abstract |
A compound (VIIa): ** Formula ** where Ra is OH, CHO, COOH, CONH2, CONH (OH), COOR6, CONHR6; and R6 is linear or branched alkyl of 1-3 carbon atoms; or a salt, ester, enol ether, enol ester, acetal, amide, ketal, orthoester, hemiacetal, hemicetal, pharmaceutically acceptable, hydrate or solvate thereof. |