ABSTRACT
[figure: see text] A tandem anionic 5-exo-dig cyclization/Claisen rearrangement sequence was used to effect a facile, "one-pot" conversion of an appropriately substituted 4-alkyn-1-ol to the tetracyclic carbon core structure of phorbol. The synthesis was conducted using readily available nonracemic starting materials to provide the target structure as a single enantiomer in high chemical yield.
Subject(s)
Polycyclic Compounds/chemistry , Polycyclic Compounds/chemical synthesis , Alkynes/chemistry , Catalysis , Cyclization , Magnetic Resonance Spectroscopy , Molecular Structure , Phorbols/chemistry , Stereoisomerism , Structure-Activity Relationship , Vinyl Compounds/chemistryABSTRACT
The scope and limitations of a tandem 5-exo dig cyclization/Claisen rearrangement sequence involving appropriately substituted 4-alkyn-1-ols as an efficient "one-pot" route to fused tricyclic ring systems is described. The reaction rates were found to be strongly dependent on the nature of the terminal substitutent of the triple bond. In some cases the entire sequence was found to proceed in good yield at temperatures as low as 115 degrees C.
