Nickel‐Catalyzed Borylation of Aryl and Benzyl 2‐Pyridyl Ethers: A Method for Converting a Robust ortho‐Directing Group

Abstract

Then ickel-catalyzed borylation of aryl 2pyridyl ethers via the loss of a2 -pyridyloxy group is described. This method allows a2 -pyridyloxy group to be used as ac onvertible directing group in C À H bond functionalization reactions.T he nickel catalyst can also borylatea rylmethyl 2-pyridyle thers,i n which the stereochemistry at the benzylic position is retained in the case of chiral secondary benzylic substrates.

Rhodium‐Catalyzed Decarbonylative Borylation of Aromatic Thioesters for Facile Diversification of Aromatic Carboxylic Acids

“…[2] One of the most straightforward approaches for facile diversification is to transform carboxylic acids into multitransformable intermediates such as organoboron compounds,w hich serve as versatile synthetic intermediates demonstrating aw ide spectrum of reactivities (Scheme 1A). [3] Indeed, recent studies, [4][5][6][7][8][9][10] including ours, [9b, 10a] on catalytic borylative transformations by cleavage of stable bonds,s uch as CÀH, [5] CÀO, [6] CÀN, [7] CÀCN, [8] CÀF, [9] and CÀS [10] bonds,h ave confirmed the validity of this approach. Herein, we report ad ecarbonylative borylation of aromatic thioesters that enabled two-step decarboxylative borylation of aromatic carboxylic acids.…”

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…A general procedure is the quaternisation of the pyridine ring, followed by treatment with NaOMe, resulting in the corresponding phenol. 865 Apart from this traditional cleavage, a few cross coupling methods have been reported by Chatani and Wang to cleave the arene–O bond and introduce a boronic ester (which can be used in subsequent cross couplings) 866 , 867 or an amino functionality 868 in its place.…”

Asymmetric remote C-H borylation of internal alkenes via alkene isomerization

“…Chiral organoboronates are of significant utility in asymmetric synthesis for constructing a wide range of other functional groups through C-B bond transformation in a stereospecific fashion 35 , 36 . To date, several strategies 37 , such as stereospecific organoboronate homologation 38 , 39 , borylation of benzylic electrophiles 40 , 41 , asymmetric hydrogenation of alkenylboronic esters 42 , 43 , and asymmetric hydroboration of alkenes 44 – 53 , have been developed for construction of chiral secondary organoboronates. However, asymmetric hydroboration of a mixture of alkenes isomers to deliver chiral products has not been previously reported.…”