[1]TetrahedronLetters,1991,vol.32,p.4733-4736
[1]JournaloftheChemicalSociety.Chemicalcommunications,1993,p.1359-1361
[1]JournalofOrganicChemistry,1992,vol.57,p.6542-6546
[1]JournalofMedicinalChemistry,1987,vol.30,p.1433-1454
[1]ChemicalandPharmaceuticalBulletin,1995,vol.43,p.450-460