728919-13-9Relevant articles and documents
Chromium-Catalyzed Selective Cross-Electrophile Coupling between Unactivated C(aryl)-F and C(aryl)-O Bonds
Fan, Fei,Zhao, Lixing,Luo, Meiming,Zeng, Xiaoming
supporting information, p. 561 - 568 (2022/03/15)
Chemically inert C(aryl)-F bonds have rarely been used to couple with other unactivated bonds, and this remains a challenge because of the difficulty of the successive cleavage of two unactivated bonds by metal catalysis. We report here the chromium-catalyzed cleavage of chemically inert C(aryl)-F bonds for coupling with unactivated C(aryl)-O bonds, allowing cross-electrophile coupling between unreactive aryl fluorides and aryl esters to be achieved in high regio- and chemoselectivity. The reactive Cr, which was formed in situ by reducing CrCl2, enables cleavage of the o-C(aryl)-F bonds to afford monovalent and quartet cyclochromate; subsequent bipyridyl-enabled insertion into the ester C(aryl)-O bond followed by reductive elimination allowed the orthogonal coupling of these two different and unactivated bonds. Mechanistic studies indicate that the bipyridyl ligand greatly enhances the reactivity of Cr in the cleavage of C(aryl)-O bonds, and the second oxidative addition may occur sluggishly compared with the reductive elimination in the catalytic cycle.
Reductive Cross-Coupling between Unactivated C(aryl)-N and C(aryl)-O Bonds by Chromium Catalysis Using a Bipyridyl Ligand
Cong, Xuefeng,Fan, Fei,Luo, Meiming,Tang, Jinghua,Zeng, Xiaoming,Zhao, Lixing
, p. 12834 - 12840 (2020/08/21)
Reductive cross-coupling between two chemically inert bonds remains a great challenge in synthetic chemistry. We report here the reductive cross-coupling between unactivated C(aryl)-N and C(aryl)-O bonds that was achieved by chromium catalysis. The simple and inexpensive CrCl2 salt, combined with important bipyridyl ligand and magnesium reductant, shows high reactivity in the successive cleavage of C(aryl)-N bonds of aniline derivatives and C(aryl)-O bonds of aryl esters, allowing the cross-coupling of these two unactivated and different bonds to occur in a reductive fashion to form a C(aryl)-C(aryl) bond. Mechanistic studies by deuterium-labeling experiments indicate that the C(aryl)-N bonds in anilines are preferentially cleaved by reactive Cr species, in which the ligation of bipyridyl with Cr by adopting a coordination model in 1:1 ratio can be considered.
Chemoselective Cross-Coupling between Two Different and Unactivated C(aryl)-O Bonds Enabled by Chromium Catalysis
Tang, Jinghua,Liu, Liu Leo,Yang, Shangru,Cong, Xuefeng,Luo, Meiming,Zeng, Xiaoming
, p. 7715 - 7720 (2020/05/20)
We report here the first example of cross-coupling between two different and unactivated C(aryl)-O bonds with chromium catalysis. The combination of a low-cost Cr(II) salt, 4,4′-di-tert-butyl-2,2′-dipyridyl (dtbpy) as the ligand, and magnesium as the reductant shows high reactivity in promoting the reductive cross-coupling of aryl methyl ether derivatives with aryl esters by cleavage and coupling of two different C(aryl)-O bonds under mild conditions. The formation of active low-valent Cr species by reduction of CrCl2 with Mg can be considered, which prefers to initially activate the C(aryl)-O bond of phenyl methyl ether with the chelation help of dtbpy and an o-imine auxiliary. The subsequent consecutive reduction, second C(aryl)-O activation, and reductive elimination allow for the achievement of selective cross-coupling of C(aryl)-O/C(aryl)-O bonds.
COMPOUNDS OF PHOSPHINANES AND AZAPHOSPHINANES, A PROCESS FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM
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Paragraph 0314; 0491; 0492; 0493, (2018/02/27)
Compounds of formula (I) wherein: Ak1 represents an alkyl chain, X represents —(CH2)m—, —CH(R)—, —N(R)—, —CH2—N(R)—, —N(R)—CH2— or —CH2—N(R)—CH2—, m and R are as defined in the description, R1 and R2 each represent H when X represents —(CH2)m—, —CH(R)—, —N(R)—, —CH2—N(R)— or —N(R)—CH2—, or together form a bond when X represents —CH2—N(R)—CH2—, R3 represents NH2, Cy-NH2, Cy-Ak3-NH2 or piperidin-4-yl, Cy and Ak3 are as defined in the description, R4 and R5, which may be identical or different, each represent H or F, their optical isomers, and addition salts thereof with a pharmaceutically acceptable acid. Medicinal products containing the same which are useful in treating conditions requiring a TAFIa inhibitor.
Synthesis of dibenzopyranones and pyrazolobenzopyranones through copper(0)/Selectfluor system-catalyzed double C[sbnd]H activation/oxygen insertion of 2-arylbenzaldehydes and 5-arylpyrazole-4-carbaldehydes
Zhang, Jian,Shi, Dongdong,Zhang, Haifeng,Xu, Zheng,Bao, Hanyang,Jin, Hongwei,Liu, Yunkui
, p. 154 - 163 (2016/12/23)
A mild and efficient protocol for the synthesis of dibenzopyranones and pyrazolobenzopyranones was developed involving a copper(0)/Selectfluor system-catalyzed double C[sbnd]H activation/oxygen insertion of 2-arylbenzaldehydes and 5-arylpyrazole-4-carbaldehydes. Preliminary mechanistic studies suggest that both water and dioxygen act as the oxygen source in the formation of pyranone scaffolds.
Solvent control of product diversity in palladium-catalyzed addition of arylboronic acid to aryl aldehydes
Das, Tuluma,Chakraborty, Amarnath,Sarkar, Amitabha
supporting information, p. 5174 - 5178 (2014/12/10)
In Pd-catalyzed arylboronic acid addition to aryl aldehydes, the expected carbinol or asymmetrical ether can be obtained as the major product by altering aqueous solvent composition. Exploiting this methodology with 2-formylbiphenyls as reaction partner, a fluorene scaffold can be readily constructed in two steps.
Facile Cu(OTf)2-catalyzed preparation of 9-tosylaminofluorene derivatives from o-arylated N-tosylbenzaldimines
Yu, Xufen,Lu, Xiyan
scheme or table, p. 2076 - 2079 (2011/05/09)
The 9-tosylaminofluorene derivatives were synthesized conveniently by Cu(OTf)2-catalyzed aza-Friedel-Crafts reaction of o-arylated N-tosylbenzaldimines in high yields. This is an efficient, atom-economic, and green method.
