scholarly journals Organocatalytic Ring Expansion of β-Lactams to γ-Lactams Through a Novel N1—C4 Bond Cleavage. Direct Synthesis of Enantiopure Succinimide Derivatives.

ChemInform ◽  
2006 ◽  
Vol 37 (1) ◽  
Author(s):  
Benito Alcaide ◽  
Pedro Almendros ◽  
Gema Cabrero ◽  
M. Pilar Ruiz
Keyword(s):  
Bond Cleavage ◽  
Direct Synthesis ◽  
Ring Expansion

Organocatalytic Ring Expansion of β-Lactams to γ-Lactams through a Novel N1−C4 Bond Cleavage. Direct Synthesis of Enantiopure Succinimide Derivatives

2005 ◽  
Vol 7 (18) ◽  
pp. 3981-3984 ◽  
Author(s):  
Benito Alcaide ◽  
Pedro Almendros ◽  
Gema Cabrero ◽  
M. Pilar Ruiz
Keyword(s):  
Bond Cleavage ◽  
Direct Synthesis ◽  
Ring Expansion

α-Ketophosphonates in the Synthesis of α-iminophosphonates

2020 ◽  
Vol 7 (2) ◽  
pp. 226-238
Author(s):  
Petro P. Ony`sko ◽  
Tetyana I. Chudakova ◽  
Vladimir V. Pirozhenko ◽  
Alexandr B. Rozhenko
Keyword(s):  
Bond Cleavage ◽  
Direct Synthesis ◽  
Equilibrium Mixture ◽  
Primary Amines ◽  
Alkyl Amines ◽  
Protic Solvents ◽  
Metallic Salts ◽  
Direct Preparation ◽  
Stage Synthesis ◽  
Aprotic Dipolar Solvent

The potentialities of condensation of α-ketophosphonates with primary amines for direct synthesis of α-iminophosphonates have been revealed. Diesters of α-ketophosphonic acids react with the primary amines by two competitive pathways: with a formation of α-iminophosphonates or a C-P bond cleavage resulting in a hydrogen phosphonate and an acylated amine. In many cases, the latter undesirable pathway is dominant, especially for more nucleophilic alkyl amines. Using metallic salts of α-ketophosphonates avoids the C-P bond cleavage, allowing direct preparation of α-phosphorylated imines by the reaction with primary amines. This strategy provides an atom economy single-stage synthesis of iminophosphonates – precursors of bio relevant phosphorus analogs of α-amino acids. Methyl sodium iminophosphonates, bearing aryl or heteryl substituents at the imino carbon atom exist in solutions at room temperature as an equilibrium mixture of Z- and E-isomers. A configuration of the C=N bond can be controlled by the solvent: changing the aprotic dipolar solvent DMSO-d6 by water or alcohols leads to the change from a predominant Z-isomer to almost an exclusive E-form. In contrast, diesters of the respective iminophosphonates exist in non-protic solvents predominantly in Econfiguration. The solvent effect on E-Z stereochemistry is demonstrated by DFT calculations.

Molybdenum-Mediated One-Pot Synthesis of Pyrazoles from Isoxazoles

Synthesis ◽  
2019 ◽  
Vol 51 (20) ◽  
pp. 3796-3804 ◽  
Author(s):  
Marine Rey ◽  
Stéphane Beaumont
Keyword(s):  
Bond Cleavage ◽  
Direct Synthesis ◽  
Molybdenum Complex ◽  
One Pot ◽  
One Pot Synthesis ◽  
Wide Range ◽  
Hydrolysis Of ◽  
Substituted Pyrazoles

A one-pot approach for the direct synthesis of substituted pyrazoles from isoxazoles is reported. The process involves isoxazole N–O bond cleavage mediated by a molybdenum complex, in situ hydrolysis of the resulting β-amino enone to the corresponding 1,3-diketone, followed by pyrazole formation in the presence of hydrazine or substituted hydrazine. Good to excellent yields and regioselectivities are obtained with nonsymmetric isoxazoles. By using readily available starting materials, a wide range of substituted pyrazoles may be synthesized by this method.

Direct synthesis of piperazines containing dithiocarbamate derivatives via DABCO bond cleavage

2020 ◽  
Vol 61 (49) ◽  
pp. 152610
Author(s):  
Farzane Jafari Asar ◽  
Farinaz Soleymani ◽  
Seyyed Emad Hooshmand ◽  
Azim Ziyaei Halimehjani
Keyword(s):  
Bond Cleavage ◽  
Direct Synthesis ◽  
Dithiocarbamate Derivatives

Visible Light-Promoted Metal-Free Reduction of Organohalides by 2-Naphthyl or 2-Hydroxynaphthyl-Substituted 1,3-Dimethylbenzimidazolines

2015 ◽  
Vol 68 (11) ◽  
pp. 1648 ◽  
Author(s):  
Eietsu Hasegawa ◽  
Kazuma Mori ◽  
Shiori Tsuji ◽  
Kazuki Nemoto ◽  
Taku Ohta ◽  
...  
Keyword(s):  
Visible Light ◽  
Halogen Bond ◽  
Light Emitting Diode ◽  
Bond Cleavage ◽  
Ring Expansion ◽  
Single Electron Transfer ◽  
Reduction Reactions ◽  
Light Emitting ◽  
Reducing Ability ◽  
Carbon Radicals

The visible light-promoted reduction reactions of some organohalides were investigated using 2-aryl-1,3-dimethylbenzimidazolines (Ar-DMBIH) possessing 2-naphthyl or 2-hydroxynaphthyl substituents. In these reduction reactions, single-electron transfer from photo-excited Ar-DMBIH, attained by Xe lamp irradiation through an appropriate glass-filter (λ > 390 nm), to the halide substrates leads to the carbon–halogen bond cleavage, followed by the rearrangements of the formed carbon radicals such as 5-exo hexenyl cyclization and the Dowd–Beckwith ring expansion. Addition of 1,8-diazabicyclo[5.4.0]undec-7-ene was found to enhance the reducing ability of hydroxynaphthyl-substituted DMBIH. A household white light-emitting diode was also used as a light source for these reactions.

Room Temperature Ring Expansion of N-Heterocyclic Carbenes and BB Bond Cleavage of Diboron(4) Compounds

2015 ◽  
Vol 21 (25) ◽  
pp. 9018-9021 ◽  
Author(s):  
Sabrina Pietsch ◽  
Ursula Paul ◽  
Ian A. Cade ◽  
Michael J. Ingleson ◽  
Udo Radius ◽  
...  
Keyword(s):  
Room Temperature ◽  
Bond Cleavage ◽  
Ring Expansion ◽  
Heterocyclic Carbenes

scholarly journals Electrochemical Ring Expansion to Synthesize Medium-Sized Lactams Through C–C Bond Cleavage

CCS Chemistry ◽  
2020 ◽  
pp. 2233-2244
Author(s):  
Kun Liu ◽  
Chunlan Song ◽  
Xu Jiang ◽  
Xin Dong ◽  
Yuqi Deng ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Ring Expansion

I2-Promoted Multicomponent Dicyclization and Ring-Opening Sequences: Direct Synthesis of Benzo[e][1,4]diazepin-3-ones via Dual C–O Bond Cleavage

2019 ◽  
Vol 21 (18) ◽  
pp. 7504-7508 ◽  
Author(s):  
Xiao Geng ◽  
Can Wang ◽  
Chun Huang ◽  
Peng Zhao ◽  
You Zhou ◽  
...  
Keyword(s):  
Ring Opening ◽  
Bond Cleavage ◽  
Direct Synthesis
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