Nordlander indole synthesis

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... 

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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