Recently, the first direct method for preparing 2,3-epoxyamides (glycidic amides)
was disclosed. Now in this letter, the enantiopure synthesis of both enantiomers of
norbalasubramide featuring this synthetic method is reported. To this end, chiral
N-allyltryptamine 12 was prepared and transformed into an inseparable mixture of diastereomeric epoxyamides
13a/13b, which were submitted to intramolecular cyclization with Cu(OTf)2 to afford a separable mixture of eight-membered ring lactams 14a and 14b. Finally, after removal of the protective group and the chiral auxiliary an enantiopure
synthesis of the title compounds was completed.
Key words
2,3-epoxyamides - glycidic amides - tandem oxidation - sodium chlorite - balasubramide
- norbalasubramide