ChemInform Abstract: Asymmetric α‐Hydroxylation of a Lactone with Vinylogous Pyridone by Using a Guanidine—Urea Bifunctional Organocatalyst: Catalytic Enantioselective Synthesis of a Key Intermediate for (20S)‐Camptothecin Analogues. Issue 23 (10th June 2014)