Selective Synthetic Routes to Sterically Hindered Unsymmetrical Diaryl Ketones via Arylstannanes

Abstract

Bulky arylstannanes and bulky aroyl chlorides are good reaction partners for the synthesis of two-, three-, and even four-ortho-substituted benzophenones, in good to excellent isolated yields (47-91%). Three simple and direct routes, with differential advantages, are proposed: (i) a catalyst-free protocol, in o-dichlorobenzene (ODCB) at 180 °C; (ii) a room temperature protocol, using AlCl(3) (0.5 equiv), in dichloromethane (DCM); and (iii) a solvent-free, indium-promoted procedure. A radical mechanism is proposed for the indium-mediated reactions.

Palladium(II) Catalyzed Cyclization-Carbonylation-Cyclization Coupling Reaction of (ortho-Alkynyl Phenyl) (Methoxymethyl) Sulfides Using Molecular Oxygen as the Terminal Oxidant

“…Benzo [b]thiophene skeletons are an important class of S-heterocycles [15][16][17][18] and are found in a variety of drugs, pesticides, and biologically active compounds that exhibit various interesting biological properties [19][20][21][22][23][24]. Diaryl ketone scaffolds are also important motifs in natural products and pharmaceuticals [25][26][27][28][29][30] (Figure 1). Androgens are known to have beneficial anabolic actions on various tissues such as bone and muscle.…”

“…Diaryl ketone scaffolds are also important motifs in natural products and pharmaceuticals [25][26][27][28][29][30] (Figure 1). Androgens are known to have beneficial anabolic actions on various tissues such as bone and muscle.…”

Gallium and Indium Compounds in Homogeneous Catalysis

“…102 Addition of di-tert-butylnitroxide (DTBN) as radical scavenger inhibits drastically the reaction, thus suggesting a radical pathway as expected with In(0). Thus, single-electron transfer (SET) from In(0) to the aroylchloride substrate initially generates an acyl radical (and InCl) that reacts with the arylstannane specifically at the ipso position to afford the final diarylketone and a triaryltin radical.…”

Ultrasound-assisted synthesis of benzophenones by Stille cross-coupling reactions. Optimization via experimental design

“…Thus, we have determined new catalyst-free procedures for the regioselective synthesis of asymmetric diaryl ketones and triaryl diketones [4], as well as the efficient synthesis of tertiary alkyl aryl ketones without the generation of the undesired decarbonylation by-products [5]. Recently, we have proposed three alternative and complementary routes for the synthesis of asymmetric sterically hindered benzophenones [6].…”