Facile syntheses of homothia‐ and homoazacalixarenes

Decahomotetrathiacalix[6]arenes were conveniently prepared from the 2:2 cyclization reactions of bis(chloromethyl)phenol‐formaldehyde trimers with 1,2‐ethanedithiol in high yields. In contrast, the simi lar reactions of the trimers with 1,3‐propanedithiol instead of 1,2‐ethanedithiol gave 1:1 macrocycles, hexahomodithiacalix[3]arenes, in good yields. Homoazacalixarenes were also prepared from the analogous reactions using piperazines. These macrocycles adopt a cone‐like form as a preferable conformation in solution.     

Catalytic Asymmetric Mannich Reaction with N‐Carbamoyl Imine Surrogates of Formaldehyde and Glyoxylate

N,O‐acetals (NOAcs) were developed as bench stable surrogates for N‐carbamoyl, (Boc, Cbz and Fmoc) formaldehyde and glyoxylate imines in asymmetric Mannich reactions. The NOAcs can be directly utilized in the chiral primary amine catalyzed Mannich reactions of both acyclic and cyclic β‐ketocarbonyls with high yields and excellent stereoselectivity. The current reaction offers a straightforward approach in the asymmetric synthesis of α‐ or β‐amino carbonyls bearing chiral quaternary centers in a practical and highly stereocontrolled manner.     

Tackling N‐Alkyl Imines with 3d Metal Catalysis: Highly Enantioselective Iron‐Catalyzed Synthesis of α‐Chiral Amines

A readily activated iron alkyl precatalyst effectively catalyzes the highly enantioselective hydroboration of N‐alkyl imines. Employing a chiral bis(oxazolinylmethylidene)isoindoline pincer ligand, the asymmetric reduction of various acyclic N‐alkyl imines provided the corresponding α‐chiral amines in excellent yields and with up to >99 % ee. The applicability of this base metal catalytic system was further demonstrated with the synthesis of the pharmaceuticals Fendiline and Tecalcet.     

Synthesis of a New Dicompartment Multifunctional Groups Ligand

Phenol‐based acyclic ligand 1,6‐bis(2‐chlorobenzyl)‐2,5‐bis(2‐hydroxy‐3‐formyl‐5‐methylbenzyl)‐2,5‐diazahexane, LH₂ and its dilithium form Li₂L possessing two dissimilar compartments having multifunctional groups were prepared through a Mannich reaction. To synthesize this ligand first, diamine compound 1,6‐bis(2‐chlorobenzyl)‐2,5‐diazahexane was prepared and then in a one‐step procedure an equivalent of diamine and two equivalents of 4‐methyl‐2‐formylphenol in the presence of an excess amount para‐formaldehyde were reacted. All characterization data for the new compounds including diimine, diamine, LH₂ and Li₂L are reported.     

One-step assembly of a chiral palladium bis(acyclic diaminocarbene) complex and its unexpected oxidation to a bis(amidine) complex

Addition of trans-N,N'-dimethyl-1,2-diaminocyclohexane to a palladium bis(arylisocyanide) complex leads to the one-step formation of the first chiral bis(acyclic diaminocarbene) complex, which is thermally stable under N(2) but undergoes slow oxidation to a bis(amidine) complex under air.     

Synthesis and Mechanism of a Main‐Chain Chiral Polymer Based on Asymmetric Cyclopolymerization

A systematic study of the asymmetric cyclocopolymerization of bis(4‐vinylbenzoate)s, derived from chiral diols, with styrene has been made from the viewpoint of synthesizing the main‐chain chiral polymer. On the basis of using over 30 chiral diols as templates, we summarize the relationship between the structure of the chiral template and the chiroptical properties of the template‐free polymer. For simple chiral diols, the chirality induction efficiency increased in the order 1,2‐diol < 1,4‐diol < 1,3‐diol. Chiral diols with two chiral centers exhibited higher chirality induction efficiency than those having one chiral center only. The chirality induction efficiency for cyclic 1,2‐diols increased with the ring size in the order 5‐ < 6‐ < 7‐ < 8‐membered rings, and that for acyclic 1,2‐diols increased with the bulkiness of the substituent at the chiral center. In addition, a chirality induction mechanism has been proposed on the basis of model radical cyclization experiments and computational studies. Chirality induction could be caused by the inhibition of the formation of one racemo unit among the four stereoisomers due to the strong dependence of the stereoselectivity in intermolecular additions on the absolute configuration of the cyclized radical. The mechanism was examined using the Lewis‐acid and monomer‐concentration effects.     

Enantiopurity analysis of new types of acyclic nucleoside phosphonates by capillary electrophoresis with cyclodextrins as chiral selectors

CE methods have been developed for the chiral analysis of new types of six acyclic nucleoside phosphonates, nucleotide analogs bearing [(3‐hydroxypropan‐2‐yl)‐1H‐1,2,3‐triazol‐4‐yl]phosphonic acid, 2‐[(diisopropoxyphosphonyl)methoxy]propanoic acid, or 2?(phosphonomethoxy)propanoic acid moieties attached to adenine, guanine, 2,6‐diaminopurine, uracil, and 5‐bromouracil nucleobases, using neutral and cationic cyclodextrins as chiral selectors. With the exception of the 5‐bromouracil‐derived acyclic nucleoside phosphonate with a 2‐(phosphonomethoxy)propanoic acid side chain, the R and S enantiomers of the other five acyclic nucleoside phosphonates were successfully separated with sufficient resolutions, 1.51–2.94, within a reasonable time, 13–28 min, by CE in alkaline BGEs (50 mM sodium tetraborate adjusted with NaOH to pH 9.60, 9.85, and 10.30, respectively) containing 20 mg/mL β‐cyclodextrin as the chiral selector. A baseline separation of the R and S enantiomers of the 5‐bromouracil‐derived acyclic nucleoside phosphonate with 2‐(phosphonomethoxy)propanoic acid side chain was achieved within a short time of 7 min by CE in an acidic BGE (20:40 mM Tris/phosphate, pH 2.20) using 60 mg/mL quaternary ammonium β‐cyclodextrin chiral selector. The developed methods were applied for the assessment of the enantiomeric purity of the above acyclic nucleoside phosphonates. The preparations of all these compounds were found to be synthesized in pure enantiomeric forms. Using UV absorption detection at 206 nm, their concentration detection limits were in the low micromolar range.     

Chiral stationary phases based on chitosan bis(4‐methylphenylcarbamate)‐(alkoxyformamide)

Highly N‐deacetylated chitosan was chosen as a natural chiral origin for the synthesis of the selectors of chiral stationary phases. Therefore, chitosan was firstly acylated by various alkyl chloroformates yielding chitosan alkoxyformamides, and then these resulting products were further derivatized with 4‐methylphenyl isocyanate to afford chitosan bis(4‐methylphenylcarbamate)‐(alkoxyformamide). A series of chiral stationary phases was prepared by coating these derivatives on 3‐aminopropyl silica gel. The content of the derivatives on the chiral stationary phases was nearly 20% by weight. The chiral stationary phases prepared from chitosan bis(4‐methylphenylcarbamate)‐(ethoxyformamide) and chitosan bis(4‐methylphenylcarbamate)‐(isopropoxyformamide) comparatively showed better enantioseparation capability than those prepared from chitosan bis(4‐methylphenylcarbamate)‐(n‐pentoxyformamide) and chitosan bis(4‐methylphenylcarbamate)‐(benzoxyformamide). The tolerance against organic solvents of the chiral stationary phase of chitosan bis(4‐methylphenylcarbamate)‐(ethoxyformamide) was investigated, and the results revealed that this phase can work in 100% ethyl acetate and 100% chloroform mobile phases. Because as‐synthesized chiral selectors did not dissolve in many common organic solvents, the corresponding chiral stationary phases can be utilized in a wider range of mobile phases in comparison with conventional coating type chiral stationary phases of cellulose and amylose derivatives.     

Synthesis of 3-substituted-2-benzothiazolinone, 2-benzoxazolinone and benzothiazoline-2-thione

The reaction of 2-benzothiazolinone, 2-benzoxazolinone or benzothiazoline-2-thione under basic conditions with various electrophiles afforded the titled compounds 1-13, 29-31 and 40-48. The 3-(substituted-aminomethyl)-2-benzothiazolinone and related compounds 14-25 were prepared by the reaction of 3-(hydroxymethyl)-2-benzothiazolinone or the appropriate 2-benzothiazolinone and formaldehyde with the appropriate amine or substituted aniline. The reaction of 9, 13 or 25 with methyl iodide afforded the quaternary ammonium iodides 26-28. The reaction of the appropriate potassium salts of various phenol with 3-(chloromethyl)-2-benzothiazolinone afforded the 3-(substituted-phenoxymethyl)-2-benzothiazolinone and related compounds 32-39. The ethyl or isopropylxanthates 49-54 were synthesized by the reaction of 3-(chloromethyl)-2-benzo-thiazolinone and appropriate compounds with potassium ethyl or isopropyl xanthate. The reaction of 3-(chloromethyl)-2-benzothiazolinone with sodium sulfide afforded the sulfide 55.     

Reactions of Bis(chloromethyl)phosphinic(-Phosphinothioic) Chlorides with Silylated Carbamates and Trimethylsilyl N-Trimethylsilylacetimidoate

Bis(chloromethyl)phosphinic chloride reacts with trimethylsilyl methylcarbamate in benzene in the presence of a base to give trimethylsilyl bis(chloromethyl)phosphinate. The same reaction performed without a solvent and in the absence of a base yields trimethylsilyl bis(chloromethyl)phosphinate and bis(chloromethyl)phosphinic anhydride. Reaction of bis(chloromethyl)phosphinic chloride with trimethylsilyl diethylcarbamate yields N,N-diethylbis(chloromethyl)phosphinic amide. The reaction of bis(chloromethyl)phosphinic (-phosphinothioic) chlorides with trimethylsilyl N-trimethylsilylacetimidoate was studied.     

Syntheses of chiral homoazacalix[4]arenes incorporating amino acid residues: molecular recognition for racemic quaternary ammonium ions

Chiral calixarene analogues incorporating amino acid residues into the macrocyclic rings were prepared from the cyclization reactions of bis(chloromethyl)phenol-formaldehyde tetramer with amino acid methyl ester in moderate yields. The macrocycles form a chiral concavity, which is induced by the chiral transmission from the point chirality of the amino acid residues to the phenol-formaldehyde tetramer unit. The macrocycles have the cavity pi-basic enough to include the quaternary ammonium ion due to the cation-pi interaction and can serve as a shift reagent for racemic ammonium ions during 1H NMR analysis.     

Phenolic resins bearing maleimide groups: Synthesis and characterization

Novel phenolic novolac resins, bearing maleimide groups and capable of undergoing curing principally through the addition polymerization of these groups, were synthesized by the polymerization of a mixture of phenol and N‐(4‐hydroxy phenyl)maleimide (HPM) with formaldehyde in the presence of an acid catalyst. The polymerization conditions were optimized to get gel‐free resins. The resins were characterized by chemical, spectral, and thermal analyses. Differential scanning calorimetry and dynamic mechanical analysis revealed an unexpected two‐stage curing for these systems. Although the cure at around 275°C was attributable to the addition polymerization reaction of the maleimide groups, the exotherm at around 150 to 170°C was ascribed to the condensation reaction of the methylol groups formed in minor quantities on the phenyl ring of HPM. Polymerization studies of non‐hydroxy‐functional N‐phenyl maleimides revealed that the phenyl groups of these molecules were activated toward an electrophilic substitution reaction by the protonated methylol intermediates formed by the acid‐catalyzed reaction of phenol and formaldehyde. On a comparative scale, HPM was less reactive than phenol toward formaldehyde. The presence of the phenolic group on N‐phenyl maleimide was not needed for its copolymerization with phenol and formaldehyde. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 641–652, 2000     

Synthesis of polymers bearing 1,3‐benzoxazine moiety in the side chains from poly(allylamine) and their crosslinking behaviors

A polymer bearing 1,3‐benzoxazine moiety in the side chain was synthesized successfully from poly(allylamine) based on a stepwise strategy consisted of three steps: (1) treatment of poly(allylamine) with salicylaldehyde to convert the amino group in the side chain into the corresponding o‐(iminomethyl)phenol moiety, (2) reduction of the o‐(iminomethyl)phenol to obtain the corresponding o‐(aminomethyl)phenol moiety, and (3) formation of 1,3‐benzoxazine moiety by the reaction of the o‐(aminomethyl)phenol with formaldehyde. The content ratio of benzoxazine moieties and o‐(aminomethyl)phenol moieties in the polymer were tunable by varying amount of formaldehyde. The presence of o‐(aminomethyl)phenol moieties exhibited a significant promoting effect on the crosslinking reaction. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Ionic organic/inorganic materials. III. Stimuli responsive hybrid hydrogels based on oligo(N,N‐dimethylaminoethylmethacrylate) and chloroalkyl‐functionalized siloxanes

Ionic organic/siloxane networks containing quaternary ammonium salt (QAS) sequences in the cross‐linking bridges were obtained by the Menshutkin reaction of oligo(N,N‐dimethylaminoethylmethacrylate) (ODMAEM) with a telechelic chloroalkylated siloxane (CAS), such as 1,3‐bis‐(chloromethyl)‐1,1,3,3‐tetramethyldisiloxane, 1,3‐bis‐(chloropropyl)‐1,1,3,3‐tetramethyldisiloxane, and α,ω‐bis(chloromethyl) oligodimethylsiloxane. The resulted structures were investigated by Fourier transform infrared spectroscopy emphasizing the presence of both organic and siloxane moieties. The thermogravimetric analysis under inert atmosphere of the networks, besides the thermal stability, gave also information on the composition of hybrid hydrogels. The morphology of the lyophilized networks was evidenced by environmental scanning electron microscopy, as a function of CAS structure and CAS: ODMAEM feed molar ratio. The swelling response of the ionic networks in water as a function of pH and counterion nature and concentration as well as the water vapors sorption capacity in dynamic regime were evaluated. The properties of the ionic hybrid hydrogels were correlated with the reactants feed molar ratio and concentration of the reaction mixture, CAS type, and the presence of a catalyst. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

含苯并15-冠-5的酚醛型和缩醛型聚合物冠醚的合成及其络合与催化性能

合成了两种新聚合物冠醚,研究了它们对钠、钾离子络合容量和催化性能.     

A study on the kinetics of condensation reaction of phenol‐modified cardanol–formaldehyde resin

Phenol‐modified cardanol–formaldehyde novolac resins have been synthesized using equal proportions of phenol and cardanol. To this mixture of phenol and cardanol, 0.6 and 0.8 mol of formaldehyde were added separately, under acidic conditions, at five different temperatures ranging between 80 and 120°C with an interval of 10°C. This was carried out for a maximum period of 6 h. The free formaldehyde and free phenol contents were determined at regular time intervals to check the completion of the reaction. The synthesized novolacs have been studied by infrared spectroscopic analysis (FT‐IR). The reaction between cardanol, phenol, and formaldehyde was found to follow a second‐order rate kinetics. The overall rate constant (k) increased with the increase of temperature. Based on the value of rate constants, various other parameters such as activation energy (E_a), change in enthalpy (Δ H) and entropy (Δ S), and free energy change (Δ G) of the reaction were also evaluated. It was found that the condensation reaction of phenol and cardanol with formaldehyde was nonspontaneous and irreversible. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 380–389, 2010     

Reactivity of Amphiphilic Calix[4]resorcinolarenes and Phenols in the Reverse Micellar System Sodium Bis(2-ethylhexyl) Sulfosuccinate-Decane-Water

The mechanism of reaction of calix[4]resorcinolarene, aminomethylated calix[4]resorcinolarene, and 2-(dimethylaminomethyl)-4-isononylphenol with ethyl 4-nitrophenyl (chloromethyl)phosphonate in the reverse micellar system anionic surfactant-sodium bis(2-ethylhexyl) sulfosuccinate-decane-water changes compared with direct micellar systems and aqueous-organic solutions. It was shown that the calix[4]resorcinolarenes and phenol studied increase the percolation threshold of the system.     

Perchlorate‐Free Pyrotechnic Formulations Utilizing Energetic Chlorine Donors: 1‐CDN, 11‐CDN, 13‐CDN

Several novel materials were investigated as energetic chlorine donors, specifically for the preparation of perchlorate‐free pyrotechnic formulations with low‐smoke output. The novel compounds, 2‐chloromethyl‐2‐methyl‐5,5‐dinitro‐1,3‐dioxane (1‐CDN), 2,2‐bis(chloromethyl)‐5,5‐dinitro‐1,3‐dioxane (13‐CDN), and 2‐(dichloromethyl)‐2‐methyl‐5,5‐dinitro‐1,3‐dioxane (11‐CDN), were formulated with a variety of fuels and oxidizers and their resulting colored flames analyzed for color quality. The preparation and preliminary characterization of these energetic chlorine donors are described.     

Chiral iridium(I) bis(NHC) complexes as catalysts for asymmetric transfer hydrogenation

The common use of NHC complexes in transition‐metal mediated C–C coupling and metathesis reactions in recent decades has established N‐heterocyclic carbenes as a new class of ligand for catalysis. The field of asymmetric catalysis with complexes bearing NHC‐containing chiral ligands is dominated by mixed carbene/oxazoline or carbene/phosphane chelating ligands. In contrast, applications of complexes with chiral, chelating bis(NHC) ligands are rare. In the present work new chiral iridium(I) bis(NHC) complexes and their application in the asymmetric transfer hydrogenation of ketones are described. A series of chiral bis(azolium) salts have been prepared following a synthetic pathway, starting from L ‐valinol and the modular buildup allows the structural variation of the ligand precursors. The iridium complexes were formed via a one‐pot transmetallation procedure. The prepared complexes were applied as catalysts in the asymmetric transfer hydrogenation of various prochiral ketones, affording the corresponding chiral alcohols in high yields and moderate to good enantioselectivities of up to 68%. The enantioselectivities of the catalysts were strongly affected by the various, terminal N‐substituents of the chelating bis(NHC) ligands. The results presented in this work indicate the potential of bis‐carbenes as stereodirecting ligands for asymmetric catalysis and are offering a base for further developments. Copyright © 2010 John Wiley & Sons, Ltd.     

Stereoselective synthesis and optical resolution of chiral calix[4]arenes with mixed ligating functionalities

Exhaustive alkylation of syn-proximal bis[(2-pyridylmethyl)oxy]calix[4]arene 1 with t-butyl bromoacetate or 2-(chloromethyl)quinoline hydrochloride in the presence of Cs₂CO₃ affords selectively a new type of inherently chiral calix[4]arenes 2a,b in the partial cone conformation. (±) 2b has been resolved into its optical antipodes by an HPLC method.