Yong-Gang Wang

Synthesis of macrosphelides H and G

Abstract A compound with furyl and vinyl groups was designed as an intermediate for synthesis of macrosphelide H. The furyl group was oxidatively transformed into the key C(5)–O(10) part by a two-step conversion of (1) NBS, H 2 O; (2) NaClO 2 without affecting the free hydroxyl group at C(3), thus furnishing the seco acid, while the Wacker oxidation at the final step was used to convert the vinyl group into acetyl group to afford macrosphelide H. This strategy was applied successfully to synthesis of macrosphelide G as well.

12(S)-Hydroxyeicosatetraenoic acid induces cAMP production via increasing intracellular calcium concentration.

We have found that a 12‐lipoxygenase metabolite of arachidonic acid, 12(S)‐hydroxy‐5Z,8Z,10E,14Z‐eicosatetraenoic acid (12‐HETE), induces cAMP production in human normal fibroblast TIG‐1 cells. This phenomenon was not observed in other cells tested including human embryonic kidney HEK293 cells. We have speculated that this specific response might be influenced by the kinds of isoform of adenylyl cyclase (AC) present in cells. We found that TIG‐1 cells specifically expressed type VIII AC. As type VIII AC is known to be activated by an increase of calcium concentration, we determined the change of intracellular Ca2+ concentration after the addition of 12‐HETE. It was elevated not only in TIG‐1 cells, but also HEK293 cells, which did not respond to 12‐HETE to produce cAMP. The addition of a calcium ionophore elevated the concentration of intracellular cAMP in TIG‐1 cells, but it was without effect in HEK293 cells. To show that the expression of this particular isoform of AC is responsible for the positive response to 12‐HETE, we transfected this AC isoform into HEK293 cells. The type VIII AC‐transfected cells, in contrast to the mock‐transfected ones, became very responsive to 12‐HETE to produce cAMP. Taken all together the data would strongly suggest that 12‐HETE specifically activates type VIII AC via increasing intracellular Ca2+ concentration.

Synthesis of Alaremycin

Methyl 5-azido-4-oxohexanoate was synthesized from 5-hexenoic acid in six steps and converted to the title compound by NaReO 4 - and CF 3 SO 3 H-catalyzed reaction in AC 2 O/CCl 4 followed by hydrolysis of the methyl ester moiety.