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a hydroxyl, cyano, carbonyl, ether bond, ester bond, sulfonic acid ester bond, carbonate, lactone ring, sultone ring, car› boxylic anhydride or haloalkyl moiety. Of the heteroatoms, oxygen is preferred. 

[0136] Of the PAGs having formula (2), those having formula (2’) are preferred. 

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[0137] In formula (2’), LA is as defined above. RHF is hydrogen or trifluoromethyl, preferably trifluoromethyl. R 301 , R $^{302 }$and R $^{303 }$are each independently hydrogen or a C$_{1 }$-C$_{20 }$ monovalent hydrocarbon group which may contain a heteroatom. The monovalent hydrocarbon groups may be straight, branched or cyclic, and examples thereof are as exemplified above for R 107 . The subscripts x and y are each independently an integer of O to 5, and z is an integer of 0 to 4. 

[0138] Examples of the PAG having formula (2) are shown below, but not limited thereto. Notably, RHF is as defined above. 

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-continued 

