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DOI: 10.1055/sos-SD-040-00241

Purchase, R.; Sainsbury, M.Science of Synthesis, (200940382.

Anionic [3,3]-sigmatropic rearrangements of N-acyl-N-phenylhydrazines are known to afford (2-aminophenyl)acetamides, but these products may be mixed with compounds formed by competing SommeletHauser-type and Stevens-type migrations.[‌90‌] The acid-catalyzed [5,5]-sigmatropic rearrangement of hydrazobenzenes that gives 4,4-diarylbiaryls is commonly known as the benzidine rearrangement. This reaction is well covered in the older literature and, more recently, is summarized in at least two papers[‌91‌,‌92‌] as well as in Science of Synthesis, Vol. 31b [AreneX (X=N, P) (Section]. As a result further discussion in this section is unnecessary, although it is observed that N,N-diarylhydrazides 97 tethered with a polyether group at the meta positions undergo the rearrangement to afford benzidines 98 strapped by a polyether unit at the 2,2-positions (Scheme 27).[‌92‌]

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