US 9,052,592 B2  57  58  (al-r-2)  The monocyclic aliphatic hydrocarbon group is preferably  a group in which one hydrogen atom is eliminated from a  monocycloalkane. The monocycloalkane is preferably one  having 3 to 6 carbon atoms, and specifically, examples thereof  include cyclopentane and cyclohexane.  The polycyclic aliphatic hydrocarbon group is preferably a  group in which one hydrogen atom is eliminated from a  polycycloalkane. The polycycloalkane is preferably one hav› ing 7 to 12 carbon atoms, and specifically, examples thereof  include adamantane, norbornane, isobornane, tricyclode› cane, and tetracyclododecane.  In the case where the cyclic hydrocarbon group represented  by Ra’ 3  is an aromatic hydrocarbon group, the aromatic  hydrocarbon group is a hydrocarbon group having at least one  aromatic ring.  This aromatic ring is not particularly limited so long as it is  a cyclic conjugated system having ( 4n+2) it electrons, and it  may be either monocyclic or polycyclic. The number of car› bon atoms of the aromatic ring is preferably 5 to 30, more  preferably 5 to 20, still more preferably 6 to 15, and especially  preferably 6 to 12. Specifically, examples of the aromatic ring  include an aromatic hydrocarbon ring such as benzene, naph› thalene, anthracene, and phenanthrene; and an aromatic het- erocyclic ring in which some of the carbon atoms constituting  the above-described aromatic hydrocarbon ring are substi› tuted with a hetero atom. Examples of the hetero atom in the  aromatic heterocyclic ring include an oxygen atom, a sulfur  atom, and a nitrogen atom. Specifically, examples of the  aromatic heterocyclic ring include a pyridine ring and a  thiophene ring.  Specifically, examples of the aromatic hydrocarbon group  in Ra’ $^{3 }$include a group in which one hydrogen atom is elimi- nated from the above-described aromatic hydrocarbon ring or  aromatic heterocyclic ring (an aryl group or a heteroaryl  group); a group in which one hydrogen atom is eliminated  from an aromatic compound containing two or more aromatic  rings (for example, biphenyl or fluorene); and a group in  which one hydrogen atom of the above-described aromatic  hydrocarbon ring or aromatic heterocyclic ring is substituted  with an alkylene group (for example, an arylalkyl group such  as a benzyl group, a phenethyl group, a 1-naphthylmethyl  group, a 2-naphthylmethyl group, a 1-naphthylethyl group,  and a 2-naphthylethyl group). The number of carbon atoms of  the alkylene group bonded to the above-described aromatic  hydrocarbon ring or aromatic heterocyclic ring is preferably  1  to  4,  more preferably  1  to 2, and especially preferably  1.  In the case where Ra’ 3  is bonded to either Rail or Ra’ 2  to  form a ring, the cyclic group is preferably a 4-membered to  7-membered ring, and more preferably a 4-membered to  6-membered ring. Specific examples of the cyclic group  include a tetrahydropyranyl group and a tetrahydrofuranyl  group.  Tertiary Alkyl Ester Type Acid Dissociable Group:  Among the above-described polar groups, examples of the  acid dissociable group which protects a carboxy group  include an acid dissociable group represented by the follow› ing general formula (al-r-2).  It is to be noted that among the  acid dissociable groups represented by the following formula  (al-r-2), a group constituted of an alkyl group is hereinafter  sometimes referred to as "tertiary alkyl ester type acid disso› ciable group" for the sake of convenience.  In the formula (a0-r2-2), Ra,1 3  is preferably the linear or  branched alkyl group exemplified as the hydrocarbon group  represented by Ra’ 3  in the formula (al-r-1), or an aliphatic  hydrocarbon group which is either a monocyclic group or a  polycyclic group. Of these, Ra,1 $^{3 }$is more preferably the group  exemplified as the aliphatic hydrocarbon group represented  by Ra’ 3 ,  which is either a monocyclic group or a polycyclic  group.  In the formula (a0-r2-2), each ofRa,1$^{2 }$and Ra,1 4  is prefer› ably independently an alkyl group having  1  to  10  carbon  atoms. The alkyl group is more preferably the group exem› plified as the linear or branched alkyl group represented by  Ra’ 3  in the formula (al-r-1), still more preferably a linear  alkyl group having  1  to 5 carbon atoms, and especially pref- erably a methyl group or an ethyl group.  In the formula (al-r2-1), the alkyl group having  1  to  10  carbon atoms represented by Ra’ $^{10 }$is preferably the group  exemplified as the linear or branched alkyl group represented  by Ra’ $^{3 }$in the formula (al-r-1). In the formula (al-r-1), as the  aliphatic cyclic group which Ra’ 11  forms together with the  carbon atom to which Ra’$^{10 }$is bonded, the groups exemplified  as the aliphatic hydrocarbon group represented by Ra’ $^{3 }$in the  formula (al-r-1), which is either a monocyclic group or a  polycyclic group, are preferable.  In the formulae, Ra’$^{10 }$represents an alkyl group having  1  to  10  carbon atoms; Ra’ 11  represents a group for forming an  aliphatic cyclic group together with the carbon atom to which  Ra’$^{10 }$is bonded; and each of Rai1 2  to Ra,1 4  independently  represents a hydrocarbon group.  [Chemical formula 22]  (al-r2-1)  (al-r2-2)  Ra’ 4  is preferably an alkyl group having  1  to 5 carbon  atoms. In the case where Ra’s and Ra’ 6  are bonded to each  other to form a ring, a group represented by the following  general formula ( al-r2-1) is exemplified. On the other hand,  in the case where Ra’$^{4 }$to Ra’$^{6 }$are not bonded to each other and  are each an independent hydrocarbon group, a group repre› sented by the following general formula (al-r2-2) is exem› plified.  Examples of the hydrocarbon group represented by Ra’ $^{4 }$to  Ra’ $^{6 }$include the same hydrocarbon groups as those exempli› fied above for Ra’ 3 •  In the formula, each ofRa’ 4  to Ra’$^{6 }$represents a hydrocar› bon group, and Ra’s and Ra’ $^{6 }$may be bonded to each other to  form a ring.  [Chemical formula 21]  Ra,12  +Ra,1 3  Rar14 