Umpolung of protons from H₂O: a metal-free chemoselective reduction of carbonyl compounds via B₂pin₂/H₂O systems

Abstract

HO is routinely described as a proton donor, however, in the presence of diboron compounds, the umpolung reaction of HO under metal-free conditions was successfully developed, which could afford hydride species, leading to a highly efficient and chemoselective reduction of C[double bond, length as m-dash]O bonds. This strategy exhibits excellent chemoselectivities toward carbonyl groups in the presence of ester, olefin, halogen, thioether, sulfonyl, cyano as well as heteroaromatic groups.

Efficient Water Reduction with sp3‐sp3 Diboron(4) Compounds: Application to Hydrogenations, H–D Exchange Reactions, and Carbonyl Reductions

“…Subjecting an unsymmetrical 1,3‐diketone to the reaction conditions resulted in the desired 1,3‐diol 53 with a good dr (7:1). In contrast, functional groups such as an ester or an amide remained untouched, as in the compounds 54 and 55 , and heteroaromatic rings proved tolerant to the reaction conditions ( 56 and 57 ) …”

Chemical aspect of sodium hypochlorite activation in obtaining favorable outcomes of endodontic treatment: An in-vitro study

“…Deuterated chloroform was picked as a deuterated solvent of choice due to its capability to dissolve the organic compounds well, both the substrate (9-fluorenol) and the product (9-fluorenone) as well as any amount of the catalyst left in the organic phase during the extraction. 27,28,31 Moreover, the use of TSP could lead to misleading results as TSP tends to be unstable in the presence of oxidative agents. If any traces of NaOCl had been left after the extraction process (which is unlikely but cannot be excluded), TSP would have got oxidized, hence making its use as a standard invalid.…”

“…Upon oxidation, the number of aromatic protons (and thus the integration of the aromatic region) is equal both in the starting material and the product and is unchanged during the oxidation. 27,28 The variable here is the benzylic signal, which decreases in its intensity (and integration) upon oxidation.…”

Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine

“…In the presence of Pd(OAc) 2 , quinolines, quinoxalines, and imidazo [2,1a] pyridines were reduced (with or without added base), [14] and imidazo [2,1a]pyridines with added PCy 3 . [15] Aldehydes and ketones were reduced in the presence of DBU, without Pd(OAc) 2 , [16] but with Pd (OAc) 2 and Cs 2 CO 3 a quinoline and a pyridine underwent ring reduction, and benzonitrile was reduced to benzylamine. [16] With CuBr/Cs 2 CO 3 , enones and ynones underwent β-borylation with (pinB) 2 followed by protiodeboronation to give the reduction products.…”

“…[15] Aldehydes and ketones were reduced in the presence of DBU, without Pd(OAc) 2 , [16] but with Pd (OAc) 2 and Cs 2 CO 3 a quinoline and a pyridine underwent ring reduction, and benzonitrile was reduced to benzylamine. [16] With CuBr/Cs 2 CO 3 , enones and ynones underwent β-borylation with (pinB) 2 followed by protiodeboronation to give the reduction products. [17,18] Similarly, a borylation/protiodeboronation pathway with CuBr/Xantphos/Cs 2 CO 3 has been utilized for the reduction of benzofuranyl ketones.…”