2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → 4,5-Dichloro-3,6-dihydroxybenzene-1,2-dicarbonitrile

Participants

Reaction Conditions

Reaction Steps

By way of general guidance,a toluene solution of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone is added to a toluene solution of a compound of formula (III-i) while maintaining a reaction temperature of about 0° C. to about 10° C. after which the reaction temperature is maintained at about 0° C. for about 1 hour to form a toluene slurry of 2,3-dichloro-5,6-dicyano-1,4-dihydroxybenzene and a compound of formula (IV-i). The slurry is filtered to remove the 2,3-dichloro-5,6-dicyano-1,4-dihydroxybenzene; the resulting waste cake of the 2,3-dichloro-5,6-dicyano-1,4-dihydroxybenzene is washed with toluene. The filtrate and toluene washings are combined and concentrated in vacuo with addition of methanol to remove most of the toluene and produce the compound of formula (IV-i) in methanol at a temperature of about 40° C. to about 45° C. To this solution an aqueous solution of sodium hydroxide is added dropwise to form a clear solution of the amino alcohol (V-i) and p-methoxybenzaldehyde upon which a solution of NaBH4 in an aqueous solution of sodium hydroxide is added dropwise, all the time maintaining a reaction temperature of about 40° C. to about 45° C. Upon addition of the solution of NaBH4 in an aqueous solution of sodium hydroxide, the reaction solution is stirred for about 30 minutes after which glacial acetic acid is added to neutralize the reaction to a pH of about 8 to about 9. Upon neutralization water is added to form a slurry and the slurry is cooled to about -15° C. to about 0° C. for about 1 hour. The cooled slurry of the amino alcohol (V-i) is filtered and washed with water to give the crude crystalline amino alcohol (V-i) as a pale yellow solid.

Provenance & Evidence