One-Pot Access to 2-oxazolines via a Castro-Stephens Coupling and Intramolecular Cyclization

Aim: Here, we have reported easy one-pot access to a series of oxazolines using a modified Castro-Stephens coupling protocol. Background: 2-oxazolines have been shown to have significant biological activity and wide-ranging applications in organic chemistry. These properties make oxazolines as heterocyclic compounds of immense importance. Objective: The objective of this study is to synthesize oxazoline derivatives via an economical and one-pot protocol. Methods: 2-oxazoline has been synthesized through Cu-powder mediated Castro-Stephens coupling and intramolecular cyclization route. The mechanism involves a rearrangement in which one of the oxygen from the N-acylamino alcohol group is liberated as water and then transferred to alkyne functionality to form 2-oxazoline derivatives. The oxazolines were characterized by NMR, mass, and XRD studies. Results: The protocol is economically viable and uses readily available Cu-powder along with DMF for cross-coupling and cyclization steps. Conclusion: We have reported a one-pot protocol to prepare 2-oxazolines using a Castro-Stephens coupling and intramolecular cyclization.