Key mechanistic features of Ni-catalyzed C-H/C-O biaryl coupling of azoles and naphthalen-2-yl pivalates

Huiying Xu, Kei Muto, Junichiro Yamaguchi, Cunyuan Zhao, Kenichiro Itami, Djamaladdin G. Musaev

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

The mechanism of the Ni-dcype-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate was studied. Special attention was devoted to the base effect in the C-O oxidative addition and C-H activation steps as well as the C-H substrate effect in the C-H activation step. No base effect in the C(aryl)-O oxidative addition to Ni-dcype was found, but the nature of the base and C-H substrate plays a crucial role in the following C-H activation. In the absence of base, the azole C-H activation initiated by the C-O oxidative addition product Ni(dcype)(Naph)(PivO), 1B, proceeds via ΔG = 34.7 kcal/mol barrier. Addition of Cs2CO3 base to the reaction mixture forms the Ni(dcype)(Naph)[PivOCs·CsCO3], 3-Cs-clus, cluster complex rather than undergoing PivO- → CsCO3 - ligand exchange. Coordination of azole to the resulting 3-Cs-clus complex forms intermediate with a weak Cs-heteroatom(azole) bond, the existence of which increases acidity of the activated C-H bond and reduces C-H activation barrier. This conclusion from computation is consistent with experiments showing that the addition of Cs2CO3 to the reaction mixture of 1B and benzoxazole increases yield of C-H/C-O coupling from 32% to 67% and makes the reaction faster by 3-fold. This emerging mechanistic knowledge was validated by further exploring base and C-H substrate effects via replacing Cs2CO3 with K2CO3 and benzoxazole (1a) with 1H-benzo[d]imidazole (1b) or quinazoline (1c). We proposed the modified catalytic cycle for the Ni(cod)(dcype)-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate. (Chemical Equation Presented)

Original languageEnglish
Pages (from-to)14834-14844
Number of pages11
JournalJournal of the American Chemical Society
Volume136
Issue number42
DOIs
Publication statusPublished - 2014 Oct 22
Externally publishedYes

Fingerprint

Benzoxazoles
Azoles
Chemical activation
Quinazolines
Gadiformes
Substrates
Acidity
Ligands

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Key mechanistic features of Ni-catalyzed C-H/C-O biaryl coupling of azoles and naphthalen-2-yl pivalates. / Xu, Huiying; Muto, Kei; Yamaguchi, Junichiro; Zhao, Cunyuan; Itami, Kenichiro; Musaev, Djamaladdin G.

In: Journal of the American Chemical Society, Vol. 136, No. 42, 22.10.2014, p. 14834-14844.

Research output: Contribution to journalArticle

Xu, Huiying ; Muto, Kei ; Yamaguchi, Junichiro ; Zhao, Cunyuan ; Itami, Kenichiro ; Musaev, Djamaladdin G. / Key mechanistic features of Ni-catalyzed C-H/C-O biaryl coupling of azoles and naphthalen-2-yl pivalates. In: Journal of the American Chemical Society. 2014 ; Vol. 136, No. 42. pp. 14834-14844.
@article{c0207b2599064ac28b8d1caf85217241,
title = "Key mechanistic features of Ni-catalyzed C-H/C-O biaryl coupling of azoles and naphthalen-2-yl pivalates",
abstract = "The mechanism of the Ni-dcype-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate was studied. Special attention was devoted to the base effect in the C-O oxidative addition and C-H activation steps as well as the C-H substrate effect in the C-H activation step. No base effect in the C(aryl)-O oxidative addition to Ni-dcype was found, but the nature of the base and C-H substrate plays a crucial role in the following C-H activation. In the absence of base, the azole C-H activation initiated by the C-O oxidative addition product Ni(dcype)(Naph)(PivO), 1B, proceeds via ΔG = 34.7 kcal/mol barrier. Addition of Cs2CO3 base to the reaction mixture forms the Ni(dcype)(Naph)[PivOCs·CsCO3], 3-Cs-clus, cluster complex rather than undergoing PivO- → CsCO3 - ligand exchange. Coordination of azole to the resulting 3-Cs-clus complex forms intermediate with a weak Cs-heteroatom(azole) bond, the existence of which increases acidity of the activated C-H bond and reduces C-H activation barrier. This conclusion from computation is consistent with experiments showing that the addition of Cs2CO3 to the reaction mixture of 1B and benzoxazole increases yield of C-H/C-O coupling from 32{\%} to 67{\%} and makes the reaction faster by 3-fold. This emerging mechanistic knowledge was validated by further exploring base and C-H substrate effects via replacing Cs2CO3 with K2CO3 and benzoxazole (1a) with 1H-benzo[d]imidazole (1b) or quinazoline (1c). We proposed the modified catalytic cycle for the Ni(cod)(dcype)-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate. (Chemical Equation Presented)",
author = "Huiying Xu and Kei Muto and Junichiro Yamaguchi and Cunyuan Zhao and Kenichiro Itami and Musaev, {Djamaladdin G.}",
year = "2014",
month = "10",
day = "22",
doi = "10.1021/ja5071174",
language = "English",
volume = "136",
pages = "14834--14844",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "42",

}

TY - JOUR

T1 - Key mechanistic features of Ni-catalyzed C-H/C-O biaryl coupling of azoles and naphthalen-2-yl pivalates

AU - Xu, Huiying

AU - Muto, Kei

AU - Yamaguchi, Junichiro

AU - Zhao, Cunyuan

AU - Itami, Kenichiro

AU - Musaev, Djamaladdin G.

PY - 2014/10/22

Y1 - 2014/10/22

N2 - The mechanism of the Ni-dcype-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate was studied. Special attention was devoted to the base effect in the C-O oxidative addition and C-H activation steps as well as the C-H substrate effect in the C-H activation step. No base effect in the C(aryl)-O oxidative addition to Ni-dcype was found, but the nature of the base and C-H substrate plays a crucial role in the following C-H activation. In the absence of base, the azole C-H activation initiated by the C-O oxidative addition product Ni(dcype)(Naph)(PivO), 1B, proceeds via ΔG = 34.7 kcal/mol barrier. Addition of Cs2CO3 base to the reaction mixture forms the Ni(dcype)(Naph)[PivOCs·CsCO3], 3-Cs-clus, cluster complex rather than undergoing PivO- → CsCO3 - ligand exchange. Coordination of azole to the resulting 3-Cs-clus complex forms intermediate with a weak Cs-heteroatom(azole) bond, the existence of which increases acidity of the activated C-H bond and reduces C-H activation barrier. This conclusion from computation is consistent with experiments showing that the addition of Cs2CO3 to the reaction mixture of 1B and benzoxazole increases yield of C-H/C-O coupling from 32% to 67% and makes the reaction faster by 3-fold. This emerging mechanistic knowledge was validated by further exploring base and C-H substrate effects via replacing Cs2CO3 with K2CO3 and benzoxazole (1a) with 1H-benzo[d]imidazole (1b) or quinazoline (1c). We proposed the modified catalytic cycle for the Ni(cod)(dcype)-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate. (Chemical Equation Presented)

AB - The mechanism of the Ni-dcype-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate was studied. Special attention was devoted to the base effect in the C-O oxidative addition and C-H activation steps as well as the C-H substrate effect in the C-H activation step. No base effect in the C(aryl)-O oxidative addition to Ni-dcype was found, but the nature of the base and C-H substrate plays a crucial role in the following C-H activation. In the absence of base, the azole C-H activation initiated by the C-O oxidative addition product Ni(dcype)(Naph)(PivO), 1B, proceeds via ΔG = 34.7 kcal/mol barrier. Addition of Cs2CO3 base to the reaction mixture forms the Ni(dcype)(Naph)[PivOCs·CsCO3], 3-Cs-clus, cluster complex rather than undergoing PivO- → CsCO3 - ligand exchange. Coordination of azole to the resulting 3-Cs-clus complex forms intermediate with a weak Cs-heteroatom(azole) bond, the existence of which increases acidity of the activated C-H bond and reduces C-H activation barrier. This conclusion from computation is consistent with experiments showing that the addition of Cs2CO3 to the reaction mixture of 1B and benzoxazole increases yield of C-H/C-O coupling from 32% to 67% and makes the reaction faster by 3-fold. This emerging mechanistic knowledge was validated by further exploring base and C-H substrate effects via replacing Cs2CO3 with K2CO3 and benzoxazole (1a) with 1H-benzo[d]imidazole (1b) or quinazoline (1c). We proposed the modified catalytic cycle for the Ni(cod)(dcype)-catalyzed C-H/C-O coupling of benzoxazole and naphthalen-2-yl pivalate. (Chemical Equation Presented)

UR - http://www.scopus.com/inward/record.url?scp=84908518377&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84908518377&partnerID=8YFLogxK

U2 - 10.1021/ja5071174

DO - 10.1021/ja5071174

M3 - Article

C2 - 25259782

AN - SCOPUS:84908518377

VL - 136

SP - 14834

EP - 14844

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 42

ER -