Copper(II) acetate promoted intramolecular diamination of unactivated olefins

A concise method for the synthesis of cyclic sulfamides and vicinal diamines is presented. This method is enabled by Cu(OAc)2 and demonstrates a new transformation for this metal. Both five- and six-membered vicinal diamine-containing heterocycles have been synthesized in good to excellent yields, and substrate-based asymmetric induction has been achieved. This is the first reported example of intramolecular diamination of olefins.     

Copper(II)-mediated oxidative cyclization of enamides to oxazoles

The copper(II)-mediated oxidative cyclization of enamides to oxazoles is reported. A range of 2,5-disubstituted oxazoles were prepared in moderate to good yields in two steps from simple amide and alkyne precursors.     

The palladium (II) acetate promoted 6-endo-trig cyclization of 1,1-dialkyl-2-silyloxy-1,5-dienes.

A route to cyclohexenones via the treatment of selected γ,δ-unsaturated enol silyl ethers with palladium (II) acetate is presented.     

Copper(II)chloride-mediated cyclization reaction of N-alkoxy-ortho-alkynylbenzamides

A regioselective intramolecular cyclization/halogenation reaction of N-alkoxy-o-alkynylbenzamides with CuCl(2)/NCS was developed. The corresponding 3-(chloromethylene)isobenzofuran-1-ones were exclusively obtained via 5-exo-dig cyclization in moderate to excellent yields within 0.5-1 h. This approach has been successfully used to synthesize a biaryl compound by the Suzuki-Miyaura reaction.     

Palladium(II) acetate mediated oxidative cyclization of omega-unsaturated alpha-cyano ketones. A facile methylenecyclopentane annulation process

A highly efficient methylenecyclopentane annulation process has been developed based on the Pd(II)-mediated oxidative cyclization of omega-unsaturated alpha-cyano ketones, readily accessed via the Michael addition of 3-butenylmagnesium bromide with 2-cyano-2-cycloalkenones.     

Dearomatization of naphthalene: novel stereoselective cyclization reactions promoted by Osmium(II)

A series of Michael acceptors has been combined with the Os(II) eta(2)-naphthalene complex (1) to form stable 1H-naphthalenium species. Under acidic conditions, these complexes undergo ring closure at C2 to form the phenanthrenone core. In contrast, the corresponding 1-methylnaphthalene complex (15) upon addition of MVK at C8 undergoes ring closure at C5 to form a bridged tricyclic complex (18). Michael addition of MVK to the naphthalene complex (1) followed by deprotonation, an inter-ring linkage isomerization, and ring closure forms a 9-methylphenalene complex (21). In all cases, the organic cyclization products may be decomplexed by heating with silver triflate and isolated in moderate yield.     

Cobalt (II) chloride promoted formation of honeycomb patterned cellulose acetate films

CoCl(2) containing honeycomb patterned films were prepared from cellulose acetate (CA)/CoCl(2)/acetone solutions by the breath figure method in a wide range of humidities. Size and pore regularity depend on the CA/CoCl(2) molar ratio and humidity. When replacing CoCl(2) with Co(NO(3))(2) or CoBr(2), no formation of ordered porosity in the cellulose acetate films is observed. According to data from scanning electron microscopy (SEM), Energy Dispersive X-ray Microanalysis (EDX), X-ray Diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, the key role in the formation of honeycomb structures can be attributed to the physical and chemical properties of CoCl(2) - hygroscopicity, low interaction with CA, and extraction from CA/CoCl(2)/acetone solution by water droplets condensed on the surface of the CA/CoCl(2) solution. Obtained films are prospective for using in catalysis, hydrogen fuel cells, and optical sensing materials.     

Copper(II) acetate and picrate complexes of sulfa drugs

Summary Copper(II) acetate and picrate complexes of sulfa drugsviz., sulfanilamide, sulfaguanidine, sulfathiazole, sulfadiazine, sulfamerazine and sulfamethazine were prepared and characterized with the help of analytical, electronic, i.r. and magnetic moment data. The complexes are paramagnetic, planar or mixed planar and octahedral, insoluble and melt (with decomposition) in the 185°–225° range. The sulfa drugs coordinate through their amino groups and the acetate or picrate ions are bonded to the metal through the -C(O)O group.     

meso-Phbox-Pd(II) catalyzed tandem carbonylative cyclization of 1-ethynyl-1-propargyl acetate

Palladium(ii) catalyzed carbonylation of 1-ethynyl-1-propargyl acetate is described; in the absence of the bisoxazoline (box) ligand, the second triple bond did not react, affording cyclic orthoesters and . The use of meso-Phbox-Pd(ii) strikingly changed the course of the reaction, yielding bicyclic lactone by tandem carbonylative cyclization as a result of insertion of the second triple bond.     

Copper iodide-catalyzed cyclization of (Z)-chalcogenoenynes

We present here our results of the efficient copper-catalyzed cyclizations of chalcogenoenynes and establish a route to obtain 3-substituted chalcogenophenes in good to excellent yields. In addition, the obtained chalcogenophenes were readily transformed to more complex products using the palladium-catalyzed cross-coupling reactions with boronic acids to give Suzuki-type products in good yields.     

Alpha-N-acetylmannosamine (ManNAc) synthesis via rhodium(II)-catalyzed oxidative cyclization of glucal 3-carbamates

[reaction: see text] Glucal 3-carbamates 1 and 7 underwent oxidative cyclization with iodobenzene diacetate or iodosobenzene in the presence of Rh2(OAc)4, providing mannosamine 2-N,3-O-oxazolidinones. With iodosobenzene, incorporation of 4-penten-1-ol provided a readily separable anomeric mixture of n-pentenyl glycosides, with the anomers exhibiting pronounced differences in reactivity as glycosyl donors. N-acylation of the sugar oxazolidinones led to alpha-selective glycosyl donors for the elaboration of various 2-mannosamine frameworks. Alternatively, the anomeric n-pentenyl glycosides of N-Cbz 2-mannosamine oxazolidinones were converted separately to oxazolidinone-opened derivatives 28alpha and 28beta. These served as stereoconvergent glycosyl donors, and the alpha-linked products were readily advanced to a variety of N-acetylmannosamine (ManNAc) frameworks, using an intramolecular O-->N acetyl transfer as the final step.     

I(2) promoted domino oxidative cyclization for one-pot synthesis of 2-acylbenzothiazoles via metal-free sp(3) C-H functionalization

An I(2) promoted domino protocol was developed to construct 2-acylbenzothiazoles from simple and readily available aromatic ketones/unsaturated methyl ketones and o-aminobenzenethiols. The reaction proceeded smoothly under metal-free and peroxide-free conditions.     

Copper(II) chloride-catalyzed Glaser oxidative coupling reaction in polyethylene glycol

Polyethylene glycol was shown to be an environmentally benign reaction medium for the copper(II) salt -catalyzed Glaser coupling reaction of terminal alkynes. In particular, oxygen as the sole oxidant worked very well for arylacetylenes even in short reaction time. The product was easily separated by extraction and the catalytic system could be reused four times without significant loss of reactivity.     

Aerobic oxidative cyclization under Pd(II) catalysis: a regioselective approach to heterocycles

[chemical reaction: see text]. An efficient Yb(OTf)3-promoted palladium-catalyzed oxidative cyclization of gamma-heteroalkenyl beta-keto amides has been developed. Under simple aerobic condition, a variety of six-, seven-, and eight-membered-ring N- and O-heterocycles were obtained regioselectively in excellent yield.     

Total synthesis of ionophores the monensin BC-rings via permanganate promoted stereospecific oxidative cyclization

Complex tetrahydrofuran 8, containing the elements of the BC-rings of monensin with four chiral centers, and functionalized for further elaboration, is synthesized via permanganate promoted stereospecific oxidative cyclization of an acyclic, achiral 1,5-diene precursor.     

Thiophenol promoted cyclization of enynes

Vinyl radicals generated by the addition of thiophenol to enynes have been shown to cyclize regioselectively giving cyclohexylidene thioethers.     

Double Hydrated Cobalt(II) Copper(II) and Nickel(II) Copper(II) Ammine Diphosphates

Synthesis of amorphous and crystalline double hydrated cobalt copper and nickel copper ammine diphosphates with a coordination structure is described.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 369–372.Original Russian Text Copyright © 2005 by Voitenko, Zhilyak, Kopilevich.     

Ti(III)-catalyzed radical cyclization of 6,7-epoxygeranyl acetate

The reductive cyclization of epoxygeranyl acetate (1) was investigated using a catalytic amount of Cp₂TiCl with various additives. The newly developed Cp₂TiCl-Mn-lutidine · HCl-BEt₃ system was found to be as effective as the reported stoichiometric system to afford the cyclized dehydro products 4 and 5 with 72% selectivity.