluded that it was produced by a chain process. Furthermore, com- 

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