The Nordlander Indole Synthesis

2- anilino acetals (equation 3) [8]. Dmitrienko and coworkers crafted pyrrolo[2,3-/]indole (1) using the Nordlander method (equation 4) [9]. 

Several additional examples of the Nordlander indole synthesis are tabulated in Table 1 [13-19]. It is obvious that some of these entries could have easily been included in the Bischler chapter because both reactions involve similar if not identical precursor synthesis and acid-catalyzed cyclizations. For example, the snbstrate in Entry 5 was prepared from the corresponding ethyl bromopyruvate. The example in Entry 3 is one of several similar Nordlander indolizations that yield heavily snbstituted nitroindoles. Likewise, the chemistry depicted in Entry 6 was applied to the preparation of several 

Indole Ring Synthesis From Natural Products to Drug Discoveryy First Edition. Gordon W. Gribble. 2016 John Wiley Sons, Ltd. Published 2016 by Jdin Wiley Sons, Ltd. 

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Scheme 3 Black Application of the Nordlander Indole Synthesis...

In 1981, Nordlander demonstrated that acetals 22 can be used as reactants in the Bischler-Mdhlau indole synthesis, providing 2,3-unsubstituted indoles in good yield. Subsequent modification was made by Sundberg in 1984. From 1998 to 2002, Moody and co-workers developed a modified Bischler indole synthesis by using rhodium(II) acetate to catalyze the reaction of N-methylanilines with a-diazo-P-ketoesters via an N-H insertion reaction of a rhodium carbenoid. The resulting a-(A -arylamino)ketones cyclize to give indoles upon treatment with BF3 or an acidic ion exchange resin. ... 

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