US 10,781,276 B2  31  32  25.0 g of the anisole solution of the pheylglyoxyloyl  chloride obtained in Synthesis Example 21 is dissolved in 35  g of methylene chloride and set to 0°  C. 4.3 g of aluminum  chloride is added thereto and the mixture is stirred at 0°  C.  for 2 hours. 35 g of pure water is added thereto, and the  mixture is stirred for 10 minutes and then phase separation  is performed. The obtained organic layer is washed twice  with 30 g of pure water, and the combined organic layer is  concentrated and purified by colunm chromatography ( ethyl  acetate/hexane=l0/90 (volume ratio)) to obtain 5.6 g of  1-( 4-methoxyphenyl )-2-phenylethanedione.  4.0 g of 1-( 4-hydroxyphenyl)-2-phenylethanedione and  0.10 g of sulfuric acid are dissolved in 12 g of methanol and  set to 25° C. 2.2 g of trimethyl orthoformate is added  dropwise thereto and the mixture is stirred for 3 hours. After  adding 0.6 g of triethylamine at 30°  C. and stirring for 5  minutes, the solvent is evaporated. 25 g of acetonitrile, 4.5  g oftriethylamine and 0.11 g of dimethylaminopyridine are  added to the obtained residue, and 6.8 g of methacrylic  anhydride diluted with 5.0 g of acetonitrile is added drop› wise at room temperature. After the dropwise addition, the  mixture is stirred at 25°  C. for 2 hours, then 64 g of 3% by  mass of aqueous NaHCO$_{3 }$ solution is added and stirred for  5 minutes. Thereafter, the mixture is extracted with 32 g of  ethyl acetate. After washing three times with 10 g of water,  the combined organic layer is concentrated and purified by  colurmi chromatography (ethyl acetate/hexane=l0/90 (vol› ume ratio)) to obtain 4.3 g of 2,2-dimethoxy-l-( 4-methacry› loxyphenyl)ethan-1-one ( compound B6).  5.0 g of 4-methoxybenzil is dissolved in 95 ml of acetic  acid. 33.2 g of 48% by mass of aqueous HBr solution is  added dropwise thereto at 70°  C. over 10 minutes. After the  dropwise addition, the mixture is stirred at 110°  C. for 70  hours. Thereafter, 150 g of water is added to crystallize. This 40  is filtered, the crystal is washed with 250 g of water and then  dried to obtain 4.1 g of 1-( 4-hydroxyphenyl)-2-phenyle› thanedione.  <Synthesis of Compound B7 Constituting Unit B>  (Synthesis Example 25) Synthesis of 9-fluorenone  O-methacryloxime (Compound B7)  (Synthesis Example 24) Synthesis of 2,2-dime› thoxy-l-( 4-methacryloxyphenyl)ethan-1-one (Com- pound B6)  [Chem. 36]  HO  ------- [Chem. 37]  (Compound B7)  4.5 g of 9-fluorenone O-methacryloxime ( compound B7)  is obtained in the same procedure as in Synthesis Example  14 except that 9-fluorenone oxime is used instead of l-(4- hydroxyphenyl)-2,2-dimethyl-1-propanone.  (Synthesis Example 23) Synthesis of  1-( 4-hydroxypheny 1)-2-pheny lethanedione  -continued  (Compound B6)  [Chem. 35]  ............ 0  ~  ~  HBr  ------- HO 