Newman-Kwart rearrangement

What is Newman-Kwart rearrangement?

The thermal transformation of N,N-dialkyl O-arylthiocarbamate into N,N-dialkyl S-arylcarbamate was reported in 1966 by Newman and Kwart. This reaction is commonly known as the Newman-Kwart rearrangement, but it has also been referred to as the Newman-Kwart reaction, Newman-Kwart synthesis, or Miyazaki-Newman-Kwart rearrangement.

Newman-Kwart rearrangement - general reaction scheme - Newman-Kwart reaction - Newman-Kwart synthesis - Miyazaki-Newman-Kwart rearrangement
Newman-Kwart rearrangement

The steric acceleration due to hindered rotation (SAHR) effect, also known as the ortho-substituent effect, has been observed to enhance the rearrangement rate of the migrating aromatic ring. Furthermore, it has been noted that the stereochemistry is retained when O-binaphthol thiocarbamate is rearranged into a dithiol derivative.

References

  • Newman, M. S. and Karnes, H. A., J. Org. Chem., 1966, 31, 3980
  • Kwart, H. and Evans, E. R., J. Org. Chem., 1966, 31, 410
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