Aleksandra Skowronska

Synthesis of isothiocyanatophosphoranes and isothiocyanatophosphonium salts via oxidative addition of thiocyanogen and ligand substitution: Novel reagents for converting hydroxy groups into thiocyanate and isothiocyanate functions under mild conditions

Abstract The oxidative addition of thiocyanogen to triphenylphosphine has been investigated by 31P NMR spectroscopy showing the formation of the isothiocyanatophosphonium salt 8. The analogous reaction between thiocyanogen and alkyl o-phenylene phosphites 7 leads to diisothiocyanatophosphoranes 9. The same products were prepared via ligand substitution from the corresponding chlorophosphonium salt 12 and alkyldichloro-o-phenylene phosphoranes 13 by the action of potassium thiocyanate in the presence of 18-crown-6-ether or more conveniently using lead thiocyanate. The phosphonium salt 8 and phosphoranes 9 were employed as convenient novel reagents for converting hydroxy groups into thiocyanate and isothiocyanate functions with high stereoselectivity under very mild conditions. The efficient synthesis of acylisothiocyanales RCONCS, R2P(O)NCS and R2P(S)NCS via addition of thiocyanogen to mixed anhydrides is of special interest.

The arbuzov reaction of triethyl phosphite with elemental iodine

Abstract Triethyl phosphite and elemental iodine in solution give transient iodotriethyl-phosphonium iodide which eliminates ethyl iodide to form diethyl phosphoroiodidate. An examination of the 31 P NMR and IR spectra over the temperature range −100° − 0°C fails to disclose any evidence for triethoxydi-iodophosphorane, contrary to a previous claim.

A divergent synthesis of thiophosphate-based dendrimers

Abstract The divergent synthesis of new dendritic polythionophosphates has been accomplished by a concise procedure involving phosphitylation of propanediol derivatives, followed by elemental sulfur addition, as the key steps.

Unexpected Formal [1+3] Cycloadditions between Azides andα-Zirconated Phosphanes: A Route to Unprecedented Phosphazide and Iminophosphorane Complexes

Polycyclic zwitterionic complexes that incorporate one or two phosphonium unit(s) as cationic center(s) and zirconocene-ate moiety(ies) as the anionic counterpart(s) can be easily prepared by either [1+3] or [1+3] and [2+3] cycloadditions which involve bi- or tricyclic alpha-zirconated phosphanes 3 or 4 and various azides. Some of these species exhibit unprecedented phosphazide chelation with bonding between the zirconium and a nitrogen atom in the alpha position relative to phosphorus. When heated, the phosphazide complexes lose dinitrogen to form stable polycyclic zwitterionic phosphonium mono- or dinuclear complexes. The solid-state structure of the two zwitterionic complexes 5 and 8 was determined by X-ray crystallography.

[Cp2ZrHCl]n a useful reducing agent in phosphorus chemistry

Selective reductions of PO, PS, >CC<, CO bonds with [Cp2ZrHCl]n are described, as well as halogen-hydride exchanges.

2,5-Dihydro-1,2-oxaphospholene derivatives by the reaction of 1,2-alkadienephosphonates and phosphorus pseudohalogenes

Abstract The interaction of 1,2-aIkadienephosphonic derivatives with phosphorus containing pseudohalogenes affords 2,5-dihydro-1,2-oxaphospholene derivatives. The structure of the new compounds is determined by NMR and IR spectroscopy.

Studies on the interaction of phosphine selenides and their structural analogues wth dihalogens and sulfuryl chloride

The phosphine selenides, tris(dimethylamino)phosphine selenide, esters of selenophosphoric acid, and esters of selenophosphonic acid react with dihalogens and sulfuryl chloride to form halogenoselenophosphonium salts (P–SeX)+X−. The latter undergo deselenization via ligand exchange to form phosphonium salts (P–X)+X− and elemental selenium. The stability of these salts depends on the substituents at the phosphorus atom and the type of counter ion. It is likely that the phosphonium salts are in equilibrium with the corresponding phosphoranes, and this is demonstrated for esters containing an o-phenylene ligand. The structures of phosphonium salts, phosphoranes and other phosphorus compounds are supported by 31P NMR spectroscopy data and electrical conductivity. Additional evidence comes from addition reactions of halogenoselenophosphonium salts to cyclohexene.

X−H (X=C, N, O, P, S) Bond Activations Induced byβ-Heterosubstituted Zirconaindenes

The azazirconacyclopentene-substituted phosphines 3 and 4 have been found to activate the C-H bonds of acetylenic systems, such as methylpropiolate, diphenylphosphinoacetylene and phenylacetylene, or of methylene compounds, such as malonitrile and diethylmalonate, to give complexes 5a-c, 6a and 6b. C-H bond activation also takes place with vinylacetate. Similar reactions with amines, alcohols, enolisable ketones, phenols, phosphonates, thiols and a second-generation SH-terminated dendrimer lead through X-H bond activation (X = N, O, P, S) to new complexes 8a-c, 9, 12 a,b, 13, 14a-c, 15, 16a and 16b. The azazirconacyclopentene-substituted amine 20 reacts to form analogous complexes. Zr-X bonds of these complexes (X = C, N, O, S) can be cleaved with diphenylchlorophosphine to give P-X phosphorus derivatives in high yield.

Arbuzov reaction of alkyl and silyl phosphites with halogens involving four- and five-co-ordinate intermediates

Low temperature 31P n.m.r. spectroscopy and chemical data have been applied to elucidate the mechanism of the Arbuzov-type reaction between phosphites and halogens. Simple and substituted trialkyl, alkyl 1,2-phenylene, and trisilyl phosphites have been allowed to react with chlorine, bromine, and iodine. In some cases intermediate halogenophosphonium salts (2) and in others halogenophosphoranes (3) are observed which then decompose into the corresponding pure highly reactive phosphorohalidates (4). It was possible to prepare stable phosphonium salts from halogenophosphonium salts (2) and halogenophosphoranes (3).

A general and stereoselective method for synthesis of tri- and tetrasubstituted alkenes

A convenient, general and stereoselective synthesis of trisubstituted alkenes and tetrasubstituted alkenes containing a cyanide function as well as trisubstituted episulphides have been elaborated. Methodology described for the preparation of these compounds is based on the corresponding readily available selenophosphates 1 and thiophosphates 2.