Syntheses of Gibberellins A₁₅ and A₂₄, the Key Metabolites in Gibberellin Biosynthesis

Gibberellins (GAs) are essential phytohormones involved in numerous aspects of plant growth and development. Notably, the biochemistry and genetics of GA biosynthesis, which is associated with their endogenous regulation, have been largely resolved; however, a crucial unsolved question remains: the precise mechanism of the stepwise oxidation and subsequent removal of C-20 from C₂₀ precursors, leading to bioactive C₁₉ gibberellins, is still unresolved. To satisfy numerous requests from biologists, practical preparations of certain GAs that were isolated in miniscule quantities are highly demanded. Herein, we report the first practical syntheses of GA₁₅ and GA₂₄, the key C₂₀ metabolites in gibberellin biosynthesis, from commercially available GA₃. The protocols are robust and offer the capacity to produce GA₂₄ and GA₁₅ under gram scales in high overall yields and thus aid in further biological and related studies

Structures of New Alkaloids from Rain Forest Trees Galbulimima belgraveana and Galbulimima baccata in Papua New Guinea, Indonesia, and Northern Australia

Following on our 60-year research on the chemical constituents of the rain forest trees Galbulimima belgraveana and Galbulimima baccata, we report the isolation of seven new alkaloids: GB14 (<b>14</b>), GB22 (<b>15</b>), GB25 (<b>16</b>), GB21 (<b>17</b>), GB23 (<b>18</b>), GB24 (<b>19</b>), and GB26 (<b>20</b>). Their structures were elucidated by a combination of spectroscopic analyses and single-crystal X-ray crystallography, as well as structure degradation and interconversion. The newly isolated alkaloids are precursors or derivatives of the known family members from our early studies and could be intermediates in the biosynthesis of the Galbulimima alkaloids. Therefore, the present study has expanded the range of structures in this family of alkaloids and provided some missing links in the biosynthetic sequences

Structures of New Alkaloids from Rain Forest Trees Galbulimima belgraveana and Galbulimima baccata in Papua New Guinea, Indonesia, and Northern Australia

Following on our 60-year research on the chemical constituents of the rain forest trees Galbulimima belgraveana and Galbulimima baccata, we report the isolation of seven new alkaloids: GB14 (<b>14</b>), GB22 (<b>15</b>), GB25 (<b>16</b>), GB21 (<b>17</b>), GB23 (<b>18</b>), GB24 (<b>19</b>), and GB26 (<b>20</b>). Their structures were elucidated by a combination of spectroscopic analyses and single-crystal X-ray crystallography, as well as structure degradation and interconversion. The newly isolated alkaloids are precursors or derivatives of the known family members from our early studies and could be intermediates in the biosynthesis of the Galbulimima alkaloids. Therefore, the present study has expanded the range of structures in this family of alkaloids and provided some missing links in the biosynthetic sequences