Formaldehyde → trans-3,4-dihydro-3-hydroxy-4-[N-(2-hydroxymethyl-3-oxo-cyclopent-1-enyl)amino]-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile

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Reaction Steps

2,98 of the title compound of example 5 are dissolved in 150 ml of acetone and a drop of a phenolphtalein-solution and the solution is mixed with 2,5 ml of a 37% formaldehyde solution three times every hour. The pH-value of the solution is kept between 8 and 9 by controlled addition of 0,1 aq. sodium hydroxide-solution. After stirring during 5 hours the reaction solution is diluted with water and the organic components are extracted with dichloromethane. Usual work up yields white crystalls of the title compound having a m.p. of 218°-220° C. (from dichloromethane/ethanol).

Provenance & Evidence