3,4,5,6-Tetrahydrophthalic anhydride → 2-(4-Chloro-2-fluorophenyl)-4,5,6,7-tetrahydro-1h-isoindole-1,3(2h)-dione

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Reaction Steps

A solution of 88 parts of 3,4,5,6-tetrahydrophthalic anhydride in 2000 parts of glacial acetic acid was treated with 84 parts of 4-chloro-2-fluoroaniline at once and stirred for one hour. After refluxing for 19 hours, 1000 parts of acetic acid were distilled from the reaction mixture. The residue from the distillation was poured over 3000 parts of ice. The resulting crystals were filtered and recrystallized from 700 parts of methanol at -40° C. after activated carbon treatment, to yield 117 parts off-white crystals of 2-(4-chloro-2-fluorophenyl)-4,5,6,7-tetrahydro-2H-isoindole-1,3-dione melting at 76.5°-78.0° C.

Provenance & Evidence