It's IUPAC name is ethyl-2-ene,-2-methyl propanoate or ethyl, -2-methyl propan-2-ene,1-oate

Structure:
CH2=C(CH3)-COOC2H5

IUPAC Name:
The IUPAC name of the given compound is 2-methylprop-2-enyl ethanoate.

Explanation:
The IUPAC name of an organic compound is derived from its structure following a set of rules defined by the International Union of Pure and Applied Chemistry (IUPAC). Let's break down the given compound and determine its IUPAC name step by step.

Step 1: Identify the longest carbon chain:
The longest carbon chain in the given compound is 4 carbons long.

Step 2: Identify the functional groups:
The functional groups in the compound are an ester group (-COO-) and an alkene group (=C-).

Step 3: Number the carbon chain:
Start numbering from the end that gives the functional groups the lowest possible locants. In this case, we start numbering from the left end.

Step 4: Name the substituents:
The substituents in the compound are a methyl group (CH3) attached to the second carbon atom and an ethoxy group (C2H5O-) attached to the third carbon atom.

Step 5: Combine the names of the substituents with the parent chain:
The name of the parent chain is but, as it contains 4 carbon atoms.

Step 6: Assign the locants to the substituents:
The locant 2 is assigned to the methyl group, and the locant 3 is assigned to the ethoxy group.

Step 7: Order the substituents alphabetically:
The substituents are named in alphabetical order, so ethoxy comes before methyl.

Step 8: Write the IUPAC name:
Putting all the pieces together, the IUPAC name of the given compound is 2-methylprop-2-enyl ethanoate.

Summary:
The IUPAC name of the given compound, CH2=C(CH3)-COOC2H5, is 2-methylprop-2-enyl ethanoate. It is derived by identifying the longest carbon chain, numbering the chain, naming the substituents, combining the names, assigning locants, ordering them alphabetically, and writing the final name.