Sesquiterpenoids, especially those with a homodrimane skeleton, are natural compounds with a wide range of pharmaceutical and biological activities [1]. The 1,3,4-thiadiazole and its derivatives are considered interesting heterocycles since they possess important pharmacological activities [2]. As starting material for the synthesis of new title compounds 11-homodrim-6,8-dien-12-oic acid 2 was used. It was obtained before from commercially available sclareolide 1in 5 steps, with an overall yield of 47%, as depicted in Scheme [3]. After that coupling reaction of acid 2 with hydrazine hydrate was performed. Subsequently, was used one-pot method, that includes the interaction of the hydrazide 3 with a series of substituted isothiocyanates, without isolation of the intermediate compounds. This reaction was carried out in the presence of triethylamine (Et3N) in water, giving desired homodrimane compounds bearing 1,3,4-thiadiazole units in 72-78% yields [4].formulaReagents: a. NH2-NH2·H2O, EtOH, delta, 5h, 85%; b. R-NCS, Et3N, H2O, delta, 18h, 72-78%. Scheme.Thesynthesis of homodrimane sesquiterpenoids with 1,3,4-thiadiazole units. The structures of compounds 4a-c were fully confirmed based on their 1H, 13C, 15N and 2D NMR data.