Palladium-Catalyzed Cross-Coupling Alkylation of Arenediazonium o-Benzenedisulfonimides

Abstract

Arenediazonium o-benzenedisulfonimides were reacted with tetramethyltin, tetrabutyltin or trialkylboranes. The reactions, carried out in the presence of palladium(II) derivatives as precatalysts, gave the methylation and alkylation products with good overall conversions. The o-benzenedisulfonimide was recovered in high yield from all the reactions and could be recycled for the preparation of other salts.In the course of evaluating the synthetic scope of a new family of diazonium salts that are particularly stable in the dry state, namely the arenediazonium o-benzenedisulfonimides 1, we focused our attention on the reactivity of the salts 1 as electrophilic reagents in palladium-catalyzed reactions. 1 In particular, we have studied cross-coupling reactions of 1 with aryltin compounds under Stille conditions, 2 in order to obtain biaryls. 3Though the literature regarding the palladium-catalyzed cross-coupling reactions between diazonium salts and aromatic or alkenyl organometallic compounds is quite extensive, 4 to our knowledge, only three examples 5 have been reported concerning the reactions of diazonium salts with alkyl organometallic compounds, in particular organotin derivatives 5a,b or esters of alkylboronic acids. 5c These reactions between arenediazonium tetrafluoroborates, 5a hexafluorophosphates 5a or hydrogen sulfate 5b and tetramethyltin, often provide low yields.The present paper describes an improved procedure for the synthesis of the toluenes 4a-m or butylarenes 5b, 5d-f and 5h, by the palladium-catalyzed cross-coupling reactions between arenediazonium o-benzenedisulfonimides 1a-m and tetramethyltin (2) or tetrabutyltin (3) (Scheme 1). Furthermore, we report a new procedure for the synthesis of butylarenes 5a-f, 5h and 5n or ethylarenes 11a-f, 5h and 5n, through palladium-catalyzed reactions between arenediazonium o-benzenedisulfonimides 1a-f, 1h and 1n and tributylborane (10) or triethylborane (9) (Scheme 2).

Nickel-Catalyzed Decarbonylative Alkylation of Aroyl Fluorides Assisted by Lewis-Acidic Organoboranes

“…In previous studies on alkylation in S–M coupling reaction, Lewis-acidic trialkylboranes have been applied to accelerate transmetalation of alkyl groups via interaction of oxygen in alkoxypalladium complexes with a boron center. 8,15 We herein describe a novel C–F bond functionalization strategy to construct alkyl–aryl scaffold starting from naturally abundant carboxylic acid (Scheme 1c).…”