Radiopharmaceutical for differential diagnosis of tuberculoma: synthesis of 2-[11C]cyano-isonicotinic acid hydrazide

The radiochemical synthesis of 2-[11C]cyano-isonicotinic acid hydrazide was accomplished. Carbon-11 labelled cyano-group was introduced at the 2-position of the pyridine ring of 1-methoxy-4-methoxycarbonyl pyridinium methyl sulfate via a Riessert-Kaufmann type reaction. The reaction was performed on a solid support (silica gel) to yield no-carrier-added methyl 2-[11C]cyano-isonicotinate in (32.4 ± 12%) (EOB) yield. This method is unique for the incorporation of [11C]HCN to base sensitive substrates. The carbon-11 labelled methyl ester was treated with hydrazine hydrate to obtain 2-[11C]cyano-isonicotinic acid hydrazide. The final radiochemical yield was 10% (EOB) and the synthesis time was approximately 35 min. (author)