Diastereoselective synthesis of strained spiro-cyclopropanooxindoles from cyclic diazoamides

Reaction of cyclic diazoamides and cyclic olefins or heteroaromatic systems using copper(I) triflate as a catalyst furnished a variety of strained spiro-cyclopropanooxindoles in a diastereoselective manner under mild reaction conditions. The effect of copper(I) triflate and rhodium(II) acetate catalysts on the cyclopropanation was also studied.     

Hydrated nickel (II) halides mediated ring opening reaction with N-tosylaziridines

An efficient and water tolerant method for the synthesis ofβ-haloamines is described utilizing hydrated nickel（Ⅱ） halides （NiX₂ⅩnH₂O X = Cl,Br,I） and aziridines as starting materials.N-Tosylaziridines reacted with NiCl₂·6H₂O or NiI₂·6H₂O givingβ-chloro -orβ-iodoamines in high yields（73-99%） within a short time,but 10 mol%of n-Bu₄NBr should be added in the reactions of N-tosylaziridines with NiBr₂·3H₂O in order to obtain the high yields of correspondingβ-bromoamines.Solvent played an important role in the reactions.The proper solvent for the reaction of NiCl₂·6H₂O was DMF,while NiBr₂·3H₂O or NiI₂·6H₂O proceeded well in 1,4-dioxane.     

Highly stereoselective cyclopropanation of glycals with cyclic diazoamides: a facile synthesis of spirooxindolyl sugar derivatives

Rhodium(II) acetate catalyzed intermolecular cyclopropanation of glycals with cyclic carbenoids generated from 3-diazo-2-oxindole has been achieved to produce a novel series of spirooxindolyl sugar derivatives in good yields under mild experimental conditions.     

Ionic liquid media resulted in more efficient regio- and stereoselective aminohalogenation of cinnamic esters

The ionic liquid, butylmethylimidazolium tetrafluoroborate ([Bmim][BF4]), was found to be superior to classical organic solvents for the metal catalyzed regio- and stereoselective aminohalogenation of cinnamic esters. The aminohalogenation reaction of cinnamic esters with p-TsNCl₂ proceeded at a faster rate (within 12 h) in the presence of a reduced amount of catalyst (CuOTf, 6.0 mol %). Good yields (76-82%) and excellent regio- and stereoselectivity (one isomer) were achieved for eight examples.     

Radical ring opening reaction of pyridine fused heterocycles with IBA-N3 catalyzed by tetra-n-butylammonium iodide

A mild, metal-free and efficient synthesis of 2,3-disubstituted acrylonitriles and α-iminonitriles through radical ring opening reaction of pyridine fused heterocycles has been developed. The tetra-n-butylammonium iodide catalyst acts as a formal one-electron donor. Compared to the previous methods, which require excessive amounts of highly explosive azide sources and the addition of oxidants, this is a safe and convenient transformation.     

Ring opening reactions of 1-arenesulfonyl-2-(bromomethyl)aziridines

The reactivity of 1-arenesulfonyl-2-(bromomethyl)aziridines with respect to lithium dialkylcyanocuprates and lithium dialkylcuprates (Gilman reagents) has been evaluated for the first time, pointing to the conclusion that these substrates can be applied successfully as synthetic equivalents for the 2-aminopropane dication synthon towards 2-alkylaziridines and α-branched N-tosylamides in good yields.     

Type 3 ring opening reaction of cyclopropanated oxabenzonorbornadienes with alcohol nucleophiles

The first examples of a Type 3 ring opening reaction of cyclopropanated oxabenzonorbornadiene (CPOBD) were found to occur using alcohol nucleophiles under acid catalyzed conditions, yielding seven-membered rings via ring expansion. Optimization of the reaction determined the ideal conditions to be 10?mol% pTsOH at 40?°C using excess alcohol nucleophile as the solvent. The scope of the reaction investigated diverse alcohol nucleophiles and bridgehead substituents on the CPOBD; in both cases the steric properties of the substituent was found in influence the yield of the reaction. Alternative Type 3 products were observed when the bridgehead substituent was an ethyl or hydroxymethyl group and limited examples of Type 3 products were formed using a palladium catalyst with alcohol nucleophiles. Mechanisms have been proposed for the formation of the Type 3 product as well as the alternative Type 3 products.     

Synthesis of 1,2,5- and 1,2,3,5-substituted pyrroles from substituted aziridines via Ag(I)-catalyzed intramolecular cyclization

An efficient synthesis of 1,2,5- and 1,2,3,5-substituted pyrroles has been achieved from the sequential reactions including a ring-opening of 1-(aziridin-2-yl)propargylic alcohols by various nucleophiles under mild condition followed by an intramolecular cyclization using Ag(I) catalyst.     

Synthesis and transition metal chemistry of a bridging diphosphinite, 1,4 bis(diphenylphosphinoxy)benzene

Diphosphinite ligand, [Ph₂POC₆H₄OPPh₂] (1), is obtained by reacting chloro diphenylphosphine, with 1,4-dihydroxy benzene in presence of triethylamine. Treatment of 1 with elemental sulfur or selenium resulted in the formation of bis(chalcogenide) derivatives, [Ph₂(E)POC₆H₄OP(E)Ph₂] (2, E = S; 3, E = Se) in almost quantitative yield. The binuclear complex [{(η⁶-p-cymene)RuCl₂}₂(Ph₂POC₆H₄OPPh₂)] (4) is produced in the reaction between [Ru(η⁶-p-cymene)Cl₂]₂ and diphosphinite 1. Similarly the reaction of 1 with [Rh(COD)Cl]₂ afforded a binuclear complex [{(COD)RhCl}₂(Ph₂POC₆H₄OPPh₂)] (5), whereas the macrocyclic complex [{(CO)RhCl}(Ph₂POC₆H₄OPPh₂)]₂ (6) is isolated in the reaction of 1 with 0.5 equiv of [RhCl(CO)₂]₂. Compound 1 on treatment with [Pd(COD)Cl₂] or [PdCl₂(SMe₂)₂] in 1:1 molar ratio produced the chloro-bridged binuclear complex [{(PPh₂O)Pd(μ-Cl)(PPh₂OH)}₂] (7) through P-O bond cleavage. Treatment of 1 with two equivalents of CuI in dichlormethane/acetonitrile (1:1) afforded a coordination polymer, [{Cu₂(μ-I)₂(Ph₂POC₆H₄OPPh₂)}_∞] (8) in moderate yield. The binuclear complex, [{AuCl}₂(μ-Ph₂POC₆H₄OPPh₂)] (9) is obtained in the reaction of compound 1 with two equiv of AuCl(SMe₂), where the ligand exhibits bridged bidentate mode of coordination. The molecular structures of 1-4, and 6 are determined by X-ray diffraction studies.     

Synthesis of novel glycosyl-1,2,3-1H-triazolyl methyl quinazolin-4(3H)-ones and their effect on GLUT4 translocation

Cu(OTf)₂ catalyzed synthesis of propargylated 2,3-dihydroquinazolin-4(1H)-ones has been accomplished from 2-amino-N-propargyl benzamides and aromatic aldehydes under MW irradiation. Next, a series of novel glycosyl triazolyl methyl quinazolin-4(3H)-ones have been synthesized by CuAAC reaction of propargylated 2,3-dihydroquinazolin-4(1H)-ones with glycosyl azides followed by iodine mediated oxidation. In this series, six compounds showed promising to significant GLUT4 translocation activity comparable to rosiglitazone.     

Ring opening of 2,3-epoxy phenyl ketones upon reaction with nitric oxide

Epoxide rings of 2,3-epoxy phenyl ketones were cleaved by nitric oxide, affording regioselectively the C-3 ring-opened products, erythro-α-hydroxyl nitrates (2), in a highly syn-selective manner (isolated yield of the erythro products up to 91%). Products were identified by NMR, MS, and X-ray crystallography. The reaction is assumed to be initiated by NO₂, unlike a nucleophilic attack.     

Ring opening of 2-(bromomethyl)-1-sulfonylaziridines towards 1,3-heteroatom substituted 2-aminopropane derivatives

1,3-Heteroatom substituted 2-aminopropane derivatives have been prepared from 2-(bromomethyl)-1-sulfonylaziridines for the first time using sodium azide or different potassium phenoxides in water in the presence of silica gel. The applicability of 1-arenesulfonyl-2-(bromomethyl)aziridines for the synthesis of functionalized sulfonamides has also been demonstrated towards different 1,3-dialkoxy-2-(tosylamino)propanes and 1,3-dialkylthio-2-(tosylamino)propanes upon treatment with the appropriate sodium alkoxide or sodium alkylthiolate in the corresponding alcohol or in methanol, respectively.     

Synthesis and Crystal Structure of Hexakis(N—allylthiourea)tetracopper(I) Tetratrifluoromethanesulfonate, [Cu4{CH2=CHCH2NHC(S)NH2}6](SO3CF3)4

Hexakis(N—allylthiourea)tetracopper(I) Tetratrifluoromethanesulfonate, [Cu₄{CH₂=CHCH₂NHC(S)NH₂}₆](CF₃SO₃)₄ (sp.gr.P2₁/n, a = 13.5463(8), b = 24.129(2), c = 19.128(1)Å, β = 108.053(6)°, Z = 4, R = 0.0440 for 13548 unique reflections) was obtained by reduction of Cu(CF₃SO₃)₂ with excess of N—allylthiocarbamide in benzene medium. Four crystallographical independent Cu atoms possess trigonal environment of three S atoms of CH₂=CHCH₂NHC(S)NH₂ moiety and form Cu₄S₆⁴⁺ adamantane—like fragments. The latteres are connected with CF₃SO₃^— anions via (C)—H···F hydrogen bonds.     

Copper (II)-catalyzed regio- and stereoselective addition of H/P(O)R2 to alkynes

Cu(acac)₂ is the new universal catalyst for β-E regio- and stereoselective syn-addition of the H–P(O)-bond of diphenylphosphine oxide, H-phosphinates, dialkylphosphites to various alkynes in the synthesis of P(O)-containing alkenes. Without additives and ligands Cu(II)-compounds showed better results than CuI or Ni(acac)₂. The catalytic system developed is tolerant to typical organic functional groups present in the alkynes and to the nature of different substituents in the H–P(O)-compounds.     

General synthesis of (1-substituted-1H-1,2,3-triazol-4-ylmethyl)-dialkylamines via a copper(I)-catalyzed three-component reaction in water

A copper(I)-catalyzed three-component reaction to form (1-substituted-1H-1,2,3-triazol-4-ylmethyl)-dialkylamines based on the Huisgen cycloaddition using amine, propargyl halide and azide in water was proposed. The process showed considerable synthetic advantages in terms of high atom economy, low environmental impact, atmospheric oxygen, wide substrate scope, mild reaction condition and good yields.     

Synthesis of conformationally restricted C2 symmetric macrodiolides via head to tail dimerization of carbonyl ylides

Tandem reaction of α-diazocarbonyl compounds in the presence of rhodium(II) acetate catalyst is described to furnish a range of conformationally restricted C₂ symmetric macrodiolides via head to tail dimerization of intramolecular carbonyl ylides.     

Synthesis of N-unsubstituted 1,2,3-triazoles via aerobic oxidative N-dealkylation using copper(II) acetate

A copper-catalyzed aerobic oxidative CN bond cleavage reaction was developed for the synthesis of 4-substituted-NH-1,2,3-triazoles. Diverse β-ketotriazoles derivatives, which are the starting materials for the aerobic oxidative CN bond cleavage reaction, were prepared from nine aryl and seven alkyl alkynes and α-azidoacetophenone by a copper(I)-catalyzed [3 + 2]cycloaddition reaction. The aerobic oxidation of α-(1,2,3-triazol-1-yl)acetophenones using a catalytic amount of copper(II) acetate in the presence oxygen under neutral conditions gave the title compounds in high yield.     

Effect of phosphorus ligands on the Cu(I)-catalyzed addition reaction of alkyl halide to an electron-deficient olefin under photo-irradiation

The addition of a haloalkane to an electron-deficient olefin catalyzed by the Cu(I) complex under photo-irradiation was enhanced by the use of ligands having increased basicity and decreased steric bulkiness.     

Highly controlling selectivity of copper(I)-catalyzed azide/alkyne cycloaddition (CuAAC) between sulfonyl azids and normal alkynes or propynoates

In this article, a combination of Cu(OAc)₂·H₂O/2-aminophenol was developed as a highly efficient and controlling catalytic system for sulfonyl azids involved CuAAC. By using this catalytic system, sulfonyl azids reacted with normal alkynes or propynoates to selectively give the ring products or the chain products, respectively, in excellent yields within minutes. HOAc in situ produced in the reaction has been proved to be a super protonation reagent, by which the unstable intermediate 5-cuprated 1,2,3-triazole was protonated efficiently to yield ring-product 1-sulfonyl 1,2,3-trizoles. The control experiments also proved that 2-aminophenol played dual roles as both ligand and reductant, which led to the cheap and chemically stable Cu(OAc)₂·H₂O being an efficient copper source for our purpose.     

Stereoselective synthesis of piperidinone and quinolinone systems via ring opening reactions using TiCl4/silyl reagents

Titanium(IV) chloride and silyl reagents mediated regio- and chemoselective ring opening reactions of oxa-bridged piperidinone ring systems were demonstrated. This methodology interestingly undergoes the stereoselective ring opening at the C-O bond of oxa-bridged piperidinone ring systems. Study of TiCl₄ with hydride or non-hydride silyl reagents furnished the product with selectivity. This protocol is highly valuable to synthesize a range of stereoselective piperidinones, quinolinones ring systems.