Synthetic transformation of higher terpenoids 31. Synthesis of 1,2,3-triazolyl-containing furan labdanoids and studies of their cytotoxic activity

16-(1-R-1,2,3-Triazol-4-ylethyl)-, 16-(1-R-1,2,3-triazol-4-ylmethoxymethyl)-, and 16-{2-(1-R-1,2,3-triazol-4-yl)-1-[(1-R-1,2,3-triazol-4-ylmethoxy)ethyl]}-substituted derivatives of methyl lambertianate were synthesized by 1,3-cycloaddition of labdanoid alkynes with azides. The compounds obtained possess considerable cytotoxicity toward the human tumor cell lines CEM-13, MT-4, and U-937. The most active compound, methyl 16-(2-{2-[(1-benzyl-1H-1,2,3-triazol-4-yl)acetyl]furan-3-yl}ethyl)lambertianate, was found to inhibit the viability of the tumor cells by 50% (CCID50) in the concentration of 7–12 μmol L−1.