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2,2-DIMETHYL-PROPIONIC ACID (1R,5R)-6,6-DIMETHYL-4-OXO-BICYCLO[3.1.1]HEPT-2-EN-2-YLMETHYL ESTER synthesis

3synthesis methods
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Yield:76163-96-7 55%

Reaction Conditions:

Stage #1: (1R,5S)-2-[(2,2-dimethylpropoyloxy)methyl]-6,6-dimethylbicyclo[3.1.1]hept-2-enewith 3,5-dimethyl-1H-pyrazole;chromium(VI) oxide in dichloromethane at -20; for 4 h;Inert atmosphere;
Stage #2: with sodium hydroxide in dichloromethane;water at -20 - 0; for 1 h;Inert atmosphere;

Steps:

12.2 Step 2: Synthesis of ((1R,5S)-6,6-dimethyl-4-oxocyclo[3.1.1]hept-2-en-2-yl)methylpivalate

Weigh chromium trioxide (5.1g, 51mmol) and 3,5-dimethylpyrazole (4.9g, 51mmol) in a flask, Add anhydrous dichloromethane (40mL) under the protection of argon, and cool down to -20 in the low-temperature reactor. After stirring for 30 minutes, slowly add dropwise a dichloromethane solution of ((1R,5S)-6,6-dimethylbicyclo[3.1.1]hept-2-en-2-yl)methylisovalerate methyl ester ( 1.0g, 4.2mmol, 10.0mL). The reaction solution was stirred at -20°C for 4 hours, and then an aqueous sodium hydroxide solution (5M, 3.3 mL) was slowly added dropwise. The temperature was raised to 0°C and stirring was continued for 1 hour. Separate the organic phase, wash with 10% hydrochloric acid solution, then wash with water and saturated brine, It was dried over anhydrous sodium sulfate, concentrated, and purified by silica gel column chromatography (ethyl acetate/petroleum ether=20/80) to obtain a colorless oil (600 mg, yield 55%).

References:

CN112047973,2020,A Location in patent:Paragraph 0243; 0247-0249