1391742-83-8Relevant articles and documents
OPTICALLY ACTIVE 2,3-BISPHOSPHINOPYRAZINE DERIVATIVE, METHOD FOR PRODUCING SAME, TRANSITION METAL COMPLEX, AND METHOD FOR PRODUCING ORGANIC BORON COMPOUND
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Paragraph 0210-0212, (2020/12/13)
An optically active 2,3-bisphosphinopyrazine derivative represented by the following general formula (1): wherein R1 represents a group selected from a branched alkyl group having 3 or more carbon atoms, an adamantyl group, an optionally substi
Copper-Catalyzed Enantioselective Markovnikov Protoboration of α-Olefins Enabled by a Buttressed N-Heterocyclic Carbene Ligand
Cai, Yuan,Yang, Xin-Tuo,Zhang, Shuo-Qing,Li, Feng,Li, Yu-Qing,Ruan, Lin-Xin,Hong, Xin,Shi, Shi-Liang
supporting information, p. 1376 - 1380 (2018/01/27)
Reported is a highly enantioselective copper-catalyzed Markovnikov protoboration of unactivated terminal alkenes. A variety of simple and abundant feedstock α-olefins bearing a diverse array of functional groups and heterocyclic substituents can be used as substrates, and the reaction proceeds under mild reaction conditions at ambient temperature to provide expedient access to enantioenriched alkylboronic esters in good regioselectivity and with excellent enantiocontrol. Critical to the success of the protocol was the development and application of a novel, sterically hindered N-heterocyclic carbene, (R,R,R,R)-ANIPE, as the ligand for copper.
Development of Enantiospecific Coupling of Secondary and Tertiary Boronic Esters with Aromatic Compounds
Odachowski, Marcin,Bonet, Amadeu,Essafi, Stephanie,Conti-Ramsden, Philip,Harvey, Jeremy N.,Leonori, Daniele,Aggarwal, Varinder K.
supporting information, p. 9521 - 9532 (2016/08/12)
The stereospecific cross-coupling of secondary boronic esters with sp2 electrophiles (Suzuki-Miyaura reaction) is a long-standing problem in synthesis, but progress has been achieved in specific cases using palladium catalysis. However, related couplings with tertiary boronic esters are not currently achievable. To address this general problem, we have focused on an alternative method exploiting the reactivity of a boronate complex formed between an aryl lithium and a boronic ester. We reasoned that subsequent addition of an oxidant or an electrophile would remove an electron from the aromatic ring or react in a Friedel-Crafts-type manner, respectively, generating a cationic species, which would trigger 1,2-migration of the boron substituent, creating the new C-C bond. Elimination (preceded by further oxidation in the former case) would result in rearomatization giving the coupled product stereospecifically. Initial work was examined with 2-furyllithium. Although the oxidants tested were unsuccessful, electrophiles, particularly NBS, enabled the coupling reaction to occur in good yield with a broad range of secondary and tertiary boronic esters, bearing different steric demands and functional groups (esters, azides, nitriles, alcohols, and ethers). The reaction also worked well with other electron-rich heteroaromatics and 6-membered ring aromatics provided they had donor groups in the meta position. Conditions were also found under which the B(pin)- moiety could be retained in the product, ortho to the boron substituent. This protocol, which created a new C(sp2)-C(sp3) and an adjacent C-B bond, was again applicable to a range of secondary and tertiary boronic esters. In all cases, the coupling reaction occurred with complete stereospecificity. Computational studies verified the competing processes involved and were in close agreement with the experimental observations.
