Hydride ions intermolecular migration

The acylation of alkanes has also been known for a long time, but for synthetic purposes is limited to simple substrates. The initial step is hydride abstraction by an acylium ion, a process well established in the presence of a powerful Lewis acid, most commonly an aluminum halide, or strong protic acid. The carbocation so formed can then undergo elimination, possibly after hydride or alkyl migration, to give an alkene which is then acylated. In the presence of excess alkane, saturated ketones are formed by a further intermolecular hydride transfer, whereas with an excess of acyl halide, the product is the (conjugated) unsaturated ketone. -" The synthetic potential is obviously likely to be limited to simple substrates. 

Methylcyclohexane and acyclic isoalkanes are better hydride donors than the methylcyclopentane. Consequently, alkenoyl chlorides are able to do intermolecular hydride ion capture giving cyclopentenones resulting from a Nazarov cyclization. Starred methyl groups undergo migration in the process. Works are in progress in this field. 

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