echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Angelw: iridium catalyzed C-H boration of fused polycyclic aromatic hydrocarbons by Hartwig group, University of California, Berkeley

    Angelw: iridium catalyzed C-H boration of fused polycyclic aromatic hydrocarbons by Hartwig group, University of California, Berkeley

    • Last Update: 2018-06-13
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com
    Peri substitution refers to the introduction of substituents into the 8-Position of 1-substituted naphthalene ring The substituents of each other's peri - position are closer in space than the substituents of each other's neighborhood Due to the rigidity of naphthalene ring skeleton and two parallel chemical bonds in peri position, the space crowded peri disubstituted naphthalene has some characteristics, such as skeleton distortion, extreme space tension, abnormal molecular spectrum, intramolecular hydrogen bond, high proton affinity and unique chemical reactivity The characteristics of peri - disubstituted naphthalene and its related condensed aromatics make it widely used in molecular and ion recognition, ligand design and catalyst However, due to the large steric hindrance, the synthesis of peri substituted compounds has always been challenging In the past, the synthesis of peri substituted molecules was faced with many problems, such as harsh reaction conditions, low yield, poor selectivity, and limited substrate (scheme 1a, 1b, 1c) Recently, the John F Hartwig group at the University of California, Berkeley reported the C-H bond peri boration reaction of 1-hydrosilylnaphthalene and PAHs under mild conditions The reaction has high functional group compatibility and the product can be further transformed (scheme 1D) Relevant articles were published on angel.chem.int.ed (DOI: 10.1002/anie.201805086) (source: angel Chem Int ed.) in order to determine the reaction conditions of C-H bond peri boration in 1-hydrosilylnaphthalene, the author took 1-dimethylhydrosilylnaphthalene 1a and B 2pin 2 as substrates, [IR (COD) ome] 2 and ligand L1-L5 as catalysts, and reacted at 80 ℃ in THF solution (Table 1) Compared with other ligands, 3,4,7,8-tetramethylphenanthroline L5 can produce product 2a in high yield (61%) The reaction yield could not be increased by changing the solvent and increasing the temperature (Table 1, entries 6-12) When B 2pin 2 was increased from 1.2 equivalent to 1.5 equivalent, the yield increased to 68% Finally, the yield of the product reached 84% after 24 hours reaction with 1.5 equivalent B 2pin 2 (source: angelw Chem Int ed.) under the optimal reaction conditions, the author investigated the range of reaction substrate (Table 2) 1-dimethylhydrosilylnaphthalene containing various functional groups can obtain the corresponding C-H bond peri-boration products in medium to good yields However, 1 t substituted by 2-methoxy group can not produce any boronization products The author speculates that the reason is that the Si-H bond in dimethylhydrosilane group with lower steric resistance is oriented to 2-substituent, while the dimethyl group with higher steric resistance is oriented to peri-c-h bond (source: angelw Chem Int ed.) PAHs and benzo aromatic heterocycles contain a large number of aromatic C-H bonds, so their selective functionalization is very challenging However, the silane guided peri boration reaction can still selectively take place in 5-hydrosilylacenaphthene 3a and 4-hydrosilyl-7,7-dimethyl-7h-benzo [de] anthracene 3b, forming the corresponding products 4A and 4B, with the yields of 75% and 54%, respectively (Table 3) A variety of PAHs can also undergo silane oriented C-H bond peri boration, resulting in 4c-4f in medium to good yield In addition, 1-substituted isoquinoline 3G - 3H can also obtain the corresponding peri - substituted product 4G - 4H under this condition (source: angelw Chem Int ed.) in order to illustrate the practicability of the reaction, the author studied the conversion of boron group and silyl group in compound 2A (scheme 2) Boric acid ester 2a was converted into peri silane boric anhydride 5 in the presence of ruthenium catalyst The C-B bond in compound 5 can form biphenyl derivatives by palladium catalyzed Suzuki coupling reaction, and can also be converted into C-Br, C-Cl and C-N bonds by copper catalyzed process Under the condition of 1.5 equivalent m-CPBA as oxidant, the C-B bond in 5 is selectively oxidized to C-O bond, while the c-Si Bond remains intact, and finally a naphthalene fused pyrrole 10 is formed The C-B and c-Si bonds in 5 can be oxidized simultaneously to naphthalene-1,8-diol by using excessive H 2O 2 in alkaline condition (source: angelw Chem Int ed.) Summary: John F Hartwig research group has developed a mild iridium catalyzed peri boration reaction of naphthalene and polycyclic aromatic hydrocarbon derivatives with hydrosilyl as the guiding group The reaction has a wide range of functional group tolerance, and greatly expanded the diversity of easily available peri - disubstituted naphthalene and related polycyclic aromatic hydrocarbons.
    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent ECHEMI's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.