ANRORC rearrangement

What is ANRORC rearrangement?

ANRORC rearrangement, also referred to as the degenerate ring transformation of heterocycles, is a process that occurs during nucleophilic substitution of heterocyclic compounds. It involves a series of steps, including initial Addition of a Nucleophile, followed by the Ring Opening and Ring Closure during the substitution (ANRORC).

This transformation, which is also known as the SN(ANRORC) reaction or degenerate ring transformation, is a widespread occurrence for heterocycles and has been known for more than a century.

An example of ANRORC rearrangement is the well-known Dimroth rearrangement. During ANRORC rearrangement, one or more of the ring atoms are replaced by identical atoms present in the nucleophilic reagent, which can be divided into two subgroups.

The first subgroup involves reactions with the leaving group as a substituent on the heterocyclic ring, known as the “outside” leaving group.

ANRORC rearrangement outside leaving group - general reaction scheme
ANRORC rearrangement “outside” leaving group

The second subgroup includes reactions with the leaving group as an integral part of the heterocyclic system, referred to as the “inside” leaving group.

ANRORC rearrangement inside leaving group - general reaction scheme
ANRORC rearrangement “inside” leaving group

References

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