Preparation of azulenyllithium and magnesium reagents utilizing halogen-metal exchange reaction of several iodoazulenes with organolithium or magnesium ate complex

Preparation of several azulenyllithium and magnesium reagents was achieved by the halogen-metal exchange reaction of iodoazulenes with n-butyllithium or lithium tri(n-butyl)magnesate at low temperature and the synthetic application of the reagents was explored.     

Direct preparation of polyfunctional amino-substituted arylmagnesium reagents via an iodine-magnesium exchange reaction

The successive addition of PhMgCl and i-PrMgCl to functionalised iodoanilines allows their conversion to the corresponding amino-functionalised Grignard reagents, which react smoothly with a range of electrophiles in high yield.     

Stereoselective preparation of functionalized acyclic alkenylmagnesium reagents using i-PrMgCl.LiCl

Acyclic functionalized alkenyl iodides are converted with high stereoselectivity to the corresponding functionalized alkenylmagnesium derivatives by the reaction with i-PrMgCl.LiCl between -40 and -20 degrees C. Functional groups such as a nitrile, chloride, iodide, and ester are readily tolerated. The conversion of an alkenyl iodide bearing a keto group to the corresponding silylated cyanohydrin allows preparation of the corresponding Grignard reagent affording, after acylation and deprotection, unsaturated 1,4-diketones.     

Preparation of 2-magnesiated 1,3,5-triazines via an iodine-magnesium exchange

Functionalized iodo- and diiodo-1,3,5-triazine derivatives readily undergo an I/Mg exchange with BuMgCl, sBuMgCl, or OctMgBr at low temperatures furnishing 2-magnesiated and 2-zincated 1,3,5-triazines (after transmetalation with ZnCl(2)). This method also offers a convenient access to dimagnesiated triazines. Furthermore, it allows the preparation of functionalized 1,3,5-triazinyl dimers and trimers, interesting for their opto-electronic properties.     

Thermal studies of hypervalent iodine reagents

The use of unconventional synthesis methods in the formation of CaO·2Al₂O₃ (CA₂) is justified because it reduces the formation temperature of the compound. CA₂ is formed by classical method at temperatures above 1,400 °C. The polymeric precursor method allows a significant temperature decrease in CA₂ synthesis reaching temperatures of 1,000 °C. This paper deals with CA₂ synthesis by “citrate” method which is often presented as Pechini method, starting from a mixture of citric acid, ethylene glycol and calcium, and aluminum nitrates. A method based on the formation of a polymeric precursor was also used, starting from a mixture of acrylic acid and nitrates of calcium and aluminum. The results showed a net difference in favor of samples obtained from acrylic acid, which by annealing at 800 °C for 1 h, contain pure CA₂. The samples obtained from citric acid, after annealing at 800 °C are amorphous. After annealing at 900 °C in all samples CA₂ is single phase.     

Stereoselective synthesis of 5-7 membered cyclic ethers by deiodonative ring-enlargement using hypervalent iodine reagents

Stereoselective synthesis of 5-7 membered cyclic ethers was achieved by deiodonative ring-enlargement of cyclic ethers having an iodoalkyl substituent. The reaction took place readily under mild conditions using hypervalent iodine compounds and an acetoxy or a trifluoroacetoxy group was introduced into the rings depending on the hypervalent iodine reagent employed. The use of hexafluoroisopropanol (HFIP) as solvent is critical.     

Preparation of highly functionalized arylmagnesium reagents by the addition of magnesium phenylselenide to arynes

The described polyfunctional arylmagnesium reagents, resulting from the highly regioselective addition of magnesium phenylselenide to functionalized arynes, can be trapped by a range of electrophiles, yielding polyfunctional selenoethers in 45-85% yields. Furthermore, these Grignard reagents can be used in Negishi cross-coupling reactions with iodoarenes after transmetalation to the corresponding arylzinc compounds, furnishing functionalized biaryl products in 55-73% yields.     

Stereoselective functionalization of cyclopropane derivatives using bromine/magnesium and sulfoxide/magnesium exchange reactions

The reaction of 2,2-dibromo-1-methyl-cyclopropanecarbonitrile (1) with i-PrMgCl in Et(2)O/CH(2)Cl(2) provides the cis-magnesium-carbenoid (2), which reacts with high retention of configuration with various electrophiles. If E = SPh, a stereoselective generation of a quaternary center via a sequential Br/Mg- and sulfoxide/Mg-exchange can be achieved. [reaction: see text]     

Tagged hypervalent iodine reagents: a new purification concept based on ion exchange through SN2 substitution

The preparation of phenylsulfonate-tagged iodine(III) reagents as well as their use in a novel purification strategy for iodine(III)-promoted reactions is described. The concept is based on ion exchange and is initiated by an azide-promoted SN2-reaction at the alkyl sulfonate followed by trapping of the resulting aryl sulfonate anion with an ion-exchange resin. The concept is successfully proven for Ru-catalyzed oxidations of alcohols, the activation and glycosidation of thioglycosides, and the SuArez reaction of pyranoses.     

An efficient route to 4-aryloxycoumarins via one-pot reactions of 4-hydroxycoumarins with hypervalent iodine reagents

Highly efficient reactions of 4-hydroxycoumarin with hypervalent iodine reagents under mild conditions are described, which give rise to 4-aryloxycoumarins in good to excellent yields.     

Metal-free oxidative amide formation with N-hydroxysuccinimide and hypervalent iodine reagents

An oxidative amide formation using N-hydroxysuccinimide and hypervalent iodine reagents was developed. The method enables a wide range of aldehydes and amines to be coupled under mild reaction conditions providing amide in good to excellent yield. The radical species in the reaction mixture was observed for the first time using ESR measurement, and along with other mechanistic investigations, a plausible mechanism of the reaction was proposed.     

Synthesis of cyclopropanes via iodine-magnesium exchange between 3-iodomethyl-1-oxacyclopentanes and organomagnesium reagents

Iodine-magnesium exchange occurs upon treatment of 3-iodomethyl-1-oxacyclopentanes with alkyl Grignard reagents or trialkylmagnesate. The resulting organomagnesium compounds undergo intramolecular nucleophilic substitution in ether to afford cyclopropane skeletons in a stereoselective manner.