Regioselective synthesis of di-aromatic ring-fused 2,8-dioxa/dithia bicyclo[3,3,1]nonane derivatives via recyclable polymeric Bronsted acid-catalyzed one-pot tandem formation of multiple chemical C-C/C-O and C-C/C-S bonds

An environmentally benign and straightforward synthetic approach for the assembly of a new class of diverse symmetrical substituted di-aromatic-fused 2,8-dioxa/dithiabicyclo[3,3,1]nonane derivatives containing methylene-bridged bicyclic framework via reusable cross-linked polystyrene-supported p- toluenesulfonic acid-catalyzed tandem reactions of substituted phenols/selected thiophenol with 1,1,3,3tetramethoxypropane under neat conditions has been reported in which four new chemical bonds (two C-C/two C-O)-(two C-C/two C-S), two new six-membered cycles, and two new stereogenic tertiary carbon centers were constructed in a single operation. The synthetic utility of this method was also demonstrated. In addition, this present protocol could be successfully extended to the selected naphthols and dihydroxynaphthalenes as the enol partner of phenols with high efficiency. The developed transformation featured high efficiency, the use of commercially accessible feedstocks, excellent regioselectivity, simple operation, gram-scale synthesis, and good functional group compatibility. Furthermore, the solvent-free conditions, easily recoverable catalyst, and efficient recycling render the protocol green, economic and sustainable. (c) 2021 Elsevier Ltd. All rights reserved.