4-Chloro-5-methyl-3-diphenylphosphino-1-phenyl-1,2,3,6-tetrahydrophosphinine as a bidentate P-ligand in a cis chelate Pt(II) complex

Double deoxygenation of a 3-phosphinoxido-1,2,3,6-tetrahydrophosphine oxide (2) led to bisphosphine 3-2 with an inverted ring P atom. The reaction of bidentate P-ligand 3-2 with dichlorodibenzonitrilo platinum(II) yielded the mixture of a novel cis chelate complex (7 = PtCl₂(3-2)) and a cis bis(3-diphenylphosphino-1,2,3,6-tetrahydrophosphininyl) complex (8 = PtCl₂(η¹-5)₂) containing two units of monodentate P-ligand 5.     

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.     

Diels-Alder adducts of 4-chloro-1,6-dihydrophosphinine derivatives: A new precursor of 2-phosphapropene

The 4-chloro-1,6-dihydrophosphinine derivatives, prepared as a mixture of 3- and 5-methyl isomers from the thermolysis of dichlorocarbene adducts with 1-R-3-methylphospholene oxide (R  Me, MeO, EtO, n-PrO, i-PrO), participate in Diels-Alder reactions with dimethyl acetylenedicarboxylate and N-phenylmaleimide. The former reactant is of special value since the 2-phosphabicyclo[2.2.2]octa-5,7-diene framework is thermally labile and undergoes retrocycloaddition by a different path, eliminating the C P bridging unit as a low-coordinate species. Thus, in the case of R  Me, the initial phosphine oxides (a mixture of isomers) have been reduced to the phosphines and these undergo straightforward fragmentations on heating at 50°C to produce 2-phosphapropene. The reactions of this transient species with water and alcohols have been investigated. Unlike the case of stabilized phosphaalkenes, hydration occurs smoothly without catalysis to produce Me₂P(O)H; addition of alcohols gives phosphinites, Me₂POR. The structure of the Diels-Alder adducts was confirmed by ³¹P, ¹H, and ¹³C NMR spectroscopy. Each of the isomeric 1,6-dihydrophosphinine oxides gives two diastereomeric adducts; partial separation of some of the resulting four-component mixtures was achieved with silica gel chromatography.     

Synthesis and fragmentation of new 2‐phosphabicyclo[2.2.2]octene 2‐oxides

The substitution pattern of the 2‐phosphabicyclo[2.2.2]octene framework and the skeleton itself were varied to obtain new cycloadducts usable in phosphorylations and to study their ability to undergo fragmentation. Thus, an N‐methyl and several P‐trialkylphenyl derivatives ( 7 and 9 , respectively) were synthesized, together with two diaza species ( 8 ) whose stereostructure was evaluated by single crystal X‐ray analysis. Mechanistic studies on the UV light‐mediated photolysis of the P‐aryl phosphabicyclooctenes ( 9 ) in the presence of methanol supports the suggestion of a novel addition–elimination reaction path. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:626–632, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10052     

Modification of D‐glucose‐based 18‐crown‐6 ethers by phosphorylation and phosphinylation

The primary hydroxy groups of head‐tail and head‐head bis(sugar)‐based crown ethers ( 1 and 3 , respectively) were acylated by (EtO)₂P(O)Cl and Ph₂P(O)Cl in a selective manner. Cation binding ability of the bis‐phosphorylated and phosphinylated macrocycles ( 2 and 4 ) was evaluated by the picrate extraction method. Introduction of the P‐moieties led to increase of the extraction ability without significant selectivity. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:267–270, 2000     

New 7‐phosphanorbornenes derived from 2‐methyl‐1‐phenyl‐ and 1‐cyclohexyl‐3‐ methyl‐2,5‐dihydro‐1H‐phosphole 1‐oxides

Novel 7‐phosphanorbornene derivatives, such as 4, 5, 10 , and 11 were synthesized utilizing 1‐phenyl‐2‐methyl‐2,5‐dihydro‐1H‐phosphole oxide ( 1 ) and 1‐cyclohexyl‐3‐methyl‐2,5‐dihydro‐1H‐phosphole oxide ( 7 ) as the starting materials. Products 4 and 10 were prepared by trapping the corresponding phosphole oxide intermediates ( 3 and 9 , respectively) by N‐phenylmaleimide, while 5 and 11 were obtained by the dimerization of 3 and 9 , respectively. The trapping reaction was studied in details; on one hand, bromo‐2,3‐dihydro‐1H‐phosphole oxides ( 6‐1 and 6‐2 ) were pointed out as the intermediates, on the other hand, the trapping reaction was optimized. Bri‐ dged P‐heterocycles 4, 5, 10 , and 11 were tested in the fragmentation‐related phosphorylation of methanol. Hydrogenation of phosphanorbornenes 4 and 5 led to the corresponding phosphanorbornanes ( 12 and 14 , respectively) and to a reductive type of retro cycloaddition. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:320–326, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20097     

A theoretical study on the mechanism of the baeyer–villiger type oxidation of 7‐phosphanorbornene 7‐Oxides

DFT computations have been performed on selected stationary points of the reaction path (reactants, intermediates, and products) of the Baeyer–Villiger type oxidation of 7‐phosphanorbornene 7‐oxide derivatives. Our computations justified the relevance of a Criegee‐type intermediate forming in the first step, analogously to the Baeyer–Villiger oxidation of ketones. The energy profile indicated a high‐energy barrier from the side of the products, supporting the kinetic character of the mechanism. The computations revealed that the mechanism does not include a previously assumed Berry‐pseudorotation step in the Criegee‐type intermediate. On the basis of the present results, we suggest that the regioselectivity of the Baeyer–Villiger type oxidation of the 7‐phosphanorbornene 7‐oxide derivatives may be determined by steric interactions between the leaving meta‐chlorobenzoate group and substituents on the 7‐phosphanorbornene skeleton in the Criegee‐type intermediate. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:759–766, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20366     

Optimized synthesis of N-heterocyclic dronic acids; closing a black-box era

To clarify the inconsistent patent literature, the synthesis of Zoledronic and Risedronic acids involving a heterocyclic acetic acid (HAA), phosphorous acid (PA) and phosphorus trichloride (PC) as the reagents, and methanesulfonic acid as the solvent was studied in detail. It was found that the best synthesis can be accomplished at 80 °C using HAA and PC in a 1:3.1 molar ratio without any PA.     

T3P®‐Mediated One‐Pot Synthesis of Bis(α‐aminophosphonates)

Two series of bis(α‐aminophosphonates) were synthesized by one‐pot three‐component reactions using 4‐phenylenediamine, an aldehyde (2 equiv) and a phosphite (2 equiv), or terephtalaldehyde, an amine (2 equiv), and a phosphite (2 equiv) together with propylphosphonic anhydride (T3P®) in both series as a coupling reagent. The bis(α‐aminophosphonates) were obtained in moderate to excellent yields. The condensations take place under mild conditions and the isolation of the products is simple.     

3J(P,C) Couplings in 3-Phosphabicyclo[3.1.0]Hexane 3-Oxides

Abstract

Vicinal phosphorus-carbon carboncouplings (³J(P,C)) measured for 3-phosphabicyclo [3.1. O] hexane 3-oxides (1 and 2) of known geometry have been studied. With one exception (see below), the dependence of the ³J(P,C) constants on the torsion angles (?) followed the Karplus-equation (³J(P,C)=Acos²?+Bcos?+C).