The six-membered transistion state is formed by coordination of the Aluminium compound. This cyclic transition state is in the 'chair' conformation. Intramolecularl hydride transfer occurs in this substrate.
The reaction is an equilibrium, which can be shifted to the product side by using excess i-PrOH or by removing the acetone byproduct formed in the hydride transfer step.
To reverse the equilibrium we can use Al(Oi-Pr)3 and excess acetone. This is known as the Oppenauer oxidation.
Aluminium alkoxides are used as they avoid complications from condensation of the aldehyde or ketone enolates.
