A. Bianco

Structure of eucommiol, a new cyclopentenoid-tetrol from Eucommia Ulmoides

Abstract Isolation of Eucommiol a new cylopentenoid-tetrol from Eucommia Ulmoides (Eucommiaceae) is described. Its structure and absolute stereochemistry have been demonstrated.

Partial synthesis of isoeucommiol, a new cyclop entenoid-tetrol

Abstract Isoeucommiol 3, a cyclopentenoid-tetrol isomer of eucommiol 1, has been prepared by NaBH4 reduction of the hemiacetal moiety of aucubigenin 4a. The mechanism of this reduction has been investigated by using NaBD4.

Iridoids—XXIII : Isolation of aucubigenin and its acid-catalyzed rearrangement

Abstract Aucubigenin 3 , the unstable aglycone of aucubin 2 , has been successfully isolated. In acidic medium 3 is converted into the acetal 6 whose structure resulted to be 1,10-anhydro-6-desoxy-7,8-dihydro-7,8-dihydroxyaucubigenin.

Revised structure of acid-catalyzed rearrangement product of aucubigenin

Abstract The 13 C NMR spectrum of 6 , the acid-catalyzed rearrangement product of aucubigenin, has led to a critical re-examination of its 1 H NMR data and instead of the previous structure 6a , the definitive structure of the add-catalyzed rearrangement product is 1,10-anhydro, 3,4-dihydro, 4-decarbomethoxy, -3α-hydroxygardenogenin 6b .

Acid catalysed rearrangements of iridoid aglycones—II : Tetracyclic acetal from asperulosidol, a non natural asperuloside derivative

Abstract The acid catalysed rearrangement of asperulosidol 5 leads to the tetracyclic acetal 7 whose structure and configuration has been determined by 1H-NMR and 13C-NMR spectroscopy, as well as by the Li/NH3 reduction of 7 to the cyclopententriol 10. The reaction course has been clarified by reacting 5 with DCl and formation of the monodeutero derivative 9.

Reduction of iridoid aglycones—III: Reactivity of lamiolgenin towards NaBH4

Abstract The reaction which occurs when lamiolgenin 2 is treated with an excess of NaBH 4 is unusually complex owing to an intramolecular aldolic condensation which leads to a bicyclo[3.2.0]heptane derivative 4 . The mechanism of this reduction has been investigated by using NaBD 4 . Spectral data (IR, 1 H NMR, 13 C NMR) of the products are presented.