Reaction of 6-hydrazino-3,4-dimethyl-1H-pyrazolo[3,4-d]pyrimidine with pregnenolone derivatives

New androsteno17,16-d]pyrazoles and -pyrazolines with pyrazolo3,4-d]pyrimidine fragments were synthesized. A reaction of 3β-hydroxypregna-5,16-dien-20-one and its 3-O-acetyl derivative with 6-hydrazino-3,4-dimethyl-1H-pyrazolo3,4-d]pyrimidine led to hydrazones at position 20 of the pregnenolone molecule, a possibility of their cyclization was studied. Upon melting, the hydrazones cyclize with the formation of pyrazoline ring annulated with ring D of the steroid at positions 16 and 17. Reflux of the hydrazones in mesitylene with AcOH leads to a mixture of two reaction products: androsteno17,16-d]pyrazole and a dodecahydro-13H-phenanthro1′,2′:5,6]pyrano2,3-d]pyrazole derivative. Apparently, this transformation proceeds through the corresponding epoxide with subsequent rearrangement, which leads to the ring D expansion.