Communication: Furanoside C-Glycosides from an O-Methyl Pyranoside: An Unexpected ß-Hydroxy-1,3-Dithiane Rearrangement

In the course of our investigations on the synthesis of enantiomerically pure anthracycline antibiotics by incorporation of chiral building blocks we prepared the O-methyl 3-deoxy-2-C-ethylribopyranoside 1.¹ The further synthetic plan required the conversion of 1 to the dithioacetal 2 followed by glycol cleavage to a partially protected 1,4-dialdehyde for coupling experiments to leucoquinizarine in a Marschalk reaction. However, the reaction sequence failed¹ and optically active rhodomycinone had to be synthezised in a different way.² A reinvestigation of the synthesis revealed that the thioacetalization of 1 using the acidic conditions recommended by Corey et al.³ did not yield the usual open chain dithioacetal 2 but rather three new unexpected products. The less polar fraction was identified by ¹H and ¹³C NMR as tetrahydrofuran derivative 3a with the dithiane ring in a ß-orientation. The solid polar fraction (12%) consisted of a nonseparable 1:2.2 mixture of the epimeric deoxygenation products 4/5.     

Practical Synthesis of Sinigrin

Abstract

Sinigrin (1), the most commonly known glucosinolate, is a naturally occurring thiosugar, widely distributed in the botanic family Cruciferae. Sinigrin was first isolated in 1839 from seeds of black mustard in the form of its potassium salt.¹ Commercially available sinigrin is obtained by extraction from horseradish.² So far a number of natural glucosinolates and their analogs have been synthesized.^3-10 The only synthesis of compound 1, leading to a crystalline product on the miligram scale, has been reported by Benn and Ettlinger³ (Scheme 1). Their procedure has been applied by Kjaer and Jensen⁴ for the synthesis of the higher homologue of sinigrin (1), but no information of the overall yield has been provided.     

A Convenient Synthesis of N-Functionalized Perfluoroalkanesulfonamides

This article describes the synthesis of new N-functionalized perfluoroalkanesulfonamides (5) with two sulfonamides functionalities. Perfluoroalkanesulfonyl fluoride underwent a reaction with 2-chloroethylamine hydrochloride or 3-bromopropylamine hydrobromide to give N-(2-chloroethyl or 3-bromopropyl) perfluoroalkanesulfonamides (1). Reaction of (1) with potassium thiocyanate gave N-(2-thiocyanatoethyl or 3-thiocyanatopropyl) perfluoroalkanesulfonamides (3). The sulfonyl chloride derivatives (4) were prepared by reaction of 3 with sulfuryl chloride. In the last step, 4 reacted with ammonia to give the bis sulfonamides derivatives (5). The structures of all new compounds prepared were determined by ¹H, ¹⁹F, and ¹³C NMR spectroscopies and by HR-MS.     

Regioselective synthesis and structures of anti-cancer 20(R)-ginsenoside Rg3 derivatives

Abstract

Regioselective synthesis of three novel palmitates of 20(R)-ginsenoside Rg₃ was accomplished via a facile strategy, along with complete assignment of their ¹H and ¹³C NMR resonances by 1D and 2D NMR (¹H-¹H COSY, DEPT 135, HSQC, HMBC, and NOESY) techniques. The derivatives were tested for in vitro anti-proliferative activities against pancreatic cancer PANC-1 cells. Compounds 2, 3, and 4 exhibited more potent activity than did 20(R)-ginsenoside Rg₃.     

Synthesis and Properties of Upper Rim Schiff Base Calix[4]arenes

The synthesis and properties of upperrim Schiff base calix[4]arenes are described in thisarticle. Tetrakis-p-bromomethylcalix[4]arene(1) reacts with hexamethylenetetramine to givetetrakis-p-formylcalix[4]arene (2) in highyield. Then upper rim Schiff base calix[4]arenes 3 can be easily synthesized by 2 reacting withappropriate alkylamines. The complexation ability of3 toward transition metals Pb²⁺, Cu²⁺and Co²⁺ was studied by UV-VIS spectrophotometry.     

HALOACETYLATED ENOL ETHERS: 16[5] REGIOSPECIFIC SYNTHESIS OF 5-TRICHLOROMETHYL-PYRAZOLES

ABSTRACT

The regiospecific synthesis and isolation of three series of 5-trichloromethyl-pyrazoles 2f–j, 3a–j and 4a–j from the cyclocondensation of 1,1,1-trichloro-4-alkoxy-3-alken-2-ones (1a–f) or trichloroacetyl containing β-diketones (1g–j) with dry hydrazine and phenyl-hydrazine is reported. It was established by ¹H- and ¹³C-NMR spectroscopy that the 5-hydroxy-5-trichloromethyl-4,5-dihydro-1H-pyrazole intermediates 2a–j were formed quantitatively.     

The Synthesis and Reactivity of Alkylaminomethylene-Diphosphonates

Abstract

A accessible method for the synthesis of various alkylaminomethylenediphos-phonates is presented. The performed Vilsmeier reagents 2 (RCONR1R²/POCl₃) react with diethyl phosphite 1 to give the products 1 in good yield.     

Hydrothermal syntheses, crystal structures and luminescent properties of two novel silver (I) complexes with 5-methyl-2-pyrazinecarboxylate

The self-assembly of 5-methylpyrazine-2-carboxylate (Hmpca) with silver nitrate generated two coordination polymers [Ag₂(Hmpca)(mpca)(NO₃)] _n (1) and [Ag(mpca)] _n (2) in the presence of Er³⁺ or Mn²⁺ via hydrothermal synthesis. The complexes have been characterized by IR, elemental analyses and single-crystal X-ray diffraction. Complex 1 possesses a novel 1D looped-chain topology structure. Complex 2 shows an extended honeycomb-like 3D framework. The luminescent properties of complexes 1 and 2 were investigated.     

(±)-6,7-丙酮缩二醇-3-酮-庚酸乙酯合成研究

用对甲苯磺酸-2,3-丙酮缩甘油酯(2)与乙酰乙酸乙酯盐、碳酸二乙酯反应, 制备β-酮酯类衍生物1. 以(±)-1,2-丙酮缩甘油为起始物, 经对甲苯磺酰化、亲核取代、脱羧等反应, 方便、高产率地合成了6,7-丙酮缩二醇-3-酮-庚酸乙酯(1). 试图通过对甲苯磺酸-2,3-丙酮缩甘油酯(2)和乙酰乙酸乙酯双阴离子反应制备6,7-丙酮缩二醇-3-酮-庚酸乙酯(1)未获成功. 所合成的化合物经元素分析, IR, ¹H NMR, ¹³C NMR和MS光谱表征.     

Synthetic route for the novel pyrimidine-substituted alkanoate,acetohydrazide, and imines: Synthon for β-lactams

A simple and efficient synthesis of novel pyrimidine-substituted alkanoate, acetohydrazide, and imines is described. The synthesis of novel ethyl 2-(2,6-dimethylpyrimidin-4-yloxy)acetate (EDMPyA) 2 was performed through S_N2 O-alkylation of 2,6-dimethyl-4-hydroxypyrimidine 1 with ethyl haloacetate. The compound EDMPyA 2 was subjected to nucleophilic substitution reaction with hydrazine hydrate to afford novel 2-(2,6-dimethylpyrimidin-4-yloxy)acetohydrazide (DMPyAH) 3. This DMPyAH 3 upon condensation with differently substituted carbonyl compounds (aldehydes/ketones) furnished DMPyAH imines (DMPyAH-I) 4a–d. These imines can be used for the preparation of unique β-lactams. The structure elucidation of all the newly synthesized compounds was performed using spectroscopy (FT-IR, ¹H and ¹³C NMR) and elemental analysis (C, H, N).     

Facile Synthesis of (2R,3S)-2-Benzyloxy-3-hydroxybutyrolactone

The heterocyclic diols derived from L-dimethyl tartrate are important chiral synthons in organic synthesis. In particular, L-threosolactone and L-threosolactam structures are versatile precursors for the synthesis of biologically active molecules. Structurally, these functionalized five-membered rings contain two hydroxyl groups with R and S stereochemistry on C-2 and C-3 respectively. The preparation of (2R,3S)-2-benzyloxy-3-hydroxybutyrolactone (3) and of its derivatives, drawing upon L-dimethyl tartrate as an inexpensive chiral starting material, is described. The presented synthetic procedures are easy and effective for preparing L-threoso analogs. This protocol is also a better alternative in a large scale setup. All structures 3–6 and 8 are characterized using ¹H and ¹³C NMR spectroscopy.     

Synthesis of Some New 1,3,2-Oxazaphosphinine, 1,3,2-Diazaphosphinine,Acyclic, and/or Cyclic α-Aminophosphonate Derivatives Containing the Chromone Moiety

The synthesis of some new 1,3,2-oxazaphosphinine 18, 1,3,2-diazaphosphinine 19, acyclic, and cyclic α-aminophosphonate derivatives 3–17 containing the chromone moiety have been achieved via reaction of 3-(phenyliminomethyl)chromone (1), 3-(phenylaminomethylene)-2-hydroxychromanone (4), and/or 3-(phenylamino-methylene)-2-(phenylamino)chromanone (5) with diethyl phosphite, tris(2-chloroethyl)phosphite, and phenylphosphonic dichloride. Structures of the products were verified on the basis of their elemental analyses, IR, ¹H, and ³¹P NMR spectral data.     

Synthesis and characterization of octakis(4,5-bis{2-[2-(1-naphthyloxy)ethoxy]ethoxy})- substituted metal-free and metallophthalocyanines

The synthesis of octakis(4,5-bis{2-[2-(1-naphthyloxy)ethoxy]ethoxy}) metal-free (4) and metallophthalocyanines (5–8) were carried out by the cyclotetramerization of a 4,5-bis{2-[2-(1-naphthyloxy)ethoxy]ethoxy}phthalonitrile (3). Newly substituted octakisphthalocyanines showed enhanced solubility in organic solvents. The new compounds were characterized by IR, ¹H-NMR, ¹³C-NMR, UV-Vis, and MS spectral data.     

Facile Synthesis of Some 3-(Benzimidazol-2-yl)- and 3,6-Di(Benzimidazol-2-yl)-9-ethyl-9H-carbazoles

A simple and efficient synthesis of novel 3-(benzimidazol-2-yl)- and 3,6-di(benzimidazol-2-yl)-9-ethyl-9H-carbazoles is described. The synthetic approach for the preparation of 2-substituted benzimidazoles 4–8 and bis-benzimidazoles 9–12 was achieved by the condensation of carbazole-3-carbaldehyde 2 and carbazole-3,6-dicarbaldehyde 3 with o-phenyldiamines in dimethylformamide or dimethylsulfoxide in moderate to excellent yield. The identities of synthesized compounds were confirmed using ¹H NMR, ¹³C NMR, infrared (IR), and high-resolution mass spectrometry (HRMS).     

Reaction of Aryl and Heterocyclylhydrazines with 2-Methylchromone: Structural Investigation of the Products

Reaction of 2-methylchromone (2) with phenylhydrazine provides 3-methyl-5-(o-hydroxyphenyl)-1-phenylpyrazole (6) as a major product. In contrast under similar conditions, heterocyclylhydrazines (8a-c) yield exclusively 5-ethyl-3-(o-hydroxyphenyl)-1-heterocyclylpyrazoles (9a-c). The structural assignments are based on an unambiguous synthesis and an analysis of NMR (¹H & ¹³C) spectral data.     

Palladium Acetate Mediated Synthesis of 3,4-Benzo and Naphtho-β-Carbolines

An efficient synthesis of 2-(N-arylaminomethyl)indole derivatives 5 in good yields in four steps from 2-bromomethyl-3-phenylthio-1-benzenesulfonyl indole¹ is reported. Palladium acetate mediated cyclisation of 5 gives benzo and naphtho-ß-carbolines (6 & 7).     

CHLOROSULPHONATION OF 2-ANILINO-1,4-NAPHTHOQUINONE AND SYNTHESIS OF NEWER SULPHONYL DERIVATIVES

Synthesis of 2-anilino-1,4-napthoquinone-3-sulphonyl chloride (2) was achieved from the reaction of the title compound with chlorosulphonic acid. The interesting derivative 2 was used as a building block for synthesis of the sulphonyl derivatives 3–24. All these sulphonyl derivatives were characterized by the physical and spectral data (IR, Mass, ¹H- and ¹³C NMR spectra).     

酰腙类化合物的合成和阴离子识别研究

本文设计合成了3种新型的酰腙类受体分子。利用紫外-可见吸收光谱及 ¹H NMR考察了其与F^-、Cl^-、Br^-、I^-、CH₃COO^-、HSO₄^-、NO₃^-等阴离子的作用。结果表明，该类受体分子能较好地识别阴离子F^-和CH₃COO^-，在DMSO溶液中主客体之间形成氢键加合物。尤其对于受体3(间苯双对硝基苯氧乙酰腙)，加入F^-和CH₃COO^-时，溶液颜色有明显变化，受体3对这两种阴离子可实现裸眼识别。     

Zinc and cobalt complexes with (2-carboxyphenoxy) acetic acid ligand: syntheses,structures, fluorescent and magnetic properties

Four binary compounds, [Zn(cpa)(H₂O)₃] (1), [Co(cpa)(H₂O)₃] (2), [Zn(cpa)(H₂O)]_n, (3) and [Co(cpa)(H₂O)]_n (4) (H₂cpa = (2-carboxyphenoxy)acetic acid), have been synthesized and structurally characterized. In mononuclear 1 or 2, the metal ion (Zn^II for 1 and Co^II for 2) is surrounded by three water molecules and one tridentate chelate cpa^2? in a distorted octahedral geometry, while in 3 or 4, the central metal ion (Zn^II for 3 and Co^II for 4) is located in a deformed square–pyramid formed by one water and two cpa^2?. Each cpa^2? is chelate bridging μ₂ coordination and forms a 1-D zigzag chain structure 2 or 3. The different synthesis conditions for 1–4 have been carefully discussed. The solid-state fluorescence measurements for 1 and 3 together with magnetic properties for 4 also have been investigated.     

Regioselective Allylation of Ketones

In connection with our work concerning synthesis of insect pheromones,¹ we became interested in reports by Lorette and Howard² in which were described a method for preparing alpha-allyl ketones. These authors reported that diallyl ketals (4), available by exchange between a ketone (1), allyl alcohol and 2,2-dimethoxypropane, suffer acid-catalyzed elimination to yield intermediate allyl enol ethers (5/6) which undergo subsequent Claisen rearrangement to provide the alpha-allyl ketone products (2/3). The scheme on the following page summarizes the conversions involved.