Stereoselective synthesis of bis-steroidal pyrazine derivatives

Some compounds of Cephalostatin family have shown anti-cancer activity against human cancer cell line and active intensity has close relationship with the stereochemistry of the substituted group, for example, β-OH at C-12 in compound 2 showed less promising results and the mixture 3 (α + β) showed a large enhancement of the activity compared to the compound 2. So, the work was concentrated on the synthesis of 12′α-derivatives (scheme 1 ) and the separable diastereomers 10 and 11 were obtained in a pure form. †Dedicated to Professor E. Winterfeldt on his 75th birthday.