One-Pot,Three-Component Coupling Reaction: Catalyst-Free Green Synthesis of Novel N-Heteroaryl α-Naphthylglycines

A series of novel N-heteroaryl α-arylglycines containing naphthol rings has been prepared by one-pot, three-component condensation reaction of glyoxalic acid, heteroaryl amines and naphthols in water at ambient temperature and under reflux conditions in moderate to high yields. The promising advantages such as removal of organic solvent, no need to catalyst, simplicity of the reaction procedure and easy product separation will be discussed in this article.     

Synthesis of 1′,3′-Dioxolan-2′-one by the Reaction of Steroidal Oxiranes with Carbon Dioxide: Synthesis of Five-Membered Cis Cyclic Carbonates

The reaction of 3β-acetoxy-5,6α-epoxy-5α-cholestane 1, its 3β-chloro analogue 2, and 5,6α-epoxy-5α-cholestane 3 with carbon dioxide gas in the presence of sodium bromide as catalyst with continuous stirring at 100 °C for 30 min affords selectively the corresponding 1′,3′,-dioxolan-2′-ones (steroidal cyclic cis-carbonates) 4–6 in excellent yields. The structures of these products have been established on the basis of their elemental analysis and spectral data (infrared, ¹H NMR, and mass).     

Synthesis of 1,2-Diazepines by the Bischler–Napieralski Reaction

A new strategy has been proposed for the synthesis of 5H-[1]benzofuro[2,3-d][1,2]diazepines containing two aryl substituents in the diazepine fragment. The key stage of the synthesis is intramolecular cyclization of the corresponding hydrazides under the Bischler–Napieralski reaction conditions.     

Pd–NHC Catalyzed Biaryl Coupling by Direct C–H Activation—A Novel Strategy for the Synthesis of Dibenzocyclooctane Lignans

Cross-coupling reactions, such as Buchwald-Hartwig arylamination and direct intramolecular biaryl coupling by C–H activation, were carried out using various Palladium-N-heterocyclic carbenes (Pd–NHC) as catalysts. The yields were good to excellent. The latter strategy was adopted to transform two dibenzylbutane lignans, isolated from the leaves of Ocotea macrophylla (Lauraceae), into the corresponding dibenzocyclooctane lignans in good overall yields.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Enantioselective Synthesis of cis-Decalin Derivatives by the Inverse-Electron-Demand Diels–Alder Reaction of 2-Pyrones

A novel strategy for the synthesis of cis-decalins by an ytterbium-catalyzed asymmetric inverse-electron-demand Diels–Alder reaction of 2-pyrones and silyl cyclohexadienol ethers is reported here. A broad range of synthetically important cis-decalin derivatives with multiple contiguous stereogenic centers and functionalities are obtained in good yields and stereoselectivities. A full set of diastereomeric substituted cis-decalin motifs are readily accessible by tuning the absolute configurations of substituted silyl cyclohexadienol ethers (R or S) as well as the ligands (R or S). The synthetic potential is showcased by the enantioselective total synthesis of 4-amorphen-11-ol, and further demonstrated by the first total synthesis of cis-crotonin.     

Synthesis of Diethyl Oxalate by a Coupling—Regeneration Reaction of Carbon Monoxide

This article describes a process for the synthesis of diethyl oxalate by a copling reaction of carbon monoxide,catalyzed by palladium in the presence of ethyl nitrite ,The kinetics and mechanism of the coupling and regeneration reaction are also discussed ,This paper presents the results of a scale-up test of the catalyst and the process based on an a priori computer simulation.     

Synthesis of Novel Bisoxazoline Ligands for the Enantioselective Diels-Alder Reaction

The Diels-Alder reaction is the most useful method for six-membered ring formation1. As a consequence, a number of effective enantioselective processes have been developed over the years 2-4. Of particular interest, metal bisoxazoline complexes formed fro…     

Synthesis of Chlorin—enediyne Dyads by Palladium—catalyzed Coupling Reaction

Methyl 9-ethylenedioxpyropheophorbide-d was prepared from methyl pyropheophorbide-a by protection of cyclic ketone with ethylene glycol,and oxidation with OsO4 in vinyl group at 2-position.The terminal alkyne was introduced into chlorin chromophore by Grignard reaction,and the enediyne moiety was constructed by a palladium-catalyzed coupling reaction with (Z)-chloroenynes.     

Ring-Closing Metathesis in the Synthesis of Cyclic α-Amino Acids

The review summarizes recent advances in the synthesis of cyclic -amino acids via intramolecular ring-closing metathesis of dienes and enynes.     

Facile Method for the Synthesis of Vicinal Azidoiodides by the Reaction of the NaN3–I2 System with Unsaturated Compounds

A facile and efficient method was developed for the synthesis of vicinal azidoiodides in 62–77% yields by the reaction of sodium azide and iodine with unsaturated compounds in methanol, aqueous methanol, or the water–methanol–tetrahydrofuran solvent system. The reaction in Et₂O or CHCl₃ produced only vicinal diiodides.     

Total Synthesis of (−)-Batrachotoxin Enabled by a Pd/Ag-Promoted Suzuki–Miyaura Coupling Reaction

Batrachotoxin is an extremely potent cardio- and neurotoxic steroidal alkaloid found in certain species of frogs, birds, and beetles. The steroidal 6/6/6/5-membered carbocycle (ABCD-ring) is U-shaped and functionalized with two double bonds, a six-membered C3-hemiacetal across the AB-ring, a seven-membered oxazepane on the CD-ring, and a dimethylpyrrolecarboxy group at the D-ring carbon chain. These structural features present an unusual and formidable synthetic challenge. Herein we report a total synthesis of batrachotoxin based on a newly devised convergent strategy through a 22-step sequence. Enantiopure AB-ring and D-ring fragments were prepared and subjected to a crucial C(sp²)−C(sp²) coupling reaction. Although both C(sp²) centers were sterically encumbered by proximal tetrasubstituted carbon atoms, Ag₂O strongly promoted the Pd(PPh₃)₄-catalyzed Suzuki–Miyaura coupling reaction at room temperature, thereby connecting the two fragments without damaging their preexisting functionalities. Subsequent treatment with t-BuOK induced Dieckmann condensation to cyclize the C-ring. The judiciously optimized functionalizations realized oxazepane formation, carbon chain extension, and pyrrole carboxylic acid condensation to deliver batrachotoxin.     

Synthesis of the Active Stilbenoids by Photooxidation Reaction of trans-e-Viniferin

Introduction It was reported that stilbene monomers showed multi-faced biological activities, such as antioxidation, antimutagen, antibacterial, antifungal activities.1 Espe-cially, isorhapontigenin and resveratrol showed potent inhibition on biosynthesis of leukotriene and its receptor antagonist.2 Some oligostilbenes exhibited more potent bioactivities than their monomers.3 In recent years, a number of oligostilbenes were isolated from natural sources, but a few of studies on their pharmacol…     

A Novel Tandem Reaction for the Synthesis of Thieno[2,3-C] Pyrazole

Instudyonnewpharmaceuticalsandagrochemicals,theapplicationofheterocyclesisaveryimportantmethod,whichcanimprovethebiologicalactivities.Intheseyears.moreandmorenewagrochemicalshavebeensynthesizedwhichhavethestructurescontainingheterocycles.especiallypy...     

Organocatalytic Enantioselective Pictet–Spengler Reaction of α-Ketoesters: Development and Application to the Total Synthesis of (+)-Alstratine A

We report herein an asymmetric Pictet–Spengler reaction of α-ketoesters. In the presence of a catalytic amount of simple alanine-derived squaramide and p-nitrobenzoic acid, reaction of tryptamines with methyl 2-oxoalkanoates afforded the corresponding 1-alkyl-1-methoxycarbonyl tetrahydro-β-carbolines (THBCs) in high yields and ee values. A primary kinetic isotope effect (KIE=4.5) using C2-deteurium-labelled tryptamine indicates that rearomatization through deprotonation of the pentahydro-β-carbolinium ion could be the rate- and enantioselectivity-determining step. A concise enantioselective total synthesis of (+)-alstratine A, a hexacyclic cagelike monoterpene indole alkaloid, featuring this reaction as a key step, was subsequently accomplished. Remeasurement of the [a]_D value of the natural product indicates that natural alstratine A is dextrorotatory rather than levorotatory as it was initially reported in the isolation paper.     

A Stereoconvergent Tsuji–Trost Reaction in the Synthesis of Cyclohexenyl Nucleosides

A highly regio- and stereoselective route to d - and l -cyclohexenyl nucleosides has been devised, using the Tsuji–Trost reaction as the key step. Contrarily to the widely accepted mechanism (involving a net retention of configuration), the reaction proceeded in a highly stereoconvergent manner, providing cis nucleosides regardless of the relative configuration of the starting materials. DFT calculations confirmed the experimental data while suggesting the origin of the stereochemical reaction outcome.     

Neat Reaction Technology for the Synthesis of Novel 1,5‐Benzodiazepines

A convenient, solvent‐free, green approach is described for the synthesis of novel 1,5‐benzodiazepines by the reaction of ethylacetoacetate, aldehyde, and o‐phenylenediamine without any catalyst at pH 7.     

Application of Suzuki Cross‐Coupling Reaction Catalyzed by Ligandless Palladium Chloride in the Synthesis of Liquid Crystals

Palladium chloride–catalyzed Suzuki cross‐coupling reaction was applied to the preparation of highly pure multiring liquid crystals with a biphenyl unit. The optimal reaction condition is the combination of 0.5 mol% PdCl₂, pyridine, and K₃PO₄, which was able to catalyze the cross‐coupling of substituted aryl bromides with substituted trans‐cyclohexylphenylboronic acids to give pure products in 38–87% yields.     

Synthesis of α-eucryptite by the sol-gel method

New method is reported for synthesis of α-eucryptite LiAlSiO₄ whose framwork structure has voids that enable its doping with lanthanides. The optical parameters of this orthosilicate and results of introduction of europium ions into its composition to create a phosphor were studied.