Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• J. V. Santiago A. H. L. Machado Grupo de Tecnologia em Síntese Orgânica, Instituto de Química, Universidade de Brasília, Campus Universitário Darcy Ribeiro, 4478, CEP 70904-970, Asa Norte, Brasília-DF, Brasil 10.3762/bjoc.12.87 Abstract The enantioselective carbenoid insertion into C(sp3)–H bonds

• pre-functionalization of the chemical structure of interest with halogen atoms or pseudohalogen functional groups. One approach that has been gaining increasing attention, by not requiring the presence of a strongly polarized chemical bond, is the C(sp3)–H bonds activation by carbenoids [1]. The

• from the rhodium atom involved in the insertion mechanism increasing therefore its electrophilic character [12]. Four specific types of chiral rhodium(II) complexes can be found as catalyst in enantioselective insertion reactions of carbenoids in C(sp3)–H bonds: carboxylates [13][14][15][16][17][18][19

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• –carbene; site-selectivity; Introduction Direct functionalization of inactivated C–H bonds, especially C(sp3)–H bonds, have attracted significant attentions in recent years. The C(sp3)–H bond activation strategies based on radical reactions and transition metal catalysis have been explored, alongside the

• simple aliphatic C(sp3)–H bonds. In this context, catalytic metal–carbene C(sp3)–H bond insertion represents an alternative and unique approach for this purpose. Metal–carbene insertion into a C(sp3)–H bond, well-recognized as one of the typical reactions of carbene species, have been studied extensively

• catalysts, the carbenic carbon of the metal–carbene species is positively charged in general, as shown by the resonance structure. Consequently, when the electron-deficient carbenic carbon approaches the C(sp3)–H bonds, the C–H bonds with high electron density will react preferentially [9]. However, the

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• . Intermediate C proceeds through intramolecular cyclization to give intermediate D. Finally, H-atom abstraction occurs between D and TBPB directly, which gives the product 5aa and regenerates radical A for the next cycle. Conclusion In summary, a metal-free cascade functionalization of unactivated C(sp3)–H

• bonds and cyclization reactions of N-substituted allylbenzamides were developed. The reaction involved cleavage of the C(sp3)–H bond, alkylation and intramolecular cyclization, affording the 4-alkyl-substituted dihydroisoquinolin-1(2H)-one derivatives with moderate to good chemical yield. The

Base metal-catalyzed benzylic oxidation of (aryl)(heteroaryl)methanes with molecular oxygen

• Hans Sterckx,
• Johan De Houwer,
• Carl Mensch,
• Wouter Herrebout,
• Kourosch Abbaspour Tehrani and
• Bert U. W. Maes

Beilstein J. Org. Chem. 2016, 12, 144–153, doi:10.3762/bjoc.12.16

• ; catalyzed; molecular oxygen; oxygenation; Introduction Direct oxidation of C(sp3)–H bonds is a useful and fast method to convert fairly unreactive substrates to useful functional groups for organic synthesis like alcohols, ketones, aldehydes and carboxylic acids. Classical oxidation protocols rely on the

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• enantioenriched products of type 16 [45]. In a subsequent study, by modifying the conditions using [MeCN]4Cu(I)PF6 as copper catalyst and 1,3-indanedione as the ligand, the sulfonamidation of primary benzylic C(sp3)–H bonds in toluene were successfully performed at 23 °C in the presence of 3-CF3C6H4CO3t-Bu, which

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• easily reduced to amine employing Fe/NH4Cl [74]. N-Nitroso directed C–H alkoxylation of arenes 74 was realized using the Pd(MeCN)2Cl2/PhI(OAc)2 oxidative system to obtain products 75 [74] (Scheme 16). 1.2 Reactions involving C(sp3)-H bonds of C-reagents with alkyl groups In some studies, directing groups

Lewis acid-catalyzed redox-neutral amination of 2-(3-pyrroline-1-yl)benzaldehydes via intramolecular [1,5]-hydride shift/isomerization reaction

• Chun-Huan Jiang,
• Xiantao Lei,
• Le Zhen,
• Hong-Jin Du,
• Xiaoan Wen,
• Qing-Long Xu and
• Hongbin Sun

Beilstein J. Org. Chem. 2014, 10, 2892–2896, doi:10.3762/bjoc.10.306

• used for the activation of C–H bonds [11][12][13][14][15][16][17][18]. Among the reported transformations, intramolecular redox processes based on direct functionalization of C(sp3)–H bonds linking with α heteroatoms are useful for the synthesis of structurally diverse amines and ether derivatives [19

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• ; Introduction Unreactive C(sp2)–H and C(sp3)–H bonds are ubiquitous in organic compounds [1][2][3][4][5][6][7], so that the development of methods for the transition metal-catalyzed C–H activation is one of the challenging goals in organic synthesis. Especially, the development of synthetic methods of C

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• reactions. Additionally, metal-free methodologies, which use TBHP, PhI(OAc)2, TBAI, I2 or Lewis/Brønsted acids, have also been employed for cross-dehydrogenative coupling reactions [48][49][50][51][52][53][54][55][56][57]. Owing to the general low reactivity of cycloalkane C(sp3)–H bonds, the direct

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• in acetophenone originated from molecular oxygen, by conducting the oxygenation in the presence of 18O2. Finally, Inoue and co-workers reported an efficient C(sp3)–N bond-forming method consisting of the chemoselective conversion of C(sp3)–H bonds in the presence of stoichiometric amounts of dialkyl

Synthesis of phenanthridines via palladium-catalyzed picolinamide-directed sequential C–H functionalization

• Ryan Pearson,
• Shuyu Zhang,
• Gang He,
• Nicola Edwards and
• Gong Chen

Beilstein J. Org. Chem. 2013, 9, 891–899, doi:10.3762/bjoc.9.102

• with results on the Pd-catalyzed PA-directed arylation of more inert C(sp3)−H bonds [29]. Cyclization of biaryl compounds to form dihydrophenanthridines. Next, we investigated the cyclization of biaryl compounds to form dihydrophenanthridines via Pd-catalyzed intramolecular dehydrogenative amination of