You might want to look into the Heck reaction
As ifilot said, you would win a Nobel Prize for this kind of chemistry, and as it happens, a Nobel Prize was awarded for the discovery of this reaction!
This can be used to join together any two carbon chains where one ends in a halogen and the other ends in a hydrogen bonded to a carbon which is part of a double or triple bond.
Here it is in its generalised format (credit Wikipedia):
As you can see, any R group which it attached to a halogen (X) will bond to another R group which ends in a double or triple bond.
The exact mechanism is a little involved so I won't bother talking about it.
So now you need halogenated alkanes and alkenes to proceed.
Look into the halogenation of alkanes. Even though
alkanes are usually unreactive, they can be halogenated in the
presence of ultraviolet light. Check out this link for more:
Look into cracking alkanes, which produces alkenes
as a result.
EDIT: There are other reactions that can join carbon chains together such as reactions involving Grignard reagents, the Wittig and the Diels-Alder reaction.