Frans-3,4-Dimethyl-3-hexene

The thermal reaction, at room temperature, of A -bicyclo[2A0]hexene (277) gave, besides polymeric material, a dimer now identified as 2,5-dimethylenetricyclo-[4,2,2,0 ]decane (278). Reaction of (277) with irons, frans-dimethyl-2,5-hexadiene gave the olefin (279) and reduction of both (278) and (279) gave cis-2,5-dimethyltri-cyclo[4,2,2,0 ]decane. The reactive double bond in (277) differs from that usually associated with thermal olefin dimerizations. In most cases, such reactivity has been associated with double bonds which are torsionally strained. In (277) the torsion angle about the double bond must be zero and the reactivity must be associated with angular deformation at the olefinic carbons. Addition of ketene to (277) gave 3-methyl-6-methylenecyclohex-2-ene-l-one. In both reaction with ketene and dimerization, [2,2,2]propellanes would appear to be reasonable intermediates. 

Butyne not 3-butyne (E)-2-Hexen-4-yne frans-2-hexen-4-yne not ( )-4-hexen-2-yne 3,3-Dimethyl-1 -butyne not 2,2-dimethyl-3-butyne... 

Thermal decomposition of cis- and frans-3,6-dimethyl-3,4,5,6-tetrahydropyridazines affords propene, cis- and frans-l,2-dimethylcyclobutanes and 1-hexene. The stereochemistry of the products is consistent with the intermediacy of the 1,4-biradical 2,5-hexadienyl. The results indicate that thermal reactions of cyclic azo compounds and cyclobutanes of similar substitution proceed with similar stereospecificity when compared at similar temperatures 79JA2069). 

Selective reduction. A mixture of the startg. peroxide, thiophenol, and Na-methoxide heated with stirring in vacuo (1 mm) whereupon at 120° an exothermic reaction occurs and the product distils frans-2,5-dimethyl-3-hexene-2,5-diol. Y 80%.—This is a new method for the selective reduction of peroxides containing carbon-carbon double bonds. Also reduction of the analogous polymeric peroxide s. K. Griesbaum, A. A. Oswald, and W. Naegele, J. Org. Chem. 29, 1887 (1964). 

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