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In the above formulae, each RL 37 may be the same or different, and represents a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms, and RL $^{38 }$represents a hydrogen atom or a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms. 

Each RL $^{39 }$may be the same or different, and represents a linear, branched, or cyclic alkyl group having 2 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. Al is as defined above. 

In the formula (A-2), RL $^{31 }$and RL $^{32 }$represent a hydrogen atom or a linear, branched, or cyclic alkyl group having 1 to 18, preferably 1 to 10 carbon atoms. Illustrative examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group, a cyclopentyl group, a cyclohexyl group, a 2-ethylhexyl group, and a n-octyl group. 

RL $^{33 }$represents a monovalent hydrocarbon group having 1 to 18, preferably 1 to 10 carbon atoms, and optionally containing a heteroatom such as an oxygen atom. For example, there may be mentioned a linear, branched, or cyclic alkyl group and a group in which a part of hydrogen atoms in these groups is substituted with a hydroxyl group, an alkoxy group, an oxo group, an amino group, an alky› lamino group, or the like. Illustrative examples thereof include the following substituted alkyl groups. 

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RL31 and RL32, RL3I and RL33’ and RL32 and RL33 may be bonded to form a ring together with the carbon atoms to which these groups are bonded; and when the ring is formed, RL3 1 , RL 32 , and RL $^{33 }$that participate in the ring formation each represent a linear or branched alkylene group having 1 to 18, preferably 1 to 10 carbon atoms. The carbon number in the ring is preferably 3 to 10, particularly preferably 4 to 10. 

Among the acid-labile groups shown by the formula (A-2), illustrative examples of the linear or branched one include groups of the following formulae (A-2)-1 to (A-2)- 35. 

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