Hoslundin, hoslundal, and hoslunddiol: three new flavonoids from the twigs of <i>Hoslundia opposita</i> (Lamiaceae)

Three new flavonoids (hoslundin 1, hoslundal 4, and hoslunddiol 6) have been isolated from the twigs of Hoslundia opposita. The structure of hoslundin has been determined mainly by the use of 2D n.m.r. long-range δC/δH correlation in conjunction with the 1D proton-coupled 13C n.m.r. spectrum, while the structures of the rest were established using 1H and 13C n.m.r. spectroscopy. The manner in which 2D n.m.r. long-range δC/δH correlation experiments are used for determining bond connectivity during the process of structural elucidation is discussed