Hunting for the Magnesium(I) Species: Formation, Structure, and Reactivity of some Donor-Free Grignard Compounds

Magnesium bromide radicals have to be prepared as high-temperature molecules and trapped as a metastable solution because a seemingly simple reduction of donor-free Grignard compounds failed. However, the essential role of magnesium(I) species during the formation of Grignard compounds could be demonstrated experimentally.     

对甲基苯甲醛的Grignard试剂合成法

二甲基苯并咪唑盐;对甲基苯甲醛的Grignard试剂合成法     

Synthesis of C-Glucosides from Grignard Reagents Prepared by Activated Magnesium

l-α-biaomo-2,3,4,6-tetra-O-acetyl-D-giucopyranose reacts with Grignard eagents prepared frorn the acnvated magnesium under very mild condition to ellord C- glucosides in a very high yield compared with Grignard Reagent prepared from usual method.β-anomer predominates in the reaction, mixture The configuration of anomers was assigned by 13C NMR spectra.     

Solvolytic and Thermolytic Reactions of Heterocyclic Pentacoordinate Silicon Compounds

When cyclic pentacoordinate SiCl compounds of the type A are reacted with methanol or water substitution of the SiCl bond and ring opening with cleavage of the SiN bond takes place with formation of tetracoordinate Si compounds. These compounds undergo an interesting thermal reaction resulting in a partial reformation of the cyclic pentacoordinate starting compounds A .     

格氏试剂异构偶联法合成辅酶Q10

报道了一种利用2-甲基-3-氯-4-(2'-甲基-3',4',5',6'-四甲氧基苯)丁烯的格氏试剂与茄尼基溴发生异构偶联, 再氧化合成辅酶Q10的新方法. 发现了烯丙式格氏试剂与卤代烷经过六元环过渡态的异构偶联反应.     

Magnesiacyclopentadienes as Alkaline‐Earth Metallacyclopentadienes: Facile Synthesis,Structural Characterization,and Synthetic Application

Metallacyclopentadienes have attracted much attention as building blocks for synthetic chemistry as well as key intermediates in many metal‐mediated or metal‐catalyzed reactions. However, metallacyclopentadienes of the alkaline‐earth metals have not been reported, to say nothing of their structures, reaction chemistry, and synthetic applications. In this work, the first series of magnesiacyclopentadienes, spiro‐dilithio magnesiacyclopentadienes, and dimagnesiabutadiene were synthesized from 1,4‐dilithio 1,3‐butadienes. Single‐crystal X‐ray structural analysis of these magnesiacycles revealed unique structural characteristics and bonding modes. Their reaction chemistry and synthetic application were preliminarily studied and efficient access to amino cyclopentadienes was established through their reaction with thioformamides. Experimental and DFT calculations demonstrated that these magnesiacyclopentadienes could be regarded as bis(Grignard) reagents wherein the two Mg? C(sp²) bonds have a synergetic effect when reacting with substrates.     

Regiodivergent and Stereospecific Aziridine Opening by Copper-Catalyzed Addition of Silicon Grignard Reagents

A stereospecific ring opening of various 2-aryl-substituted aziridines with silicon Grignard reagents under copper catalysis is reported. The regiochemical outcome is governed by the steric demand of the silicon nucleophile. The LiCl introduced with the magnesium reagent R₃SiMgX⋅2 LiCl is shown to enhance the S_N2-type displacement of the carbon-nitrogen bond by coordination to the aziridine nitrogen atom.     

含硅有机锗化合物的合成

报道了一类含硅有机锗化合物的合成。从Ｍｅ３ＳｉＣｌ，ＲＸ，ＧｅＯ２出发，经过氯化、格氏反应、亲核取代等反应，制得目标化合物－－二〔烃基二甲硅基甲基〕锗的二氯化物。它们的结构经元素分析和红外表征。     

In Situ Grignard Metalation Method for the Synthesis of Hauser Bases

The in situ Grignard Metalation Method (iGMM) is a straightforward one-pot procedure to quickly produce multigram amounts of Hauser bases R₂N-MgBr which are valuable and vastly used metalation reagents and novel electrolytes for magnesium batteries. During addition of bromoethane to a suspension of Mg metal and secondary amine at room temperature in an ethereal solvent, a smooth reaction yields R₂N-MgBr under evolution of ethane within a few hours. A Schlenk equilibrium is operative, interconverting the Hauser bases into their solvated homoleptic congeners Mg(NR₂)₂ and MgBr₂ depending on the solvent. Scope and preconditions are studied, and side reactions limiting the yield have been investigated. DOSY NMR experiments and X-ray crystal structures of characteristic examples clarify aggregation in solution and the solid state.     

Structure Formation Principles and Reactivity of Organolithium Compounds

Organolithium chemistry! An overview of the structure formation principles and the strong structure–reactivity relationship of lithium organics is given. By means of the commonly used lithium bases the deaggregation of the oligomeric parent structures to small adducts is presented (see examples) and compared to the related chemistry of lithiosilanes.

     

Synthesis,Characterization, and Structure of Some Silicon Containing Diorganotin(IV) Complexes of Salicylaldehyde Thiosemicarbazones

Abstract

Four diorganotin(IV) complexes, bis[(trimethylsilyl)methyl]tin salicylaldehyde thiosemicarbazonate monohydrate(1), bis[(trimethylsilyl)methyl]tin 3-methoxysalicylaldehyde thiosemicarbazonate (2), bis[(trimethylsilyl)methyl]tin 5-tert-butyl-3-methylsalicylaldehyde thiosemicarbazonate (3), and bis[(trimethylsilyl)methyl]tin 2-oxylnaphthaldehyde thiosemicarbazonate (4) have been synthesized by reactions of (Me₃SiCH₂)₂SnCl₂ with the corresponding semicarbazone. The four complexes were characterized by IR and NMR spectroscopy and elemental analyses. The X-ray studies of compounds 1 and 4 showed that the thiosemicarbazone ligands act as tridentate ligands chelating to the central tin atoms, and thus the tin atoms were five coordinated in trigonal bipyramidal geometry for both compounds.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis and Structural Characterization of Butadienylcalcium-based Heavy Grignard Reagents and a Ca4[O] Inverse Crown Ether Complex

The structure elucidation of heavy Grignard reagents (RAeX, Ae=Ca, Sr, and Ba, X=halides) has been greatly strived after, mainly because of their inaccessibility and remarkable instability. The synthesis of a series of butadienylcalcium compounds is presented, including 1-calcio-4-lithio-1,3-butadiene, 1,4-dicalcio-1,3-butadiene, and a Ca₄[O] inverse crown ether complex, via the reaction between 1,4-dilithio-1,3-butadienes and calcium iodide in THF. Single-crystal X-ray analysis of these unprecedented heavy Grignard reagents revealed unique structural characteristics and bonding modes. Preliminary reaction chemistry was investigated. This study provides a novel class of alkenyl heavy Grignard reagents and a useful synthetic strategy for otherwise unavailable reactive organometallic compounds.