Synthesis of (-)-centrolobine by Prins cyclizations that avoid racemization.
[formula: see text] The segment-coupling Prins cyclization avoids two of the problems common to other Prins cyclization protocols: side-chain exchange and partial racemization by reversible 2-oxonia Cope rearrangement. Model studies demonstrate the stereochemical fidelity of Prins cyclizations using alpha-acetoxy ethers compared with direct aldehyde-alcohol Prins reactions. Furthermore, we propose a mechanism for the racemization observed in some intermolecular Prins cyclizations. Two straightforward syntheses of optically pure (-)-centrolobine highlight the utility of Prins cyclizations.
Marumoto
Shinji
S
Department of Chemistry, 516 Rowland Hall, University of California-Irvine, Irvine, California 92697-2025, USA.
Jaber
James J
JJ
Vitale
Justin P
JP
Rychnovsky
Scott D
SD
D000900:Anti-Bacterial Agents / Q000138:chemical synthesis*; D003500:Cyclization; D007202:Indicators and Reagents; D009904:Optical Rotation; D011714:Pyrans / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000900:Anti-Bacterial Agents; D007202:Indicators and Reagents; D011714:Pyrans; C432457:centrolobin