What is the IUPAC name of the compound shown? The parent chain must be the longest chain containing the double bond; the double bond gets the lowest locant before substituents.

The compound is 3,4,4-trimethylpent-1-ene. The double bond takes priority for the low locant, so numbering starts at the CH2= end (locant 1), not at the tert-butyl end. The longest chain with the C=C is five carbons, with methyls at C3, C4, C4. The name 3-tert-butylbut-1-ene picks a shorter chain.