28  US 8,283,102 B2  27  $^{1}$H-NMR (chloroform-d3, reference: tetramethylsilane):  (ppm) 1.63-2.05 (m, 15H), 4.78 (m, 2H), 7.05 (d, 2H), 7.38 (d,  2H), 7.55-7.78 (m, !OH), and  ester diphenyl-4-methacroyloxy-phenylsulfonium salt was  observed by $^{1}$H-NMR (see FIG.  9):  $^{1}$H-NMR (chloroform-d3, reference: tetramethylsilane):  (ppm) 2.05 (s, 3H), 4.98 (t, 2H), 7.38-7.78 (m, 15H), 7.91 (d,  2H), 8.12 (d, 2H),  About 10 g of the diphenyl-4-hydroxyphenylsulfonium  trifluoromethanesulfonate salt manufactured in the synthesis  example 3 and about 9.7 g of an adamantane-1-carboxylic  acid-2,2-difluoro-2-sulfo-ethyl ester sodium salt were dis› solved in about 100 ml of an MC and about 100 ml of water,  and a synthesis reaction (see Equation 11 below) was per› formed while strongly stirring for three hours. In this  instance, a process of the synthesis reaction was observed by  $^{19}$F NMR using a small amount of an extracted organic phase.  The organic phase was extracted when the synthesis reaction  was terminated, and washed using the MC of a soluble solvent  and hexane of a sparingly soluble solvent. Next, the solvents  were removed, and drying under a reduced pressure was  performed to obtain about 11.47 g (a yield: about 81.7%) of  an adamantane-1-carboxy lie acid-2,2-difluoro-2-sulfo-ethy 1  ester diphenyl-4-hydroxyphenylsulfonium salt, and a struc› ture of the adamantane-1-carboxylic acid-2,2-difluoro-2- sulfo-ethyl ester diphenyl-4-hydroxyphenylsulfonium salt  was observed by $^{1}$H-NMR (see FIG.  10):  About 11.47 g of the adamantane-1-carboxylic acid-2,2- difluoro-2-sulfo-ethyl ester diphenyl-4-hydroxyphenylsulfo› nium salt, about 1.95 ml of methacryloyl chloride, and about  25.5 mg of 4-methoxyphenol (MEHQ) were mixed and  stirred in about 150 ml of an MC, about 5 ml of diisopropy› lethylamine (DIPEA) was gradually dropped using a drop› ping funnel under an ice bath, and a synthesis reaction (see  Equation 12 below) was performed while stirring for about  three hours at room temperature. In this instance, 4-dimethy› laminopyridine (DMAP) was used as a reaction catalyst, and  a process of the synthesis reaction was observed by $^{19}$F NMR  using a small amount of an extracted organic phase. The  organic phase was extracted when the synthesis reaction was  terminated, and washed using IN HCl, distilled water, a satu› rated sodium bicarbonate aqueous solution, and distilled  water in the stated order (three times).  Next, a solvent was removed, and washing with the MC of  a soluble solvent and hexane of a sparingly soluble solvent  was preformed. Next, the solvents were removed, and drying  under a reduced pressure was performed to obtain about 10.8  g (a yield: about 85%) of an adamantane-1-carboxylic acid- Synthesis Example 11  Adamantane-1-carboxylic  Acid-2,2-difluoro-2-sulfo-ethyl Ester  Dipheny 1-4-methacroy loxy-pheny lsulfonium Salt  Synthesis  Synthesis Example 12  Adamantane-1-carboxylic  acid-2,2-difluoro-2-sulfo-ethyl Ester  Diphenyl-4-hydroxyphenylsulfonium Salt Synthesis  [Equation 11]  Qo  O-¢s+_o-~-CF 3  ~  0  ~  I  OH  0  0  Na+_o/fi’-..c/’--....o-n  0 ,,  V  Q"  0  MC/DW  OH  [Equation 10]  Q"  0  ~I  OH  1) DIPEA, 2) DMAP  3)MEHQ 