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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 2 (28th November 2013)
Record Type:
Journal Article
Title:
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 2 (28th November 2013)
Main Title:
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
<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>We have developed a catalytic asymmetric synthesis of (<italic>S</italic>)‐4‐ethyl‐6, 6‐(ethylenedioxy)‐7, 8‐dihydro‐4‐hydroxy‐1<italic>H</italic>‐pyrano[3, 4‐<italic>f</italic>]indolizine‐3, 10(4<italic>H</italic>)dione (<bold>5 a</bold>), a synthetic intermediate for (20<italic>S</italic>)‐camptothecin analogues. A key step in this synthesis is an asymmetric α‐hydroxylation of a lactone with a vinylogous pyridone structure (<bold>8 a</bold>) by using a guanidine–urea bifunctional organocatalyst. The present oxidation was successfully applied to the synthesis of C20‐modified derivatives of (+)‐C20‐desethylbenzylcamptothecin (<bold>13</bold>).</p> </abstract>