Reactivity of Dialumane and Dialumene Compounds toward Alkenes

The reactions of dialumane [L(thf)AlAl(thf)L] (1, L=[{(2,6-iPr(2)C(6)H(3))NC(Me)}(2)](2-)) with stilbene and styrene afforded the oxidation/insertion products [L(thf)Al(CH(Ph)CH(Ph))AlL] (2) and [L(thf)Al(CH(Ph)CH2)Al(thf)L] (3), respectively. In the presence of Na metal, precursor 1 reacted with butadienes, possibly through the reduced dialumene or the carbene-like :AlL species, to yield aluminacyclopentenes [LAl(CH2C(Me)C(Me)CH2)Na](n) (4a) and [Na(dme)(3)][LAl(CH2C(Me)CHCH2)] (4b, dme=dimethoxyethane) as [1+4] cycloaddition products, as well as the [2+4] cycloaddition product 1,6-dialumina-3,8-cyclodecadiene, [{Na(dme)}(2)][LAl(CH2C(Me)C(Me)CH2)(2)AlL] (5). The possible mechanisms of the cycloaddition reactions were studied by using DFT computations.