45  US 9,360,753 B2  46  -continued  -continued  (A-1)-4  rH,,  ••  ,(~I  (A-1)-5  i(CH,)"’’(tf  1  (A-1)-6  R37  (CH2)a1YO  0  1(CH,S,Y0{6]  0  R37  (A-1)-8  "’’••yo’Y:::]  0  R39  1(cH,J.,Yo’K2)  l  0  R37  (A-1)-10  tcH,J.,,(~  (A-2)-1  -CH2-0-CH3  (A-2)-2  -CH2-0-CH2-CH3  (A-2)-3  -CH2-0-(CH2)2-CH3  (A-2)-4  -CH2-0-(CH2)3-CH3  (A-2)-5  CH3  I  -CH2-0-CH-CH3  (A-2)-6  CH3  I  -CH2-0-C-CH3  I  CH3  (A-2)-7  CH3  I  -CH-O-CH3  (A-2)-8  CH3  I  CH2  I  -CH-O-CH3  (A-2)-9  CH3  I  (CH2)2  I  -CH-O-CH3  (A-2)-10  CH3  I  -CH-O-CH2-CH3  (A-2)-11  CH3  I  CH2  I  -CH-O-CH2-CH3  (A-2)-12  CH3  I  (CH2h  I  -CH-O-CH2-CH3  (A-2)-13  CH3  I  -CH-O-(CH2Ji-CH3  (A-2)-14  CH3  I  CH2  I  -CH-O-(CH2Ji-CH3  (A-2)-15  CH3  I  (CH2)2  I  -CH-O-(CH 2 )i-CH3  (A-2)-16  -t-o---(J  (A-2)-17  -t-o-o  (A-2)-18  CH3  I  -C-O-CH3  I  CH3  Herein R$^{37 }$is each independently a straight, branched or  cyclic C$_{1 }$-C$_{10 }$alkyl group or C$_{6}$-C$_{20 }$aryl group, R$^{38 }$is hydro- gen or a straight, branched or cyclic C$_{1 }$-C$_{10 }$alkyl group, R 39  is each independently a straight, branched or cyclic C$_{2}$ -C$_{10 }$ alkyl group or C$_{6}$-C$_{20 }$aryl group, and al is as defined above.  Of the acid labile groups of formula (A-2), the straight and  branched ones are exemplified by the following groups hav- ing formulae (A-2)-1 to (A-2)-69. 