Solvolysis rates and .beta.-deuterium secondary kinetic isotope effects of some tertiary and secondary alk-5-enyl derivatives. Evidence for .pi.-participation

Tertiary 1,1-dimethylalk-5-enyl chlorides solvolyze in 80% v/v ethanol with no or moderate rate enhancements attributable to π-participation. However, secondary β-deuterium kinetic isotope effects (KIE, two deuterated methyl groups) are significantly reduced (k H /k D =1.22-1.57) relative to the saturated analogues (k H /k D =1.80), indicating participation of the double bond. Secondary 1-methylalk-5-enyl tosylates show the same trends, i.e., no or very moderate rate enhancements but reduced β-deuterium secondary KIE relative to the saturated analogue