Metal-free domino Cloke-Wilson rearrangement-hydration- dimerization of cyclopropane carbaldehydes: A facile access to oxybis(2-aryltetrahydrofuran) derivatives Raghunath Dey 1 , Shruti Rajput 1 , Prabal Banerjee * Department of Chemistry, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab,140001, India article info Article history: Received 28 January 2020 Received in revised form 14 February 2020 Accepted 22 February 2020 Available online xxx Keywords: Cyclopropanes Metal-free PTSA Domino reaction Oxybis(2-aryltetrahydrofuran) derivatives abstract In this work, we have demonstrated a metal-free transformation of cyclopropane carbaldehydes to oxybis(2-aryltetrahydrofuran) derivatives via a domino Cloke-Wilson rearrangement-hydration-dimer- ization sequence. Commercially inexpensive p-toluene sulfonic acid (PTSA) was used as a Brønsted acid catalyst, and reactions were conducted in an open-flask. Detection of reaction intermediates were carried to get an insight into the reaction pathway. © 2020 Elsevier Ltd. All rights reserved. 1. Introduction Construction of invaluable molecular scaffold from a readily available starting material always remains a key interest in syn- thetic organic chemistry [1a]. More importantly, designing the method to access the target in a cheaper, eco-friendly, and user- friendly manner is highly appealing [1b]. From that perspective, domino strategy has evolved as a convenient approach towards the development of the sustainable synthetic route [1c]. In this notion, due to the ease of preparation and foreseeable reactivity, donor-acceptor cyclopropane has been utilized as a venerable three carbon synthon in various synthetic trans- formation (Scheme 1)[2e5]. In the presence of a nucleophile, it undergoes a homo Michael addition to deliver ring-opened/1,3- bifunctionalized products. It can participate in annulation re- actions with different polar species to render a wide range of het- ero- and carbocyclic compounds. Over the last few decades, the annulation of donor-acceptor cyclopropane has been widely explored with various carbonyl compounds, nitriles, imines, al- kenes, azides, ylides, nitrones, etc. Soon after, these methods have been realized as the potential synthetic tool to generate molecular complexity. Some of them also implicated to synthesize complex natural products [3]. Recently, we utilized various annulation of donor-acceptor cyclopropane to synthesize diverse nitrogen het- erocycles like tetrahydropyridines, hexahydropyrrolo[1,2 b]pyr- idazines, 2H furo[2,3c]pyrroles, and others [4]. Apart from these reactions of donor-acceptor cyclopropane, because of its inherent reactivity, it voluntarily takes part in certain structural changes like dimerization and rearrangement [5]. Research group of Tomilov, Trushkov, Budynina, and others utilized dimerization of cyclopro- pane to construct diverse heterocycles and carbocycles. In a series of reports, very elegantly, they have explored an array of dimer- ization of donor-acceptor cyclopropanes. These investigations gave us the sense that, under proper kinetic trigger, cyclopropane itself is capable of converting into many valuable scaffolds. However, most of the reported dimerizations are metal cata- lyzed process. These metal catalyzed reactions are associated with several drawbacks like sometimes the effective catalyst is toxic, often moisture sensitivity of the Lewis acid creates difficulties in handling, many times Lewis acids are expansive [6]. Therefore, recently, the exploration of reactivity of donor- acceptor cyclopropane under metal-free regime has been attrac- ted enormous attention. One remarkable approach towards metal- free activation of donor-acceptor cyclopropane is the secondary * Corresponding author. E-mail address: prabal@iitrpr.ac.in (P. Banerjee). 1 These two authors contributed equally. Contents lists available at ScienceDirect Tetrahedron journal homepage: www.elsevier.com/locate/tet https://doi.org/10.1016/j.tet.2020.131080 0040-4020/© 2020 Elsevier Ltd. All rights reserved. Tetrahedron xxx (xxxx) xxx Please cite this article as: R. Dey et al., Metal-free domino Cloke-Wilson rearrangement-hydration-dimerization of cyclopropane carbaldehydes: A facile access to oxybis(2-aryltetrahydrofuran) derivatives, Tetrahedron, https://doi.org/10.1016/j.tet.2020.131080