Cl.[CH3:2][C:3]1([CH3:23])[CH:7]([C:8]2[CH:13]=[CH:12][C:11]([CH3:14])=[CH:10][CH:9]=2)[C:6]2[C:15]([CH3:22])=[C:16]([NH2:21])[C:17]([CH3:20])=[C:18]([CH3:19])[C:5]=2[O:4]1.[NH4+]>CO.O>[CH3:2][C:3]1([CH3:23])[CH:7]([C:8]2[CH:9]=[CH:10][C:11]([CH3:14])=[CH:12][CH:13]=2)[C:6]2[C:15]([CH3:22])=[C:16]([NH2:21])[C:17]([CH3:20])=[C:18]([CH3:19])[C:5]=2[O:4]1To a mixture of N-[4-hydroxy-3-[2-methyl-1-(4-methylphenyl)-1-propenyl]-2,5,6-trimethylphenyl]formamide (740 g) and isobutanol (2220 ml) was added concentrated hydrochloric acid (2220 ml) under nitrogen stream and the mixture was refluxed under heating for 5 hr. The mixture was stirred at 0 to 5° C. for 1 hr. The crystals were collected by filtration and washed with toluene to give 2,2,4,6,7-pentamethyl-3-(4-methylphenyl)-2,3-dihydro-1-benzofuran-5-amine hydrochloride. This hydrochloride was dissolved in a mixed solution of methanol (5180 ml)/water (740 ml) at 55 to 60° C. To the solution was added dropwise 25% aqueous ammonium at 50° C. to adjust the pH to 8.5, and the mixture was stirred for 30 min. The precipitated crystals were collected by filtration and washed with methanol/water (1:1) to give the title compound (587.2 g, yield 87.4%).
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