Preparation of aryl benzyl ketones by [1,2]-Wittig rearrangement

Katritzky, Alan R.; Zhang, Yuming; Singh, Sandeep K.

doi:10.3998/ark.5550190.0003.716

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Reactivity Of Substituents Attached To Ring Nitrogens1

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2020

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Cited by 4 publications

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“…For the derivatives of aromatic aldehydes (R 1 = aryl), LDA is a base strong enough to pull the benzylic proton from ether 777 to give anion 778 . The subsequent [1,2]-Wittig rearrangement produces alkoxide 779 which spontaneously expels benzotriazole anion to furnish ketone 780 <2002ARK(vii)146> . In the case of formaldehyde derivatives (R 1 = H), a stronger base, Bu n Li, is required to do the job; however, it is difficult to stop the reaction sequence at the ketone stage, and alcohols 781 are obtained as the major products <2000H(53)1783> .…”

Section: Reactivity Of Substituents Attached To Ring Nitrogensmentioning

confidence: 99%

1,2,3-Triazoles

Rachwał

Katritzky

2008

Comprehensive Heterocyclic Chemistry III

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Section: Reactivity Of Substituents Attached To Ring Nitrogensmentioning

confidence: 99%

1,2,3-Triazoles

Rachwał

Katritzky

2008

Comprehensive Heterocyclic Chemistry III

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[1,2]‐Wittig Rearrangement

2010

Comprehensive Organic Name Reactions and Reagents

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The transformation of an ether into a secondary alkoxide via a [1,2]‐carbon shift by treatment of the ether with a strong base such as alkyl lithium is generally known as the [1,2]‐Wittig rearrangement. Similarly, the analogous transformation of thioether into thiol is called the thio ‐Wittig rearrangement, and the corresponding conversion of imine is known as imino 1,2‐Wittig rearrangement. The driving force for this reaction is the instability of the α‐oxygenated carbanion. The reaction rate has been reported to increase with more base. It has been noticed that the yield of the [1,2]‐Wittig rearrangement is usually low, and the reaction might be complicated by other reactions. It has been found that the [1,2]‐Wittig rearrangement is solvent dependent. In spite of the fact that the [1,2]‐Wittig rearrangement proceeds via homolytic dissociation and the radical recombination mechanism, the stereogenicities of the two proradical centers are retained to appreciable extents. This reaction has limited applications in organic synthesis.

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