Facile conversion of 23-hydroxyspirosolane into pregnane

Two novel reactions with regard to steroidal alkaloid sapogenols obtained from ripe tomato have been found. These reactions have been attained by simple facile method in only refluxing with pyridine and water. One is isomerization of a spirosolane derivative, isoesculeogenin A (2), into a rare solanocapsine derivative, esculeogenin B (3), disclosing a chemical correlation between isoesculeogenin A and esculeogenin B. Another is conversion of a 23-hydroxyspirosolane derivative, esculeogenin A (1), into a pregnane derivative (4), presenting an epoch-making method for derivation of steroidal hormone material.