Interaction of 1,2‐alkadienephosphonic dialkyl esters with sulfenyl‐ and selenenylbromides

The reactivity of dialkyl esters of 1, 2‐alkadienephosphonic acids toward sulfenyl‐ and selenenyl‐bromides has been investigated. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:156–222, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20083     

New benzylpiperazine derivatives bearing mono‐ and bis‐dialkyl substituted 1,2,4‐triazoles

Cycloaddition of the 1‐aza‐2‐azoniaallenes 3 with p‐cyanobenzyl chlorides afforded, after spontaneous rearrangement, the 1,5‐dialkyl‐3‐[4‐chloromethyl)phenyl]‐1H‐[1,2,4]‐triazoles 6 . A series of 1,5‐dialkyl‐1H‐[1,2,4]‐triazol‐3‐yl)benzyl‐piperazines 7 and 8 were prepared from direct condensation of 6 with piperazine and N‐methylpiperazine, respectively. The structures of the newly synthesized products were identified by 2D NMR spectroscopy. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:28–32, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20061     

Enantioselective reduction of dialkyl 4‐(dialkoxyphosphoryl)‐3‐oxobutanoates by baker's yeast

Dialkyl 4‐(dialkoxyphosphoryl)‐3‐oxobutanoates ( 1 ), upon yeast‐mediated bioreduction, afforded chiral dialkyl 4‐(dialkoxyphosphoryl)‐3‐hydroxybutanoates ( 2 ) in moderate to good yields and ee values. Significant improvement was reported for the preparation of dialkyl 4‐(dialkoxyphosphoryl)‐3‐oxobutanoates ( 1 ), the key substrates of this bioreductive conversion. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:153–156, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10011     

A convenient synthesis of 5‐(O,O‐dialkylphosphoryl)‐4‐aryl‐3,4‐dihydropyrimidin‐2(1H)‐ones

A general and convenient route for the synthesis of dihydropyrimidines bearing the phosphoryl moiety by a one‐pot cyclocondensation involving aldehydes, urea, and O,O‐dialkyl‐2‐oxo‐propanephosphonates, using ytterbium triflate as catalyst, is reported. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:13–17, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10058     

Studies on organophosphorus compounds 105: A facile synthesis of dialkyl 6‐substituted‐4‐hydroxy‐2‐trifluoromethylquinoline‐3‐phosphonates

For the investigation of biological activities of trifluoromethylated heterocyclic compounds bearing a phosphoryl moiety, a series of N‐aryliminophosphonates were obtained by reaction of dialkyl 1‐methoxycarbonylmethylphosphonates with trifluoroacetimidoyl chlorides using NaH as a deprotonating agent. The resulting intermediates underwent cyclization on refluxing in toluene to give dialkyl 6‐substituted‐4‐hydroxy‐2‐trifluoromethylquinoline‐3‐phos‐phonates. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:240–243, 2000     

Catalytic synthesis of dialkyl sulfides from dialkyl disulfides

Dialkyl disulfides R₂S₂ where R = Me, Et, or Pr, both as individual compounds and as their mixtures, isolated from petroleum products can turn into alkanethiols and dialkyl sulfides under the action of catalysts having strong acid sites and medium-strength basic sites on their surface. In a helium atmosphere, the main conversion products are alkanethiols, while dialkyl sulfides form in low yield at a selectivity of no higher than 20%. A much higher dialkyl sulfide selectivity is attained in the reaction involving methanol. The most efficient catalyst for this reaction is alumina, with which the dialkyl sulfide selectivity is up to 99%.     

Novel synthesis of N,N′‐dialkyl cyclic ureas using sulfur‐assisted carbonylation and oxidation

The first example of cyclic urea synthesis from secondary amines by the use of sulfur‐assisted carbonylation and oxidation was established. By combined sulfur‐assisted carbonylation of secondary α,ω‐diamines under an ambient pressure of carbon monoxide at 20°C with oxidation by molecular oxygen (0.1 MPa, 20°C), a facile synthetic method for N,N′‐dialkyl cyclic ureas including 1,3‐dimethyl‐2‐imidazolidinone was developed. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:64–68, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20508     

Synthesis and characterization of second‐generation S,S‐dialkyl‐S‐(dimethylhydroxyphenyl)sulfonium salt photoinitiators

A new, simplified method has been developed for the synthesis of S,S‐dialkyl‐S‐(dimethylhydroxyphenyl)sulfonium salt cationic photoinitiators. This novel method has successfully been used for the preparation of S,S‐dialkyl‐S‐(3,5‐dimethyl‐4‐hydroxyphenyl)sulfonium and S,S‐dialkyl‐S‐(3,5‐dimethyl‐2‐hydroxyphenyl)sulfonium salts showing a wide variation in the length and structure of the alkyl chains on the positively charged sulfur atom. These photoinitiators can also be prepared with a wide variety of different anions. The manipulation of the lengths of the alkyl chains permits the design of compatible photoinitiators for highly nonpolar monomers and oligomers such as epoxy‐functional silicones, epoxidized polybutadiene, and epoxidized vegetable oils. This article describes the synthesis and characterization of these photoinitiators. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2556–2569, 2003     

Mechanical properties and thermal analysis of low‐density polyethylene + polypropylene blends with dialkyl peroxide

Polypropylene + low density polyethylene (PP + LDPE) blends involving 0, 25, 50, 75 and 100 wt% of PP with dialkyl peroxide (DAP) were prepared by melt blending in a single‐screw extruder. The effects of adding dialkyl peroxide on mechanical and thermal properties of PP + LDPE blends have been studied. It was found that at lower concentrations of peroxide (e.g., 0–0.08 wt% of dialkyl peroxide) LDPE component is cross‐linked and Polypropylene (PP) is degraded in all compositions of PP + LDPE blends. Mechanical properties (Tensile strength at break, at yield and elongation at break), Melt flow index (MFI), hardness, Scanning Electron Microscope (SEM) and thermal analyses (DSC) of these blends were examined. Because of serious degradation or cross‐linking the mechanical properties and the crystallinty (%) of those products were decreased as a result of increasing peroxide content. Copyright © 2009 John Wiley & Sons, Ltd.     

Reactions of N,N-(dialkyl)arylthioacetamides with dialkyl acetylenedicarboxylates

2-(Alkoxycarbonylmethylidene)-4-aryl-5-(dialkylamino)thiophen-3(2H)-ones were synthesized by condensation of N,N-(dialkyl)arylthioacetamides with dialkyl acetylenedicarboxylates. Intermediate substituted vinylic sulfides were isolated. When heated or in the presence of an acid or a base, they undergo cyclization into thiophenes.     

Accelerating effects of N‐aryl‐N′,N′‐dialkyl ureas on epoxy‐dicyandiamide curing system

This report focuses on epoxy‐dicyandiamide (DICY) curing system accelerated by N‐aryl‐N′,N′‐dialkyl urea, aiming at clarifying the accelerating mechanism and the relationship between accelerating effect and molecular structure of the accelerators. Nine N‐aryl‐N′,N′‐dialkyl ureas were synthesized and investigated with measurements of differential scanning calorimetry, thermo gravimetric/differential thermal analysis and NMR spectroscopy. The results revealed that the ureas released the corresponding secondary amines by the thermal dissociation in the presence of epoxide, which led to the formation of tertiary amines that catalyze the addition reaction of DICY to epoxide. Moreover, a tendency that the ureas able to release more compact amines exhibited higher acceleration effects was discovered. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Lanthanide amides [(Me3Si)2N]3Ln(µ‐Cl)Li(THF)3‐catalyzed phospho‐aldol‐brook rearrangement reaction of dialkyl phosphites with isatins

The tetracoordinated lanthanide amides [(Me₃Si)₂N]₃Ln(µ‐Cl)Li(THF)₃ were found to serve as highly active catalysts for the phospho‐Aldol‐Brook rearrangement reaction of various dialkyl phosphites and isatins. The reactions produced dialkyl 2‐oxoindolin‐3‐yl phosphates in good to excellent yields in the presence of 1 mol% [(Me₃Si)₂N]₃La(µ‐Cl)Li(THF)₃ at room temperature within 5 min. A mechanism for this highly efficient process was proposed. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:449–456, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21036     

Organosilicon compounds XVII. Introduction of the dialkyl phosphonate and dialkyl thiophosphonate moieties on an organosilicon substituted heterocyclic system

A number of new dialkyl 2-(5-trisubstitutedsilyl)thienylphosphonates and thiophosphonates as well as dialkyl 2-(5-trisubstitutedsilyl)furylphosphonates and thiophosphonates were prepared via reaction of the 5-(trisubstitutedsilyl)-2-lithiothiophenes and furans with dialkyl chloro-phosphate and dialkyl chlorothiophosphate. Moreover, some diethyl 2-[5-(trisubstitutedsiIyl)-2-thienyl] ethyl thiophosphates are reported.     

Catalytic hydrophosphorylation of dialkyl 2-allylmalonates

The reaction of dialkyl hydrogen phosphites and diphenylphosphine oxide with dialkyl 2-allylmalonates in the presence of [Pd(Ph₃P)₄] is studied. The addition of the hydrophosphoryl compounds to the multiple bond is established to proceed by the Markovnikov rule. The reaction is accompanied by the side process of malonate dealkoxycarbonylation whose contribution to the main process depends on the nature of the reagents.     

Microwave‐assisted phospha‐michael addition of dialkyl phosphites,a phenyl‐H‐phosphinate,and diphenylphosphine oxide to maleic derivatives

A series of new >P(O)‐substituted succinic derivatives was synthesized by the microwave‐assisted phospha‐Michael addition of dialkyl phosphites, ethyl phenyl‐H‐phosphinate, and diphenylphosphine oxide to N‐phenyl and N‐methyl maleimide, as well as to maleic acid anhydride. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:235–240, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21007     

ESR study of the radicals obtained from adducts of dialkyl itaconates with bromotrichloromethane

Three kinds of bromides were prepared from the reaction of dialkyl itaconates with bromotrichloromethane as precursors of analogous radicals for the propagating radicals of some dialkyl itaconates, i.e., the methyl, deuterated methyl, and adamantyl ester derivatives. The radicals were generated by photoirradiation of a toluene solution of the bromides in the presence of hexabutylditin at −60 to 60°C, and ESR spectra were recorded. Hyperfine splitting and the temperature dependence of the linewidth were determined. The β-deuterated radicals were also characterized to determine a coupling to β-hydrogens. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1969–1978, 1999     

Synthesis of α‐hydroxy‐methylenebisphos‐phonates by the microwave‐assisted reaction of α‐oxophosphonates and dialkyl phosphites under solventless conditions

The synthesis of hydroxy‐methylenebisphosphonates ( 2a–c ) by the addition of dialkyl phosphite to the carbonyl group of the corresponding α‐oxophosphonate ( 1a–c ) was studied under microwave irradiation (MW) and solventless conditions in the presence of dialkylamine as the catalyst. After optimization, products 2a and 2b were obtained selectively and in good yields avoiding the formation of the phosphonate‐phosphate by‐product ( 3a and 3b ) that is the result of a rearrangement. The MW‐assisted synthesis of hydroxybisphosphonates ( 2a and 2b ) offers complete conversions and a chemoselectivity of 100% as compared to the not so efficient thermal reaction. At the same time, the phenyl‐substituted methylenebisphosphonate 2c could be obtained in only 75% selectivity. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:350–354, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20558     

Reaction of γ-benzylideneaminopropanol with dialkyl phosphorochloridites

Reactions of dialkyl phosphorochloridites with 3-(N-benzylideneamino)propan-1-ol follow two pathways giving rise to linear dialkyl 1-(3-chloropropylamino)benzylphosphonates and diastereomeric cyclic 2-alkoxy-2-oxo-3-phenyl-1,4,2-oxazaphosphepanes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1453–1455, June, 2005.     

Rationalization of the stereochemistry of an addition of dialkyl phosphites to certain chiral aldimines: The experimental and theoretical approach

The absolute configuration of an α‐P stereogenic center in two diastereomeric O,O‐dialkyl α‐aminophosphonates ( 3 ), arising from an induced 1,3‐asymmetric phosphite addition to the CN bond of furfural‐derived Schiff bases ( 1 ), was established from single product ¹H NMR data. Such spectra were interpreted with anisotropic shielding in relation to the AM1 and MNDO/d structures of 3 ; the former ones turned out to be closer to the obtained experimental results (¹H NMR spectra of 3 , crystallographic database study). Since favored 3‐21G geometries of starting imines 1 were modeled as well, it was inferred that a stereochemical outcome of this reaction is governed by Cram selectivity. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:120–125, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10005     

Synthesis of dialkyl(1-allyl-3-arylprop-2-yn-1-yl)-and dialkyl(1-allyl-3-alkenylprop-2-yn-1-yl)amines by the stevens rearrangement

The Stevens rearrangement of dialkyl(allyl)(3-arylprop-2-yn-1-yl)-and dialkyl(allyl)(3-alkenyl-prop-2-yn-1-yl)ammonium bromides gave dialkyl(1-allyl-3-arylprop-2-yn-1-yl)-and dialkyl(1-allyl-3-alkenyl-prop-2-yn-1-yl)amines. Here, the allyl group acts as migrating group, and 3-aryl-or 3-alkenylprop-2-yn-1-yl, as receiving one. The yields of the Stevens rearrangement products fall down as the alkyl chain becomes longer, as well as with introduction of a methyl group into the meta or para position of the aromatic ring.