Advanced Synthesis and Catalysis p. 1285 - 1305 (2011)
Update date:2022-08-05
Topics:
Huang, Chunhui
Chernyak, Natalia
Dudnik, Alexander S.
Gevorgyan, Vladimir
A novel, easily removable and modifiable silicon-tethered pyridyldiisopropylsilyl directing group for C-H functionalizations of arenes has been developed. The installation of the pyridyldiisopropylsilyl group can efficiently be achieved via two complementary routes using easily available 2-(diisopropylsilyl)pyridine (5). The first strategy features a nucleophilic hydride substitution at the silicon atom in 5 with aryllithium reagents generated in situ from the corresponding aryl bromides or iodides. The second milder route exploits a highly efficient room-temperature rhodium(I)-catalyzed cross-coupling reaction between 5 and aryl iodides. The latter approach can be applied to the preparation of a wide range of pyridyldiisopropylsilyl- substituted arenes possessing a variety of functional groups, including those incompatible with organometallic reagents. The pyridyldiisopropylsilyl directing group allows for a highly efficient, regioselective palladium(II)-catalyzed mono-ortho-acyloxylation and ortho-halogenation of various aromatic compounds. Most importantly, the silicon-tethered directing group in both acyloxylated and halogenated products can easily be removed or efficiently converted into an array of other valuable functionalities. These transformations include protio-, deuterio-, halo-, boro-, and alkynyldesilylations, as well as a conversion of the directing group into the hydroxy functionality. In addition, the construction of aryl-aryl bonds via the Hiyama-Denmark cross-coupling reaction is feasible for the acetoxylated products. Moreover, the ortho-halogenated pyridyldiisopropylsilylarenes, bearing both nucleophilic pyridyldiisopropylsilyl and electrophilic aryl halide moieties, represent synthetically attractive 1,2-ambiphiles. A unique reactivity of these ambiphiles has been demonstrated in efficient syntheses of arylenediyne and benzosilole derivatives, as well as in a facile generation of benzyne. In addition, preliminary mechanistic studies of the acyloxylation and halogenation reactions have been performed. A trinuclear palladacycle intermediate has been isolated from a stoichiometric reaction between diisopropyl(phenyl)pyrid-2-ylsilane (3a) and palladium acetate. Furthermore, both C-H functionalization reactions exhibited equally high values of the intramolecular primary kinetic isotope effect (kH/k D=6.7). Based on these observations, a general mechanism involving the formation of a palladacycle via a C-H activation process as the rate-determining step has been proposed.
View MoreShanghai Rich Chemicals Co., Ltd
website:http://www.richchemical.com
Contact:+86-21-20255798
Address:Pudong Shanghai,China
Nanjing Chemzam Pharmtech Co., Ltd.
Contact:+86-25-86462165,+86-13915979898
Address:C5-1,6 Maiyue Road,Maigaoqiao,Nanjing,Jiangsu,China
Suzhou Health Chemicals Co., Ltd.
website:http://www.healthchems.com
Contact:13776257979
Address:No. 338, Jingang Avenue,
Daicel Chiral Technologies (China)CO.,LTD
Contact:021-5046-0086*8
Address:Part C, FL 5, the 16th Building, No. 69, XiYa Road, WaiGaoQiao Free Trade Zone, Shanghai, 200131, P.R.China
Shanghai Dynamic Industrial Co.,Ltd.
website:http://www.shdynamic.com
Contact:86-021 3392 6680
Address:Room 805 Information Tower, No.1403 Minsheng Road, Pudong New Area, Shanghai 200135, P. R. China
Doi:10.1107/S2053229618013232
(2018)Doi:10.1039/c1ob05512g
(2011)Doi:10.1021/ol2016059
(2011)Doi:10.1016/j.tetlet.2011.05.024
(2011)Doi:10.1002/anie.201101366
(2011)Doi:10.1016/j.tet.2011.05.056
(2011)