Tetraalkyl Hydroxymethylene-bisphosphonate and Dialkyl 1-Diphenylphosphinoyl-1-hydroxy-ethylphosphonate Derivatives by the Pudovik Reaction and Their Rearranged Products

The reaction of diethyl α-oxoethylphosphonate and diethyl oxobenzylphosphonate with diethyl phosphite, dimethyl phosphite, and diphenylphosphine oxide affords, depending on the substrates and conditions (nature and quantity of the amine catalyst, temperature, and solvent), the Pudovik adduct and/or the corresponding >P(O)–CH–O–P(O)< product formed by rearrangement. The nature of the substituent on the central carbon atom (a methyl or phenyl group) influences the inclination for the rearrangement. The asymmetric products (either adducts or rearranged species) with different P(O)Y functions (Y = RO or Ph) exhibit interesting NMR features.

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Pyruvic acid is attached through its central carbon atom to the amino terminus of the recombinant DNA-derived DNA-binding protein Ner of bacteriophage Mu.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)41747-4 ◽

1992 ◽

Vol 267 (27) ◽

pp. 19101-19106

Author(s):

K Rose ◽

M.G. Simona ◽

L.A. Savoy ◽

P.O. Regamey ◽

B.N. Green ◽

...

Keyword(s):

Carbon Atom ◽

Dna Binding ◽

Pyruvic Acid ◽

Recombinant Dna ◽

Binding Protein ◽

Dna Binding Protein ◽

Amino Terminus ◽

Bacteriophage Mu ◽

Central Carbon Atom ◽

Central Carbon

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Ab initio charge density analysis of (B6C)2 and B4C3 species How to describe the bonding pattern?

Canadian Journal of Chemistry ◽

10.1139/v06-059 ◽

2006 ◽

Vol 84 (5) ◽

pp. 771-781 ◽

Cited By ~ 13

Author(s):

Cina Foroutan-Nejad ◽

Gholam Hossein Shafiee ◽

Abdolreza Sadjadi ◽

Shant Shahbazian

Keyword(s):

Quantum Theory ◽

Carbon Atom ◽

Charge Density ◽

Ab Initio ◽

Atoms In Molecules ◽

Central Carbon Atom ◽

B3lyp Method ◽

Central Carbon ◽

Density Analysis ◽

Concrete Ring

In this study, a detailed topological charge density analysis based on the quantum theory of atoms in molecules (QTAIM) developed by Bader and co-workers, has been accomplished (using the B3LYP method) on the CB62 anion and three planar isomers of the C3B4 species, which had been first proposed by Exner and Schleyer as examples of molecules containing hexacoordinate carbon atoms. The analysis uncovers the strong (covalent) interactions of boron atoms as well as the "nondirectional" interaction of central carbon atom with those peripheral atoms. On the other hand, instabilities have been found in the topological networks of (B6C)2 and B4C3(para) species. A detailed investigation of these instabilities demonstrates that the topology of charge density has a floppy nature near the equilibrium geometries of the species under study. Thus, these species seems to be best described as complexes of a relatively concrete ring containing boron or carbon atoms and a central carbon atom that is confined in the plane of the molecule, but with nondirectional interactions with the surrounding atoms.Key words: hypervalency, hexacoordinate carbon, quantum theory of atoms in molecules, charge density analysis, ab initio methods.

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Theoretical Investigation on the Role of the Central Carbon Atom and Close Protein Environment on the Nitrogen Reduction in Mo Nitrogenase

ACS Catalysis ◽

10.1021/acscatal.5b02577 ◽

2016 ◽

Vol 6 (3) ◽

pp. 1567-1577 ◽

Cited By ~ 37

Author(s):

Li Rao ◽

Xin Xu ◽

Carlo Adamo

Keyword(s):

Carbon Atom ◽

Theoretical Investigation ◽

Nitrogen Reduction ◽

Central Carbon Atom ◽

Central Carbon ◽

Protein Environment

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Hydroboration of acyclic allenes with disiamylborane

Canadian Journal of Chemistry ◽

10.1139/v69-172 ◽

1969 ◽

Vol 47 (6) ◽

pp. 1083-1086 ◽

Cited By ~ 23

Author(s):

D. S. Sethi ◽

G. C. Joshi ◽

D. Devaprabhakara

Keyword(s):

Carbon Atom ◽

Transition State ◽

Steric Effects ◽

Electrophilic Attack ◽

Terminal Carbon Atom ◽

Central Carbon Atom ◽

Central Carbon

The present investigation demonstrates the hydroboration of 1,2-nonadiene, phenylpropadiene, 3-phenyl-1,2-butadiene, 4,5-nonadiene, and tetramethylallene with disiamylborane. All the allenes except tetramethylallene underwent 100% conversion. Examination of the products indicated preferential electrophilic attack of boron on the least substituted terminal carbon atom in the case of 1,2-nonadiene, phenylpropadiene, 3-phenyl-1,2-butadiene, and on the central carbon atom in 4,5-nonadiene. In tetramethylallene boron, attack was exclusively on the central carbon atom. These results have been explained in terms of steric effects on a four-centered transition state.

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