Silica gel and polystyrene supported aluminum chloride as heterogeneous catalysts for the preparation of α‐aminophosphonates

Silica gel supported aluminum chloride (SiO₂‐AlCl₃) and cross‐linked polystyrene‐supported aluminum chloride (PS‐AlCl₃) are environment‐ friendly heterogeneous catalysts for the condensation of amines and aldehydes with diethyl phosphite to afford α‐aminophosphonates. These solid acid catalysts are stable (as bench top catalysts) and can be easily recovered and reused without appreciable change in their efficiency. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:418–422, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20629     

Triterpenoids from Rhaponticum Uniflorum

The isolation and identification of twenty‐one components (including four new triterpenoid saponins and one new triterpenoid acid) from the root of Rhaponticum uniflorum (L.) DC. (Compositae) are described. Their structures were determined on the basis of spectral analysis and chemical trans formation. The new compounds were identified as 3‐O‐α‐L‐arabinopyranosyl‐urs‐12,18(19)‐dien‐28‐oic acid β‐D‐glucopyranosyl ester, 3β‐ hydroxyurs‐12,18(19)‐dien‐28‐oic acid β‐D‐glucopyranosyl ester, 3β‐hydroxyurs‐12,19(29)‐dien‐28‐oic acid β‐D‐glucopyranosylester, 3‐O‐α‐L‐arabinopyranosyl‐urs‐9(11),12‐dien‐28‐oic acid β‐D‐glucopyranosyl ester and 2 α,3 α, 19α,25‐tetrahydroxyurs‐12‐en‐23,28‐dioic acid.     

The Kabachnik–Fields and Pudovik Reactions on the Basis of E,Z‐Citral and Its Imines and (R,S)‐Citronellal

The Kabachnik–Fields reaction of E,Z‐citral with diethyl phosphite in the presence of isobutylamine has been found to form α‐aminophosphonates. The Pudovik reactions of diethyl phosphite with prenyl imines prepared on the basis of E,Z‐citral with isobutylamine also allowed us to obtain the same α‐aminophosphonates. We have managed to synthesize α‐aminophosphonates by the reaction of O,O‐dialkyl trimethylsilyl phosphites with prenyl imines in the presence of water or diethylamine. α‐Aminophosphonates were also synthesized by the reaction of diethyl phosphite with (R,S)‐citronellal in the presence of alkylamines. α‐Aminophosphonates obtained showed bacteriostatic activity against Staphylococcus aureus and Bacillus cereus. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:36–42, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21060     

Synthesis and structure of new types of organogermanium compounds containing α‐amino acid or α‐aminophosphonic acid moieties

A series of germasesquioxides and germatranes containing α‐amino acid or α‐aminophosphonic acid moieties was synthesized by the reaction of β‐trichlorogermylpropionyl chloride with α‐amino acid esters or α‐aminophosphonates. The structures of all products were confirmed by ¹H NMR, ³¹P NMR, and IR spectra, and elemental analyses. The intramolecular monocyclic penta‐coordinated structure of the trichlorogermyl intermediate was determined by X‐ray diffraction. The X‐ray analyses showed that the geometry about the germanium atom was a slightly distorted trigonal bipyramid, and a coordinate covalent bond exists between the oxygen and the germanium atoms. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 73–78, 1999     

An Eco‐friendly Three Component Manifold for the Synthesis of α‐Aminophosphonates under Catalyst and Solvent‐free Conditions,X‐ray Characterization and Their Evaluation as Anticancer Agents

A series of α‐aminophosphonates were synthesized through one‐pot condensation of aryl aldehydes, aryl amines and diethyl phosphite in the absence of any catalyst and organic solvents. All the synthesized α‐aminophosphonates were characterized by spectral and elemental analysis and in the case of compound 4j by X‐ray crystallography. Some of these new α‐aminophosphonate derivatives were found to have cytotoxic activity on the cancer cell line DU145 in vitro by the MTT method.     

Synthesis and antitumor activity of novel α‐aminophosphonates from diterpenic dehydroabietylamine

A series of novel α‐aminophosphonates were synthesized from diterpenic dehydroabietylamine, and their structures were characterized by IR, ¹H NMR, and ³¹P NMR spectroscopy. Their antitumor activities against SMMC7721 liver cancer cells were evaluated by the MTT method. Compounds 4 and 6 exhibited higher activities even at very low concentrations, and the inhibition ratios reached 75% and 79% at 0.1 µM, respectively. The inhibition ratio of compound 9 reached 99% after 72‐h incubation. α‐Aminophosphonates with a fluorine atom and a nitro group fused to the benzene ring exhibited higher activities. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:512–516, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20471     

Polycondensation of trialkoxysilane monomers accelerated by neighboring group participation of urea moiety

(Phenylaminomethyl)trimethoxysilane (= α‐amino‐siloxane) was treated with various isocyanates to obtain a series of siloxanes having urea moieties (= α‐urea‐siloxanes). Their hydrolysis‐condensation reactions were monitored with ²⁹Si NMR, to reveal that they exhibited much higher reactivity than a urea‐siloxane derived from [3‐(phenylamino)propyl]trimethoxysilane (= γ‐amino‐siloxane). When compared with the derivation of the γ‐amino‐siloxane into the corresponding γ‐urea‐siloxane, those of the α‐amino‐siloxane into the corresponding α‐urea‐siloxanes were accompanied by much larger shifts of the ²⁹Si NMR signal toward a higher magnetic field. These results suggested that the location of the urea moiety in the α‐urea‐siloxanes was favorable to its intramolecular coordination to the silicon atom to exhibit its “neighboring group participation” that promoted transformation of the tetravalent silicon center into the pentavalent one, which is more electrophilic to make the siloxanes more susceptive to undergo the hydrolysis and condensation reactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6654–6659, 2008     

Synthesis of α‐aminophosphonates from α‐hydroxyphosphonates; a theoretical study

Two types of reactions, namely the Pudovik reaction of benzaldehyde and acetophenone with diethyl phosphite as well as the substitution of the α‐hydroxyphosphonates so‐formed by primary amines to afford α‐aminophosphonates, were evaluated by quantum chemical calculations at the B3LYP/6‐31G(d,p) level. An unexpected neighboring group effect was found to enhance the substitution. A series of new α‐aminophosphonates was synthesized by the microwave‐assisted substitution of α‐hydroxyphosphonates by alkylamines.     

Synthesis of O,O‐Diphenyl N‐trichlorogermanylpropiono‐α‐aminophosphonates

A variety of novel O,O‐Diphenyl N‐(trichlorogermanyl)propiono‐α‐aminophosphonates were synthesized by the reaction of β‐(trichlorogermanyl) propionyl chloride with diphenyl α‐aminophosphonates in the presence of triethylamine. The structures of all of the products were confirmed by ¹H‐NMR spectroscopy, elemental analyses, and IR spectroscopy. Data of ¹H‐NMR and IR spectroscopic determinations indicated the title compounds to be pentacoordinated organogermanium compounds. The results of bioassay showed that some of the title compounds possess potential anticancer activity. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 5–8, 1999     

Chemical Constituents from the Roots of Patrinia Rupestris

Phytochemical investigation of the roots of Patrinia rupestris afforded a new triterpenoid patrirupin A ( 1 ) and a new iridoid patrirupin B ( 2 ), as well as three known triterpenoids: 3‐oxo‐olean‐12‐en‐28‐oic acid ( 3 ), ursolic acid ( 4 ), α‐amyrin ( 5 ), three known iridoids: isovaltratum ( 6 ), 11‐ethoxyviburtinal ( 7 ), homobaldrinal ( 8 ), five known steroids: ergosterol ( 9 ), ergost‐6,22‐diene‐3β,5α,8α‐triol ( 10 ), 6‐hydroxenone ( 11 ), β‐sitosterol ( 12 ), daucosterol ( 13 ), and two known flavones: 1‐hydroxy‐5‐methoxy xanthen‐9‐one ( 14 ), 3′,4′,5,7‐tetrahydroxyflavanone ( 15 ). The new compounds were characterized by means of spectroscopic methods including UV, IR, 1D, 2D NMR and HRESIMS, and the known ones were established on the basis of comparing their NMR data with those of the corresponding compounds in the literature.     

SO3H‐functionalized ionic liquids catalyzed the synthesis of α‐aminophosphonates in aqueous media

SO₃H‐functionalized halogen‐free ionic liquids were prepared and used as efficient and recyclable catalysts for the synthesis of α‐aminophosphonates at room temperature via the one‐pot three‐component condensation reaction in aqueous media with good yields of 80–96%. The postprocessing was simple, and the catalysts could be reused at least six times without noticeably decreasing the catalytic activity. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:546–550, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20644     

α‐Aminophosphonates and α‐Aminophosphine Oxides by the Microwave‐Assisted Kabachnik–Fields Reactions of 3‐Amino‐6‐methyl‐2 H‐pyran‐2‐ones

The microwave‐assisted Kabachnik–Fields reaction of a series of 3‐amino‐6‐methyl‐2H‐pyran‐2‐ones, paraformaldehyde, and dialkyl phosphites or diphenylphosphine oxide led to α‐aminophosphonates or α‐aminophosphine oxides, respectively. The α‑aminophosphonates were obtained under solvent‐free conditions, whereas the α‑aminophosphine oxides in acetonitrile. The novel products were characterized by NMR and mass spectral data. © 2013 Wiley Periodicals, Inc. Heteroatom Chem 24:221–225, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21086     

P‐Dodecylbenzenesulfonic Acid: A Highly Efficient Catalyst for One‐Pot Synthesis of α‐Aminophosphonates in Aqueous Media

A highly efficient one‐pot three‐component reaction of aldehydes or ketones, amines, and trimethyl or triethyl phosphite catalyzed by p‐dodecylbenzensulfonic acid is developed for the synthesis of α‐aminophosphonates at room temperature in water. © 2013 Wiley Periodicals, Inc. Heteroatom Chem 24:174–178, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21079     

Structure elucidation and total assignment of 1H and 13C NMR data for a new bisdesmoside saponin from Cordia piauhiensis

Extensive 1D (¹H NMR, HBBD‐¹³C NMR, DEPT‐¹³C NMR) and 2D (COSY, TOCSY, NOESY, HMQC and HMBC) NMR analysis was used to characterize the structure of a new bisdesmoside saponin isolated from the methanol extract of stems of Cordia piauhiensis Fresen as 3β‐O‐[α‐L ‐rhamnopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl]ursolic acid 28‐O‐[β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranosyl] ester. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and evaluation of new phosphonic acid‐functionalized acrylamides with potential biomedical applications

Phosphorus‐containing acidic monomers are able to interact with the inorganic phase of mineralized tissues such as enamel, dentin, and bone. From this perspective, three phosphonic acid‐containing acrylamide monomers with different lengths of alkyl chains were synthesized to be used for both self‐etching dental adhesives and mineralized hydrogel scaffolds. Monomers were synthesized by the reaction of α‐aminophosphonates (diethyl aminomethylphosphonate, diethyl 2‐aminobutan‐2‐ylphosphonate, and diethyl 2‐aminooctan‐2‐ylphosphonate) with acryloyl chloride followed by the hydrolysis of phosphonate groups by using trimethylsilyl bromide. The properties such as pH in the range of mild self‐etching adhesives, hydrolytic stability, high rate of copolymerizations with 2‐hydroxyethyl methacrylate (HEMA) and HEMA/glycerol dimethacrylate, giving high‐molecular‐weight polymers on thermal polymerization, and strong decalcification ability of hydroxyapatite make these monomers good candidates for self‐etching adhesives, although no appreciable effect of the number and size of the α‐substituents was observed. Hydrogel scaffolds containing phosphonic acid groups were fabricated, characterized, and mineralized. Altogether, the results suggest that these phosphonic acid‐containing monomers have suitable properties to be used in fabrication of biomaterials for both dental and bone tissue engineering applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2755–2767     

Zn(OAc)2•2H2O‐catalyzed synthesis of α‐aminophosphonates under neat reaction

A series of novel α‐aminophosphonates have been prepared by one‐pot three‐component condensation in the presence of a zinc acetate (Zn(OAc)_2•2H₂O) catalyst at 50°C under solvent‐free conditions with excellent yields. The major advantages of the present method are high yields, a short reaction time, and solvent‐free reaction conditions. Their antimicrobial activity was evaluated, and some of them showed significant activity. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:160–165, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20765     

New One‐Pot Three‐Component Synthesis of N‐Phenyl α‐Aminophosphonates

New one‐pot three‐component reactions employing aldehydes, triphenylphosphite, and N‐[(phenylamino)carbonyl]glycine ethyl ester in refluxing xylene readily afford N‐phenyl α‐aminophosphonates in low to moderate yields.     

Theoretical study of structural features of endo,exo double bonds and side chain in 14α‐demethylation of lanosterol

The 14α‐demethylation of biosynthetic reactions is carried out exclusively by lanosta‐8,24‐dien‐3β‐ol (lanosterol). Theoretical calculations were done to determine the importance of this structure with the Hartree–Fock scheme. It was modeled on structures similar to lanosterol with variations on the endo between C8? C9 (lanosta‐7,24‐dien‐3β‐ol and lanosta‐6,24‐dien‐3β‐ol) as compared with the exo between C24? C25 (Lanosta‐8‐en‐3β‐ol) and the size of the side chain (27‐norlanosta‐8‐en‐3β‐ol, 26,27‐dinorlanosta‐8‐en‐3β‐ol, 25,26,27‐trinorlanosta‐8‐en‐3β‐ol, 24,25,26,27‐tetranorlanosta‐8‐en‐3β‐ol, 23,24,25,26,27‐pentanorlanosta‐8‐en‐3β‐ol, 22,23,24,25,26,27‐hexanorlanosta‐8‐en‐3β‐ol). Energetic, electronic, and orbital evidence was found. The theoretical data were analyzed and were found to be important for the 14α‐demethylation, the presence of HOMO on the region C8? C9 and C14? C14¹, a negative charge on the outgoing methyl C14¹. This atomic charge varies with the size of the side chain, and with the modification of the endo and exo double bonds. The conformation of the structure of the steroid is also related to its reactivity. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Ruthenium‐catalyzed carbonylative cycloaddition reactions involving carbonyl and imino groups as assembling units

This paper describes carbonylative cycloaddition reactions catalyzed by Ru₃(CO)₁₂. Ru₃(CO)₁₂ was found to catalyze an intramolecular Pauson–Khand‐type reaction. Carbonylative cycloaddition reactions involving a carbonyl group in aldehydes, ketones, and esters as a two‐atom assembling unit were also achieved in the presence of Ru₃(CO)₁₂ as the catalyst. The reaction of 5‐hexyn‐1‐al and 6‐heptyn‐1‐al derivatives with CO in the presence of Ru₃(CO)₁₂ resulted in cyclocarbonylation from which bicyclic α, β‐unsaturated lactones were obtained. Intermolecular [2 + 2 + 1] carbonylative cycloaddition of alkenes, ketones, and CO was also catalyzed by Ru₃(CO)₁₂ as the catalyst to give saturated γ‐lactone derivatives. Simple ketones were not applicable, but ketones having a C?O or C?N group at the α‐position served as a good substrate. These reactions could be extended to carbonylative cycloaddition of the corresponding imines leading to γ‐butyrolactam derivatives. The [4 + 1] carbonylative addition of α,β‐unsaturated imines leading to unsaturated γ‐lactams was achieved with Ru₃(CO)₁₂. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 201–212; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20149