2,3-sigmatropic rearrangement
2,3-Sigmatropic rearrangements are a type of
anionic.[1]
The general scheme for this kind of rearrangement is:
Atom Y may be sulfur, selenium, or nitrogen. If Y is nitrogen, the reaction is referred to as the Sommelet–Hauser rearrangement if a quaternary ammonium salt is involved or the aza-Wittig reaction if an alpha-metalated tertiary amine is involved; if Y is oxygen, then it is called a 2,3-Wittig rearrangement (not to be confused with the well-known Wittig reaction, which involves a phosphonium ylide). If Y is sulfur, the product can be treated with a thiophil to generate an allylic alcohol in what is known as the Mislow–Evans rearrangement.
A [2,3]-rearrangement may result in carbon-carbon bond formation. It can also be used as a
ring-expansion reaction.[2]
Stereoselectivity
2,3-sigmatropic rearrangements can offer high
syn
product.
endo
orientation in transition state.
References
- OCLC 642506595