This is likened to the addition of two alkyl groups into ethylene.
So it has four alkyl groups and potentially carries two negative charges.
One of the adjacent alkyl groups then migrates to the positive carbon in a 1,2-shift.
The starting compound is a dihydro-1,3-oxazine with an alkyl group in the 2 position.
In the latter case, competitive addition of the alkyl group to the nitrile takes place.
Typically one of the alkyl groups on the amine is larger than the others.
R does not need to be an alkyl group but can also be more complicated.
These include true alkyl groups, and have been known for a longer time than some of the other alkylating agents.
Alkylation is the transfer of an alkyl group from one molecule to another.
Common names often are made by taking the name of the alkyl group, and adding the word "alcohol".