N → C2 → C3 migration of the dichlorophosphino group in the synthesis of phosphorylated NH‐pyrroles

A successive N → C₂ → C₃ migration of the dichlorophosphino group has been found to occur in phosphorylation of unsubstituted pyrrole with phosphorus trichloride. As a result of this migration, a number of hitherto unknown C‐phosphorylated N‐unsubstituted pyrroles have been obtained. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:671–676, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20495     

Synthesis and characterization of N,N‐diethyldithiocarbamate complexes of 2‐alkoxycarbonylethyltin trichloride

N,N‐Diethyldithiocarbamate complexes of 2‐alkoxycarbonylethyltin trichloride, ROCOCH₂CH₂ SnCl_3?x[S₂CNEt₂]_x (R = CH₃ ( a ); CH₃CH₂ ( b ); CH₂?CHCH₂ ( c ); CH₃CH₂CH₂ ( d ); CH₃CH₂CH₂CH₂ ( e ); x = 1 ( 1 ), 2 ( 2 )) were synthesized and characterized by means of elemental analysis, IR, and NMR (¹H, ¹³C and ¹¹⁹Sn) spectra. The crystal structure of 1b (i.e. R = CH₃CH₂, x = 1) was determined and shows that the tin atom adopts a distorted octahedral geometry with both a five‐membered chelate ring, formed via carbonyl coordination to tin, and a four‐membered chelate ring, formed by the bidentate dithiocarbamate. The spectral data and ab initio calculations indicate that intramolecular carbonyl‐oxygen to tin coordination in 1a–1e persists, but not in 2a–2e , owing to the preference of the dithiocarbamate ligands to chelate the tin centre. Copyright © 2005 John Wiley & Sons, Ltd.     

A facile synthesis of 2‐amino‐1,3‐selenazole by reaction of N,N‐unsubstituted selenourea with ketone

2‐Dialkylamino‐1,3‐selenazoles were yielded by the reaction of N,N‐unsubstituted selenoureas with ketones in the presence of ferric chloride. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:88–92, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20180     

Synthesis and structural consideration of 1‐chloro‐N,N′,N″‐tris(pentafluorophenyl)azagermatrane: Azagermatrane with the shortest intramolecular N → Ge bond

Two compounds of a novel‐type azagermatrane, N(CH₂CH₂NC₆F₅)₃Ge‐Hal: HalCl ( 1 ), Br ( 2 ), were prepared via a metathetical reaction of trilithium salt of tetramine, N[CH₂CH₂N(Li)C₆F₅]₃, with corresponding GeHal₄. A single crystal structure of 1 was determined by the X‐ray diffraction study: The compound shows the strongest transannular N_ax → Ge interaction (2.148(7) Å) among other studied azagermatranes. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:738–741, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20476     

1,2‐migration in N‐phosphano functionalized N‐heterocyclic carbenes

1,2‐Migration of the phosphano‐group to the carbene center in N‐phosphano functionalized N‐heterocyclic carbenes has been studied by density functional theory (DFT) calculations. An intramolecular mechanism with a three‐center transition state structure seems to be most plausible for the isolated carbenes, while an intermolecular pathway catalyzed by azolium salts may be preferable for a migration proceeding in the course of generating the carbenes in situ. Our calculations show that amino‐substitution at the phosphorus atom and an enhanced nucleophilicity of the heterocycle scaffold facilitate the phosphorus shift. Calculated singlet‐triplet energy gaps do not correlate with thermodynamic stability of the studied carbenes and their disposition toward the 1,2‐rearrangement. © 2014 Wiley Periodicals, Inc.     

[N,N′‐Bis(3‐aminopropyl)ethylenediamine‐κ4N,N′,N′′,N′′′](trithiocyanurato‐κ2N,S)zinc(II) ethanol solvate

In the crystal structure of the title compound, [N,N′‐bis(3‐­amino­propyl)­ethyl­enedi­amine‐κ⁴N,N′,N′′,N′′′][1,3,5‐triazine‐2,4,6(1H,3H,5H)‐tri­thionato(2−)‐κ²N,S]­zinc(II) ethanol sol­vate, [Zn(C₈H₂₂N₄)₂(C₃HN₃S₃)]·C₂H₆O, the Zn^II atom is octa­hedrally coordinated by four N atoms [Zn—N = 2.104 (2)–2.203 (2) Å] of a tetradentate N‐donor N,N′‐bis(3‐­amino­propyl)­ethyl­enedi­amine (bapen) ligand and by two S and N atoms [Zn—S = 2.5700 (7) Å and Zn—N = 2.313 (2) Å] of a tri­thio­cyanurate(2−) (ttcH²⁻) dianion bonded as a bidentate ligand in a cis configuration. The crystal structure of the compound is stabilized by a network of hydrogen bonds.     

N‐N migration of a carbamoyl group in a pyrazole derivative revealed by NMR

During a synthesis of 5‐amino‐4‐(6‐methoxy‐2‐methylpyridin‐3‐yl)‐3‐methyl‐1H‐pyrazole‐1‐carboxamide (see Scheme 1), a side‐reaction produced 3‐amino‐4‐(6‐methoxy‐2‐methylpyridin‐3‐yl)‐5‐methyl‐1H‐pyrazole‐1‐carboxamide as a by‐product that forms an equilibrium with the target‐compound. The structure of the by‐product was elucidated by the interpretation of 1D and 2D (HMQC, HMBC) NMR data where ¹H‐¹⁵ N HMBC correlations revealed the position of carbamoyl group attachment on the pyrazole. Comparison of structures of the target‐compound and the by‐product showed that the latter resulted from N‐N migration of the carbamoyl group in the target‐compound. Copyright © 2013 John Wiley & Sons, Ltd.     

Superacid‐catalyzed Friedel–Crafts phosphination of 2‐hydroxybiphenyls with phosphorus trichloride

Cyclic phosphorus compounds, 6H‐dibenz[c,e][1,2]oxaphosphorin‐6‐oxide derivatives, were efficiently synthesized by the Friedel–Crafts reaction of 2‐hydroxybiphenyls with phosphorus trichloride in the presence of superacids, especially trifluoromethanesulfonic acid (TfOH) as a catalyst. TfOH was investigated for the first time as an effective catalyst for the aromatic phosphination of 2‐hydroxybiphenyls.     

Differentiation of α‐COOH from β‐COOH in aspartic acids by N‐phosphorylation

The biomimic reactions of N‐phosphoryl amino acids, which involved intramolecular penta‐coordinate phosphoric‐carboxylic mixed anhydrides, are very important in the study of many biochemical processes. The reactivity difference between the α‐COOH group and β‐COOH in phosphoryl amino acids was studied by experiments and theoretical calculations. It was found that the α‐COOH group, and not β‐COOH, was involved in the ester exchange on phosphorus in experiment. From MNDO calculations, the energy of the penta‐coordinate phosphoric intermediate containing five‐member ring from α‐COOH was 35 kJ/mol lower than that of the six‐member one from β‐COOH. This result was in agreement with that predicted by HF/6‐31G** and B3LYP/6‐31G** calculations. Theoretical three‐dimensional potential energy surface for the intermediates predicted that the transition states 4 and 5 involving α‐COOH or β‐COOH group had energy barriers of ΔE=175.8 kJ?mol^?1 and 210.4 kJ?mol^?1, respectively. So the α‐COOH could be differentiated from β‐COOH intramolecularly in aspartic acids by N‐phosphorylation. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 41–51, 2001     

[N,N′‐Bis(2,6‐diisopropylphenyl)acenaphthene‐1,2‐diimine‐1κ2N,N′]heptacarbonyl‐1κC,2κ3C,3κ3C‐di‐μ3‐tellurido‐triiiron(II)(2 Fe—Fe)

The sterically hindered title complex, [Fe₃Te₂(C₃₆H₄₀N₂)(CO)₇], was obtained by substitution of two carbonyl groups in the [Fe₃(μ₃‐Te)₂(CO)₉] cluster by the bulky redox‐active N,N′‐bis(2,6‐diisopropylphenyl)acenaphthene‐1,2‐diimine (dpp‐BIAN) ligand. The asymmetric unit contains two molecules of the same geometry. The C=N bond lengths in dpp‐BIAN indicate a rather low level of electron transfer from the cluster core to the dpp‐BIAN ligand.     

Acetato(N‐phenylpyridine‐2‐carboxamidato‐κ2N,N)(N‐phenylpyridine‐2‐carboxamide‐κ2N1,O)copper(II)

The title complex, [Cu(C₁₂H₉N₂O)(C₂H₃O₂)(C₁₂H₁₀N₂O)], is a neutral Cu^II complex with a primary N₃O₂ coordination sphere. The Cu centre coordinates to both a deprotonated and a neutral molecule of N‐phenylpyridine‐2‐carboxamide and also to an acetate anion. The coordination around the metal centre is asymmetric, the deprotonated ligand providing two N donor atoms [Cu—N = 1.995 (2) and 2.013 (2) Å] and the neutral ligand providing one N and one O donor atom to the coordination environment [Cu—N = 2.042 (2) Å and Cu—O = 2.2557 (19) Å], the fifth donor being an O atom of the acetate ion [Cu—O = 1.9534 (19) Å]. The remaining O atom from the acetate ion can be considered as a weak donor atom [Cu—O = 2.789 (2) Å], conferring to the Cu complex an asymmetric octahedral geometry. The crystal structure is stabilized by intermolecular N—H...O, C—H...O and C—H...π interactions.     

Synthesis of β-（ 1→6）-Branched （ 1→3）-Glucononaoside with Alter-nate β- and α-Bonds in the Backbone

Lauryl glycoside of β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]α-D-Glcp-(1→3)-β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]α-D-Glcp-(1→3)-β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]β-D-Glcp was synthesized through 3 3 3 strategy. 3-O-Allyl-2,4,6-tri-O-benzoyl-β-D-glucopyranosyl-(1→3)- -[2, 3, 4, 6-tetra-O-benzoyl-β-D-glucopyranosyl-(1→6)-] 1,2-O-isopropylidene-α-D-glucofuranose was used as the key intermediate which was converted to the corresponding trisaccharide donor and acceptor readily.     

Chlorido[N,N′‐dibenzyl‐N′′‐(trichloroacetyl)phosphoramidato‐κ2O,O′](1,10‐phenanthroline‐κ2N,N′)copper(II)

In the title complex, [Cu(C₁₆H₁₆Cl₃N₃O₂P)Cl(C₁₂H₈N₂)], the Cu^II cation presents a square‐pyramidal environment, where the CuO₂N₂ base is formed by two O atoms from carbonyl and phosphoryl groups, and by two N atoms from a 1,10‐phenanthroline molecule. A coordinated Cl atom occupies the apex. N—H...Cl hydrogen bonds link the molecules into one‐dimensional chains. The trichloromethyl group is rotationally disordered over two positions, with occupancies of 0.747 (7) and 0.253 (7).     

N,N′‐Dibenzyldithiooxamide

The title compound, alternatively known as N,N′‐di­benzyl­ethane­di­thioamide, C₁₆H₁₆N₂S₂, lies about an inversion centre and contains a planar trans‐di­thiooxamide fragment characterized by a strong intramolecular hydrogen bond between the S atom and the adjacent amide H atom in the solid state, with an S?N distance of 2.926 (1) Å. The aryl substituent is oriented orthogonal to the mean plane of the trans‐di­thiooxamide fragment due to steric hindrance and this effect is discussed.     

Synthesis of N,N‐Bis(dialkoxyphosphinoylmethyl)‐ and N,N‐Bis(diphenylphosphinoylmethyl)‐β‐ and γ‐amino acid Derivatives by the Microwave‐Assisted Double Kabachnik–Fields Reaction

The title compounds were synthesized by the microwave‐assisted, mostly solvent‐free bis Kabachnik–Fields condensation of β‐alanine and γ‐aminobutyric acid or their esters with formaldehyde and >P(O)H species, such as dialkyl phosphites and diphenylphosphine oxide.     

N,N,N′,N′,N″‐Pentamethyl‐N″‐[(trifluorosilyl)methyl] phosphoric triamide. First example of the existence of intramolecular PO→Si coordination bond in the Si‐containing phosphoric triamides

The N,N,N′,N′,N″‐pentamethyl‐N″‐(trifluorosilylmethyl)phosphoric triamide O?P(NMe₂)₂N(Me) CH₂SiF₃ with intramolecular P?O→Si coordination was formed by the reaction of N,N,N′,N′,N″‐pentamethyl‐N″[(triethoxysilyl)methyl]phosphoric triamide with BF₃·Et₂O. Copyright © 2007 John Wiley & Sons, Ltd.     

A novel one‐dimensional metal–organic framework with a μ‐cyanido‐argentate group: catena‐poly[[(5,5′‐dimethyl‐2,2′‐bipyridyl‐κ2N,N′)silver(I)]‐μ‐cyanido‐κ2N:C]

The design and synthesis of metal coordination and supramolecular frameworks containing N‐donor ligands and dicyanidoargentate units is of interest due to their potential applications in the fields of molecular magnetism, catalysis, nonlinear optics and luminescence. In the design and synthesis of extended frameworks, supramolecular interactions, such as hydrogen bonding, π–π stacking and van der Waals interactions, have been exploited for molecular recognition associated with biological activity and for the engineering of molecular solids.The title compound, [Ag(CN)(C₁₂H₁₂N₂)]_n, crystallizes with the Ag^I cation on a twofold axis, half a cyanide ligand disordered about a centre of inversion and half a twofold‐symmetric 5,5′‐dimethyl‐2,2′‐bipyridine (5,5′‐dmbpy) ligand in the asymmetric unit. Each Ag^I cation exhibits a distorted tetrahedral geometry; the coordination environment comprises one C(N) atom and one N(C) atom from substitutionally disordered cyanide bridging ligands, and two N atoms from a bidentate chelating 5,5′‐dmbpy ligand. The cyanide ligand links adjacent Ag^I cations to generate a one‐dimensional zigzag chain. These chains are linked together via weak nonclassical intermolecular interactions, generating a two‐dimensional supramolecular network.