Synthesis of new symmetrical bis-steroidal pyrazine analogues from diosgenin

New symmetrical bis-steroidal pyrazine dimers that are cephalostatins/ritterazines analogues have been prepared easily from a cheap, readily available natural steroid (diosgenin). These dimers were obtained by classical, condensation of α-amino ketones in order to construct the pyrazine rings. The three dimers differ in the functionalized diosgenin: (25R)-5α,6β-dihydroxy-5α-spirosta-3-one, (25R)-4,5α-epoxy-5β-spirosta-3,6-dione and (25R)-5α-hydroxy-5α-spirosta-3,6-dione respectively.     

Synthesis of bis-diosgenin pyrazine dimers: new cephalostatin analogs

A convenient synthesis for bis-diosgenin pyrazine dimers, cephalostatin analogues is reported. These symmetrical dimeric steroid-pyrazines were obtained by the classical condensation of -amino ketones, the most efficient method for pyrazine ring construction.