The present invention provides processes for making 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid as well as intermediates and processes for making the intermediates. Also provided are crystalline forms of the compound and the intermediates.

The present invention provides processes for making 2-((3R,5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-(isopropylsulfonyl)-3-methylbutan-2-yl)-3-methyl-2-oxopiperidin-3-yl)acetic acid as well as intermediates and processes for making the intermediates. Also provided are crystalline forms of the compound and the intermediates.

A radiation-sensitive composition includes: an onium salt compound represented by formula (1); a polymer including a structural unit (I) which includes an acid-dissociable group; and a solvent. W is a cyclic structure having 3 to 40 ring members formed together with the two carbon atoms; a formula between the two carbon atoms below represents a single bond or a double bond, , A is one of groups represented by formulae (A-1) to (A-7); R.sup.1 is a monovalent organic group having 1 to 20 carbon atoms, a cyano group, a nitro group, a carboxy group, a hydroxy group, an amino group, a halogen atom, or a thiol group, when there are a plurality of R.sup.1s, the plurality of R.sup.1s are same as or different from each other; m.sub.1 is an integer of 0 to 4; and Z.sup.+ is a monovalent radiation-sensitive onium cation.

##STR00001##

A radiation-sensitive composition includes: an onium salt compound represented by formula (1); a polymer including a structural unit (I) which includes an acid-dissociable group; and a solvent. W is a cyclic structure having 3 to 40 ring members formed together with the two carbon atoms; a formula between the two carbon atoms below represents a single bond or a double bond, , A is one of groups represented by formulae (A-1) to (A-7); R.sup.1 is a monovalent organic group having 1 to 20 carbon atoms, a cyano group, a nitro group, a carboxy group, a hydroxy group, an amino group, a halogen atom, or a thiol group, when there are a plurality of R.sup.1s, the plurality of R.sup.1s are same as or different from each other; m.sub.1 is an integer of 0 to 4; and Z.sup.+ is a monovalent radiation-sensitive onium cation.

##STR00001##