(3AR,4R,5R,6AS)-5-(BENZOYLOXY)HEXAHYDRO-2-OXO-2H-CYCLOPENTA[B]FURAN-4-CARBOXALDEHYDE [3AR(3A-ALPHA,4ALPHA,5BETA,6A-ALPHA)]-(-)-5-(BENZOYLOXY)HEXAHYDRO-2-OXO-2 H-CYCLOPENTA[B]FURAN-4-CARBOXALDEHYDE [3ar(3aa,4a,5b,6aa)]-(-)-5-(benzoyloxy)hexahydro-2-oxo-2h-cyclopenta[b]furan-4-carboxaldehyde