1,3-Dibromopropane → HCID 20400661, compound

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Reaction Steps

Provided one of the residues R1 or R2 is an alkylcarbonylalkyl group, profitably one can proceed in the way, that the corresponding 4,5,6,7-tetrahydro-4,6-dioxo-pyrazolo-[3,4-d]-pyrimidine is alkylated with a ω-ω'-dibromalkane to ω-alkyl derivative which is treated with acetoaceticester and the reaction product is subjected to a ketone decomposition reaction. For example by such a reaction with the 7-ethyl-4,5,6,7-tetrahydro-1-methyl-4,6-dioxo-1H-pyrazolo-[3,4-d]-pyrimidine with 1,3-dibromopropane, the 5-(3-bromopropyl)-7-ethyl-4,5,6,7-tetrahydro-1-methyl-4,6-dioxo-1H-pyrazolo-[3,4-d]-pyrimidine is obtained, which upon acetoaceticester condensation and subsequent ketone decomposition yields the 7-ethyl-4,5,6,7-tetrahydro-1-methyl-4,6-dioxo-5-(5-oxo-n-hexyl)-1H-pyrazolo-[3,4-d]-pyrimidine. The alkylcarbonyalky rest can also be introduced by direct alkylation reaction of the appropriate 4,5,6,7-tetrahydro-4,6-dioxo-pyrazolopyrimidine, preferably as a sodium salt, with an alkylcarbonylalkylhologenide, preferably a chloride or a bromide. For example a 5-oxo-n-hexyl group can be introduce by using 1-bromohexanone-5.

Provenance & Evidence