Covering: 1969 to 2018Azepinoindole natural products can be broadly classified as being of monoterpenoid or non-monoterpenoid origin. The non-monoterpenoid azepinoindoles have not received as much attention in the literature as their more revered monoterpenoid counterparts. In this review, an overview of all non-monoterpenoid azepinoindoles is provided. Various biological and chemical aspects are discussed, including their isolation, biosynthesis and the elegant total synthesis studies that have been inspired by these alkaloids.

The total synthesis of the azepinobisindole alkaloid iheyamine A is described. The successful strategy hinged on an intermolecular cross-Mannich reaction between 5-methoxy-3-acetoxyindole and a protected tryptamine to access an unsymmetrical 2,2'-bisindole, which was subsequently converted into iheyamine A via a deep-blue 3-indolone intermediate. VT H NMR infers that iheyamine A exists as a mixture of tautomers that undergo intermediate chemical exchange on the NMR time scale. The intermolecular cross-Mannich reaction described herein is a viable alternative to metal-catalyzed cross-coupling strategies commonly employed to access 2,2'-bisindoles.

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The synthesis of 3‐amidofurans is laborious due to the difficulty installing a nitrogen substituent at the C3 position of the furan heterocycle. 3‐Acetamido‐5‐acetylfuran (3A5AF), readily available from chitin, is a versatile biorenewable platform that can be converted into a range of functionally rich 3‐amidofurans, streamlining access to this underexplored heteroaromatic chemical space.

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