A cascade double 1,4-addition/intramolecular annulation strategy for expeditious assembly of unsymmetrical dibenzofurans
Open Access
- 25 March 2021
- journal article
- research article
- Published by Springer Science and Business Media LLC in Communications Chemistry
- Vol. 4 (1), 1-10
- https://doi.org/10.1038/s42004-021-00478-2
Abstract
Existing synthetic routes for accessing dibenzofuran core have intrinsic regioselectivity, limiting the substitution patterns available in heteropolycyclic arene products. Here we report a double 1,4-conjugate addition/intramolecular annulation cascade reaction between propargylamines and two equivalents of imidazolium methylides that allows efficient access of structurally versatile dibenzofurans. This transition metal-free protocol proceeds smoothly under bench-top air atmosphere and offers easy manipulation of substituents on the dibenzofuran core, and also provides good-to-excellent product yields with good functional group tolerance, particularly the –Br and –Cl groups which are often incompatible with existing metal-catalyzed C–C and/or C–O bond ring-forming processes. It is worth noting that ladder-type π-systems with all-arene quarternary carbon structure can be straightforwardly generated upon simple late-stage functionalization.Keywords
Funding Information
- Natural Science Foundation of Anhui Province (1808085MB41)
- National Natural Science Foundation of China (21772001)
- Research Grants Council, University Grants Committee (14304519-19P)
- Chinese University of Hong Kong (4442353)
- Guangdong Science and Technology Department (2019A1515011357)
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