62. Stereoselective total syntheses of (±)-chanoclavine I and (±)-isochanoclavine I by an intramolecular nitrone-olefin/cycloaddition. Preliminary communication
    Oppolzer, W.; Grayson, J. I.
    Helv. Chim. Acta 1980, 63, 1706-1710

The racemic alkaloids chanoclavine I (1) and isochanoclavine I (2) have been synthesized stereoselectively from indole-4-carbaldehyde (3) by a sequence of 11 operations in overall yields of 14% and 2.4%, respectively. The key step 6 → 8(Scheme 2) involves a transient nitrone 7 which undergoes a regio- and stereoselective intramolecular cycloaddition to a 1,2-disubstituted olefinic bond.

DOI : 10.1002/hlca.19800630639