C-S Bond Cleavage Reactions of Sulfonediimines

Abstract

Nucleophilic C-S bond cleavage of Sulfonediimines to Sulfinamidine-type Structures is discussed     

Dimethylsulfonium Methylide in Methylation of Silylphosphines

Selective monodesilylation of bissilylated alkyl- or arylphosphines under the action of dimethylsulfonium methylide and the subsequent methylation of the resulting silyl phosphides with the sulfonium salt offers a convenient route to difficultly accessible monosilylated secondary methylalkyl(aryl)phosphines.     

Pressure-Induced Polymerization: Addition and Condensation Reactions

Under pressure of 1–100 GPa, unsaturated organic molecules tend to form covalent bond to each other for a negative enthalpy change, which often produces polymeric materials with extended carbon skeleton. The polymerization reactions typically happen in crystal, which promotes the topochemical process. This review summarized the topochemical polymerization processes of several alkynes, aromatics, and alkynylphenyl compounds, including the critical crystal structures before the reaction, bonding process, and the structure of the products. Secondly, this review also summarized the condensation reaction identified in the polymerization process, including the elimination of small molecules such as NH₃, etc.     

Quantum-Mechanical Modeling of the Concerted Ring Cleavage Reactions

Russian Journal of Physical Chemistry A - Quantum-chemical modeling of the retro-Diels–Alder reaction is performed for the cycles of different structure as examples: with (a) alkyl...     

Laser-Induced Addition Reactions of Iodine with Acetylene

Laser-induced addition reactions of iodine with acetylene at 5145 and 4880 Å excitation wavelengths are studied, while trans-1,2-diiodoethylene is identified as the exclusive reaction product. A sequential addition reaction mechanism initiated by iodine atoms from the direct photodissociation process or collisional induced dissociation can be inferred.     

Mechanochemistry and Eco-Bases for Sustainable Michael Addition Reactions

The Michael addition reaction was revisited with a full focus on sustainability combined with efficiency, using mechanochemistry in mild conditions. First, the synthesis of cyclopentenone derivatives was chosen as a model reaction to find optimal conditions in mechanochemistry while using classical but weak bases. The reaction was efficient (84–95% yields), fast (2–6 h), solvent free, and required 0.1 equivalent of base. Aiming to reach greener conditions, classical bases were then replaced using new bio-sourced bases, called Eco-bases, that were easily prepared from plants and led to heterogeneous catalysts. The composition and structure of Eco-bases were characterized by MP-AES, XRPD, EBSD/EDS, HRTEM/EDX and ion chromatography. Interestingly, a high ratio of potassium was observed with the presence of K₂Ca(CO₃)₂ for the most effective Eco-base. The new Eco-bases were used for the mechanical-assisted construction of functionalized alkenone derivatives. The versatility of the method has been successfully applied with good to excellent yields to different Michael donors and acceptors. Eco-bases were recycled and reused four times with the same performances. Combining Eco-bases and mechanochemistry in Michael addition reactions allowed reaching a maximum degree of sustainability (efficient, rapid, low catalyst loading, solvent-free reactions with bio-sourced catalysts) and participating in the development of mechanochemistry in sustainable chemistry.     

有机反应中“断键”与产物规律剖析

在高中有机化学教学中学生面对复杂的分子结构有些茫然,特别是判断产物方面抓不住共价键“断键”规律,因此无法书写出正确的有机产物,笔者根据当前中学化学教学实际总结出九个方面共价键的“断裂“规律,对培养学生分析问题和解决问题,书写正确有机反应方程式将有所帮助。     

The Crotyl Alcohol Dianion: Addition Reactions

Conditions are developed for the generation and subsequent addition of crotyl alcohol dianion.     

2H-1,2,3-Diazaphospholes in Addition Reactions

Abstract

2H-1,2,3-Diazaphospholes activity depends on the nature of substituents in 2,4,5-positions of the diazaphosphole ring. 5-Methy1-2-pheny1 (acety1)-1,2,3-diazaphospholes 1,2 react with the alcohols at room temperature, and 2-cyclohexyl-4,5-tetramethylen-1,2,3-diazaphosphole -3-at 65°C. The adduct 4 degrades to cyclohexanon-N-cyclohexyl-N-methyl-nydrasone 5.     

Lipase-Catalyzed Phospha-Michael Addition Reactions under Mild Conditions

Organophosphorus compounds are the core structure of many active natural products. The synthesis of these compounds is generally achieved by metal catalysis requiring specifically functionalized substrates or harsh conditions. Herein, we disclose the phospha-Michael addition reaction of biphenyphosphine oxide with various substituted β-nitrostyrenes or benzylidene malononitriles. This biocatalytic strategy provides a direct route for the synthesis of C-P bonds with good functional group compatibility and simple and practical operation. Under the optimal conditions (styrene (0.5 mmol), biphenyphosphine oxide (0.5 mmol), Novozym 435 (300 U), and EtOH (1 mL)), lipase leads to the formation of organophosphorus compounds in yields up to 94% at room temperature. Furthermore, we confirm the role of the catalytic triad of lipase in this phospha-Michael addition reaction. This new biocatalytic system will have broad applications in organic synthesis.     

Michael-Type Addition Reactions of Some Enamines to Arylidenepyrazolones

The reaction of the arylidenepyrazolones (1_b-d) with l-morpholinocyclohexene (E₂) in refluxing acetonitrile leads to the less substituted alkylated enamines 3_b-d. On the other hand, the more substituted alkylated enamines 2_a-d are formed when 1_a-d react under the same conditions with l-piperidinocyclohexene (E₁). The nature of the enamine is crucial. Nucleophilic attack of the enamine on the α, β-unsaturated carbonyl system of 1 gives rise to a zwitterionic intermediate which through α -proton loss leads to different Michael-type adducts depending on the enamine.     

3-Pyrrolidinones: Michael Addition and Schmidt Rearrangement Reactions

Various spiro-pyrano[3,2-b]pyrrolo-2-oxoindolines 3a–d and dicyano-pyrano[3,2-b]pyrroles 5a–e have been synthesized in the present study by Michael addition of 3-pyrrolidinones 1 to isatin-3-ylidenes 2 and arylidenemalononitrile 4. Hexahydro-4-oxo-1-aryl-pyrimidine-5-carboxylic acids 7a,b were synthesized from 1 by Schmidt rearrangement.