Diterpenes from Coleus forskohlii (WILLD.) BRIQ. (Labiatae).
Three new minor labdane diterpene glycosides, forskoditerpenoside C, D, and E (1-3), and a novel labdane diterpene forskoditerpene A (4) were isolated from the ethanol extract of the whole plant of Coleus forskohlii. Their structures and relative stereochemistry were elucidated on the basis of extensive spectroscopic analyses including 1D-, 2D-NMR, and HR-ESI-MS experiments. Compounds 1-3 showed an unusual 8,13-epoxy-labd-14-en-11-one glycoside pattern. They showed relaxative effects on isolated guinea pig tracheal spirals in vitro. Compound 4 with a cyclopropyl, confirmed by a single-crystal X-ray diffraction determination, is the first known labdane derivative with a spiro element.
Minor diterpenoids of Coleus forskohlii
The structures of four diterpenoids, isolated from the roots of Coleus forskohlii, have been elucidated as 7β-acetoxy-6β,9α-dihydroxy-8,13-epoxy-labd-14-en-11-one (7), 6β,7β,9α-trihydroxy-8,13-epoxy-labd-14-en-11-one (8), 6β-hydroxy-8,13-epoxy-labd-14-en-11-one (9), 8,13-epoxy-labd-14-en-11-one (10) by spectral analysis in comparison with forskolin (1) and its congeners.
Catalytic removal of tert-butyldimethylsilyl (TBS) ether by PVP-I
Abstract A mild, efficient and rapid protocol the deprotection of alcoholic TBDMS ethers using PVP-1 as catalyst in methanol, the procedure of deprotection of various TBDMS ethers were found to be very convenient, easy work-up, high yielding.