Stereoselective synthesis of 1,4,2‐oxazaphosphorines as precursors of chiral α‐aminophosphonic acids by intramolecular heterocyclization of β‐aldiminoalkylphosphites

The intramolecular version of nucleophilic additon of phosphites to imines was carried out for the first time taking as an example β‐aldiminoalkylphosphites, formed from chlorophosphites and β‐aldiminoalcohols [N‐(benzylidene)‐2‐aminoethanol and R‐(+)‐N‐(benzylidene)‐2‐aminobutanol‐1]. In these reactions, stereoisomeric 1,4,2‐oxazaphosphorines were obtained in good yields. R‐(+)‐N‐(benzylidene)‐2‐aminobutanol‐1 being used as a precursor, nucleophilic attack by P(III) atom on electrophilic C atom of the CN group proceeds stereospecifically with participation of only re‐face of the two possible diastereotopic faces of the imine double bond to give the epimeric at phosphorus (3R,5R)‐2‐(β‐chloroethyl)‐2‐oxo‐3‐phenyl‐5‐ethyl‐1,4,2‐oxazaphosphorines as precursors of nonracemic α‐aminophosphonic acids. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:56–61, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10054     

Intermolecular cyclocondensation of arylchloropyruvates in the synthesis of 2,3-dihydrofuran-3,5-dicarboxylic acid derivatives

Methyl arylchloropyruvates undergo intermolecular self-condensation in the presence of a catalytic amount of a base under high-temperature conditions (~250°C) with the formation of 3,4-diaryl-2-oxo-2,3-dihydrofuran-3,5-dicarboxylic acid derivatives.     

1-Alkoxy-7-hydroxy-1,3-dihydrofuro[3,4-<Emphasis Type="Italic">c</Emphasis>]pyridinium Salts

New salt structures have been synthesized from pyridoxal and various organic and inorganic acids.     

Molecular and crystal structure of 19-nor-4α(6-hydrazonocarbonyl-3,4,5-trihydroxytetrahydropyran-2-oxycarbonyl)-16-hydrazono-ent-beyeran

Russian Chemical Bulletin - X-ray crystallography was used to study molecular and crystal structure of...     

Graphs of unbranched hexagonal systems with equal values of the wiener index and different numbers of rings

Graphs of unbranched hexagonal systems consist of hexagonal rings connected with each other. Molecular graphs of unbranched polycyclic aromatic hydrocarbons serve as an example of graphs of this class. The Wiener index (or the Wiener number) of a graph is defined as the sum of distances between all pairs of its vertices. Necessary conditions for the existence of graphs with different numbers of hexagonal rings and equal values of the Wiener index are formulated, and examples of such graphs are presented.     

Degeneracy of some matrix graph invariants

New matrices associated with graphs and induced global and local topological indices of molecular graphs were proposed recently by Diudea, Minailiuc and Balaban. These matrices in canonical form are matrix graph invariants. A combined degeneracy of such invariants is considered. For every case of degeneracy corresponding graphs are presented.     

Reaction of (phenylenedioxy)trihalophosphoranes with arylacetylenes: VI. Regiochemistry of the reaction of 2,2,2-trihalo-5-methylbenzo[<Emphasis Type="Italic">d</Emphasis>][1,3,2]dioxaphospholes with arylacetylenes

NMR and IR spectroscopy and X-ray diffraction were used to show that the reaction of 2,2,2-trichloro- and 2,2,2-tribromo-5-methylbenzo[d][1,3,2]dioxaphospholes with para-substituted arylacetylenes proceeds with regioselective formation of 4-aryl-2-halo-7-methyl-2-oxobenzo[e][1,2]oxaphosphorines. With the trichlorophosphole, selective chlorination of the phenylene fragment in the para position to the endocyclic oxygen atom occurs. With the tribromophosphole, 6-bromo- and unsubstituted benzo[e][1,2]oxaphosphorines are formed as major products. The molecular and supramolecular structure of some of the obtained oxaphosphorines was studied by X-ray diffraction.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 1953–1972.Original Russian Text Copyright © 2004 by Mironov, Shtyrlina, Varaksina, Gubaidullin, Azancheev, Dobrynin, Litvinov, Musin, Konovalov.For communication V, see [1].This revised version was published online in April 2005 with a corrected cover date.