Stereoselective Synthesis of β‐Lactams by Using D‐Mannitol‐Derived Oxazolidin‐2‐one as a Chiral Auxiliary

Abstract

Chiral oxazolidin‐2‐ones containing isopropylidene and cyclohexylidene functionalities, readily available from D‐mannitol, have been demonstrated to undergo highly diastereoselective β‐lactam synthesis via the Staudinger reaction with Mukaiyama reagent. Stereoselectivity for cis‐β‐lactam was the result of the [2?+?2] cycloaddition reaction of ketene to trans imines, and cyclohexylidene showed better yield and stereoselectivity than the isopropylidene auxiliary.     

Synthesis of 2-Oxazolines from Ethyl α-Cyanocinnamate Derivatives with Acetamide and N-Bromosuccinimide

An efficient method for the one-pot synthesis of 2-oxazolines from ethyl α-cyanocinnamate derivatives with acetamide and N-bromosuccinimide(NBS) in the presence of K₃PO₄ was developed. The reaction was performed smoothly and cleanly to give 2-oxazolines in good to excellent yields(up to 95%) in acetone at room temperature. Thirteen examples were investigated and the results indicated that a large range of α-cyanocinnamate derivatives could be suitable for this method. Based on the outcomes of experiment, a possible consecutive nucleophilic addition-cyclization pathway was proposed.     

Synthesis of Pyrazoles by the Condensation of C(α)- and Trianions with Esters

In addition to our previous papers^2,3 on the preparation of pyrazoles from the C(α), N-dianions of phenylhydrazones and C(α), N, N-trianions of hydrazones, we wish to report preliminary results on (I) the preparation and condensation of methylhydrazone dianions with methyl benzoate followed by acid cyclization, (II) the condensation of the dianions of phenylhydrazone with methylformate, and the preparation and condensation of the trianions of cyclopentanone (III) and α - tetralone (IV) hydrazones.     

Reaction of Methyl Vinyl Sulfone with Schiff Bases Derived from α-Alanine Methyl Ester and Aromatic Aldehydes

Russian Journal of Organic Chemistry - Schiff bases derived from α-alanine methyl ester and aromatic aldehydes reacted with methyl vinyl sulfone in toluene at 20°C in the presence of...     

Tetra‐n‐butylammonium Hydroxide (TBAH)–Catalyzed Knoevenagel Condensation: A Facile Synthesis of α‐Cyanoacrylates, α‐Cyanoacrylonitriles,and α‐Cyanoacrylamides

Tetra‐n‐butylammonium hydroxide (TBAH) has been utilized as a novel and efficient catalyst for the Knoevenagel condensation of aldehydes with acidic methylene compounds such as methyl‐ and ethylcyanoacetate, malononitrile, and cyanoacetamide to afford substituted olefins.     

Synthesis and Crystal Structure of a New Mononuclear Cadmium（Ⅱ） Cryptate Derived from the Condensation of Tri（2-aminoethyl）amine with Glyoxal

1 INTRODUCTION In recent years many efforts have been devoted to the preparation and characterization of pendant- arm macrocyclic complexes due to the fact that the ligating groups attached to the macrocyclic skeleton can offer additional donor groups to maintain the coordination sphere of metals in the macrocycles[1～7]. In this way, functionalized pendant arm macrocyc- lic complexes have been designed and prepared so as to mimic the structures and properties of certain metalloenzymes and…     

Efficient Synthesis of β‐Amino Alcohols Catalyzed by Niobium Pentachloride: Regioselective Ring Opening of Epoxides with Aromatic Amines

Epoxides undergo a rapid ring‐opening reaction with aromatic amines catalyzed by niobium pentachloride under mild reaction conditions. All the reactions were carried out at room temperature to afford the corresponding β‐amino alcohols in excellent yields and with high regioselectivity.     

Synthesis of 5‐Cyano‐1,3‐dioxoalkanes by Reaction of 1,3‐Dicarbonyl Dianions with Bromoacetonitrile

5‐Cyano‐1,3‐dioxoalkanes were prepared by reaction of 1,3‐dicarbonyl dianions with bromoacetonitrile.     

Cation‐Exchange Resins: Efficient Heterogeneous Catalysts for Facile Synthesis of Dibenzoxanthene from β‐Naphthol and Aldehydes

β‐Naphthol reacts with alkyl and aryl aldehydes in the presence of Indion‐130 to give 14‐alkyl/aryl‐14H[a,j]dibenzoxanthenes in good yield.     

Bifunctional Carbanionic Synthesis of Fully Bio-Based Triblock Structures Derived from β-Farnesene and ll-Dilactide: Thermoplastic Elastomers

Current environmental challenges and the shrinking fossil-fuel feedstock are important criteria for the next generation of polymer materials. In this context, we present a fully bio-based material, which shows promise as a thermoplastic elastomer (TPE). Due to the use of β-farnesene and L-lactide as monomers, bio-based feedstocks, namely sugar cane and corn, can be used. A bifunctional initiator for the carbanionic polymerization was employed, to permit an efficient synthesis of ABA-type block structures. In addition, the “green” solvent MTBE (methyl tert-butyl ether) was used for the anionic polymerisation, enabling excellent solubility of the bifunctional anionic initiator. This afforded low dispersity (Đ=1.07 to 1.10) and telechelic polyfarnesene macroinitiators. These were employed for lactide polymerization to obtain H-shaped triblock copolymers. TEM and SAXS revealed clearly phase-separated morphologies, and tensile tests demonstrated elastic mechanical properties. The materials featured two glass transition temperatures, at - 66 °C and 51 °C as well as gyroid or cylindrical morphologies, resulting in soft elastic materials at room temperature.     

Efficient Synthesis of O-Succinimidyl-(tert-Butoxycarbonylamino)methyl Carbamates Derived from α-Amino Acids Accelerated by Ultrasound: Application to the Synthesis of Ureidodipeptides

The synthesis of O-succinimidyl-(tert-butoxycarbonylamino)methyl carbamates employing isocyanates made through the Curtius rearrangement of Boc-amino acid azides in the presence of N-hydroxysuccinimide under the influence of ultrasound is described.     

Iodine-catalyzed Efficient Synthesis of β-Keto Esters from Aldehydes and Ethyl Diazoacetate Under Solvent-free Conditions

An efficient procedure for the synthesis of β-keto esters from the reaction of aldehydes and ethyl diazoa-cetate catalyzed by iodine at room temperature under solvent-free conditions has been described. The catalytic procedure has the advantages of easily available catalyst,mild reaction conditions,high yields,and easy work-up.     

γ‐Spiroiminolactone Synthesis by Reaction of Acetylenic Esters and α‐Dicarbonyl Compounds in the Presence of Aryl Isocyanide

The highly reactive 1∶1 intermediate produced in the reaction of aryl isocyanides and acetylenic esters was trapped by the α‐dicarbonyl compounds to yield γ‐spiroiminolactone derivatives in good yields.     

Synthesis and Crystal Structure of 4-（4,6-Dimethoxylpyrimidin-2-yl）- 3-thiourea Carboxylic Acid Ethyl Ester

4-（4,6-Dimethoxyl-pyrimidin-2-yl）-3-thiourea carboxylic acid ethyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at room temperature. The crystal structure was determined by X-ray diffraction analysis. Crystallographic data： C10H14N4O4S, M, = 286.31, monoclinic, space group C2/c with a = 2.5309（3）, b = 0.67682（6）, c = 1.74237（19） nm, β = 114.744（3）°, V= 2.7106（5） nm3, Dc = 1.403 g/cm3, p = 0.225 mm-1, F（000） = 1200, Z= 8, R= 0.0514 and wR= 0.1529.     

Enzymatic Synthesis of γ-Glutamylmethylamide from Glutamic Acid γ-Methyl Ester and Methylamine Catalyzed by Escherichia coli Having γ-Glutamyltranspeptidase Activity

A new method for the synthesis of γ-glutamylmethylamide is presented. Glutamic acid γ-methyl ester was used as substrate for γ-glutamylmethylamide synthesis catalyzed by Escherichia coli with γ-glutamyltranspeptidase activity. Reaction conditions were optimized by using 300 mM glutamic acid γ-methyl ester and 3,000 mM methylamine at pH 10 and 40 °C. Bioconversion rate of γ-glutamylmethylamide reached 87 % after 10 h. γ-Glutamyltranspeptidase was reversibly inhibited only when glutamic acid γ-methyl ester was above 300 mM.     

Condensation of γ-bromodypnone with thiocarbamides: Synthesis of 4,4-disubstituted 4,5-dihydro-1,3-thiazol-2-amines and thiazolidin-2-ones

The reaction of 4-bromo-1,3-diphenyl-2-buten-1-one with thiourea or N,N′-diphenylthiourea gives 2-(2-amino-4-phenyl-4,5-dihydro-1,3-thiazol-4-yl)-and 2-[3,4-diphenyl-2-(phenylimino)-1,3-thiazolidin-4-yl]-1-phenyl-1-ethanone — the products of nucleophilic substitution of the halogen atom and Michael addition at position 3 of the 2-buten-1-one system. A similar reaction with thiosemicarbazide and 1-phenylthiosemicarbazide gives the 4-(2-oxo-2-phenylethyl)-4-phenyl-and 4-(2-oxo-2-phenylethyl)-3,4-diphenyl-1,3-thiazolidin-2-one hydrobromides respectively. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 103–110, January, 2008.     

Synthesis, Crystal Structure and Cytotoxic Activity of a Novel Nickel(II) Complex with Schiff Base Derived from Salicylhydrazide

A novel Schiff base complex with π-conjugated system, [Ni(L1)2(py)2] 1 (L1 = (E)-N'-(2,4-dichlorobenzylidene)-2-oxidobenzohydraizide), was synthesized and characterized by elemental analysis and single-crystal X-ray determination. Complex 1 crystallizes in the monoclinic system, space group P21/n with a = 12.8286(10), b = 16.3573(13), c = 19.0206(14) , β = 108.2920(10)o, V = 3789.6(5) 3, Z = 4, Mr = 833.17, Dc = 1.460 g/cm3, μ = 0.843 mm-1, F(000) = 1704, the final R = 0.0537 and wR = 0.0640 for 3836 observed reflections with I > 2σ(I). In the molecular structure of 1, the NiII atoms are six-coordinated by two N and two O atoms from two Schiff base ligands (L1) and two N atoms from two pyridine solvent molecules to form a distorted octahedral geometry. The cytotoxic activities of complex 1 have been experimentally studied against a human HeLa cell in vitro.     

Note Synthesis and Characterization of Some New Polyesters from 4, 4′-Dicarboxyacetyldiphenyl Ether and its Dimethyl Ester

In continuation of the work in connection with the synthesis and characterization of polyketoetheresters [1], the present paper describes the synthesis of structurally related polyketoetheresters in which the ether linkage is in the acid moiety of the repeat unit. The polyesters listed in Table 1 were prepared by polycondensation of equimolar amounts of 4,4′-dicarboxyacetyldiphenyl ether (DCADPE) and the required diacetate of dihydroxyarenes and/or of the dimethyl ester of DCADPE and the required aliphatic diol or arene diol in the presence of zinc acetate.     

Synthesis of New Surfactants Mono and Bipolar Derived from 1,2,4‐Triazole‐5‐thione

Abstract

3‐Phenyl‐1,2,4‐triazole‐5‐thione (PTS) and 3‐methyl‐1,2,4‐triazole‐5‐thione (MTS) are prepared in two steps. The first is a condensation of the thiosemicarbazide with the benzoyl chloride and the acetyl chloride for the PTS and MTS respectively in pyridinic medium. This step leads to the formation of 1‐benzoylthiosemicarbazide and 1‐acetylthiosemicarbazide. The 1‐acetylthiosemicarbazide is also prepared with a new method consisted of a simple solvolysis the thiosemicarbazide in acetic acid for 4 hr. The second is the intramolecular cyclization in methanol with the presence of the sodium methalate leads to the formation of the PTS and the MTS in good yields. The alkylation of MTS and PTS under the conditions of solid–liquid phase transfer catalysis (PTC) allowed us to synthesize some new mono and bipolar surfactants compounds derived from 1,2,4‐triazole‐5‐thione in good yields.