The pyridine‐based halogenated hydrazone derivatives (E)‐N′‐benzylidene‐2‐(6″‐chloroazin‐2″‐yl)oxyacetohydrazide (6a), (E)‐N′‐(3′‐chlorobenzylidene)‐2‐(6″‐chloroazin‐2″‐yl)oxyacetohydrazide (6b) and ...(E)‐N′‐(3′‐bromobenzylidene)‐2‐(6″‐chloroazin‐2″‐yl)oxyacetohydrazide (6c) have been obtained using 6‐chloro‐2‐hydroxypyridine. The structure of the products (6a–c) has been verified using X‐ray crystallography and spectroscopic approaches. A single‐crystal X‐ray diffraction (SC‐XRD) investigation showed that the structures are stabilized by intermolecular attractive forces. Additionally, density functional theory (DFT) has been adopted to explore the structural properties, vibrational spectra, noncovalent interactions and frontier molecular orbitals using the B3LYP/6‐311 + G(d,p) level. The nonlinear optical properties of the title compounds were calculated using the CAM‐B3LYP/6‐311 + G(d,p) level. Frequency analysis confirmed the stability of the molecules, and an excellent correlation was observed between the DFT‐ and SC‐XRD‐based structural parameters. The SC‐XRD analysis confirmed that the dimers of 6a, 6b and 6c are linked by hydrogen‐bonding interactions. Natural bond orbital (NBO) analysis also reconfirmed the strength of intermolecular hydrogen‐bonding and hyperconjugative interactions. NBO investigation was also utilized to analyze the atomic charges. Moreover, Fourier transform infrared and natural population analyses endorsed that there are significant N H⋅⋅⋅O C hydrogen‐bonding linkages in dimeric structures of the compounds. The hydrogen‐bonding network and different sorts of hyperconjugative interactions are the main reasons for the stability of the products in the solid state. The highest occupied and lowest unoccupied molecular orbital energies and first‐order nonlinear optical properties of these molecules are reported. The quantum chemical parameters were derived using frontier molecular orbital energies.
The pyridine based halogenated hydrazones derivatives were synthesized and their structures were verified using single crystal X‐ray diffraction (SC‐XRD) and spectroscopic approaches. SC‐XRDinvestigation showed that the structures are stabilized by intermolecular attractive forces. Moreover, density functional theory (DFT) was adopted to explore the structural properties, vibrational spectra, non‐covalent interactions, frontier molecularorbitals(FMOs) and nonlinear optical (NLO) studies of entitled compounds using.B3LYP/6–311+G(d,p) level.
A dual photocatalytic sulfonylation‐arylation of electron‐rich alkenes is described. By combining sulfinate salts, (hetero)‐aryl‐bromides and 2,3‐dihydrofuran under Ru and Ni dual catalysis, over 35 ...examples of aryl‐sulfonylated scaffolds could be obtained in good to excellent yields, under mild reaction conditions and high diastereoselectivity.
A dual photocatalytic sulfonylation‐arylation of electron‐rich alkenes is described. This protocol proceeds under mild reaction conditions and high functional group tolerance, streamlining the access to densely functionalized sulfonylated architectures from simple precursors and in high diastereoselectivities.
A simple procedure for the copper‐catalyzed synthesis of 3‐(N‐heteroaryl)acrylonitriles was developed. Using a combination of Lewis and Brønsted acids, this one‐pot procedure undergoes via a radical ...conjugated addition and dehydration processes, without isolation of any intermediate, affording the acrylonitriles. This diastereoselective approach allowed the synthesis of a broad scope of quinazoline derivatives (22 examples) with moderate to good yields and good functional‐group tolerance and could be extended to other N‐heterocyles such as quinolines and isoquinolines. Based on control experiments, a mechanistic proposal for this new transformation is also presented.
A one‐pot synthesis of new acrylonitriles using a combination of Lewis and Brønsted acid catalysts was developed. Under the optimized conditions, 22 quinazoline, quinoline, and isoquinoline derivatives were prepared containing electron‐donating or electron‐withdrawing groups. A mechanistic pathway was proposed via a radical conjugated addition of β‐nitrostyrenes to methylazaarenes followed by dehydration processes.
The iron(III)‐promoted synthesis of densely‐substituted 4H‐chalcogenchromene from organochalcogen propargylamines in the presence of diaryl dichalcogenides is reported. Subsequent ...C2‐functionalization with electrophiles and potassium trifluoroborate salts via Suzuki‐Miyaura coupling reaction are also presented. A plausible mechanism based on HRMS experiments is proposed and discussed.
The steroselective oxa‐Michael addition of the phenol moiety present in tyrosine and 3‐iodotyrosine to different propargyl aldehydes delivered products with predominantly Z stereochemistry, as ...evidenced by X‐ray crystallography analysis. When ethyl propiolate was used as the propargyl ester source, the products were achieved with exclusively E stereochemistry with yields ranging from 17% to 91%. The oxa‐Michael addition compounds served as substrates in the synthesis of 5‐ and 6‐membered heterocyclic compounds. The atmosphere applied to the reaction medium directly influenced the formation of the products. When an inert atmosphere of nitrogen was applied, a 2‐aryl‐3‐formyl‐5‐alanylbenzofuran core was selectively obtained via a Heck intramolecular reaction, while the reactions carried out under a carbon monoxide atmosphere led exclusively to 6‐alanyl‐2‐arylflavone derivatives via reductive intramolecular acylation.
Herein we describe a compelling sequential methodology for obtaining optically active α‐arylmethanols‐1,2,3‐triazoles. The approach is based on the enantioselective alkynylation of aldehydes followed ...by a one‐pot two‐step desilylation/CuI‐catalyzed azide‐alkyne 1,3‐dipolar cycloaddition (CuAAC), providing the corresponding products with excellent yields and high levels of enantioselectivity. Furthermore, the click chemistry can be performed without affecting the enantiomeric excess. The application of the reaction has been demonstrated in the synthesis of a 1,2,3‐triazole analog of antihistaminic and anticholinergic drug (R)‐orphenadrine.
Click here! Chiral arylmethanols bearing 1,2,3‐triazoles are achieved using a sequential approach based on the enantioselective alkynylation of aldehydes followed by a one‐pot two‐step desilylation/CuAAC, providing the corresponding products with excellent yields and high enantioselectivity. The application of the reaction has been demonstrated in the synthesis of a 1,2,3‐triazole analog of antihistaminic and anticholinergic drug (R)‐orphenadrine.
A mild stereo‐ and regioselective Cu‐catalyzed hydroboration method for the synthesis of (Z)‐seleno‐alkenyl boronates and (Z)‐thio‐alkenylboronates from internal alkynes in the presence of ...commercially available B2pin2 is presented. This highly selective transformation relies on the use of N‐heterocyclic carbene (NHC) complex IPrCuCl as the active catalytic species. We also explore the functionalization of the alkenylboronates obtained via oxidation to give α‐chalcogeno ketones, useful building blocks for the synthesis of more complex chalcogen‐containing molecules.
Selective hydroboration: A mild stereo‐ and regioselective Cu‐catalyzed hydroboration method for the synthesis of (Z)‐seleno‐alkenyl boronates and (Z)‐thio‐alkenylboronates from internal alkynes in the presence of commercially available B2pin2 is presented. This highly selective transformation relies on the use of N‐heterocyclic carbene (NHC) complex IPrCuCl as the active catalytic species. We also explore the functionalization of the alkenylboronates obtained via oxidation to give α‐chalcogeno ketones, useful building blocks for the synthesis of more complex chalcogen‐containing molecules.
A practical, and efficient microwave‐assisted, three‐step Sonogashira cross‐coupling/Deacetonation/Cycloaddition sequence has been developed for the synthesis of a variety of 4‐aryl‐1,2,3‐triazoles ...from readily available starting materials. The important features of this synthetic sequence include the use of inexpensive 2‐methyl‐3‐butyn‐2‐ol as an acetylene surrogate, 2‐Me‐THF as a bio‐based solvent, short reaction time, good yields, avoiding the isolation of volatile terminal alkynes.
This work presents a novel and simple route to synthesize 4‐aryl‐1,2,3‐triazole by the three‐step Sonogashira cross coupling/Deacetonation/Cycloaddition three‐step sequence under microwave irradiation. Furthermore, the protocol proceeds under mild conditions starting from 2‐methyl‐3‐butyn‐2‐ol as an acetylene surrogate in the presence of bio‐based solvent 2‐Me‐THF.
Indole derivatives substituted at the C‐2 position have shown important biological activities. Due to these properties, several methods have been described for the preparation of structurally diverse ...indoles. In this work, we have synthesized highly functionalized indole derivatives via Rh(III)‐catalyzed C‐2 alkylation with nitroolefins. Under the optimized condition, 23 examples were prepared with 39–80 % yield. Moreover, the nitro compounds were reduced and submitted to the Ugi four‐component reaction, furnishing a series of new indole‐peptidomimetics in moderate to good overall yields.
An efficient C−H activation protocol for nitroalkylation of indoles at the C‐2 position using easily available nitroolefins is described. This method gives access to nitroalkylindoles, strategic frameworks for the preparation of primary 2‐nitroindoleamines, which were employed in the synthesis of new Ugi peptidomimetics, compounds of recognized pharmacological interest.
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