Many drimane sesquiterpenoids exhibit various types of biological activity [1]. In continuation of our investigation on the synthesis of nitrogen-containing drimane and homodrimanesesquiterpenoids [2, 3], we herein describe the synthesis of 5-(Δ8,9- bicyclohomofarnesenyl)-1,3,4-oxadiazol-2(3H)-one (7) and 2-amino-5-(Δ8,9-bicyclohomo-farnesenyl)-1,3,4-oxadiazol (8) from commercially available norambreinolide (1) according to the scheme:

Reagents and conditions: a) DMSO, P2O5, CH2Cl2, 0°C, 10 min, 20°C, 45 min; Et3N, 0°C, 10 min, 20°C, 45
min, 95%; b) NaClO2, NaH2PO4•2H2O, 2-Me-2-butene, t-BuOH, 20°C, 2h, 94%; c) (COCl)2, C6H6, 20°C, 1 h,
N2H4•H2O(98%), CH2Cl2 CDI, Et3N, THF, 0°C, 5h, 20°C, 12h, 92%; f)
BrCN, NaHCO3, dioxane, 20°C, 5 h, 90%.
The structures of the newly obtained compounds were established on the basis of their
spectral date (IR, 1H- and 13C NMR, mass-spectra).
References:
1. B.J. Jansen, A de Groot, Nat. Prod. Reports, 2004, 21, 449.
2. K. Kuchkova, A. Aricu, E. Secara et.al., Med. Chem. Res., 2014, 23, 1559.
3. A.N. Aricu, K.I. Kuchkova, A.N. Barba et.al., Chem. Nat. Compd, 2016, 52, 1029.