ABSTRACT
Radical reactions are powerful in the synthesis of diverse molecular scaffolds bearing functional groups. In previous review articles, we have presented 1,2-difunctionalizations, remote 1,3-, 1,4-, 1,5-, 1,6- and 1,7-difunctionalizations, and addition followed by cyclization reactions. Presented in this paper is radical cyclization followed by the second functionalization reaction. The second functionalization could be realized by atom transfer reactions, radical or transition metal-assisted coupling reactions, and reactions with neutral molecules, cationic and anionic species.
ABSTRACT
Radical reactions are powerful in creating carbon-carbon and carbon-heteroatom bonds. Designing one-pot radical reactions with cascade transformations to assemble the cyclic skeletons with two new functional groups is both synthetically and operationally efficient. Summarized in this paper is the recent development of reactions involving radical addition and cyclization of dienes, diynes, enynes, as well as arene-bridged and arene-terminated compounds for the preparation of difunctionalization cyclic compounds. Reactions carried out with radical initiators, transition metal-catalysis, photoredox, and electrochemical conditions are included.
ABSTRACT
This work describes a general strategy for metal-catalyzed cross-coupling of fluoroalkyl radicals with aryl halides under electrochemical conditions. The contradiction between anodic oxidation of fluoroalkyl sulfinates and cathodic reduction of low-valent nickel catalysts can be well addressed by paired electrolysis, allowing for direct introduction of fluorinated functionalities into aromatic systems.
ABSTRACT
Multicomponent reactions (MCRs) have inherent advantages in pot, atom, and step economy (PASE). This important green synthetic approach has gained increasing attention due to high efficiency, minimal waste, saving resources, and straightforward procedures. Presented in this review article are the recent development on 5-compoment reactions (5CRs) of the following six types: (I) five different molecules A + B + C + D + E; pseudo-5CRs including (II) 2A + B + C + D, (III) 2A + 2B + C, (IV) 3A + B + C, (V) 3A + 2B, and (VI) 4A + B. 5CRs with more than five-reaction centers are also included.
ABSTRACT
We report a chelation-assisted C-H arylation of various indoles with sterically and electronically diverse (hetero)arylsilanes enabled by cost-effective Cp*-free cobalt catalysis. Key to the success of this strategy is the judicious choice of copper(II) fluoride as a bifunctional sliane activator and catalyst reoxidant. This methodology features a broad substrate scope and good functional group compatibility. The synthetic versatility of this protocol has been highlighted by the gram-scale synthesis and late-stage diversification of biologically active molecules.
ABSTRACT
Correction for 'Consecutive multicomponent reactions for the synthesis of complex molecules' by Sanjun Zhi et al., Org. Biomol. Chem., 2019, DOI: 10.1039/c9ob00772e.
ABSTRACT
Multicomponent reactions (MCRs) involving a minimum of three reactants or reaction centers are conducted in one pot and with a single operational step. This synthetic method has a good pot, atom and step economy in the preparation of diverse and complex molecular scaffolds. Consecutive MCRs, also known as sequential or multiple MCRs, by combining two or more MCRs, exhibit even higher synthetic efficiency, product structural diversity, and molecular complexity. This review article highlights the Ugi, Groebke-Blackburn-Bienaymé, Biginelli, Huisgen, Petasis, Gewald, and Asinger reaction-initiated consecutive MCRs.
ABSTRACT
Pyrroles are an important group of heterocyclic compounds with a wide range of interesting properties, which have resulted in numerous applications in a variety of fields. Despite the importance of these compounds, there have been few reports in the literature pertaining to the synthesis of pyrroles from simple alkenes using a one-pot sequential 1,3-dipolar cycloaddition/aromatization reaction sequence. Herein, we report the development of a benzoyl peroxide-mediated oxidative dehydrogenative aromatization reaction for the construction of pyrroles. We subsequently developed a one-pot tandem reaction that combined this new method with a well-defined silver-catalyzed 1,3-dipolar cycloaddition reaction, thereby providing a practical method for the synthesis of multisubstituted pyrroles from easy available alkenes. The mechanism of this oxidative dehydrogenative aromatization reaction was also examined in detail.
ABSTRACT
This article highlights research papers published in 2011 and 2012 on fluorous linker-assisted synthesis of biologically interesting small molecules and biomolecules.
Subject(s)
Fluorocarbons/chemistry , Fluorocarbons/chemical synthesis , Chemistry Techniques, Synthetic , Small Molecule Libraries/chemical synthesis , Small Molecule Libraries/chemistryABSTRACT
A novel copper-catalyzed aminobromination-elimination process has been developed, which provides an easy access to alpha,beta-unsaturated vicinal haloamindes derivatives from readily available alpha,beta-unsaturated ketones and esters in good to excellent yields. The isolated intermediate discloses that the current system proceeds through the aminobromination process.
Subject(s)
Alkenes/chemistry , Copper/chemistry , Ketones/chemistry , Alkenes/chemical synthesis , Amination , Catalysis , Esters/chemical synthesis , Esters/chemistry , Halogenation , Ketones/chemical synthesis , Models, MolecularABSTRACT
The combinations of N-methyl-p-toluenesulfonamide/NBS and N-ethyl-p-toluenesulfonamide/NBS were found to be good nitrogen/halogen resources for the aminohalogenation of alpha,beta-unsaturated ketones in the presence of Ni(OAc)(2) as the catalyst for the synthesis of vicinal haloamino ketone derivatives. The introduction of N-alkyl groups to the nitrogen resources resulted in excellent regio- and stereoselectivity for both electron-donating and electron-withdrawing group-attached unsaturated ketone substrates. The structure of the resulting products has been unambiguously confirmed by X-ray crystal structure analysis.
Subject(s)
Acetates/chemistry , Chalcones/chemistry , Ketones/chemistry , Organometallic Compounds/chemistry , Sulfonamides/chemistry , Catalysis , Crystallography, X-Ray , Halogenation , Ketones/chemical synthesis , Molecular Conformation , StereoisomerismABSTRACT
A new combination of catalyst and co-additive has been found for aminohalogenation reaction of beta-methyl-beta-nitrostyrenes with N,N-dichloro-p-tolunesulfonamide (4-TsNCl(2)). The reaction was achieved by using MnSO(4) as the catalyst together with tolunesulfonamide to give vicinal haloamino nitroalkanes with opposite regiochemistry to that generated from other electron-deficient olefins observed previously. The reaction proceeded smoothly at room temperature under nitrogen atmosphere to give useful to good yields and excellent regio and stereoselectivity. A mechanism involving the formation of chloronium intermediate was proposed to explain the resulting regio and stereochemistry.
ABSTRACT
In the title compound, C(16)H(17)ClN(2)O(4)S, the dihedral angle between the phenyl and benzene rings is 19.4â (2)°. The crystal packing is stabilized by inter-molecular N-Hâ¯O hydrogen bonds, as well as by intra- and inter-molecular C-Hâ¯O hydrogen bonds.
ABSTRACT
[reaction: see text] An efficient route to 1-aroyl-3-aryl-4-substituted imidazole-2-thiones (2, 4-6) has been developed. The methodology involves the cyclization of 1-aroyl-3-arylthioureas with a variety of carbonyl compounds bearing alpha-H in the presence of bromine and triethylamine.