- Practical acetalization and transacetalization of carbonyl compounds catalyzed by recyclable PVP-I
-
A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild reaction condition, short reaction time, recyclable of catalyst and broad substrates scope with excellent yields.
- Cao, Fu-Rong,Lu, Guangying,Ren, Jiangmeng,Wang, Di,Zeng, Bu-Bing
-
-
- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
-
We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
-
supporting information
p. 1068 - 1075
(2018/05/23)
-
- Acid-catalyzed highly diastereoselective and effective synthesis of 1,3-disubstituted tetrahydropyrano[3,4-b]indoles
-
We successfully explored for the first time that trifluoroacetic acid (TFA) can effectively catalyze the oxa-Pictet-Spengler reaction of secondary tryptophols and acetals to synthesize 1,3-disubstituted 1,3,4,9-tetrahydropyrano[3,4-b]indoles in high yield (up to >99%) and diastereoselectivity (>20:1). The secondary tryptophols were synthesized from indole-3-acetic acid. The one-pot synthesis of tetrahydropyrano[3,4-b]indoles was successfully developed from secondary tryptophols and in situ prepared acetals from aldehydes and trimethylorthoformate and thus the cost-efficiency of the protocol was effectively enhanced. Finally, the catalytic asymmetric synthesis of the 1,3-disubstituted tetrahydropyrano[3,4-b]indole was also demonstrated after enantioselective achievement of highly enantiopure secondary tryptophols.
- Wang, Pei,Zhao, Jia-Zhen,Li, Hong-Feng,Liang, Xiang-Ming,Zhang, Ya-Lun,Da, Chao-Shan
-
supporting information
p. 129 - 133
(2016/12/23)
-
- Phosphorylated Polyacrylonitrile Fibers as an Efficient and Greener Acetalization Catalyst
-
A novel solid acid catalyst (PANEAPF) is developed by immobilization of phosphoric acid on polyacrylonitrile fiber through covalent bonding. Various characterization techniques such as elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. are utilized to confirm the successful grafting and the stability of the fiber catalysts during application. PANEAPF shows high catalytic activity in the acetalization of aldehydes owing to the high utilization efficiency of its functionalized acid sites. In addition, the strong polarity micro-environment in the surface layers of PANEAPF make it highly suitable for catalytic application in both water and alcohol. Furthermore, the fiber catalyst can be applied to the acetalization of aldehydes in a continuous-flow process at room temperature, and shows excellent reactivity and superior recyclability (over 20 times). The many advantages of PANEAPF such as simple preparation, convenient regulation of acid amount, high durability, and eco-friendly process make it very attractive for fixed-bed reactors in the chemical industry.
- Xu, Gang,Cao, Jian,Zhao, Yali,Zheng, Lishuo,Tao, Minli,Zhang, Wenqin
-
supporting information
p. 2565 - 2575
(2017/09/25)
-
- Nanomolar β-lactamase inhibitors
-
New carboxyphenyl-glycylboronic acid transition-state analog inhibitors, representative of a class of compounds effective against class C β-lactamase AmpC. The new compounds improve inhibition by over two-orders of magnitude compared to analogous glycylboronic acids, with Ki values as low as 1 nM.
- -
-
Page/Page column 39
(2010/11/28)
-
- Development of an enzyme-linked immunosorbent assay for the pyrethroid insecticide cyhalothrin
-
A competitive enzyme-linked immunosorbent assay (ELISA) was developed for detection of the pyrethroid insecticide cyhalothrin. Three haptens with an amine or propanoic acid terminus were synthesized and then conjugated with bovine serum albumin to give immunogens. Eight polyclonal antisera produced by rabbits were screened for titers and affinity using three different coating antigens. The antiserum CWB-C had the highest affinity with cyhalothrin and a low affinity with fenvalerate, fenpropathrin, deltamethrin, and fluvalinate. The half-maximum inhibition concentration for cyhalothrin was 37.2 μg/L, and the limit of detection was 4.7 μg/L. The recoveries of different concentrations of cyhalothrin (0.1-2500 μg/L) from fortified tap water, well water, and wastewater samples as determined with the ELISA were 81-114%.
- Gao, Hongbin,Ling, Yun,Xu, Ting,Zhu, Weiwen,Jing, Hongyu,Sheng, Wei,Li, Qing,Li, Ji
-
p. 5284 - 5291
(2007/10/03)
-
- COMPOUNDS TO TREAT AMYLOIDOSIS AND PREVENT DEATH OF BETA-CELLS IN TYPE 2 DIABETES MELLITUS
-
The invention discloses aromatic amides and sulfonates to treat or prevent type 2 diabetes mellitus (T2DM), the pathological consequences of T2DM, to inhibit amyloidosis or to prevent death of β-cells of the pancreas.
- -
-
Page/Page column 47; 48
(2010/11/24)
-
- A remarkable bismuth nitrate-catalyzed protection of carbonyl compounds
-
Bismuth nitrate has been found to be an outstanding catalyst for the protection of carbonyl compounds as acetal, ketal, mixed ketal and thioketal with an excellent yield.
- Srivastava, Neeta,Dasgupta, Swapan K.,Banik, Bimal K.
-
p. 1191 - 1193
(2007/10/03)
-
- A new molecular iodine-catalyzed acetalization of carbonyl compounds
-
A new and facile molecular iodine-catalyzed acetalization of carbonyl compounds has been developed. Useful selectivity has also been demonstrated.
- Basu, Manas K.,Samajdar, Susanta,Becker, Frederick F.,Banik, Bimal K.
-
p. 319 - 321
(2007/10/03)
-
- Tetrabenzo[ab,f,jk,o][18]annulene: Synthesis, crystal structure analysis, ab initio quantum-chemical studies of intermolecular interactions in the gas phase and in crystalline states, photodimerization and photopolymerization
-
The synthesized title compound 8 crystallizes in three different modifications, which were investigated by electron crystallography, high resolution electron microscopy and X-ray structural analysis. The formation of molecular pairs was studied by an ab initio quantum-chemical approach. The calculated "dimers" were compared to the mutual orientations of nearest neighboring molecules in the crystal structures and to covalently bonded dimers obtained by a topochemical photodimerization.
- Yu, Richeng,Yakimansky, Alexander,Voigt-Martin, Ingrid G.,Fetten, Michael,Schnorpfeil,Schollmeyer, Dieter,Meier, Herbert
-
p. 1881 - 1890
(2007/10/03)
-
- Development of an Enzyme-Linked Immunosorbent Assay for the Detection of the Pyrethroid Insecticide Fenpropathrin
-
A competitive enayme-linked immunosorbent assay (ELISA) was developed for the quantitative detection of fenpropathrin [(RS)-α-cyano-3-phenoxybenzyl-2,2,3,3-tetramethylcyclopropanecarboxylate]. Polyclonal antisera were isolated from rabbits immunized with two different fenpropathrin hapten conjugates. One hapten contained an amino function; the other contained a carboxyl group for conjugation to carrier proteins. Mollusk hemocyanins, thyroglobulin, and fetuin were used as carrier proteins. The antisera varied greatly in their affinities for fenpropathrin. A homologous assay system using the coating antigen format was the most sensitive. The IC50 for fenpropathrin was 20 μg/L, and the lower detection limit was 2.5 μg/L. Pyrethroids, such as phenothrin, permethrin, resmethrin, fenvalerate, deltamethrin, cyfluthrin, and cypermethrin, and the pyrethroid metabolites, 3-phenoxybenzoic acid and fenpropathrin acid, did not cross-react significantly in this assay. Ten percent acetone or methanol and a pH of 4 were determined to be optimum assay conditions. Various cationic, anionic, and nonionic detergents had no significant effect on the assay.
- Wengatz, Ingrid,Stoutamire, Donald W.,Gee, Shirley J.,Hammock, Bruce D.
-
p. 2211 - 2221
(2007/10/03)
-
- Enantioselective and diastereoselective molecular recognition of cyclic dipeptides by a C2 macrolactam host
-
Two synthetic, optically active, C2 symmetric macrolactam hosts 11b and 11c have been synthesized from L-leucine, and other simple starting materials, in an 11-step, convergent synthesis. These new macrocycles, which were conceived with the aid of current molecular modeling software, were designed to complex neutral amides in organic solvents through complementary intermolecular hydrogen bonding. The hosts, which are made up of two short peptide strands alternately interlinked with two rigid aromatic spacer units to form a large macrocyclic structure, feature a binding site that consists of a convergent, ordered array of amide functions. 1H NMR and solution FT-IR spectroscopy demonstrated that in CDCl3 11b and 11c each bound the five various stereoisomers of the cyclic dipeptides cyclo-Gly-Leu and cyclo-Leu-Leu, with association constants ranging from 70 to 2260 M-1 (±15%). 11b was capable of moderately high enantioselective and diastereoselective molecular recognition (ΔΔGenan = 0.97-1.23 kcal/mol, ΔΔGdia = 0.28-0.95 kcal/mol) of the various chiral diketopiperazines and preferred guests bearing one or more side chains of the L configuration. In contrast, the diastereomeric host 11c showed very little enantioselectivity (ΔΔGenan = 0.09-0.17 kcal/mol), but did show diastereoselectivity (ΔΔGdia = 0.44-0.54 kcal/mol) and showed a modest preference for guests with side chains of the D configuration. Molecular modeling studies, as well as 1H NMR data, suggest that these hosts are conformationally flexible and bind to the guests with an induced-fit mechanism. The host-guest complexes are stabilized through the formation of three to four intermolecular amide-amide hydrogen bonds in the binding cavity of the macrocycle as well as favorable van der Waals contacts between the hydrocarbon surfaces of the host and guest. The stereoselective binding observed is most likely due to the slight energetic differences in the intermolecular hydrogen bonding patterns that stabilize the host-guest complexes, which are in turn due to the varying degrees of steric interactions that occur between the side chains of the guest and of the host. It is anticipated that the strength, and the degree, of the selectivity in binding of the guests by hosts 11b,c could be improved upon through additional structural modifications.
- Cristofaro, Michael F.,Chamberlin, A. Richard
-
p. 5089 - 5098
(2007/10/02)
-
- Variable Electronic Properties of the CSNMe2 Group
-
The ?I value for the CSNMe2 group has been determined and the value of 0.23 indicates that this group is inductively electron withdrawing.The effect of the p-CSNMe2 group on the solvolysis rate of cumyl chloride has also been determined and, relative to the p-H analogue, this group has a negligible effect on rate. p-CSNMe2 substitution slows the hydrolysis rate of substituted benzaldehyde dimethyl acetals. p-CSNMe2 substitution enhances the solvolysis rate of ArCH(OMs)PO(OEt)2.These variable rate effects on reactions involving cationic intermediates have been interpreted in terms of variable electronic properties of the CSNMe2 group.This group can be cation stabilizing, electroneutral, or cation destabilizing, depending on the charge demands of specific cations.This is a result of a conjugative interaction of CSNMe2 with a cationic center and resultant delocalization of positive charge onto sulfur.The importance of such conjugation is a function of the amount of transition-state charge developed on the carbon bearing the CSNMe2 group.The electronic effects of the amphielectronic p-CSNMe2 group are compared to the more conventional effects of CONMe2 and the m-CSNMe2 analogues.
- Creary, Xavier,Aldridge, Timothy
-
p. 4280 - 4285
(2007/10/02)
-