One‐pot carboxylative cyclization of propargylic alcohols and CO2 catalysed by N‐heterocyclic carbene/Ag systems

A series of N ‐heterocyclic carbene (NHC)/Ag systems were developed for the carboxylative assembly of propargylic alcohols and carbon dioxide (CO₂). With the catalysis of these catalytic systems, a variety of target α‐alkylidene cyclic carbonates could be obtained smoothly under atmospheric CO₂ pressure in straightforward one‐pot processes. Particularly, these reactions could be performed without any stoichiometric addition of bases or additives. Further mechanistic investigation reveals that the excellent activities are attributed to the effective activations of CO₂ accomplished by the NHCs via the formation of the NHC‐CO₂ adducts.     

Preparation and Application of Solid,Salt‐Stabilized Zinc Amide Enolates with Enhanced Air and Moisture Stability

The treatment of various N‐morpholino amides with TMPZnCl⋅LiCl (TMP=2,2,6,6‐tetramethylpiperidyl) and Mg(OPiv)₂ in THF at 25 °C provides solid zinc enolates with enhanced air and moisture stability (t _1/2 in air: 1–3 h) after solvent evaporation. These enolates undergo Pd‐ and Cu‐catalyzed cross‐couplings with (hetero)aryl bromides as well as allylic and benzylic halides. The arylated N‐morpholino amides were converted into various ketones by LaCl₃⋅2 LiCl mediated acylation with Grignard reagents. The new, solid enolates were used to prepare a potent anti‐breast‐cancer drug candidate in six steps and 23 % overall yield.     

可见光诱导的1,n-烯炔的自由基串联环化反应研究进展

碳氮杂环化合物广泛存在于天然产物、生物活性分子、药物等相关化合物以及许多其他精细化学品中.近年来,发展了大量的合成方法制备该类化合物.其中,可见光诱导的l,n-烯炔的自由基串联环化反应条件绿色友好、操作简单、化学选择性和官能团兼容性好,已成为制备该类化合物的强有力工具.本文主要根据自由基产生的类型概述了近来可见光诱导的...     

New Possible Applications of Heavy Main-Group Elements in Organic Synthesis

Aside from elements of the 2nd row, and one element of the 3rd row of the periodic system—Si, P, S, and Se, respectively, whose organoelement groups such as Me₃Si and Ph₃P^⊕ have proven useful in numerous organic syntheses—other elements of the 3rd as well as 4th and 5th row (Ge, As, Sn, Sb, Te, Pb, Bi) can also be used as components of synthetically useful organoelement groups, the elements As, Sn, and Pb, in particular, offering certain advntages over the others. Some of these organoelement groups are suitable equivalents for Li- or halogen-substituents attached to carbon; they stabilize carbanionic centers (minimum of this effect at the 3rd-row elements), and owing to their suitability as leaving groups in β-eliminations, also open up interesting synthetic possibilities. The thermally unduced syn- and silica-gel induced anti-elimination of Ph₃Sn, Ph₂Sb, Ph₃Pb, together with β-OH, are novel. With the newly synthesized compounds Ph_nEl—Ch₂—Li (El = Sn, Pb, As, Sb, Bi) and other α- and β-lithiated R_nEl- and Ph₂As(O)-reagents such organoelement groups can be introduced into organic compounds and exploited in organic and organoelement synthesis.     

Silicone nanomicelle dyeing method on polyester fibre: Comparative evaluation of chemical properties,fastness properties,and DFT

Disperse Red 177(9a), Disperse Red 343(9b), Disperse Blue 165(9c), Disperse Blue 165.1(9d), Disperse Blue 366(9e), and Disperse Blue 148(9f) were examined in the solvent. During silicon nanomicelle dyeing, we employed 9(a–f) azo disperse dyes on polyester. On polyester fabric, dye 9(a–f) offers equal washing, light, and rubbing fastness in both the conventional and silicone nanomicelle techniques. The dye can now be transported directly into the fibre core without the use of auxiliary dyes owing to the reduction in the particle size of azo dyes, which is made possible by nanoemulsions superior dispersion. The levelling property of the dispersed dye is enhanced by the dyeing process. When both techniques are applied, the lightfastness properties of all dyes are improved. It provides a very good to outstanding protection factor for textile materials. These 9(a–f) azo disperse dyes have moderate to outstanding photostability, net electrophilicity index, and lightfastness.     

KI-Mediated Chlorine Gas-Free Synthesis of 3,3-Dichloro-2-oxindole Derivatives

An efficient and environmentally friendly methodology for 3,3-dichlorination and 2-oxidation of indole derivatives is described. Using KI as promotor, MCl (M=K, Na) as chlorine source, and oxone as oxidant, the reaction proceeds smoothly affording various functionalized 3,3-dichloro-2-oxindoles in moderate to excellent yields. This strategy can also be extended to 3-substituted indoles. With a broad substrate scope, it is a practical approach to 3,3-disubstituted-2-oxindoles.     

Catalyst- and Oxidant-Free Electrochemical Regioselective Halogenation and Trifluoromethylation of 4H-Pyrido[1,2-a]pyrimidin-4-ones

The catalyst-free electrochemical halogenation and trifluoromethylation of 4H-pyrido[1,2-a]pyrimidin-4-ones was realized under external-oxidant-free conditions. This strategy provides an easy and green access to functionalized new 4H-pyrido[1,2-a]pyrimidin-4-one derivatives with broad scope, good functional group tolerance and high regioselectivity.     

Photoinduced Reaction of α-Bromoacetophenone with Thiosulfonate: Synthesis of β-Keto Thiosulfone

A photoinduced synthesis of β-keto thiosulfone/β-keto selenosulfone by the reaction of α-bromoacetophenone with thiosulfonate/selenosulfonate under metal-free and visible light irradiation conditions is developed. Two C−S bonds or one C−S bond and one C−Se bond were constructed simultaneously.