Highly Efficient Synthesis of 1,3-Dioxanes via Prins Reaction in Brønsted-Acidic Imidazolium Ionic Liquid

Abstract

The high-yielding synthesis of a wide variety of 1,3-dioxanes via the Prins reaction under mild conditions has been demonstrated using Brønsted-acidic imidazolium ionic liquid [bmim(SO₃H)][OTf] or bmimOTf. The use of ionic liquid makes this synthesis simple, convenient, cost-effective, and environmentally friendly. Furthermore, bmimOTf was conveniently separated from the products and can be easily recycled for the Prins reaction with excellent yields. This method works well with a variety of aliphatic aldehydes including formaldehyde, acetaldehyde, propionaldehyde, and cyclohexanecarboxaldehyde.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

GRAPHICAL ABSTRACT

Keywords:

• Aldehydes
• dioxanes
• ionic liquids
• Prins reaction
• styrenes

ACKNOWLEDGMENTS

The authors thank the University Sophisticated Instrument Center, KUD, for IR, GC, GC-MS, and ¹H and ¹³C NMR. The authors also thank M. V. Kulkarni for useful discussion.

Notes

^a Conversion based on GC-MS analysis.

^b Isolated yields of pure products; NI: no isolation.

^c Reaction was carried out in bmimOTf (in absence of MeCN).

^a Isolated yields of pure products; NR; no reaction.

^b The reactions were carried out with recycled bmimOTf, cycle 1.

^c The reactions were carried out with recycled bmimOTf, cycle 2.

^d The reactions were carried out with recycled bmimOTf, cycle 3.