The pig liver esterase (PLE)-catalyzed kinetic resolution of half-esters derived from prochiral diesters is described. Generally, the PLE-catalyzed enantioselective hydrolysis of prochiral diesters affords the corresponding half-esters in high yield, because further hydrolysis of the half-esters does not typically occur. However, we found that some half-esters undergo PLE-catalyzed hydrolysis when they are gradually added to a PLE suspension in a potassium phosphate buffer at pH 8.0 via a syringe pump, leading to the kinetic resolution of the half-esters. (c) 2013 Elsevier Ltd. All rights reserved.
Enantioselective Total Synthesis of (+)-Ophiobolin A
The enantioselective total synthesis of (+)‐ophiobolin A is described. This total synthesis features the construction of the spiro CD ring of (+)‐ophiobolin A through a stereoselective intramolecular Hosomi–Sakurai cyclization reaction, the joining of the A ring to the CD ring by using a reaction reported by Utimoto, and the construction of the ophiobolin eight‐membered carbocyclic ring through ring‐closing