Tomasz A. Modro

PHOSPHONIC SYSTEMS. 2. FUNCTIONAL GROUP AND SKELETON MODIFICATIONS IN DIETHYL ESTERS OF 2-PROPENYL (AND 2-PENTENYL) PHOSPHONIC ACIDS

Abstract Diethyl 2-propenylphosphonate (la) undergoes complete prototropic isomerisation to the 1-propenyl derivative; in the presence of alkoxide ions the reaction is followed by P-addition and transesterification. Alkylation of allylic anions derived from la and its 2-pentenyl analogue (lb) occurs, with one exception, exclusively at α-C.

Transition state activity coefficients in the acid-catalyzed hydrolysis of amides

The transition-state activity coefficient approach has been applied to the acid-catalyzed hydrolysis of benzamide and its N-alkyl derivatives. For all systems (with the exception of the N-tert-butyl derivative which reacts via carbon–nitrogen bond cleavage) a uniform type of medium dependence of is observed. The reaction shows a pronounced destabilization of S≠ over the whole region of acidity studied, practically identical to that found for the AAc-2 type of ester hydrolysis. This is interpreted in terms of an AoT2 mechanism of amide hydrolysis, that is the rate-determining formation of the oxonium-type tetrahedral intermediate from the O-protonated form of substrate conjugate acid.

A novel ‘tent-like’ structure of a copper(I) aggregate. The crystal and molecular structure of nona[N-(diethoxythiophosphoryl)-N′-phenylisothioureato]decacopper(I) perchlorate

The pale yellow complex formed by the reaction of copper(II) and N-(diethoxythiophosphoryl)-N′-phenylthiourea is shown to be a cationic CuI aggregate, [Cu10{(EtO)2P(S)–NC(S–)NHPh}9]+ Crystals were obtained with ClO4– as a counter ion and the structure of the aggregate was determined by X-ray diffraction. The unit cell is triclinic, space group P, with a= 16.06(1), b= 22.19(1), c= 22.455(6)A, α= 90.16(3), β= 108.63(4), γ= 91.37(5)°, and Z= 2. The intensities of 8 903 reflections were collected (θmax·= 18°). The final weighted residual for 7 249 reflections with I > 2σ(I) was 0.100. Each aggregate comprises: ten CuI atoms arranged in an approximate tetrahedron whose sides are each delineated by three Cu atoms; nine ligand molecules, each chelating one copper atom via two sulphur atoms; and one perchlorate anion neutralising the positive charge carried by a single, non-chelated copper. This CuI10S18 core represents the novel member of a family of copper–sulphur aggregates. Observed Cu–Cu distances (3.11–4.06 A) indicate the absence of any significant metal–metal bonding. Sulphur co-ordination varies from one and two for PS centres to two and three for C–S– groups.

PHOSPHONIC SYSTEMS. 7. REACTIONS OF 2,3-EPOXYPHOSPHONATES WITH NUCLEOPHILES: PREPARATION OF 2,3-DISUBSTITUTED ALKYLPHOSPHONIC ESTERS AND RELATED SYSTEMS

Abstract Diethyl 2,3-epoxyalkylphosphonates react regioselectively with various nucleophilic reagents yielding 2-hydroxy-3-substituted alkylphosphonic esters. The 2-hydroxy functionality can be easily converted into an ester or ether derivative. The reaction of diethyl 2,3-epoxypropylphosphonate with ketone enamines does not lead to hydroxyketophosphonates, but results in the incorporation of the 3-phosphonopropylidene group (CH—CH2—CH2—PO3Et2) into the position 2 of the parent ketone.

Benzo[b]thiophenium S,C-ylides: Preparation, structure and comparison with thiophenium analogues

Abstract A series of new S,C-ylides derived from benzo[b]thiophene and β-dicarbonyldiazocompounds were prepared and characterised. NMR ( 1 H, 13 C) studies revealed that ylides substituted additionally at position 2 of the thiophene ring can exist as pairs of diastereoisomers, not interchangeable at room temperature. The slow exchange between two sites was attributed to the restricted rotation about the ylidic SC bond. The crystal structure determined for one ylide demonstrated different molecular environment for two parts of the β-dicarbonyl ylidic substituent with respect to the benzothiophene ring. The prepared ylides were found to be much less reactive than the previously studied thiophenium S,C-ylides.

Phosphonic systems Part 9. Solution and solid state structure of R,R (S,S) stereoisomers of the adducts of diethyl(1-cyclohexenyl)methylphosphonate and aldehydes

Abstract The solution and solid state structures of single stereoisomers of α-adducts of diethyl(1-cyclohexenyl)methyl-phosphonate and three aldehydes were determined by NMR spectroscopy and by X-ray diffraction. In both phases, the molecules exist in virtually the same conformation, involving gauche orientation of the PO 3 Et 2 and the 2-hydroxy groups, and trans orientation of the former group and the R group of the aldehyde molecule. In the crystal, this conformation is retained in spite of the fact that PO⋯HO hydrogen bonding occurs inter- and not intramolecularly.

Phosphoric amides. 15N NMR study of the P—N bonding in acyclic and cyclic compounds

31P and 15N NMR spectra of 11 cyclic and non‐cyclic phosphoramidates were measured. Comparison of the closely related structures demonstrated correlation between the bond angles at nitrogen and the 15N NMR chemical shifts and the 1J(P,N) coupling constants. 15N NMR parameters allowed the exo‐ and endocyclic nitrogens to be distinguished and could be related to the hydrolytic stability of the P—N bonds.

Structural study of arylmethyldiphenylferrocenylphosphonium salts

Abstract The effect of the ferrocenyl group (Fc) directly bonded to the phosphonium phosphorus atom has been compared with the effect of the phenyl group by examining crystal and molecular structure of two benzyldiphenylferrocenylphosphonium salts, and the shielding effects in the NMR spectra of four pairs of diphenylferrocenyl and triphenylphosphonium ions. The results indicate weak electron-donating effects of the Fc group, with some contribution of theCp+PR3 ylidic resonance structure.

Phosphonic systems. Part 3. Diethyl prop-2-enylphosphonate, a new and versatile substrate in carbon–carbon bond formation

The reactions of lithiated diethyl prop-2-enylphosphonate with α,β-unsaturated ketones and carboxylic esters are described. In simple cases the conjugate addition of the lithium phosphonate via its α- or γ-carbon atom has been observed. In most cases, however, the phosphonate salt has been shown to act as a γ-donor, and a β-acceptor, yielding, in a sequence of reactions, carbocyclic products containing two (or three) new carbon–carbon bonds.

DIALKYLAMINO GROUP TRANSFER FROM TITANIUM (IV) TO PHOSPHORYL CENTRE. STRUCTURE-REACTIVITY STUDIES

Abstract Reaction between phosphoryl substrates, (EtO),P(O)X(X ˭ H, R, OR) and dialkylaminoderivatives of Ti(IV), Ti(NR2)nCI4-n and Mn(NEt,), leads to the exchange of one or both EtO groups for the NR, substituent. The reactivity of the system depends on electronic, as well as steric, effects of both substrates, and approximately correlates with the Lewis acid-base interactions between the substrates, as measured by the i.r. spectroscopy.