Defluorinative Diborasodiation of Benzotrifluorides with Bis(pinacolato)Diboron and Sodium

Abstract

Treatment of benzotrifluorides with sodium dispersion in the presence of bis(pinacolato)diboron results in diborative reduction to yield the corresponding diborylbenzylsodium species. The anionic species react not only with reactive organic halides but also with aromatic carbonyl compounds to yield the corresponding alkenylboron compounds via Peterson-type olefination. The success of the generation of the diborylbenzylsodium species lies in immediate capture of initially formed unstable difluorobenzylsodium with co-existing reduction-resistant bis (pinacolato)diboron.

Cross-Coupling Polymerization of Organosodium for Polythiophene Synthesis

“…In summary, cross-coupling polymerization of organosodium was achieved by employing a nickel catalyst. The present polymerization serves as a new class of cross-coupling of organosodium by transition-metal catalysis in addition to the recent report by Asako, Takai, and co-workers, in which the formation of organosodium was shown to take place smoothly when metallic sodium dispersed in a mineral oil (SD) was employed and the carbanion formed was shown to undergo reactions with a variety of organic electrophiles. − Although several arylated sodium species have been employed for transition-metal-catalyzed cross coupling, such an example has only been shown to take place with a rather limited substrate scope. Coupling reactions have been performed after the transformation into a much more stable metallic species as zinc, boron, etc.…”

“…We envisaged that it is challenging to utilize much more reactive and less controllable but abundant sodium instead of other metallic species such as lithium, magnesium, zinc, etc. for polythiophene synthesis in the fields of both organometallic chemistry and polymer synthesis. − Herein we report that polythiophene synthesis can be achieved by employing deprotonative generation of metalated polythiophene 1 (M = Na) with a bulky sodium amide and that subsequently a nickel-catalyzed cross-coupling polymerization tolerates the use of the thus-formed thiophene–sodium species as an organometallic monomer (Scheme ).…”

Reductive Ring Opening of Arylcyclopropanecarboxamides Accompanied by Borylation and Enolate Formation

“…Recently, we have been interested in the combined use of alkali metals and reduction-resistant electrophiles to develop new reductive transformations for organic synthesis . Reduction-resistant electrophiles other than proton sources have realized trapping of reductively generated unstable carbanion species to synthesize versatile products.…”

Reductive Cleavage of Propargylic Ethers with Alkali Metal: Application to the Synthesis of Allenylboronates

“…Because we and others have been interested in using sodium dispersion in organic synthesis, we chose sodium dispersion as a reducing agent for metalation of propargylic ether 1a (Table ). To quantify the efficiency of the metalation, we chose boron electrophiles to trap the metalated species to yield allenylboronates.…”

“…1,2 Although generation of allenylic/propargylic alkali metals from the corresponding ethers might be easy to envision, here we disclose the first example of such generation. 5 Because we 6 and others 7 have been interested in using sodium dispersion in organic synthesis, we chose sodium dispersion as a reducing agent for metalation 8 of propargylic ether 1a (Table 1). To quantify the efficiency of the metalation, we chose boron electrophiles to trap the metalated species to yield allenylboronates.…”