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New di-, tri-, tetra-, and pentanorlabdane compounds with thiosemicarbazone and 1,3-thiazole fragments were synthesized. Their antifungal and antibacterial activities were studied. The main advantages of this research were the available starting material, i.e., the natural labdane diterpenoid (–)-sclareol, which was isolated from renewable resources, and the high probability of biological activity combined with the low toxicity of these compounds because of their natural origin.

Series of drimane and homodrimane sesquiterpenoids with oxadiazole and thiadiazole fragments were synthesized. Their antifungal and antibacterial activities were studied.

Using sclareol and sclareolide as starting materials, the guanidine derivatives of 12-amino-11-dihomodrimane-8α-ol and 13-amino-14,15-bis-dinorlabd-8(9)-ene were synthesized by the reaction of the corresponding amines with sodium hydrogencyanamide in ethanol – water solution. Monoacyl- and diacylguanidines were prepared from activated with N,N-carbonyldiimidazole Δ8,9-bicyclohomofarnesenoic acid by the reaction with guanidine. Their structures were confirmed by the 1H and 13C NMR, IR spectral and elemental analysis data. The compounds 12, 13 and 15 were screened for their antiproliferative and cytotoxicity activities against Colo 205, Colo 320 and MRC 5 human lung fibroblasts with respect to standard drug, Cisplatin. The compounds 12 and 15 exhibits excellent results than positive control. Hence these two compounds may be act as drug lead molecules in cancer chemotherapy.

Drimenic acid was synthesized in six steps from norambreinolide. Reaction of drimenic acid with oxalyl chloride produced iso-drimenic acid chloride, which reacted with heterocyclic amines (2-aminopyrimidine, 2-aminopyrazine, 4-aminopyrimidine, N-aminocarbazole, and 3-amino-1,2,4-triazole) to form amides of iso-drimenic and albicanic acids. The structures of the amides were elucidated by spectral methods and an X-ray structure analysis.

12,12′-Azino-di-8′-hydroxy-11-dihomodrimane, N,N′-di-(8′-hydroxy-11-dihomodrim-12-ylidene)-adipic acid dihydrazide, N,N′-di-(∆8,13-bicyclohomofarnesenoyl)-hydrazine, and hydrazides of ∆8,9- and ∆8,13-bicyclohomofarnesenoic acids were synthesized.

Amides of ∆ 8,13 -bicyclohomofarnesoic acid containing 1,2,4-triazole and carbazole rings were synthesized in eight steps from commercially available norambreinolide. The compounds were prepared by reacting the acid chloride with the heterocyclic amines 3-amino-1,2,4-triazole and N-aminocarbazole. Their structures were elucidated by spectral methods and x-ray crystal structure analyses.