Asymmetric alkylation of N‐acylisoindolin‐1‐ones via α‐bromoimides: A novel route to 1‐substituted isoindolines

Key intermediate in the synthesis of the title compounds 9a‐c and 10a‐c was the chiral α‐bromoimide 1 which has been prepared by radical bromination of the corresponding N‐acylisoindolin‐1‐one 13. 1 was alkylated with silyl enol ethers under Lewis acid catalysis using α‐amidoalkylation methodology. N,N‐diacyliminium ion 14 is presumably the intermediate in this reaction. Further transformations of the alkylated compounds yielded 1‐substituted isoindolines as target compounds.     

Development of an Amperometric Biosensor for β‐N‐Oxalyl‐L‐α,β‐Diaminopropionic Acid (β‐ODAP)

An amperometric method for the determination of the neurotoxic amino acid β‐N‐oxalyl‐L ‐α,β‐diaminopropionic acid (β‐ODAP) using a screen printed carbon electrode (SPCE) is reported. The electrode material was bulk‐modified with manganese dioxide and used as a detector in flow injection analysis (FIA). The enzyme glutamate oxidase (GlOx) was immobilized in a Nafion‐film on the electrode surface. The performance of the biosensor was optimized using glutamate as an analyte. Optimum parameters were found as: operational potential 440 mV (vs. Ag/AgCl), flow rate 0.2 mL min^?1, and carrier composition 0.1 mol L^?1 phosphate buffer (pH 7.75). The same conditions were used for the determination of β‐ODAP. The signal was linear within the concentration range 53–855 μmol L^?1 glutamate and 195–1950 μmol L^?1 β‐ODAP. Detection limits (as 3σ value) for both analytes were 9.12 and 111.0 μmol L^?1, respectively, with corresponding relative standard deviations of 3.3 and 4.5%. The biosensor retained more than 73% of its activity after 40 days of on‐line use.     

A novel synthetic route to N‐protected 1‐aminoalkylphosphonates

Dialkyl and dithioalkyl N‐protected 1‐aminoalkylphosphonates were synthesized using reactions of benzyl carbamate, aldehydes and chlorophosphites, or dithioalkyl chlorophosphite, respectively. This represents a novel synthetic method for 1‐aminoalkylphosphonates. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:417–421, 2000     

A New Route to N‐Aryl 2‐Alkenamides,N‐Allyl N‐Aryl 2‐Alkenamides,and N‐Aryl α,β‐Unsaturated γ‐Lactams from N‐Aryl 3‐(Phenylsulfonyl)propanamides

A series of N‐aryl 2‐alkenamides were produced efficiently by treating N‐aryl 3‐(phenylsulfonyl)‐propanamides with potassium tert‐butoxide in THF at 0°C. With out isolation, it was further treated with an additional equivalent of potassium tert‐butoxide and allyl bromide to give N‐allyl N‐aryl 2‐alkenamides in one pot in good yields. Followed by a ring‐closing metathesis reaction, these N‐allyl N‐aryl 2‐alkenamides were respectively converted into corresponding N‐aryl α,β‐unsaturated γ‐lactams in moderate yields.     

Synthesis and antioxidant activities of novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters and ketimines

Novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters 2a–g ( 3a–g ) and N‐aryl (and N‐alkyl) ketimines 2h–j ( 3h–j ) were synthesized in high yields (80–99%) from their corresponding γ‐ and δ‐keto esters and ketones in this study. The structures of the synthesized compounds were clarified by Fourier transform infrared (FT‐IR), NMR (¹H and ¹³C), mass spectrometry, and elemental analyses. Isomerizations [E/Z] were also determined by their ¹H NMR spectra. The free‐radical scavenging activity of imines was evaluated using the 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) method. The relationships between the structure and antioxidant activity of these compounds are discussed. Among these compounds, 2a–c (at the concentration 1000 μg/mL) exhibit high antioxidant activity similar to those of the standards (butylated hydroxyanisole [ BHA], butylated hydroxytoluene [ BHT], and ascorbic acid).     

Elementary reaction analysis of the radical polymerization of α‐ethyl β‐N‐(α′‐methylbenzyl)itaconamates carrying (RS)‐ and (S)‐α‐methylbenzylaminocarbonyl groups

The polymerizations of α‐ethyl β‐N‐(α′‐methylbenzyl)itaconamates carrying (RS)‐ and (S)‐α‐methylbenzylaminocarbonyl groups (RS‐EMBI and S‐EMBI) with dimethyl 2,2′‐azobisisobutyrate (MAIB) were studied in methanol (MeOH) and in benzene kinetically and with electron spin resonance (ESR) spectroscopy. The initial polymerization rate (R_p) at 60 °C was given by R_p = k[MAIB]^{0.58 ± 0.05}[RS‐EMBI]^{2.4 ± 0.l} and R_p = k[MAIB]^{0.61 ± 0.05}[S‐EMBI]^{2.3 ± 0.l} in MeOH and R_p = k[MAIB]^{0.54 ± 0.05}[RS‐EMBI]^{1.7 ± 0.l} in benzene. The rate constants of initiation (k_df), propagation (k_p), and termination (k_t) as elementary reactions were estimated by ESR, where k_d is the rate constant of MAIB decomposition and f is the initiator efficiency. The k_p values of RS‐EMBI (0.50–1.27 L/mol s) and S‐EMBI (0.42–1.32 L/mol s) in MeOH increased with increasing monomer concentrations, whereas the k_t values (0.20?7.78 × 10⁵ L/mol s for RS‐EMBI and 0.18?6.27 × 10⁵ L/mol s for S‐EMBI) decreased with increasing monomer concentrations. Such relations of R_p with k_p and k_t were responsible for the unusually high dependence of R_p on the monomer concentration. The activation energies of the elementary reactions were also determined from the values of k_df, k_p, and k_t at different temperatures. R_p and k_p of RS‐EMBI and S‐EMBI in benzene were considerably higher than those in MeOH. R_p of RS‐EMBI was somewhat higher than that of S‐EMBI in both MeOH and benzene. Such effects of the kinds of solvents and monomers on R_p were explicable in terms of the different monomer associations, as analyzed by ¹H NMR. The copolymerization of RS‐EMBI with styrene was examined at 60 °C in benzene. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1819–1830, 2003     

An α‐hydrazinoalkylphosphonate as building block for novel N‐phosphonoalkylheterocycles

α‐Hydrazinoalkylphosphonate 3 is a useful building block for the syntheses of novel N‐phosphonoalkylheterocycles. N‐phosphonoalkylpyrazoles 8 and 9 were prepared by the cyclization reaction of 3 with multifunctioned ethenes 5 and 6 in ethanol under reflux. N‐Phosphonoalkyltriazole 10 was synthesized from 3 with N‐dimethylthiomethylene benzoyl amide 4 in ethanol under reflux. The structures were confirmed by IR, ¹H NMR, mass spectroscopy, and elemental analysis. At the same time, the preparation of 4 was investigated. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:384–386, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10173     

A novel stereoselective synthesis of (Z)‐α‐arylsulfanyl‐α,β‐unsaturated ketones via Stille coupling of (E)‐α‐arylsulfanylvinylstannanes with acyl halides

(E)‐α‐Arylsulfanylvinylstannanes react with acyl halides in the presence of a catalytic amount of Pd(PPh₃)₄ and CuI cocatalyst to give stereoselectively the corresponding (Z)‐α‐arylsulfanyl‐α,β‐unsaturated ketones in good yields. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:218–223, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20536     

Lanthanum immobilized on chitosan: a highly efficient heterogeneous catalyst for facile synthesis of novel (α,β‐unsaturated) β‐aminoketones

A new heterogeneous catalyst, lanthanum immobilized on chitosan, was synthesized and used for the aza‐Michael reaction of β‐enaminone under microwave irradiation. The characteristic structural features of the catalyst were determined using Fourier transform infrared spectroscopy, powder X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, transmission and scanning electron microscopies and inductively coupled plasma atomic emission spectroscopy. The stability of the catalyst was evaluated using thermogravimetric analysis. The use of recyclable catalyst and glycerol as solvent makes this procedure environmentally benign and economically viable. Copyright © 2016 John Wiley & Sons, Ltd.     

An efficient synthesis of telechelic poly (N‐isopropylacrylamides) and its application to the preparation of α,ω‐dicholesteryl and α,ω‐dipyrenyl polymers

Poly(N‐isopropylacrylamide)s (PNIPAMs) with cholesteryl or pyrenyl moieties at each chain end (CH‐PNIPAMs or Py‐PNIPAMs) were prepared via end‐group modification of α,ω‐dimercapto poly(N‐isopropylacrylamides), ranging in molecular weight from ～ 7000 to 45,000 g mol^?1 with a polydispersity index of 1.10 or lower. The telechelic thiol functionalized PNIPAMs were obtained by aminolysis of α,ω‐di(isobutylthiocarbonylthio)‐poly(N‐isopropylacrylamide)s (iBu‐PNIPAMs) obtained by reversible addition‐fragmentation chain transfer (RAFT) polymerization of N‐isopropylacrylamide in the presence of the difunctional chain transfer agent, diethylene glycol di(2‐(1‐isobutyl)sulfanylthiocarbonylsulfanyl‐2‐methyl propionate) (DEGDIM). The self‐assembly of the polymers in water was assessed by fluorescence spectroscopy, using the intrinsic emission of Py‐PNIPAM or the emission of pyrene added as a probe in aqueous solutions of CH‐PNIPAM. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 314–326, 2008     

α-D-Glycosyl-Substituted α,α-D-Trehaloses with (1 → 4)-Linkage: Syntheses and NMR Investigations

Two symmetrical trehalose glycosyl ‘acceptors’ 4 and 6 were prepared and three of the unsymmetrical type, 8 , 10 , and 11 . Glucosylation of symmetrical ‘acceptor’ 4 gave a higher yield of trisaccharide (44%) than protect ve-group manipulation, namely via selective debenzylidenation 2 → 9 or monoacetylation 2 → 5 which proceeded in moderate yields (33–34%). A comparison of catalysts in the cis-glucosylation of trehalose ‘acceptor’ 10 with tetra-O-benzyl-β-D -glucopyranosyl fluoride 13 profiled triflic anhydride ((Tf)₂O) as a new reactive promoter yielding 92% of trisaccharide 14 , deblocking gave the target saccharide α-D -glucopyranosyI-( 1 → 4 )-α,α-D -trehalose. ¹H-NMR spectra of most compounds were analyzed extensively. The use of the ID TOCSY technique is advocated for its time efficiency, if needed supplemented by ROESY experiments.     

Use of Ph3P=N‐Li: Synthesis of α,β‐unsaturated nitriles from α,β‐unsaturated esters via the formation of N‐(α,β‐unsaturated acyl) phosphinimines

The reaction of Ph₃P=NLi with various α,β‐unsaturated esters gives access to new N‐(α,β‐unsaturated acyl) phosphinimines, which can undergo intramolecular aza‐Wittig reactions (at 65–110°C) to afford the corresponding nitriles. The structures of all new compounds were established by elementary analyses, IR, ¹H‐, ¹³C‐, and ³¹P‐NMR spectroscopy. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 49–54, 1999     

Palladium(II) acetate catalyzed efficient synthesis of N‐aryl‐α,β‐unsaturated amides via carbonylative addition of aniline derivatives to aromatic alkynes

A series of new N‐aryl‐α,β‐disubstituted amides (gem or E1; trans or E2) were synthesized in good yields by carbonylative addition of aniline derivatives 1a–f to aromatic alkynes 2a,b catalyzed by Pd(OAc)₂ and 1,3‐bis(diphenylphosphino)propane. The catalytic synthesis of tertiary α,β‐unsaturated amides was also successfully achieved. Traces of products were observed in the absence of p‐toluenesulfonic acid used as an additive. The reaction is sensitive to the type of phosphine ligand and solvent. Copyright © 2002 John Wiley & Sons, Ltd.     

Facile regiospecific syntheses of N‐α,N‐1(τ)‐dialkyl‐l‐histidines

Two diverse methodologies describe the first synthesis of suitably protected N‐α,N‐1(τ)‐dialkyl‐Lhistidine derivatives. Synthesis of suitably protected N‐α,N‐1(τ)‐dialkyl‐L‐histidines 7‐9 containing different alkyl groups at the N‐α and N‐1(τ) positions was achieved in four steps starting from L‐histidine methyl ester. Whereas, in the one‐step alternate route N‐α‐Boc‐L‐histidine methyl ester upon direct and simultaneous N‐α and N‐1(τ) alkylation with various alkyl halides in the presence of sodium hydride in DMF easily afforded N‐α,N‐1(τ)‐dialkyl‐L‐histidines 14 containing identical alkyl group at the N‐α and N‐1(τ) positions in high yields. Both procedures allowed facile entry to methyl and other higher alkyl groups at the N‐α‐position of the histidine ring     

[2,6‐Bis(5‐methyl‐2‐pyridyl)phenyl‐κ3N,C1,N′]chloridoplatinum(II)

In the title compound, [Pt(C₁₈H₁₅N₂)Cl], the Pt^II centre adopts a distorted square‐planar coordination geometry due to the pincer‐type monoanionic N–C–N tridentate ligand. The planar complexes stack viaπ–π interactions to form two‐dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer‐type N–C–N complexes, which exhibit a one‐dimensional columnar stacking.     

(η3‐Allyl‐2κ3C)(chloro‐1κCl)(μ‐N,N′‐diethyldithioxamidato‐1:2κ4S,S′:N,N′)[diphenyl(2‐pyridyl)phosphine‐1κP]palladium(II)platinum(II) chloroform solvate

The title compound, [PdPtCl(C₃H₅)(C₆H₁₀N₂S₂)(C₁₇H₁₄NP)]·CHCl₃, was obtained by deprotonation of the initial platinum(II) complex of the di­thio­xamide and subsequent reaction with [Pd(η³‐C₃H₅)(μ‐Cl)]₂. Both metal atoms exhibit a square‐planar coordination geometry, with the two planes forming a dihedral angle of 21.7 (2)°. The di­thio­xamide bis‐chelating bridge is flat.     

Synthesis of optically active N‐protected α‐aminoketones and α‐amino alcohols

A series of optically active N‐protected α‐aminoketones were synthesized via the Grignard reaction of the Weinreb amides of the N‐tert‐butoxycarbonyl amino acids. Reduction of the α‐aminoketones by sodium borohydride resulted in the corresponding 1,2‐amino alcohols. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:603–606, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10195