Boulton-Katritzky reaction

The 1H, 13C, and 15N NMR chemical shifts of the (Z)-phenylhydrazones of 5-alkyl-and 5-aryl-3-benzoyl-l,2,4-oxadiazoles have provided information on the ground-state electronic distribution.27 The effects of the substituents on the chemical shifts of N(4) and C(5) correlate with kinetic results of the rearrangement of 1,2,4-oxadiazoles to 1,2,3-triazoles (Boulton-Katritzky reaction) support the importance of the leaving group. 

The paper of Frenna, Spinelli et al. contained data on the kinetics of the rearrangement of 3-benzoyl-5-phenyl-l,2,4-oxadiazole 129 into the corresponding 2-aryltriazoles 130 (Boulton-Katritzky reaction) [114]. 

Boroxazothienopyridines, 4, 1029-1032 Borsche synthesis, 3, 44 Botrydiplodin mass spectrometry, 4, 585 Boulton-Katritzky rearrangement, 5, 288 Bovine milk xanthine oxidase substrates, 1, 234 Bradsher reaction... 

Boulton-Katritzky rearrangement, 5, 258 Pyrazol-5-one, 4-arylazo-reactions, 5, 262 Pyrazol-5-one, 4-arylidene-configuration, 5, 208... 

In the case of Bfx bearing imsaturated groups at the 4-position, an important ring-opening ring-reclosure process leads to new heterocycles. This reaction, known as the Boulton-Katritzky rearrangement, has been studied for different 4-unsaturated moieties to produce new benzo-heterocycles, i.e.. 

Furoxans and benzofuroxans undergo thermal and photochemical ring cleavage, reactions with nucleophiles, Boulton-Katritzky rearrangement, reduction and deoxygenation, ring transformation, etc. (see also Section 5.05.6.2). 

Furazans are formed via the Boulton-Katritzky rearrangement of the oximes of several classes of 3-acyl-l-oxa-2-azoles, including 1,2,4-oxadiazoles, isoxazoles, and furazans. These reactions have been intensively investigated over many years, and the literature comprehensively reviewed <81 AHC(29)i4i, 90KGS1443> the latter survey deals specifically with the exploitation of such rearrangements for furazan synthesis. 

The benzofuroxan phenylene ring is subjected to electrophilic substitution, in particular, nitration reaction. If the nitro group is introduced into the position neighboring to the heterocycle, the nitro compound formed undergoes the so-called Boulton-Katritzky rearrangement [155-161],... 

A DFT study of the Boulton-Katritzky rearrangement of (5i )-4-nitrosobenz[c]isoxazole and its anion indicated that these reactions have a pseudopericyclic character <04JOC7013>. 

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