Newman–Kwart rearrangement
| Newman-Kwart rearrangement | |
|---|---|
| Named after | Melvin Spencer Newman Harold Kwart |
| Reaction type | Rearrangement reaction |
| Identifiers | |
| Organic Chemistry Portal | newman-kwart-rearrangement |
| RSC ontology ID | RXNO:0000412 |
The Newman–Kwart rearrangement is a type of rearrangement reaction in which the aryl group of an O-aryl thiocarbamate, ArOC(=S)NMe2, migrates from the oxygen atom to the sulfur atom, forming an S-aryl thiocarbamate, ArSC(=O)NMe2.[1][2][3] The reaction is named after its discoverers, Melvin Spencer Newman[4] and Harold Kwart.[5]
The Newman–Kwart rearrangement is one of the most important ways of synthesising thiophenols. A phenol (1) is deprotonated with a base such as DABCO or NaH and reacted with a thiocarbamoyl chloride (2) to form an O-aryl thiocarbamate (3). Heating 3 to around 250 °C causes it undergo Newman–Kwart rearrangement to an S-aryl thiocarbamate (4). Alkaline hydrolysis or similar cleavage yields a thiophenol (5).[6]
Mechanism
The Newman–Kwart rearrangement is intramolecular; it proceeds via a four-membered cyclic transition state.[3][6]
See also
References
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