scholarly journals Iodocyclisation of Electronically Resistant Alkynes: Synthesis of 2-Carboxy (and sulfoxy)-3-iodobenzo[b]thiophenes

2021 ◽  
Vol 74 (1) ◽  
pp. 65 ◽  
Author(s):  
Shuqi Chen ◽  
Bernard L. Flynn
Keyword(s):  
Schiff Base ◽  
Carboxy Group ◽  
Pyridine Ring ◽  
Radical Mechanism ◽  
Addition Reactions ◽  
Electrophilic Attack ◽  
Reaction Conditions ◽  
Highly Effective ◽  
Alkyne Coupling

The iodocyclisation of alkynes bearing tethered nucleophiles is a highly effective method for the construction and diversification of heterocycles. A key limitation to this methodology is the 5-endo-dig iodocyclisation of alkynes that have an unfavourable electronic bias for electrophilic cyclisation. These tend to direct electrophilic attack of the iodonium atom to the wrong carbon for cyclisation, thus favouring competing addition reactions. Using our previously determined reaction conditions for the 5-endo-dig iodocyclisations of electronically resistant alkynes, we have achieved efficient synthetic access to 2-carboxy (and sulfoxy)-3-iodobenzo[b]thiophenes. The corresponding benzo[b]furans and indoles were not accessible under these conditions. This difference may arise due to the availability of a radical mechanism in the case of iodobenzo[b]thiophenes. The 2-carboxy functionality of the iodocyclised products can be further employed in iterative alkyne-coupling iodocyclisation reactions, where the carboxy group or an imine (Schiff base) partakes in a second iodocyclisation to generate a lactone or pyridine ring.

scholarly journals Synthesis and Structural Characterization of (E)-4-[(2-Hydroxy-3-methoxybenzylidene)amino]butanoic Acid and Its Novel Cu(II) Complex

Molbank ◽  
10.3390/m1179 ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. M1179
Author(s):  
Eleftherios Halevas ◽  
Antonios Hatzidimitriou ◽  
Barbara Mavroidi ◽  
Marina Sagnou ◽  
Maria Pelecanou ◽  
...  
Keyword(s):  
Schiff Base ◽  
Gamma Aminobutyric Acid ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Polymeric Compound ◽  
Bridging Ligands ◽  
1H And 13C Nmr ◽  
One Dimensional ◽  
Ft Ir

A novel Cu(II) complex based on the Schiff base obtained by the condensation of ortho-vanillin with gamma-aminobutyric acid was synthesized. The compounds are physico-chemically characterized by elemental analysis, HR-ESI-MS, FT-IR, and UV-Vis. The complex and the Schiff base ligand are further structurally identified by single crystal X-ray diffraction and 1H and 13C-NMR, respectively. The results suggest that the Schiff base are synthesized in excellent yield under mild reaction conditions in the presence of glacial acetic acid and the crystal structure of its Cu(II) complex reflects an one-dimensional polymeric compound. The molecular structure of the complex consists of a Cu(II) ion bound to two singly deprotonated Schiff base bridging ligands that form a CuN2O4 chelation environment, and a coordination sphere with a disordered octahedral geometry.

Ring-opening Addition Reactions of 1-tert-Butoxycarbonyl-3,4- epoxypiperidine with Amine Nucleophiles

2010 ◽  
Vol 65 (2) ◽  
pp. 197-202 ◽  
Author(s):  
Boja Poojary ◽  
Lim Hee-Jong
Keyword(s):  
Ring Opening ◽  
Addition Reactions ◽  
Reaction Conditions ◽  
Different Types

Ring-opening addition reactions of 1-tert-butoxycarbonyl-3,4-epoxypiperidine leading to the formation of the corresponding regioisomeric trans-β -aminoalcohols were carried out with three different types of amine nucleophiles under different reaction conditions with a view to study the reactivity and regioselectivity.

Ring-opening copolymerization of epoxide and dianhydride in the presence of manganese(III) asymmetrical bis-Schiff base catalysts

2014 ◽  
Vol 92 (11) ◽  
pp. 1098-1105 ◽  
Author(s):  
Deng-Feng Liu ◽  
Lu-Qun Zhu ◽  
Jing Wu ◽  
Li-Ying Wu ◽  
Xing-Qiang Lü
Keyword(s):  
Schiff Base ◽  
Ring Opening ◽  
Monomer Conversion ◽  
Structure Design ◽  
Steric Effects ◽  
Chain Growth ◽  
Electronic Effects ◽  
Reaction Conditions ◽  
Base Catalysts ◽  
Electronic And Steric Effects

Based on a series of asymmetrical bis-Schiff base H2Ln (n = 1–4) ligands with different electronic and steric effects, a series of [Mn(Ln)Cl] complexes 1–4 are obtained and shown to be effective catalysts in ring-opening copolymerization of epoxides and dianhydrides. Through the structure design, the input of electron-withdrawing bromine substituent para to the phenoxide group of the complexes is considerately beneficial to the improved activities. Moreover, steric and electronic effects of the suitable MeO substituent at the ortho orientation on the phenoxide group may both play a role in the formation of alternating ring-opening copolymers under the identical reaction conditions. In three cocatalysts tested, n-Bu4NBr is positive to monomer conversion and chain growth of polymer.

Michael addition reactions of chiral glycine Schiff base Ni (II)‐complex with 1‐(1‐phenylsulfonyl)benzene

Chirality ◽  
2020 ◽  
Vol 32 (6) ◽  
pp. 885-893 ◽  
Author(s):  
Keita Nagaoka ◽  
Haibo Mei ◽  
Yunjie Guo ◽  
Jianlin Han ◽  
Hiroyuki Konno ◽  
...  
Keyword(s):  
Schiff Base ◽  
Michael Addition ◽  
Addition Reactions

scholarly journals Aroylhydrazone Schiff Base Derived Cu(II) and V(V) Complexes: Efficient Catalysts towards Neat Microwave-Assisted Oxidation of Alcohols

2020 ◽  
Vol 21 (8) ◽  
pp. 2832
Author(s):  
Manas Sutradhar ◽  
Tannistha Roy Barman ◽  
Armando J. L. Pombeiro ◽  
Luísa M. D. R. S. Martins
Keyword(s):  
Schiff Base ◽  
Aliphatic Alcohol ◽  
Cinnamyl Alcohol ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Benzyl Alcohols ◽  
X Ray ◽  
Microwave Assisted ◽  
Tert Butyl Hydroperoxide ◽  
Oxidation Of Alcohols

A new hexa-nuclear Cu(II) complex [Cu3(μ2-1κNO2,2κNO2-L)(μ-Cl)2(Cl)(MeOH)(DMF)2]2 (1), where H4L = N′1,N′2-bis(2-hydroxybenzylidene)oxalohydrazide, was synthesized and fully characterized by IR spectroscopy, ESI-MS, elemental analysis, and single crystal X-ray diffraction. Complex 1 and the dinuclear oxidovanadium(V) one [{VO(OEt)(EtOH)}2(1κNO2,2κNO2-L)]·2H2O (2) were used as catalyst precursors for the neat oxidation of primary (cinnamyl alcohol) and secondary (1-phenyl ethanol, benzhydrol) benzyl alcohols and of the secondary aliphatic alcohol cyclohexanol, under microwave irradiation using tert-butyl hydroperoxide (TBHP) as oxidant. Oxidations proceed via radical mechanisms. The copper(II) compound 1 exhibited higher catalytic activity than the vanadium(V) complex 2 for all the tested alcohol substrates. The highest conversion was found for 1-phenylethanol, yielding 95.3% of acetophenone in the presence of 1 and in solvent and promoter-free conditions. This new Cu(II) complex was found to exhibit higher activity under milder reaction conditions than the reported aroylhydrazone Cu(II) analogues.

Variation of nuclearity in NiII complexes of a Schiff base ligand: crystal structures and magnetic studies

CrystEngComm ◽  
2019 ◽  
Vol 21 (31) ◽  
pp. 4620-4631 ◽  
Author(s):  
Tanmoy Kumar Ghosh ◽  
Prithwish Mahapatra ◽  
Subrata Jana ◽  
Ashutosh Ghosh
Keyword(s):  
Schiff Base ◽  
Crystal Structures ◽  
Schiff Base Ligand ◽  
Magnetic Coupling ◽  
Magnetic Studies ◽  
Reaction Conditions

Four NiII complexes have been synthesized by changing the reaction conditions and stoichiometry of the reactants. The magnetic coupling in the NiII4 complex is ferromagnetic whereas that in the NiII6 complex is antiferromagnetic.

Cinchona alkaloid-based chiral catalysts act as highly efficient multifunctional organocatalysts for the asymmetric conjugate addition of malonates to nitroolefins

2015 ◽  
Vol 13 (40) ◽  
pp. 10216-10225 ◽  
Author(s):  
Veeramanoharan Ashokkumar ◽  
Ayyanar Siva
Keyword(s):  
Michael Addition ◽  
Quaternary Ammonium ◽  
Conjugate Addition ◽  
Quaternary Ammonium Salts ◽  
Cinchona Alkaloid ◽  
Ammonium Salts ◽  
Addition Reactions ◽  
Chiral Catalysts ◽  
Reaction Conditions ◽  
Highly Efficient

New pentaerythritol tetrabromide based chiral quaternary ammonium salts have been prepared and used as organocatalysts for enantioselective Michael addition reactions between various nitroolefins and Michael donors under mild reaction conditions with very good chemical yields and ee's.

Catalytic asymmetric addition reactions leading to carbon-carbon bond formation: Phenyl and alkenyl transfer to aldehydes and alkynylation of α-imino esters

2006 ◽  
Vol 78 (2) ◽  
pp. 267-274 ◽  
Author(s):  
Jian-Xin Ji ◽  
Jing Wu ◽  
Lijin Xu ◽  
Chiu-Wing Yip ◽  
Kim Hung Lam ◽  
...  
Keyword(s):  
Bond Formation ◽  
Optically Active ◽  
Amino Acid Derivatives ◽  
Addition Reactions ◽  
Terminal Alkynes ◽  
Reaction Conditions ◽  
Carbon Carbon Bond ◽  
Catalytic Asymmetric ◽  
High Yields ◽  
Imino Esters

Optically active tertiary aminonaphthol ligands were obtained by a new, convenient procedure and were found to catalyze the enantioselective alkenyl and phenyl transfer to aldehydes in high yields and excellent enantiomeric excesses (ee's). The catalytic asymmetric introduction of alkynyl functionality to α-amino acid derivatives was realized by the direct addition of terminal alkynes to α-imino ester in the presence of chiral copper(I) complex under mild reaction conditions.

scholarly journals Gold(i)-catalysed dehydrative formation of ethers from benzylic alcohols and phenols

2015 ◽  
Vol 17 (7) ◽  
pp. 3819-3825 ◽  
Author(s):  
Richard M. P. Veenboer ◽  
Steven P. Nolan
Keyword(s):  
Reaction Conditions ◽  
Benzylic Alcohols ◽  
Highly Effective

A well-defined NHC–gold(i) complex has been shown highly effective in the formation of ethers from secondary benzylic alcohols and phenols under mild reaction conditions.

Radical Metal-Free Borylation of Aryl Iodides

Synthesis ◽  
2017 ◽  
Vol 49 (21) ◽  
pp. 4759-4768 ◽  
Author(s):  
Sandra Pinet ◽  
Mathieu Pucheault ◽  
Virginie Liautard ◽  
Mégane Debiais
Keyword(s):  
Steric Hindrance ◽  
Radical Mechanism ◽  
Electronic Effects ◽  
Simple Metal ◽  
Reaction Conditions ◽  
Metal Free ◽  
Aryl Iodides ◽  
Reaction Proceeds ◽  
Electronic Effects Of Substituents

A simple metal-free borylation of aryl iodides mediated by a fluoride sp2–sp3 diboron adduct is described. The reaction conditions are compatible with various functional groups. Electronic effects of substituents do not affect the borylation while steric hindrance does. The reaction proceeds via a radical mechanism in which pyridine serves to stabilize the boryl radicals, generated in situ.

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