Dioxomolybdenum Complexes as Excellent Catalysts for the Deoxygenation of Aryl Ketones to Aryl Alkenes

Abstract

This work describes a new methodology for the selective deoxygenation of aryl ketones to the corresponding aryl alkenes catalyzed by dioxomolybdenum complexes using silanes as reducing agents. The best results were obtained with the system PhSiH3/MoO2Cl2(H2O)2 (5–10 mol %), which was very efficient for the deoxygenation of a large variety of aryl ketones to alkenes in excellent yields. This new methodology has the advantages of using an inexpensive, environmentally friendly, easily prepared, and air‐stable catalyst in ether solution.

Highly Efficient Deoxygenation of Aryl Ketones to Arylalkanes Catalyzed by Dioxidomolybdenum Complexes

“…Similarly to our observations in the deoxygenation reactions of ketones to the corresponding alkenes described in our previous work, also in this study the best results were obtained with the dioxidomolybdenum complexes [MoCl 2 O 2 (H 2 O) 2 ], [MoCl 2 O 2 ], [MoCl 2 O 2 (DMSO) 2 ], and [MoCl 2 O 2 {(4‐ClPh) 2 SO} 2 ]. In contrast, only a moderate yield of xanthene (52 %) was observed in the reaction catalyzed by [MoCl 2 O 2 (Bipy)] (10 mol‐%) (Table , entry 6), and low yields of xanthene were isolated in the presence of the dioxido complexes [MoO 2 (acac) 2 ] (10 mol‐%), [MoCl 2 O 2 (OPPh 3 ) 2 ] (10 mol‐%), and [MoCl 2 O 2 (DMF) 2 ] (10 mol‐%) (Table , entries 7–9).…”

“…After this, our group developed another very efficient method for the selective deoxygenation of aryl ketones to aryl alkenes using the inexpensive and environmental friendly catalyst [MoCl 2 O 2 (H 2 O) 2 ], with PhSiH 3 as reducing agent . During the development of this method we obtained a very interesting result in the reaction of flavone, a natural product, which allowed the conversion of the carbonyl group into a methylene group in 80 % yield [Equation ].…”

A Highly Regioselective and Practical Synthesis of α‐Aryl Ketones under a Cooperative Cascade Effect of an Ionic Liquid and Tetrabutylammonium Fluoride

“…However their conversion into α‐aryl ketone is sparsely reported, despite the central importance of α‐aryl ketones as key intermediate for various important compounds viz. diarylisoxazoles, stilbenes and anthranilodinitrile etc as well as it′s application in pharmaceuticals and as bioactive molecules.…”

A selective, efficient and environmentally friendly method for the oxidative cleavage of glycols

“…20 Based in that experience and the related deoxygenation of sulfoxides with glycerol, 21 we selected easily and conveniently prepared MoO 2 Cl 2 (dmso) 2 as catalyst, 22 for exploring the oxidative cleavage of benzopinacol (1,1,2,2-tetraphenylethane-1,2-diol) with DMSO (Table 1). 23 After some 70 experimentation we found that under microwave irradiation and using toluene as solvent at 130 ºC only one equiv. of DMSO was needed for complete cleavage of the model diol (entries 12).…”

“…The E factor for the oxidative cleavage of 2,3-diphenylbutane-2,3-diol, selected as model, under the optimized microwave heating conditions is 50.1 (including the organic solvent employed for the extraction). Notably, the E factor calculated for the same 70 substrate under the recycling conditions (Scheme 1), where the amount of solvent employed for the extraction was optimized, dropped to 11.2. 28 These values are in the range of typical E factors of processes in fine-chemical companies and pharmaceutical industries.…”