Total synthesis of aspidostomide G from a brominated tryptamine.

The first total synthesis of aspidostomide G using a brominated tryptamine is described. The synthetic route features several notable aspects: (a) the starting material, compound 13, contains a built-in hydroxy group and was transformed to the Sonogashira reaction precursor; (b) the construction of the indole ring was achieved through a transition-metal catalyzed synthesis and a 5-endo-dig cyclization. The desired indole 9 was synthesized in only 7 steps with an overall yield of 54% and required only three columns; (c) a late C2-bromination was achieved by using the 4-acetoxyindole analogue 14c.

Recyclable and reusable ionic liquid-supported azo precursors in Mitsunobu reactions.

A new type of azo precursor, ionic liquid-supported hydrazidecarboxylate, was synthesized and applied in Mitsunobu reactions. The developed reagent is recyclable during the reaction and reusable after recovery by the ionic liquids. The ionic liquid-based azo precursor in conjugation with PhI(OAc)2 has been proved to be useful in the formation of carbon-oxygen, carbon-nitrogen, and carbon-sulfur bonds.