The Use of Sodium Chlorite in the Direct Synthesis of Glycidic Amides: Enantiopure Synthesis of Both Enantiomers of Norbalasubramide
摘要:
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.
The asymmetricepoxidation of electron‐deficient olefins has been achieved using inexpensive and readily available prolinols as catalysts with good to excellent yields and enantioselectivities. The utility of the resulting chiral epoxides was illustrated by elaboration to several synthetically useful compounds featuring a concise synthesis of (−)‐(5R,6S)‐balasubramide.