Yield: 67.7%

Reaction Conditions:

with hydrogenchloride;tin(II) chloride dihdyrate at 20; for 3 h;Inert atmosphere;Heating;

Steps:

1.1-1
Then, 1.40 g (0.0073 mol) of the intermediate A1 obtained above and 6.0 g of concentrated hydrochloric acid (hydrochloric acid concentration 36% by weight) were placed in a 30 mL two-necked flask, and under nitrogen flow (5 mL /min), while stirring using a magnetic stirrer,A solution prepared by dissolving 5.5 g of tin chloride dihydrate in 5.5 g of concentrated hydrochloric acid (hydrochloric acid concentration 36% by weight) was slightly poured while paying attention to the reaction heatWas added. After the addition, the mixture was stirred at room temperature for about 3 hours.Thereafter, the obtained reaction solution was added to a beaker containing 100 g of pure water and 100 g of ethyl acetate while stirring.A potassium hydroxide solution was gradually added thereto, and when the pH of the aqueous solution became around 10, the mixture was stirred for a while, the organic phase was extracted with a separating funnel, magnesium sulfate (anhydrous) was added to the extracted organic phaseIn addition, dehydrated. After removing the solid matter (inorganic matter) from the organic phase, the solvent was concentrated using an evaporator, and after that silica gel column chromatography (developing solvent: ethyl acetate) was appropriately carried out, And concentration and vacuum drying were carried out to obtain 0.8 g of Intermediate A2. The yield based on the intermediate A1 was 67.7 mol%.

References:

Nippon Shokubai Co Ltd;Heinai, Tatsushi;Aoki, Masanori JP2018/168335, 2018, A Location in patent:Paragraph 0130; 0131; 0134