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Prins-Friedel-Crafts Cyclization: Synthesis of Diversely Functionalized Six- Membered Oxacycles



Prins cyclization is a well-established synthetic protocol to generate a wide range
of important oxygen heterocycles. It is a cyclization reaction performed by an oxocarbenium
ion that undergoes an intramolecular pi-bond attack to construct a new carbon-carbon bond.
When this cyclization process is conjugated with Friedel-Crafts reaction, it further expands
the synthetic potential by fabricating two different carbon-carbon bonds in one single reaction.
Different acid catalysts mediated the coupled Prins-Friedel-Crafts reaction which is conducted
both in stepwise as well as in tandem fashion. In the stepwise route, three different
reacting components were utilized whereas, the tandem methodology required proper modification
of the initial substrate molecule. An array of allylic, propargylic, other related alkenols,
and carbonyl reactants were employed to carry out the cyclization process. Several oxygenated
heterocycles equipped with diverse functionalities were constructed in a stereoselective manner which again
reinforced the significance of this cyclization protocol undoubtedly. The present mini-review highlights the utilization
of different one-pot stepwise Prins-Friedel-Crafts reactions and the subsequent development of cascade Prins-
Friedel-Crafts cyclization process to furnish intricate molecular architectures of vital six-membered oxacycles.
