824-91-9Relevant articles and documents
Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
supporting information, p. 5022 - 5037 (2021/05/04)
Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
Rhodium(II)-Catalyzed Aryl C?H Carboxylation of 2-Pyridylphenols with CO2
Cai, Zhihua,Li, Shangda,Gao, Yuzhen,Li, Gang
supporting information, p. 4005 - 4011 (2018/09/20)
A protocol for C?H carboxylation of electron-deficient 2-pyridylphenols with CO2 through a Rh(II)-catalyzed C?H bond activation under redox-neutral conditions has been developed. A suitable phosphine ligand was crucial for this reaction. This m
Total synthesis of [13C]2-, [13C]3-, and [13C]5-isotopomers of xanthohumol, the principal prenylflavonoid from hops
Ellinwood, Duncan C.,El-Mansy, Mohamed F.,Plagmann, Layhna S.,Stevens, Jan F.,Maier, Claudia S.,Gombart, Adrian F.,Blakemore, Paul R.
, p. 639 - 648 (2017/11/27)
Xanthohumol [(E)-6′-methoxy-3′-(3-methylbuten-2-yl)-2′,4′,4″-trihydroxychalcone], he principal prenylated flavonoid from hops, has a complex bioactivity profile, and 13C-labeled isotopomers of this compound are of potential use as molecular probes and as analytical standards to study metabolism and mode of action. 1,3-[13C]2-Xanthohumol was prepared by an adaptation of the total synthesis of Khupse and Erhardt in 7 steps and 5.7% overall yield from phloroglucinol by a route incorporating a cascade Claisen-Cope rearrangement to install the 3′-prenyl moiety from a 5′-prenyl aryl ether and an aldol condensation between 1-[13C]-2′,4′-bis(benzyloxymethyloxy)-6′-methoxy-3′-(3-methylbuten-2-yl)acetophenone and 1′-[13C]-4-(methoxymethyloxy)benzaldehyde. The 13C-atom in the methyl ketone was derived from 1-[13C]-acetyl chloride while that in the aryl aldehyde was derived from [13C]-iodomethane. Tri- and penta-13C-labeled xanthohumols were similarly prepared by applying minor modifications to the route.
