Synthesis of the Marine Pyrroloiminoquinone Alkaloids, Discorhabdins

Many natural products with biologically interesting structures have been isolated from marine animals and plants such as sponges, corals, worms, etc. Some of them are discorhabdin alkaloids. The discorhabdin alkaloids (discorhabdin A-X), isolated from marine sponges, have a unique structure with azacarbocyclic spirocyclohexanone and pyrroloiminoquinone units. Due to their prominent potent antitumor activity, discorhabdins have attracted considerable attention. Many studies have been reported toward the synthesis of discorhabdins. We have accomplished the first total synthesis of discorhabdin A (1), having the strongest activity in vitro among discorhabdins in 2003. In 2009, we have also accomplished the first total synthesis of prianosin B (2), having the 16,17-dehydropyrroloiminoquinone moiety, by a novel dehydrogenation reaction with a catalytic amount of NaN3. These synthetic studies, as well as syntheses of the discorhabdins by various chemists to-date, are reviewed here

<Session 1: Fish Telemetry I>How sudden illumination in nighttime changes the behavior of schooling juvenile Pacific bluefin tunas in an open sea net cage?

19–22 May 2018 Kyoto, JapanOn the cultivation of Pacific blufin tunas Thunnus orientalis in an open sea net cage, it is reported that sudden illumination in nighttime caused by car and fishing light can cause a harmful effect on the fish survival. In this study, behaviour response of schooling juvenile Pacific bluefin tunas (size: 210 - 250 mm) to the sudden illumination change in nighttime was monitored in an open sea net cage (12m x 12m in width, and 6m in depth) by using animal-mounted acceleration/angular velocity data loggers (200 Hz). Two types of illuminator were simulated: car light for 8 fish and fishing underwater light for 11 fish. When the car light was intermittently illuminated over the sea surface for more than 3 min (10 sec on and 10 sec off), the fish significantly increased the max/mean/standard deviation of acceleration and angular velocity with occasional burst, and decreased the similarity in movement cycle. However, no death was observed. The fishing underwater light was turned on and off for 30 sec and 1 min respectively, and the procedure was repeated for 5 times. The fish significantly increased the max/mean/standard deviation of acceleration and angular velocity with more occasional burst than the car light. The responsiveness to the illumination significantly decreased with the repeated times of illumination. One of the fish reached 230.5 m/s_2 in acceleration and 4333 deg/s in angular velocity, and died probably because of the collision to the net wall

Diastereoselective Desymmetrization of Symmetric Dienes and its Synthetic Application

The desymmetrization of symmetric compounds is a useful approach to obtain chiral building blocks. Readily available precursors with a prochiral unit could be converted into complex molecules with multiple stereogenic centers in a single step. In this review, recent advances in the desymmetrization of symmetric dienes in the diastereotopic group differentiating reaction and its synthetic application are presented