Asymmetric Total Synthesis of (+)-Virosine A via Sequential Nucleophilic Cyclizations onto an Activated Formamide
摘要:
The first synthesis of tetracyclic alkaloid virosine A is reported. The natural alkaloid was prepared in only 13 steps, in an enantioenriched form. The azabicyclo[2.2.2]octane core was efficiently assembled using a key Vilsmeier-Haack and Mannich cyclizations sequence performed in one pot.
An efficient formal synthesis of balanol via the asymmetric epoxide ring opening reaction
作者:Michael H. Wu、Eric N. Jacobsen
DOI:10.1016/s0040-4039(97)00192-5
日期:1997.3
An efficient formal synthesis of balanol is described. The thirteen-step sequence features a highly enantioselective (92% ee) ring opening of 1,4-cyclohexadiene monoepoxide with TMSN3 catalyzed by the Cr-salen complex 3. A selective Beckmann rearrangement followed by amide reduction and nitrogen functionalization affords 2, thus completing a formal synthesis of balanol in 31% overall yield.