NHOAc mediated domino Knoevenagel/Diels-Alder cyclocondensation of β-ketosulfones 1 and o-formyl allylbenzenes 2 provides sulfonyl oxabenzo[3.3.1]bicyclic core 4 in a cosolvent of toluene and HOAc (v/v = 1/1) at reflux for 3 h. The intermediate 3 contains a chalcone motif. The uses of various ammonium salts and solvent systems are investigated for facile and efficient transformation. The plausible mechanisms have been proposed and the DFT calculations have been included.

In this article, a facile two-step and one-pot synthetic route for the preparation of substituted aryl dihydronaphthalenes starting from 2-allylbenzaldehydes via Grignard 1,2-addition and Bi(OTf)-catalyzed intramolecular olefinic cyclization has been developed. A five-membered ring indene skeleton is also prepared via olefin isomerization, 1,2-addition followed by cyclization. Some key structures are determined using single-crystal X-ray crystallography. A possible mechanism is presented herein.

PdCl 2 /CuCl 2 /Bi(OTf) 3-promoted intramolecular domino annulation of sulfonyl o-allylarylchromanones provides tetracyclic sulfonyl dibenzooxabicyclo[3.3.1]nonanes and bicyclic arylnaphthalenes with good to excellent yields in MeOH at room (25°C) and refluxing (65°C) temperature, respectively. The starting sulfonyl o-allylarylchromanones can be easily obtained from the intermolecular cyclocondensation of αsulfonyl o-hydroxyacetophenones and o-allylbenzaldehydes. The uses of various catalysts and solvent systems are investigated herein for convenient transformation. A plausible mechanism is proposed and discussed. This protocol provides one-pot ring closure via carbon-carbon (CÀ C) bond formation.

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NH4OAc/PdCl2/CuCl2 mediated domino double cyclocondensation of α-sulfonyl o-hydroxyacetophenones and 2-allylbenzaldehydes provides tetracyclic sulfonyl dihydrobenzo­[c]­xanthen-7-one core with good to excellent yields in MeOH. The intermediates contain a 3-sulfonyl flavanone motif. Only water is generated as a byproduct. The use of various catalysts and reaction conditions is studied for the facile-operational conversion.

Under the oxygen atmosphere conditions, PdCl 2 /CuCl 2-mediated one-pot Wacker-type decarboxylative benzannulation of sulfonyl o-allylchalcones provides sulfonyl naphthalenes and carboxylic acids in MeOH at reflux. A plausible mechanism is proposed and discussed herein. This high-yield protocol provides a highly effective intramolecular ring-closure via one carbon-carbon double bond (C=C) formation.

The development of intramolecular carbonyl-ene type cyclocondensation of oxygenated o-phenylallylbenzaldehydes in refluxing decalin is reported. The facile and easy-to-operate thermolytic rearrangement procedure generates substituted naphthalenes in good to excellent yields.