Blog

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, Djamaladdin G Musaev, and Kenichiro Itami

J. Am. Chem. Soc. 2014, Accepted Manuscript. DOI: 10.1021/ja5071174



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.

Related post

  1. Creation of negatively curved po…
  2. Hindered Biaryls by C–H Coupling…
  3. Pyridine-Based Dicarbene Ligand:…
  4. Discovery of Plant Growth Stimul…
  5. Decarbonylative Diaryl Ether Syn…
  6. C-H Activation Generates Period-…
  7. Annulative π-Extension (APEX) of…
  8. Theoretical Elucidation of Poten…

Twitter@Itami Lab

Itami Lab Facebook

Instagram@Itami Lab

This error message is only visible to WordPress admins

Error: API requests are being delayed. New posts will not be retrieved.

There may be an issue with the Instagram access token that you are using. Your server might also be unable to connect to Instagram at this time.

Error: API requests are being delayed for this account. New posts will not be retrieved.

There may be an issue with the Instagram access token that you are using. Your server might also be unable to connect to Instagram at this time.

Error: No posts found.

Make sure this account has posts available on instagram.com.

Click here to troubleshoot

最近の記事

Flickr@Itamilab

天池先輩からコーヒースープ伴夫妻からのお歳暮です!潤さん、宮村さん、ありがとうございます!!武藤さん、ビールありがとうございます!平賀大都わーいやなさん、あつしさん、ありがとうございます!!だいぶ前だけど、Stripes look #ootdHalloween lookラインを洗う時ですら格好良く。戸谷先生教育実習!imageけいしゅう、誕生日おめでとう!誕生日は英吉家!!3年生に名古屋ぼろ勝ちアピール中!!アリシア卒業おめでとう女子会!
PAGE TOP