Highly Enantio- and Diastereoselective Hydrogenation of Cyclic Tetra-Substituted β-Enamido Phosphorus Derivatives

Catalytic asymmetric hydrogenation of enamido phosphorus derivatives is one of the most efficient methods for the construction of chiral amino phosphorus products, among which the congested tetra-substituted substrates remains an unaddressed challenge. In this study, we utilize a commercially available Rh-Josiphos system for the efficient and stereoselective hydrogenation of a wide set of tetra-substituted cyclic β-enamido phosphonates/phosphine oxides, thus enabling access to chiral β-amino phosphorus compounds featuring two vicinal stereocenters. This protocol was broadly applicable to different ring systems possessing various phosphonate/phosphine oxide groups and further applied in the preparation of amino-phosphine ligands. DFT mechanistic explorations indicate that the C=C migratory insertion into Rh^III−H bond could be the rate- and stereo-determining step. The origins of stereoselectivity are revealed through distortion/interaction analysis, which is primarily regulated by distinguished dispersion interactions and steric repulsions.     

Synthesis of 5 β-Chloro-4α-methoxysantonin Oxime

The newderivative 5-chloro-4-methoxysantonin oximewasprepared from5-chloro-4-methoxysantonin by reaction with hydroxylamine hydrochloride in the presence of pyridine. The structure was established by IR, UV, and PMR spectroscopies.     

Synthesis of β-d-glucopyranosyl- and β-d-galactopyranosylamines from 4-bromo-3-methylaniline and 2-amino-5-bromopyridine

The possibility of coupling of d-glucose and d-galactose with 4-bromo-3-methylaniline, 2,4,6-tribromoaniline, and 2-amino-5-bromopyridine was studied. The substituent in the aromatic ring was found to influence the conditions and possibility of the reaction. The yields of β-d-glucopyranosyl- and β-d-galactopyranosylamines from 4-bromo-3-methylaniline and 2-amino-5-bromopyridine were 50–65%; 2,4,6-tribromoaniline did not react at all.     

Highly Selective Preparation of 3-and 6-Modified Mannose/Altrose Derivatives

Introduction Asacoretrisaccharide,the3,6branchedtriman nosaccharideunit(Manα16Man31αMan)iswidely expressedonalotofglycoproteins.Itexistsinallas paragines linkedoligosaccharides(N glycans)andthe majorConAbindingepitopeonoligosaccharide type carbohydrate[…     

Solid-phase Synthesis of Unsaturated β-Dicarbonyl Compounds from Polymer-supported 4-（Phenylseleno）morpholine

The solid-phase synthesis of unsaturated β-dicarbonyl compounds has been reported.     

Organic Phosphorus-Suflur Compounds Derived from 1,3,2λ5,4λ5-Dithiaphosphetane 2,4-Disulfides. Synthesis and Properties

The results of author's research into the thiophosphorylating ability of 1,3,2⁵,4⁵-dithiadiphosphetane 2,4-disulfides in reactions with Group II, IV, V, and VI p-element derivatives containing E-X bonds (X = O, S, N) are summarized. New syntheses of organic phosphorus-sulfur compounds with P(S)SE (E = B, Al, C, Si, Ge, Sn, Ph, P, As, Sb, Bi, S) structural fragments are developed. Structural peculiarities and spectral and chemical properties of a series of representatives of these classes of organophosphorus compounds are discussed.     

Synthesis of Related Compounds of Carotenoid

类胡萝卜素是一类奇特的色素，由高等植物和微生物光化学合成，作为防止单线氧通过光敏反应产生危害的必要基团，类胡萝卜素最近受到了关注。类胡萝卜素联于富勒烯上，既可大大增加在可见光区域光诱导电子转移的有效吸收断面，又可抑制富勒烯敏化单线氧的危害能力。合成了类胡萝卜素的相关化合物，报道的某些反应条件先进且简洁。     

Regio- and Diastereoselective Synthesis of β-Lactam-Triazole Hybrids via Passerini/CuAAC Sequence

Passerini (P-3CR) and Passerini-Smiles reactions were investigated in azetidine-2,3-diones, affording the corresponding 3,3-disubstituted-β-lactams with complete diastereoselectivity in high yields. The study has been carried out using different isocyanides, carboxylic acids, and phenols showing the scope of both reactions. In addition, the regioselective synthesis of highly functionalized β-lactam-triazole hybrids has been developed via a Passerini/CuAAC sequence. Interestingly, the use of dialkynes/diazides or trialkynes/triazides as linkers in the CuAAC step has allowed the synthesis of C(2) and C(3) symmetric β-lactam-triazole hybrids, respectively.     

Diastereoselective Synthesis of Monofluorocyclohexenes through Photocatalyzed Cascade Cyclization of gem-Difluoroalkenes and α,β-Unsaturated Carbonyl Compounds

Monofluoroalkenes are nonhydrolyzable mimetics of amides. Previous work focused on the synthesis of non-cyclic monofluoroalkenes. However, diastereoselective synthesis of monofluorocyclohexenes from non-cyclic substrates is challenging. Herein, we report the first photocatalyzed cascade cyclization reactions of readily available α,β-unsaturated carbonyl compounds and gem-difluoroalkenes for the synthesis of highly functionalized monofluorocyclohexenes. The reaction shows broad substrate scope with high diastereoselectivity (>30 examples, up to 86 % yield, >20 : 1 dr). The post-reaction transformations of the products demonstrate the synthetic potential of this methodology.     

Studies on Glycosides VI. Facile Synthesis of Alkyl α-and β-D-Glucopyranosides

A facile Method for the synthesis of alkyl α- and β-D-glucopyranosides using 1-0-trimethylsilyt-2,3,4,6-tetra-O-benzyl-α-D-glucopyranose by the promotion of BF₃ET₂O was reported. The mixture of α -and β-anomers, in which β-anomers predominated, was obtained in good yields.     

Synthesis of Substituted 3H-Indole-modified β-Cyclodextrin

Substituted 3H-indole modified β-cyclodextrin (β-CD) was prepared by the reaction of 6-deoxy-6-[(2-aminoethyl)amino]-β-CD (CDen) with 2-[(p-amino)phenyl]-3, 3-dimethyl-5-car-boxyl-3H-indole (substituted 3H-indole) in the presence of dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt). The product has been characterized by means of elementalanalysis, MS and ^1H NMR.     

Synthesis and Biological Evaluation of Novel 1, 5-Diarylpyrazole-3-carboxamide Compounds as Inhibitors of ALK5

Many diaryl or triaryl substituted imidazoles and triazoles are known to be selective inhibitors of transforming growth factor β1(TGF-β1) type 1 receptor (ALK5)1-3. SB-431542, one of the leading compound of 2-pyridyl substituted triarylimidazole, is an …     

Highly Stereoselective Synthesis of trans-3-Aryl-4-carbethoxy-2,3-dihydro-2-fur-2＇-oyl-5-methylfurans

Multi-substituted dihydrofurans are valuable intermediates for the synthesis of natural products and pharmaceuticals. Considerable attention has been focused on the development of efficient and regioselective methods for their preparation. Using K2CO3 as a base, with the reaction of fur-2-oylmethyltriphenylarsonium bromide 1 and ethyl 2-acetyl-3-arylacrylate 2 in tetrahydrofuran at room temperature, we found an efficient protocol was achieved to synthesize trans-3-aryl-4-carbethoxy-2,3-dihydro-2-fur-2＇-oyl-5-methylfurans 3 in good yield with high stereoselectivity. The structure of compound 3 was confirmed by IR, ^1H NMR, MS and HRMS. The mechanism for the formation of 3 was proposed.     

Condensation of 1-Substituted 5-Aminopyrazoles with β-Dicarbonyl Compounds

Condensation of N-substituted 5-aminopyrazoles with -diketones occurs with the formation of pyrazolo[4,5-b]pyridines. Depending on the conditions, their reaction with -keto acids can give either 6-oxo- or 4-oxopyrazolo[4,5-b]pyridines.     

Synthesis of 2-and 5-(1,1-Dimethyl-1,2,5,6-tetrahydropyridinium-3-yl)oxadiazoline Iodides

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｃｅｎｔｌｙ ,ｔｈｅｉｎｃｒｅａｓｉｎｇｄｅｍａｎｄｆｏｒｅｆｆｅｃｔｉｖｅｔｒｅａｔ ｍｅｎｔｏｆｎｅｕｒｏｄｅｇｅｎｅｒａｔｉｖｅｄｉｓｅａｓｅｓ ,ｐａｒｔｉｃｕｌａｒｌｙＡｌｚｈｅ ｉｍｅｒ’ｓｄｉｓｅａｓｅ (ＡＤ) ,ｉｓｂｅｃｏｍｉｎｇｍｏｒｅａｎｄｍｏｒｅｕｒ ｇｅｎｔ.ＡｍｏｎｇｔｈｅｒｅｓｅａｒｃｈｅｓｉｎｔｈｅｒａｐｅｕｔｉｃｓｆｏｒＡＤ ,ｍａｎｙｍｕｓｃａｒｉｎｉｃｃｏｍｐｕｎｄｓｎｏｔｏｎｌｙａｒｅｂｅｎｅｆｉｃｉａｌｉｎｔｈｅｔｒｅａｔ ｍｅｎｔｏｆＡ…     

Highly Efficient One-Pot,Three-Component Synthesis of β-Aminoketones Catalyzed by Fe(O2CCF3)3

A highly efficient one-pot, three-component synthesis of β-aminoketones was demonstrated using the cost-effective, noncorrosive, and easily available Fe(O₂CCF₃)₃ as a catalyst for the first time. The method can be employed to synthesize a wide range of target compounds and to introduce different functional groups into the β-aminoketone skeleton. Additionally, the method consistently has the advantages of good yields, short reaction time, and simply experimental workup procedure, which makes it a useful process for the synthesis of functionalized β-aminoketones.     

Synthesis of CF3-containing β-hetaryl-substituted enones

A procedure was developed for the synthesis of previously unknown CF₃-containing -azolyl-substituted enones by the reactions of 1,1,1-trifluoro-4-sulfonyl-3-butene-2,2-diols with various azoles. Quaternization of the azolyl group with methyl triflate afforded -azolium-substituted enones in quantitative yields.     

Diastereoselective conjugate addition of organocuprates to N-[4-(Dibenzylaminobutenoyl)]oxazolidinone. Synthesis of chiral β-substituted γ-aminoacids

The first conjugate addition reaction of organocuprates to N-enoyl oxazolidinone where a γ-nitrogen atom is present into α,β-unsaturated system is described. The reaction gave syn-products in moderate yields and high diastereomeric ratios. The removal of chiral oxazolidinone moiety and N-deprotection of amino group furnished chiral β-substituted γ -amino acids.