Abstract  Procedures are described for separation of the alpha, beta 1, and beta 2 subunits of the voltage-sensitive sodium channel from rat brain by gel filtration in sodium dodecyl sulfate (SDS) before and after reduction of intersubunit disulfide bonds or by preparative SDS-gel electrophoresis. Partial proteolytic maps of the SDS-denatured subunits indicate that they are nonidentical polypeptides. They are all heavily glycosylated and contain complex carbohydrate chains that bind wheat germ agglutinin. The apparent molecular weights of the separated subunits were estimated by gradient SDS-gel electrophoresis, by Ferguson analysis of migration in SDS gels of fixed acrylamide concentration, or by gel filtration in SDS or guanidine hydrochloride. For the alpha subunit, SDS-gel electrophoresis under various conditions gives an average Mr of 260,000. Gel filtration methods give anomalously low values. Removal of carbohydrate by sequential treatment with neuraminidase and endoglycosidase F results in a sharp protein band with apparent Mr = 220,000, suggesting that 15% of the mass of the native alpha subunit is carbohydrate. Electrophoretic and gel filtration methods yield consistent molecular weight estimates for the beta subunits. The average values are: beta 1, Mr = 36,000, and beta 2, Mr = 33,000. Deglycosylation by treatment with endoglycosidase F, trifluoromethanesulfonic acid, or HF yields sharp protein bands with apparent Mr = 23,000 and 21,000 for the beta 1 and beta 2 subunits, respectively, suggesting that 36% of the mass of the native beta 1 and beta 2 subunits is carbohydrate.

Abstract  The heptacosapeptide amide corresponding to the entire amino acid sequence of chicken secretin was synthesized by assembling four peptide fragments followed by deprotection with thioanisole-mediated trifluoromethanesulfonic acid in TFA. The deprotected peptide was purified by gel-filtration on Sephadex G-25, followed by ion-exchange chromatographies on CM-cellulose and DEAE-Sepharose. Synthetic peptide stimulated the flow of pancreatic alkaline juice and decreased systemic blood pressure in rats.

Abstract  Hybridomas were developed that secreted monoclonal antibodies against two proteokeratan sulfates (PKS) from rabbit corneal stroma. A total of 28 antibodies were isolated, all of the IgG type with kappa light chains. All were found to react with both PKSs. As judged by immunohistochemical staining, none of them reacted with scleral or conjunctival components, nor with sections of skin, but all reacted with nasal cartilage. When tested by enzyme-linked immunosorbent assays, against components of the proteoglycans, all of the antibodies reacted with keratan sulfate-peptide (isolated from papain digests of PKS or of cartilage proteoglycan), and all but two reacted with oligosaccharide-containing protein cores (prepared by keratanase treatment of PKS). Reactivity with cores was probably due to residual portions of the keratan sulfate chains since the endogenous oligosaccharide-peptides (non-sulfated, non-keratan sulfate oligosaccharides isolated after papain digestion of PKS) were not active. None of the antibodies reacted with protein cores made by removal of carbohydrate by hydrolysis with trifluoromethanesulfonic acid. All except one reacted with fragments of keratan sulfate (made by keratanase digestion). These observations are evidence for structural requirements at three different levels of completeness of the antigen for recognition among the various antibodies. In addition, none of the antibodies reacted immunohistochemically with macular dystrophic corneas, confirming the finding of others that the defect lies in the keratan sulfate portion of the proteoglycans.

Abstract  One of the distinct features of metal-tetrazolate complexes is the possibility of performing electrophilic additions onto the imine-type nitrogens of the coordinated five-membered ring. These reactions, in particular, provide a useful tool for varying the main structural and electronic properties of the starting tetrazolate complexes. In this paper, we demonstrate how the use of a simple protonation-deprotonation protocol enables us to reversibly change, to a significant extent, the light-emission output and performance of a series of Re(I)-tetrazolate-based phosphors of the general formulation fac-[Re(N(∧)N)(CO)3L], where N(∧)N denotes diimine-type ligands such as 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) and L represents a series of different 5-aryl tetrazolates. Indeed, upon addition of triflic acid to these neutral Re(I) complexes, a consistent blue shift (Δλmax ca. 50 nm) of the emission maximum is observed and the protonated species also display increased quantum yield values (4-13 times greater than the starting compounds) and longer decay lifetimes. This alteration can be reversed to the initial condition by further treating the protonated Re(I) complex with a base such as triethylamine. Interestingly, the reversible modulation of luminescent features by the same protonation-deprotonation mechanism appears as a quite general characteristic of photoactive metal tetrazolate complexes, even for compounds in which the 2-pyridyl tetrazolate ligands coordinate the metal center with a bidentate mode, such as the corresponding Ir(III) cyclometalates [Ir(C(∧)N)2L] and the Ru(II) polypyridyl derivatives [Ru(bpy)2L](+). In these cases, the protonation of the starting materials leads to red-shifted and more intense emissions for the Ir(III) complexes, while almost complete quenching is observed in the case of the Ru(II) analogues.

Abstract  To characterize the carbohydrate moieties of the insulin receptor on IM-9 lymphocytes, the cells were surface iodinated and solubilized, and the insulin receptors were precipitated with anti-receptor antibody. The precipitates were resuspended, subjected to either enzymatic digestion or chemical treatment with trifluoromethanesulfonic acid and the relative mobilities of the alpha and beta subunits before and after treatment were analyzed by polyacrylamide gel electrophoresis and autoradiography. The results indicate that the alpha subunit possesses primarily N-linked carbohydrate which is both complex (Endoglycosidase F sensitive) and polymannose (Endoglycosidase H sensitive). The beta subunit also contains polymannose oligosaccharide units and has, in addition, a substantial amount of carbohydrate which is removed by chemical treatment but is not susceptible to Endoglycosidase F, suggesting the presence of O-linked saccharides. The apparent molecular weights of the core protein of the mature alpha and beta subunits as determined by gel electrophoresis following complete deglycosylation are 98 kDa and 80 kDa, respectively.

Abstract  The use of 4'-bromo-2-hydroxyacetophenone trifluoromethanesulfonate ester (4'-bromophenacyl triflate) in the preparation of carboxylic acid 4'-bromophenacyl ester derivatives for spectrophotometric detection in high-performance liquid chromatography is described. The reagent is prepared in 66% yield by the reaction of 4'-bromo-2-diazoacetophenone with trifluoromethanesulfonic acid in anhydrous sulfur dioxide and is stable for 3-6 months. Reactions of 10(-6) M carboxylate N,N-diisopropylethylammonium salts with this reagent in acetonitrile at room temperature proceed to completion in 1-5 min. Optimal rates of reaction are obtained with a 10-fold equivalent excess of alkylating agent and 5 equivalents of N,N-diisopropylethylamine present. The process has been applied successfully to mono-, di- and tricarboxylic and sterically hindered carboxylic acids.

Abstract  Highly enantio- and diastereoselective transannular ketone-ene reactions are catalyzed by a new chromium(III) triflate tridentate Schiff base complex. Electronically unactivated keto-olefins undergo heteroene reactions at ambient temperature to afford enantioenriched bicyclic alcohols, common structural motifs in natural products. The kinetic resolution of a configurationally stable planar-chiral cyclodecenone is also described.

Abstract  3-Alkenylation or 3-alkylation of indole with propargylic alcohols could be efficiently controlled by the catalyst. In the presence of triflic acid, 3-alkenylation of indole occurred and a 3,4-dihydrocyclopenta[b]indole skeleton was effectively constructed in moderate to excellent yields via a cascade process. In the presence of Cu(OTf)(2), 3-alkylation of indole resulted in the formation of 3-propargylic indole, which could be further converted into 2-iodo-1,4-dihydrocyclopenta[b]indoles in the presence of N-iodosuccinimide and boron trifluoride etherate. Possible mechanisms related to the 3-alkenylation or 3-alkylation of indole and their extension to the formation of 3,4-dihydrocyclopenta[b]indoles or 1,4-dihydrocyclopenta[b]indoles are postulated and discussed.

Abstract  β-Glycosyl imidinium triflate is generated from participating thioglycoside donors for disarmed-armed iterative glycosylations and one-pot oligosaccharide synthesis.

Abstract  A clean and efficient diacetoxylation reaction of alkenes catalyzed by triflic acid using commercially available peroxyacids as the oxidants has been developed. This method was also applied in oxidative lactonizations of unsaturated carboxylic acids in good to high yields.

Abstract  Chiral primary-tertiary diamine/TfOH was found to catalyze kinetic resolution of racemic syn-aldols of cyclohexanones in ionic liquid effectively, affording the chiral syn-aldols with up to 99:1 syn/anti and 99% ee.

Abstract  The hydrogenation of imines to amines in the presence of catalytic amounts of zinc triflate has been demonstrated for the first time. In addition, an efficient procedure for the reductive hydroamination of alkynes to amines is presented using zinc triflate as a catalyst precursor. In both protocols a variety of different functional groups are tolerated, and the reactions proceed smoothly in high yields.

Abstract  The title compound containing dihydroceramide as a ligand for CD1d was accomplished using the mannosyl, glucosaminyl, and fucosyl donors, and a sphinganine analogue, as suitable building blocks. The 2-O-unprotected mannosyl donor was coupled effectively with the sphinganine analog to afford the mannnosyl sphinganine derivative. The coupling of the glucosaminyl donor with the mannnosyl sphinganine acceptor required triflic acid as a promoter and the promoter change to silver triflate led to the undesired glycal production. The reduction of azide group using Zn powder was the key process, in which the amount of acetic acid was restricted to avoid the benzoyl migration and N-trichloroacetyl deprotection. The trisaccharide glycolipid was sulfonated at the 3-position of fucose moiety.

Abstract  The asymmetric hydrogenation of tetrasubstituted α,β-unsaturated ketones has been accomplished using an in situ formed rhodium-Josiphos catalyst. The reaction is enhanced by addition of catalytic zinc(II) triflate, which significantly improves turnover frequency while suppressing epimerization of the products.

Abstract  Treatment of 2-epoxy-1-alkynylbenzenes with electron-rich alkenes and a [AuCl(PR(3))]/AgX catalyst in CH(2)Cl(2) led to the formation of 2-alkenyl-1-(2,3-dihydrofuran-4-yl)benzenes. This transformation comprises of a gold-catalyzed redox reaction to form a gold alpha-carbonylcarbenoid initially, which then reacts in situ with an alkene in a [3+2] cycloaddition. A range of alkenes are amenable to this tandem reaction, amongst them alpha-substituted styrenes, enol ethers, and 2,3-dimethylbutadienes. Deuterium-labeling experiments suggest a stepwise mechanism for the alpha-carbonylcarbenoid/alkene [3+2] cycloaddition. The resulting 2,3-dihydrofuran products allow access to diverse oxacyclic compounds through a stereoselective ene-oxonium reaction initiated by treatment with HOTf (1 mol %; Tf=trifluoromethanesulfonyl). A stepwise pathway is proposed for this reaction. The feasibility for direct transformation of 2-alkenyl-1-alkynylbenzenes into the desired 2,3-dihydrofuran products through initial m-chloroperbenzoic acid oxidation, followed by the addition of gold catalyst and alkene, has also been demonstrated.

Abstract  Treatment of pink titanium(iii) triflate (0.045 M) with HF in triflic acid (CH(3)SO(3)H) converts Ti(iii) rapidly to a 1 : 1 mixture of Ti(IV) and green Ti(II): (2 Ti(III) + 4 HF --> TiF(4) + Ti(II) + 4 H(+)). This disproportionation is half complete when [HF] added is 0.027 M. Substituted 1,4-benzoquinones are reduced rapidly by Ti(iii) in the absence of fluoride, yielding straightforward logarithmic curves, but reactions of the same quinones with Ti(ii) in fluoride media exhibit more complex profiles, the major portions of which are zero order in oxidant. These reactions are strongly catalyzed by added Ti(iv). Analyses of complex curves are consistent with a reaction sequence initiated by Ti(ii)-Ti(iv) disproportionation, forming Ti(iii), which reacts with the quinone, yielding the quinhydrone, QH . The latter is rapidly reduced by Ti(ii). Values of rate constants obtained from these analyses are in agreement with those for reductions of quinones by Ti(iii), in the absence of fluoride.

Abstract  A silver triflate-catalyzed tandem reaction of N'-(2-alkynylbenzylidene)hydrazide with silyl enolate is described, which generates the unexpected H-pyrazolo[5,1-a]isoquinolines in good to excellent yields. Intramolecular cyclization, nucleophilic addition, condensation, and aromatization may be involved in the reaction process.

Abstract  Direct catalytic asymmetric Mannich-type reactions of gamma-butenolides are described. A chiral Lewis acid/amine base/Brønsted acid combination was used to catalyze a gamma-addition of gamma-butenolides to N-diphenylphosphinoyl imines, affording the products in up to >99% yield, anti/syn = >97:3, and 84% ee. The use of a catalytic amount of TfOH in addition to La(OTf)3/Me-PyBox/TMEDA was important for improving yield and stereoselectivity.

Abstract  A synthesis of new unsymmetric trifluoromethylsulfonylimino(nonafluoro-n-butyl-sulfonylimino)trifluoromethanesulfonic acid (1b) is reported. During the silylation reactions studies of bis(perfluoroalkylsulfonylimino)trifluoromethanesulfonic acids (1a,b) it was shown that reaction proceeds exclusively on the central oxygen atom to give trimethylsilyl esters. The obtained esters along with several trimethylsilylesters of sulfonic acids have been studied by 29Si-NMR spectroscopy and an attempt to estimate the strength of bis(perfluoroalkylsulfonylimino)trifluoromethanesulfonic acids by the 29Si-NMR chemical shifts of their trimethylsilylesters was made, resulting in the conclusion that these compounds may be cited as the strongest organic Brønsted acids.

Abstract  Diarylvinylidenecyclopropanes undergo a [3 + 2] cycloaddition reaction with MeCN in the presence of Brønsted acid TfOH to give the corresponding 3,4-dihydro-2 H-pyrrole derivatives 2 in moderate to excellent yields under reflux within a short time. As for the diarylvinylidenecyclopropane substrate containing a strongly electron-donating methoxy group on the benzene ring, the reaction leads to the formation of a different type of 3,4-dihydro-2 H-pyrrole derivatives 4 under the same conditions.

Abstract  Two organic ligands based on bis-(2-pyridyl)pyrazole (Hbpp) functionalized with a para-methylenebenzoic acid (Hbpp-R(a)) or its ester derivative (Hbpp-R(e)) were prepared and characterized. The ester-functionalized ligand was then used to prepare a series of related dinuclear ruthenium complexes of general formula [Ru(II)2(L-L)(bpp-R(n))(trpy)2](m+) (L-L=mu-Cl, mu-acetato, or (H2O)2; n=e or a; trpy=2,2':6',2''-terpyridine; m=2 or 3). The complexes were characterized in solution by 1D and 2D NMR spectroscopy, UV/Vis spectroscopy, and electrochemical techniques. The [Ru(II)2(mu-Cl)(bpp-R(e))(trpy)2](PF6)(2) complex was further characterized in the solid state by X-ray diffraction. The complexes containing the free carboxylic acid ligand were anchored onto rutile TiO2 and treated with 0.1 M triflic acid solution to generate the homologous water-oxidation catalysts TiO(2)-[Ru(II) (2)(H2O)(2)(bpp-R(a))(trpy)2]2+. This new hybrid material catalytically oxidizes water to molecular oxygen in a heterogeneous manner using Ce(IV) as chemical oxidant. The generation of molecular oxygen is accompanied by the formation of carbon dioxide as well as some leaching of the Ru catalyst.

Abstract  The ligands HN(CH2-2-C5H4N)2, BPMA, and PhCH2N(CH2-2-C5H4N)2, BBPMA, react with Na[AuCl4] to give the cationic complexes [AuCl(BPMA-H)]+ and [AuCl(BBPMA)]2+, respectively. The amido complex [AuCl(BPMA-H)]+ undergoes easy inversion at the amido nitrogen atom and can be reversibly protonated by triflic acid to give [AuCl(BPMA)]2+. The complex [AuCl(BBPMA)]2+ is easily decomposed in aqueous solution by cleavage of a carbon-nitrogen bond or, in dilute HCl solution, by protonation of the ligand to give [BBPMAH2]Cl[AuCl4] The complexes [BBPMAH2]Cl[AuCl4] and [BBPMAH2]Cl[AuCl2] can be formed by direct reaction of BBPMA with H[AuCl4]. Unusual forms of gold(III)...gold(III) and gold(III)...gold(I) aurophilic bonding are observed in the salts [AuCl(BPMA-H)][PF6] and [AuCl(BPMA-H)][AuCl2], respectively. The first comparison of the structures of gold(III) amine and amido complexes, in the cations [AuCl(BPMA-H)]+ and [AuCl(BPMA)]2+, indicates that there is little ppi-dpi bonding in the amido-gold bond and that the amide exerts a stronger trans influence than the amine group.

Abstract  Ionic liquid reagents created by addition of 1 equiv of either CF3CO2H or CF3SO3H to N-pentylpyridinium bromide exhibit excellent chemical reactivities as surrogate HBr reagents in ring-opening reactions of cyclopropyl ketones as well as of 2,2-difluorocyclopropyl ketones to form the respective 3-bromopropyl or 3-bromo-2,2-difluoropropyl ketones in good to excellent yields.

Abstract  P-type photochromic diarylethenes having a diethylamino group can switch to T-type photochromic system by the addition of trifluoromethanesulfonic acid as external stimuli.