The dihalomethane-halide H 2 C(X)-X•••X -(X = Cl, Br) halogen bonding was detected in a series of the cis-[PdX(CNCy){C(NHCy)=NHC 6 H 2 Me 2 NH 2 }]X•CH 2 X 2 (X = Cl, Br) associates by single-crystal XRD followed by DFT calculations. Although ESP calculations demonstrated that the σ-hole of dichloromethane is the smallest among all halomethane solvents (the maximum electrostatic potential is only 2.6 kcal/mol), the theoretical DFT calculations followed
Communications Figure 2. 14 N NMRs pectra of dinitrobi-1,2,5-oxadiazoles 1a and 1b in [D 6 ]acetone. Figure 3. X-ray crystal structure of 1a.Atoms are represented by ellipsoids at the 50% probability level. The short intramolecular contact corresponding to noncovalent interactions is shownbyd ashed lines.Figure 4. X-ray crystal structure of 1b.Atoms are represented by ellipsoids at the 50% probabilitylevel.
A direct approach to the synthesis of previously unknown 1H-1,2,3-triazolylfuroxans, involving nucleophilic substitution of the nitro group in nitrofuroxans followed by catalytic [3+2] cycloaddition of intermediate azidofuroxans to 1,3-ketoesters, is reported. The scope of the triazolylfuroxans was additionally diversified through a number of transformations of the functional groups attached to the 1,2,3-triazole ring. The cytotoxic activity of the newly synthesized triazolylfuroxans and of previously reported hetarylfuroxans was studied. The NO-donor capability of selected synthesized hetarylfuroxans was measured by the Griess reaction using a spectrophotometric technique.
A new approach to hetaryl carbamates through a tandem condensation/rearrangement reaction of 2‐aminohetarene N‐oxides was developed. The developed reaction is suitable for both five‐ and six‐membered heterocycles and proceeds through the condensation of 2‐aminohetarene N‐oxide with trimethyl orthoformate followed by intramolecular N‐oxide oxygen transfer. For five‐membered hetarene N‐oxides (furoxans), the intramolecular rearrangement is catalyzed by a cyanide anion, while for six‐membered hetarene N‐oxides (azines), Lewis acid catalysis is sufficient. The developed protocol is characterized by operational simplicity and high efficiency, resulting in carbamoyl derivatives in good and high yields.magnified image
Novel regioselective approach to the synthesis of (1H-1,2,3-triazol-1-yl)furoxans based on Lewis acid-catalyzed Wolff cyclocondensation of aminofuroxans with diazo-β-dicarbonyl compounds has been developed. This approach allows to involve aminofuroxans as substrates which are very weak nucleophiles and usually do not participate in reactions with common electrophiles.
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