New Synthesis of Diethyl Auylphosphonates and Diethyl Alkenylphosphonates

Organometallic reagents readily added to diethyl l-(trimethylsilyl) vinylphosphonate 1 by virtue of the polarizing silyl group. Quenching with acetic acid, methyl iodide, and carbonyl compounds gave synthetically useful diethyl alkylphosphonates 6 and diethyl alkenylphosphonates 8 respectively.     

The gas-phase conformation of 3,7-dimethyl-3,7-diazabicyclo[3.3.1]nonane

The gas-phase conformation of the title compound (1) is discussed in reference to its photoelectron spectrum. The experimental lone-pair/lone-pair splitting (0.51 eV), when compared with that of similar diamines and with the results of three sets of MO calculations (MINDO/3, MNDO and STO-3G), leads to the conclusion that 1 exists in the chair-chair conformation. A remarkable sensitivity of the calculations to slight changes in the geometry is noted, and it is suggested that calculations of this type must include geometry-optimization. The question of through-space vs through-bond inteaction of the nitrogen lone pairs was explored by performing MNDO calculations in which the N-N resonance integrals were set to zero. These calculations indicate that in the chair-chair conformation the N-N interaction is mainly through-space. The ¹³CNMR and Ni(acac)₂-induced ¹³C shifts of 1 are discussed.     

An Efficient Synthesis of Diethyl 1-Aminoalkylphosphonate Hydrochlorides via the Intermediate Diethyl 1-Azidoalkylphosphonates

The title compounds 4 have been obtained in high yields in a one-step sequence by the Mitsunobu reaction of diethyl 1-hydroxyalkylphosphonates 1 with hydrazoic acid, and subsequence treatment of the inter-mediate azides 2 with triphenylphosphine, followed by hydrolysis of the iminophosphoranes 3 with water.     

Diethyl 1-acylaziridine-2,2-dicarboxylates

Chemistry of Heterocyclic Compounds -     

Spatial Structure of Isomers of 3,7-Dialkoxyalkyl-3,7-diazabicyclo[3.3.1]nonan-9-ols

The spatial structure of 3,7-dialkoxyalkyl-3,7-diazabicyclo[3.3.1]nonan-9-ols has been investigated with the aid of ¹H and ¹³C NMR spectroscopy. It was shown that the secondary alcohols studied exist in solution predominantly in a chair-boat conformation which proved to be energetically more favorable than a chair-chair conformation due to the formation of an intramolecular hydrogen bond (IMHB) between the unshared pair of electrons on the nitrogen atom and the hydrogen atom of the hydroxyl group.     

Diethyl benzoylphosphonate as a ligand

Summary Complexes (2 : 1) of diethyl benzoylphosphonate (debp) with 3d metal perchlorates were synthesized and characterized by means of i.r. and electronic spectral, magnetic susceptibility and conductance measurements. In new complexes of the types [M(debp)₂(OClO₃)(OH₂)](ClO₄) (M = Fe, Co, Zn) and [Fe(debp)₂(OClO₃)(OH₂)](ClO₄)₂, both debp ligands function as bidentate chelating agents, coordinating through the P=O and C=O oxygens. In contrast, in the manganese(II) and nickel(II) complexes, which are of the [M(debp)₂(OClO₃)(OH₂)₂](ClO₄) type, one debp acts as a bidentate chelating ligand, while the second debp is unidentate, coordinating only through the P=O oxygen. Hexacoordination in the new cationic complexes is completed by coordination of aqua and unidentate perchlorato ligands, which are in competition for sites in the inner coordination sphere of the central metal ion with the weak debp ligand. On the other hand, debp, owing to its bulkiness, and especially the presence of the benzoyl substituent, introduces sufficiently severe steric hindrance during coordination. As a result of this, the formation of [M(debp)₃]ⁿ⁺ tris-chelate cationic complexes with the 3 d metal ions under study does not seem to be possible.     

Molecular structure of 3,7-dimethyl-9-thia-3,7-diazabicyclo[3.3.1]nonane-9,9-dioxide

By a single crystal X-ray diffraction study the molecular structure of 3,7-dimethyl-9-thia-3,7-diazabicyclo[3.3.1]nonane-9,9-dioxide having a chair-chair conformation with a diequatorial arrangement of methyl groups at nitrogen atoms is determined. Compound 1 C₈H₁₆N₂O₂S crystallizes in the space group Pnma with the following cell parameters: a = 11.0262(3) Å, b = 14.4490(3) Å, c = 6.1780(3) Å.