161395-96-6Relevant articles and documents
Paternò-Büchi reaction versus hydrogen abstraction in the photochemical reactivity of alkenyl boronates with benzophenone
D'Annibale, Andrea,D'Auria, Maurizio,Prati, Fabio,Romagnoli, Chiara,Stoia, Sonia,Racioppi, Rocco,Viggiani, Licia
, p. 3782 - 3795 (2013)
The photochemical reaction between some alkenyl boronates and benzophenone is described. While a pinacol alkenyl boronate derivative gave the corresponding oxetane, the MIDA esters gave a tertiary alcohol derived from allylic hydrogen abstraction by triplet benzophenone and coupling of the radicals thus obtained. A theoretical work at DFT level of theory performed on a MIDA ester explained this behaviour showing that the formation of the tertiary alcohol is the most probable reaction. Furthermore, the theoretical calculations showed that the Paternò-Büchi reaction occurs giving the C,C biradical intermediate and this result is not in agreement with the previous described hypothesis where electron poor alkenes gave mainly the C,O biradical intermediate.
Isonicotinate Ester Catalyzed Decarboxylative Borylation of (Hetero)Aryl and Alkenyl Carboxylic Acids through N-Hydroxyphthalimide Esters
Cheng, Wan-Min,Shang, Rui,Zhao, Bin,Xing, Wei-Long,Fu, Yao
supporting information, p. 4291 - 4294 (2017/08/23)
Decarboxylative borylation of aryl and alkenyl carboxylic acids with bis(pinacolato)diboron was achieved through N-hydroxyphthalimide esters using tert-butyl isonicotinate as a catalyst under base-free conditions. A variety of aryl carboxylic acids possessing different functional groups and electronic properties can be smoothly converted to aryl boronate esters, including those that are difficult to decarboxylate under transition-metal catalysis, offering a new method enabling use of carboxylic acid as building blocks in organic synthesis. Mechanistic analysis suggests the reaction proceeds through coupling of a transient aryl radical generated by radical decarboxylation with a pyridine-stabilized persistent boryl radical. Activation of redox active esters may proceed via an intramolecular single-electron-transfer (SET) process through a pyridine-diboron-phthalimide adduct and accounts for the base-free reaction conditions.
Superparamagnetic copper ferrite nanoparticles catalyzed aerobic, ligand-Free, regioselective hydroboration of alkynes: Influence of synergistic effect
Mohan, Balaji,Park, Kang Hyun
, p. 78 - 84 (2016/04/05)
We discovered a general and comprehensive approach for the regioselective hydroboration of terminal and internal alkynes to synthesize vinylboronates using inexpensive and magnetically separable copper ferrite nanoparticles at low catalyst loading using Bis(pinacolato)diboron in the absence of ligand and additives, under mild and greener conditions. A diverse range of functional groups was tolerated in the reaction, including allene and enones, and the corresponding boronates were obtained in high yields under air. Moreover, the assynthesized alkenylboronates were used as precursors to prepare wide variety of vinylorgano chalcogenides regioselectively, in high yields. The present protocol enable the conversion of Csp-H bonds to make Csp2-B bonds via activation of B-B bond, followed by formation of Csp2-Se (Te or S) bonds via activation of Se (Te or S)- Se (Te or S) bonds in a regioselective manner. Deuterium isotope labeling studies showed that the proton source of vinyl boronate stem from the solvent employed.
