Isosteviol acylphosphonates

A reaction of ent-16-oxobeyeran-19-oic acid (isosteviol) with an excess of PCl3 gives the corresponding acid chloride as a sole product. The latter reacts with trialkyl phosphites and dialkyl trimethylsilyl phosphites to yield acylphosphonates inert to nucleophilic reagents.     

Enantioselective Reaction of 2H-Azirines with Phosphite Using Chiral Bis(imidazoline)/Zinc(II) Catalysts

The first highly enantioselective nucleophilic addition reaction of phosphites with 2H-azirines has been developed. The reaction was applied to various 3-substituted 2H-azirines using novel chiral bis(imidazoline)/Zn^II catalysts to afford products in good yield with high enantioselectivity. The transformation of the obtained optically active aziridines showed that 2H-azirines act as either α,β- or β,β-dicarbocationic amine synthons.     

Enantioselective Reaction of 2H‐Azirines with Phosphite Using Chiral Bis(imidazoline)/Zinc(II) Catalysts

The first highly enantioselective nucleophilic addition reaction of phosphites with 2H ‐azirines has been developed. The reaction was applied to various 3‐substituted 2H ‐azirines using novel chiral bis(imidazoline)/Zn^II catalysts to afford products in good yield with high enantioselectivity. The transformation of the obtained optically active aziridines showed that 2H ‐azirines act as either α,β‐ or β,β‐dicarbocationic amine synthons.     

Oxidative diphosphonylation of 1,4-dihydropyridines and pyridinium salts

An oxidative double phosphonylation of dihydropyridines 1 and pyridinium salts 2 is achieved through the use of dialkyl phosphites, DDQ, and triethylamine. Acceptable to good yields of 2, 6-diphosphonylated-1,2-dihydropyridines 3 are obtained in a one-pot reaction involving tandem nucleophilic addition/oxidation processes. Isomerization of 3 to the more stable 2,4-diphosphonylated-1, 4-dihydropyridine 4 was observed in some cases.     

Lithium–Bromide Exchange versus Nucleophilic Addition of Schiff's base: Unprecedented Tandem Cyclisation Pathways

By exploring lithium–bromide exchange reactivity of aromatic Schiff's bases with tert-butyllithium (tBuLi), we have revealed unprecedented competitive intermolecular and intramolecular cascade annulation pathways, leading to valuable compounds, such as iso-indolinones and N-substituted anthracene derivatives. A series of reaction parameters were probed, including solvent, stoichiometry, sterics and organolithium reagent choice, in order to understand the influences that limit such ring-closing pathways. With two viable reactivity options for the organolithium on the imine; namely, nucleophilic addition or lithium–bromide exchange, a surprising competitive nature was observed, where nucleophilic addition dominated, even under cryogenic conditions. Considering the most commonly used solvents for lithium–bromide exchange, tetrahydrofuran (THF) and diethyl ether (Et₂O), contrasting reactivity outcomes were revealed with nucleophilic addition promoted in THF, while Et₂O yielded almost double the conversion of cyclic products than in THF.     

Iodine(III)‐Mediated para‐Selective Direct Imidation of Anilides

The direct, nucleophilic imidation of acetanilide derivatives has been performed under mild, iodine(III)‐mediated or ‐catalyzed conditions, employing lithium triflimide as the nitrogen source. The reaction exhibits exclusive regioselectivity for the para position and shows a good tolerance for varied functional groups at both the ortho or meta positions. Preliminary mechanistic data suggest that the LiNTf₂ reagent plays a key role in the reactivity.     

Reaction of Polyhalo Semiquinoid Structures Originating from 4-Aroyl(arylsulfonyl)oximino-2,5-cyclohexadiene-1-ones with Arylsulfinic Acids

Stable semiquinoid structures, 4-aroyl(arylsulfonyl)oximino-2,6-dimethyl-5,6-dichloro-2-cyclohexen-1-ones, do not react with dialkyl phosphites, alcohols, tosylhydrazine, p-toluidine, and hydrazoic acid. In reactions with arylsulfinic acids occurs a nucleophilic substitution of chlorine at the sp ³-hybridized C⁵ carbon in the minor Z-isomer yielding 4-aroyl(arylsulfonyl)oximino-5-arylsulfonyl-2,6-dimethyl-6-chloro-2-cyclohexen-1-ones.     

A new reaction of phosphorylated N-sulfonylimines with hydrophosphoryl agents involving C → N transfer of phosphoryl groups

Hydrophosphoryl nucleophilic agents add to the CN bond of N-sulfonyltrichloroacetimidoylphosphonates to give unstable C,C-diphosphorylated adducts, which undergo competitive 1,2-C → N phosphorotropic rearrangement and dehydrochlorination with the formation of aza-Perkow reaction products, C,N-diphosphorylated dichlorovinylsulfonamides. This is the first reliably identified case of an aza-Perkow transformation for acid phosphites and their initial nucleophilic attack at the C atom of the azomethine bond in the aza-substrates.     

Synthesis of Pyrano[3,2‐c]quinoline‐3‐carboxaldehyde and 3‐(Ethoxymethylene)‐pyrano[3,2‐c]quinolinone and Their Chemical Behavior toward Some Nitrogen and Carbon Nucleophiles

Synthesis of novel 3‐(ethoxymethylene)‐pyrano[3,2‐c]quinolinone and pyrano[3,2‐c]quinoline‐3‐carboxaldehyde was accomplished efficiently via a simple method. These two scaffolds were used as precursors to afford new biologically interesting products in good yield and short reaction times. The chemical reactivity of ethoxy methylene 2 and carboxaldehyde 3 toward different nucleophilic reagents was studied. Structures of the new synthesized compounds were elucidated by their analytical and spectral data.     

Action of Nucleophilic Phosphorus Reagents on Heterocyclic cis-Disulfides

As a contribution to previous studies of the reaction of phosphorus nucleophiles with heterocyclic cis-disulfides,^1,2 the reactivity of trialkyl phosphites 2 toward 5-p-chlorophenyl-4-cyano-1,2-dithiol-3-thione 1a, 5-phenyl-1,2,4-dithiazol-3-thione 1b and its 3-carbonyl derivative 1c has now been investigated.     

Preparation of poly(ether ketone)s derived from 2,5‐furandicarboxylic acid via nucleophilic aromatic substitution polymerization

From the viewpoint of the suppression of the petroleum consumption, aromatic poly(ether ketone)s (PEKs) were prepared by the nucleophilic aromatic substitution polymerization of 2,5‐bis(4‐fluorobenzoyl)furan (BFBF) synthesized from biomass and aromatic bisphenols. The model reaction of BFBF and p‐methoxyphenol revealed that BFBF possessed enough reactivity for the nucleophilic aromatic substitution reactions. The polymerizations of BFBF and aromatic bisphenols afforded high molecular weight polymers with good yields in N‐methylpyrrolidone and diphenyl sulfone for several hours. The longer polymerization time brought about the formation of insoluble parts in any solvents and reduction of molecular weight. The obtained PEKs were thermoplastics and exhibited good thermal stability, mechanical properties, and chemical resistance comparable to common high‐performance polymers. The thermal properties were tunable with the structure of bisphenols. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3094–3101     

Stereoselective synthesis of 1,4,2‐oxazaphosphorines as precursors of chiral α‐aminophosphonic acids by intramolecular heterocyclization of β‐aldiminoalkylphosphites

The intramolecular version of nucleophilic additon of phosphites to imines was carried out for the first time taking as an example β‐aldiminoalkylphosphites, formed from chlorophosphites and β‐aldiminoalcohols [N‐(benzylidene)‐2‐aminoethanol and R‐(+)‐N‐(benzylidene)‐2‐aminobutanol‐1]. In these reactions, stereoisomeric 1,4,2‐oxazaphosphorines were obtained in good yields. R‐(+)‐N‐(benzylidene)‐2‐aminobutanol‐1 being used as a precursor, nucleophilic attack by P(III) atom on electrophilic C atom of the CN group proceeds stereospecifically with participation of only re‐face of the two possible diastereotopic faces of the imine double bond to give the epimeric at phosphorus (3R,5R)‐2‐(β‐chloroethyl)‐2‐oxo‐3‐phenyl‐5‐ethyl‐1,4,2‐oxazaphosphorines as precursors of nonracemic α‐aminophosphonic acids. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:56–61, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10054     

Reactivity of Cage-Like Amines toward p-Toluenesulfonyl Chloride and Diphenyl Chlorophosphate in Acetonitrile

The nucleophilic reactivity of amines of the norbornane, norbornene, and adamantane series toward ptoluenesulfonyl chloride and diphenyl chlorophosphate in acetonitrile at 25°C is determined mainly by the steric factor. Parameters characterizing spatial accessibility of the reaction center in the amine molecule have been determined. Cage-like substituents show no appreciable effect on the amine reactivity, as compared to common alkyl groups.     

Diastereoselective Synthesis of meso-Bisphosphonates from Trialkyl(aryl) Phosphites and Activated Acetylenes in the Presence of 4-Nitrophenol

The reaction between trialkyl(aryl) phosphites and dibenzoylacetylene or dimethyl acetylenedicarboxylate in the presence of 4-nitrophenol leads to stable meso-bisphosphonate derivatives in good yields.     

Synthesis of 4-amino-1,2,3,4-tetrahydropyridine derivatives by intramolecular nucleophilic addition of tertiary enamides to in-situ generated imines

The reactivity of stable tertiary enamides in nucleophilic addition reaction with various in-situ generated imines was explored. Under very mild conditions, formyl-bearing tertiary enamides reacted with both aromatic and aliphatic amines to form imine intermediates. In the absence or presence of p-toluenesulfonic acid as a catalyst, intramolecular nucleophilic addition of enamide to imine functionality proceeded effectively to produce diverse 4-amino-1,2,3,4-tetrahydropyridine derivatives in good to excellent yields.     

Diastereoselective Synthesis of meso-Bisphosphonates from Trialkyl(aryl) Phosphites and Activated Acetylenes in the Presence of 4-Nitrophenol

Summary. The reaction between trialkyl(aryl) phosphites and dibenzoylacetylene or dimethyl acetylenedicarboxylate in the presence of 4-nitrophenol leads to stable meso-bisphosphonate derivatives in good yields.     

双环笼状磷酸酯衍生物的研究Ⅵ:4-取代-2,6,7-三氧杂-1-磷杂双环[2.2.2]辛烷的反应研究

双环笼状亚磷酸酯类衍生物由于其笼状结构所引起的张力及高位阻性 ,使得它同一般直链亚磷酸酯类化合物相比,在亲核取代反应性等方面有关明显的不同.本文用化合物1分别同SO~2Cl~2,Cl~2, Br~2, PCl~5等反应,结果表明,1均发生了类Arbuzov反应,生成具有相同立体构型的开环产物.本文还对化合物2的磷酰化反应进行了研究,发现在这类高位阻性的双环笼状亚磷酸酯衍生物的磷酰化反应中,DMAP是一个较有效的催化剂.     

LIQUID AMMONIA AS A MEDIUM IN THE CONVENIENT PREPARATION OF AMMONIUM O,O-DIALKYL PHOSPHOROTHIOATE AND AMMONIUM O,O-DIALKYL PHOSPHOROSELENOATE

Ammonium O,O-dialkyl phosphorothioate and O,O-dialkyl phosphoroselenoate were conveniently synthesized from dialkyl phosphites and elemental sulfur and selenium in liquid ammonia in good yields.