A Two-Step Synthesis of Camphosultam

Modifications of the known route to camphosultam led to an easy two-step process. The unique intermediate is simply isolated by filtration. The overall yield is 66% on a hundred gram scale.     

A Two-Step Synthesis of Mimosamycin

The marine antibiotic mimosamycin, and a number of analogues, have been prepared in two steps by cycloaddition of a 1,4-benzoquinone or naphthoquinone with 2-aza-bis(1,3-t-butyldimethylsilyloxy)-1,3-buta-diene, hydrolytic work-up of the adduct, and phase-transfer catalysed alkylation of the resultant isoquinolin-3-ones.     

A New Two-Step Stereospecific Synthesis of Glycidic Spiroacetals

ABSTRACT

The spiroacetal moiety has received much attention in recent years owing to its occurence in several biologically important natural products.¹ In that field, the antibiotics avermectins,² milbemycins³ and papulacandins⁴ are of particular interest to us because a carbohydrate precursor could be employed for their syntheses.^5-7 other glycidic spiroacetals were obtained by photocarbocyclization of 2-carbophenyl-β-D-glucopyranosides.⁸     

A Convenient Two-Step One-Pot Synthesis of Alkylthiophosphoramidates Derivatives

N-thiophosphonylamino groups have been greatly overlooked as potentially potent, transition-state analogues, or tetrahedral--intermediate inhibitors of metalloproteases. Alkylthiophosphoramidates derivatives were synthesized y reaction of O-isopropyl phosphorodichloridothioate with an amino acid este followed by hydrolysis in 2M NH 4 OH. The reaction was monitored by 31 P NMR spectroscopy.     

The Application of Allyl as a Protecting Group in the Preparation Of Dinucleoside Carbonate

Inthepastseveralyears,antisenseoligonucleotidesandtheanalogueshavebeenproposedasanewclassofpharmaceuticals.Thetechnologyofantisenseisbasedontheantisensenucleotidesbindingtothetargetsequence(sensestrand)bybase-pairingtoinhibitgeneexpression'.Amajoradvantageofthestrategyisinthepotentialspecificityofaction.Theoretically,ifthenucleotidesequenceofthetargetmoleculeisknown,itispossibletowritedowndirectlythecorrespondentstructureofantisensestrand.However,inordertomakethisstrategysuccessful,theantisens…     

One Pot Phase Transfer Synthesis of O-Alkyl,S-Methyl Dithiocarbonates (Xanthates)

O-Alkyl, S-methyl dithiocarbonates of phenol, benzyl, primary and secondary alcohols were prepared in a one pot procedure under phase transfer catalysis conditions.     

氯代烷烃、硫粉和氢亚磷酸酯一步合成S-烷基硫磷酸酯

S-苄基硫磷酸酯和S-烷基硫磷酸酯在农药中有着重要的应用。 本文发展了一种无需催化剂,仅在碱作用下,氯代烷烃、硫粉以及氢亚磷酸酯三组份一步生成S-烷基硫磷酸酯的绿色经济方法,该反应可以在一步反应中同时构建磷—硫键和碳—硫键。 以苄氯及衍生物、硫粉、氢亚磷酸酯在碳酸铯的促进下,室温反应,共合成了17个S-苄基硫磷酸酯,产率为70%~99%。 同时,实现了脂肪链的氯代烃、硫粉和氢亚磷酸酯的反应,在三乙胺的促进下,在空气中60 ℃反应,共合成了13个S-烷基硫磷酸酯,产率为45%~93%。 本方法在合成上和工业上将具有较好的应用前景。     

A Two-Step Spin Crossover in

Measurement of magnetic susceptibility with temperature of a powdered iron(III) catecholate complex clearly indicated a two-step spin-crossover process S=(1/2)<-->S=5/2. The picture shows the plot of chi(M)T against temperature.     

Two-Step Oxidation Synthesis of Sulfur with a Red Aggregation-Induced Emission

Sulfur is not normally considered a light-emitting material, even though there have been reports of a dim luminescence of this compound in the blue-to-green spectral region. Now, it is shown how to make red-emissive sulfur by a two-step oxidation approach using elemental sulfur and Na₂S as starting materials, with a high photoluminescence quantum yield of 7.2 %. Polysulfide is formed first and is partially transformed into Na₂S₂O₃ in the first step, and then turns back to elemental S in the second step. The elevated temperature and relatively oxygen-deficient environment during the second step transforms Na₂S₂O₃ into Na₂SO₃ incorporated with oxygen vacancies, thus resulting in the formation of a solid-state powder consisting of elemental S embedded in Na₂SO₃. It shows aggregation-induced emission properties, attributed to the influence of oxygen vacancies on the emission dynamics of sulfur by providing additional lower energy states that facilitate the radiative relaxation of excitons.     

Individual Isomers of Dinucleoside Boranophosphates as Synthons for Incorporation into Oligonucleotides: Synthesis and Configurational Assignment

Individual isomers of the protected boranophosphates 5a and 5b , i.e., the N⁶‐benzyl‐2′‐deoxy‐5′‐O‐(4,4′‐dimethoxytrityl)adenosin‐3′‐yl 2′‐deoxy‐4‐O‐(4‐nitrophenyl)uridin‐5′‐yl boranophosphates, were synthesized via stereospecific silylation and boronation of their H‐phosphonate precursors. 2D‐NMR Spectroscopic studies yielded an initial assignment of the isomer configuration, which was further confirmed unambiguously by a parallel chemical synthesis. Deprotection of the `dimers' 5a and 5b yielded the individual [P(R)]‐ and [P(S)]‐isomers 7a and 7b , respectively, i.e., the 2′‐deoxyadenosin‐3′‐yl 2′‐deoxycytidin‐5′‐yl boranophosphates. Their substrate properties toward phosphodiesterase I were identical to those of the previously characterized isomers of dithymidine boranophosphate. The protected `dimers' 5a and 5b can be used as synthons to incorporate the boranophosphate linkage with a defined configuration to selected positions of an oligonucleotide chain.     

A Remarkable Two-Step Synthesis of Diverse 1,4-Benzodiazepine-2,5-diones Using the Ugi Four-Component Condensation

A two-step, general synthesis of 1,4-benzodiazepine-2,5-diones (BZDs) is presented. This synthesis employs an Ugi four-component condensation using a convertible isocyanide (1-isocyanocyclohexene), followed by an acid-activated cyclization reaction. This synthesis represents a dramatically improved route to BZDs over those currently in the literature. In addition, since amino acids are not used as inputs, the potential for molecular diversity is much greater than that with existing syntheses. It was also found that BZDs substituted with methylenes at the C-3 and N-4 positions display conformational isomerism in the NMR spectra at room temperature. Variable-temperature NMR experiments support this observation and offer the interesting conclusion that the BZD core structure, in certain examples, might not be as rigid as previously supposed.     

A Convenient Synthesis Of 3-Arylcoumarins From Arylacetonitriles

The condensation of salicylaldehydes with various arylacetonitriles catalyzed by anion-exchange resins such as Amberlite IRA 900, leads to the corresponding 3-arylcoumarins in good yields and selectivity.     

Synthesis Of A New Series Of Cyclic Pseudopeptides Containing Pyridine As Backbone Modifier

A new class of cyclic pseudo-peptides which contains pyridine and cystine in the backbone structure was synthesized by a simple three-step preparation. The structures of products were characterized by spectroscopic and conventional analytical methods.     

Synthesis of Monodisperse Colloidal ZnS Spheres by an Acid-Free Two-Step Approach

In this work, we demonstrate a new two-step method for preparing monodisperse ZnS colloidal spheres. The method contains a hot-injection step for making primary particles as seeds and a heating-up step for aggregation growth of secondary colloidal spheres. Instead of the most commonly used thioacetamide in previous studies, thiourea (TU) was selected as the sulfur source. The temperature-dependent thermal decomposition rate of TU makes the releasing of S²⁻ and nucleation of ZnS under proper kinetic control, meanwhile making the reaction a mild and acid-free process. By separating the two steps and using a milder sulfur precursor, monodisperse ZnS colloidal spheres have been prepared. Their diameters can be delicately tuned in the range from 54 to 172 nm through simply changing the amount of Zn and S precursor. The optical properties of the obtained ZnS spheres were studied by extinction and PL measurements, and they exhibit size-dependent optical behavior.     

功能化离子液体中两步高效合成N-取代硫脲

两步高效合成N-取代硫脲：（1）在[emim]SCN中以酰与伯胺为起始原料先合成得到N-烃基-N＇-酰基硫脲,反应速度快,产率高,功能化离子液体既作为第一步反应原料,又作为反应介质;（2）N-烃基-N′-酰基硫脲在NaOH/H2O/EtOH体系中以近100%的转化率水解得目标产物.提供了一种高效合成N-取代硫脲的绿色、...     

A New Method of Introducing SCH3 and SCD3 Groups to Phosphorothioates

Abstract

A new synthesis of phosphorothioates starting from phosphites and cyanuric chloride (TCT)-activated DMSO is reported herein. This method enables the incorporation of SCH₃ and SCD₃ groups into phosphorothioates in good yields. The labeling purities of the products are excellent.     

A Convenient Synthesis Of Isopropyl Ethers from Secondary Alcohols

A convenient synthesis of isopropyl ethers from the corresponding secondary alcohols has been developed, involving acetate formation, conversion to the enol ether via an organotitanium reagent, and subsequent catalytic hydrogenation to the isopropyl ether.     

A New And Convenient Synthesis Of Some Substituted Thiohydantoins

3-Substituted thiohydantoins (2a-g) were synthesized in satisfactory yields by the reaction of N-substituted thioureas (la-g) with chloroacetylchloride in the presence of triethylamine under reflux in dioxane. S-Alkylated products (7, 8) were obtained from the reaction of 3-p-tolyl -thiohydantoin (2d) with p-nitrobenzylchloride and 3-phenyl-5-chloromethyl-I,2,4-oxadiazole.     

Synthesis Of Isomaltose Analogues

ABSTRACT

Preparation of the α-glucosides 11, 12, 13 and 14 were accomplished through glycosylation of racemic trans-1-hydroxy-2-(hydroxymethyl)cyclohexane using 2-thiopyridyl tetra-O-benzyl-glucoside as the glycosyl donor in acceptable overall yield for α-selectivity, but with poor regioselectivity. Glycosylation under thermodynamic control using tetrabenzyl glucopyranose acetate and trimethylsilyl triflate as the promotor gave similar results. The unprotected glucosides 12 and 13 were separated and characterized by NMR spectroscopy. Similarly methyl 4-deoxy-α-isomaltoside (5a) was prepared through halide catalyzed glycosylation of methyl 2,3-di-O-benzoyl-4-deoxy-α-D-glucopyranoside (15) in acceptable yield and the unprotected compound characterized by NMR spectroscopy. Compounds 5a, 12a, 13a and the mixture 11a and 14a were all tested as substrates for the enzyme glucoamylase from Aspergillus niger and proved to be very poor substrates for the enzymic hydrolysis.