| http://www.w3.org/ns/prov#value | - No. 398,083 the heterocyclic compounds are condensed by reaction with one or more condensing reagents of the formula: SiX wherein X is a halogen atom, e.g. Cl, Br, I or F, or an R or OR radical in which R is as defined above and the reagent contains at least two halogen atoms.
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