Patent ID: 8273908

Claim:
A process for the preparation of a compound of formula II wherein R 1 and R 2 independently are hydrogen or a hydroxy- or hydrocarbyl group; or wherein R 1 and R 2 together are a double bonded oxygen; R 3 is hydrogen; R′ 4 is a nitrobenzophenone group; and R 5 and R 6 independently are hydrogen or a hydroxy- or hydrocarbyl group; from a compound of formula I wherein, R 1 , R 2 , R 3 , R 5 and R 6 are as defined above and R 4 is hydrogen; wherein the compound of formula I is reacted under alkaline conditions with 2-chloro-5-nitrobenzophenone in the presence of an alkanolic solvent and the compound of formula II is directly crystallized from this alkanolic solvent.