Solid Phase Synthesis of Ethyl β-Substituted Indolepropionates

A facile solid phase synthesis of ethyl β-substituted indolepropionates is reported. Condensation between indole, polymer-supported cyclic malonic acid ester and aldehyde yielded the trimolecular adducts, which was cleaved by pyridine/EtOH to release the final products in good yield with high purity.     

An Efficient Approach to Spirosesquiterrenes. Synthesis of (±)β-Vetivone.

(±)β-Vetivone and (±) 10-epi-β-vetivone have been synthesized in 6 steps via an efficient spiroannelation-functionalization sequence.     

An Efficient Synthesis of the α-D-Glucopyranosyl-(1−>2)-α-L-Rhamnopyranosidic Unit

Abstract

The α-D-glucopyranosyl-(1?>2)-L-rhamnopyranosyl sequence is present in some repeating units of bacterial polysaccharides,¹ as those found in the Shigella type or in various Streptococcal strains.     

An Efficient and Stereoselective Synthesis of (-)-Massoialactone

ThebafkofCmptOcampmassoiQ,fromNet'Guinea,hasbecnusedformWcentUriesasaconshtUentofnahvemedicines.(-)oossoia1actone(1)wasfirstisolatedfromthebafkoil.1ItsplainsimctUretvasassignedtobe1a2andthenconfirmedbyti1eSyntilesisofitSracemate.3toter(-)-Massoialactonewasals0isolatedasadefensesubStancefromtwoSPeCiesoffOnnicineantSofU1egenusCanIPonotuscollectedinWesternAusimlia.4Aflavorsubstanceisolatedfromcanemolasseswasshot`ntobe(-)Alassoia1actone.5ItsabsoluteconfigUrahonwasdetenulnedasRbycomParin…     

One Step Synthesis of α-Substituted α, β-Unsaturated Aldehydes

Abstract

The conversion of carbonyl compounds into cmologated α, β-unsaturated aldehydes (“formylolefination”) is a highly useful transformation in organic synthesis. A large number of methods have been reported for effecting such a chain lengthening. These proceed mainly via silylated intermediates or via phosphorylated reagents. The “phosphonate-strategy” has found widespread use, but leads exclusively to α,β-unsaturated aldehyess, non-substituted in the α-position.     

An Efficient Method for the Synthesis of Aliphatic α-Organothio Aldoximes

Theimportanceofthealiptlatica-organothioaldoxilnecompounds3inthepreparationofvariouspesticidesiswellestablished.Moleculescomprisingthea-organothiooximemoietyhavebeenreportedtoexhibitwiderangeofbiologicalactivities,Suchasinsecticidal.nematocidal,miticidalactivity1'2.Inthesynthesisofthecompounds3,thea-chlorinationofthecorrespolldingaliphaticaldoximeIisthekeystep.Inconventionalmethods.thealiphaticaldoximeIisa-chlorinatedbychlorine(CI=),thentheresultinghydroximeacidchloride2istreatedwithsodiumal…     

An Efficient Synthesis of (±)-Cycloillicinone

An efficient synthesis of (±)-cycloillicinone was accomplished in five steps from sesamol. The title compound was obtained via a biomimetic Diels–Alder cycloaddition between illicinone A and β-trans-ocimene as the key step.     

The First Efficient Approach from α-(-)-Santonin to Dihydroagarofuran Sesquiterpene

The naturally occurring dihydroagarofuran compounds have been demonstrated to show some important bioactive activities, such as insect antifeedant, antitumor activities.¹ Synthetic research of this kind of compounds have been attracting the increasing interest of organic chemists. Because a total synthesis of polyol skeleton involved too many steps,² our synthetic efforts are focusing on search for a short and efficient approach and thus, we begin with readily available α-(-)-santonin(1). The creative key steps include generation of C₅-OH, the stereochemical reversion at C-7 and the cyclization of tetrahydrofuran. A successful approach is shown in the following scheme.     

Synthesis of 2-(2-Thienyl)benzimidazoles by the Reaction of 2-(Mercaptomethyl)benzimidazole With β-Electrophilic Esters

New 2-(2-di- and tetrahydrothienyl)benzimidazole compounds were prepared by the ring closure reactions of 2-(mercaptomethyl)benzimidazole^1,2 (1) and α,β-unsaturated compounds activated with electron-withdrawing groups.     

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.     

One-Pot, Three-Component Coupling Approach to the Synthesis of α-Iminocarboxamides

A one-pot, three-component coupling was accomplished via the nucleophilic addition of an alkylsamarium(III) species to isocyanides and the subsequent addition of the resultant imidoyl samarium(III) species to isocyanates under mild conditions for the formation of α-iminocarboxamides. The developed sequential C-C bond-forming procedure enabled the rapid synthesis of the α-iminocarboxamides in good to excellent yields from readily available starting materials.     

An Efficient Synthesis of 2-Oxazolidinones by Palladium-catalyzed Oxidative Carbonylation of β-Aminoalcohols and 2-Aminophenol under Mild Conditions

Oxidative carbonylation of β-aminoalcohols and 2-aminophenol in Pd(OAc)2/I2 catalytic system to produce the corresponding 2-oxazolidinones was conducted with high yields and selectivities in short reaction time. Mild reaction conditions, high catalytic turnover frequency value, improved yields and selectivities are the remarkable features exhibited by this process.     

Solid-Phase Synthesis of (E)-3-Substituted Acrylonitriles from Polystyrene-Supported α-Selenoacetonitrile

A facile method for solid-phase organic synthesis of (E)-3-substituted acrylonitriles in good yields using polystyrene-supported α-selenoacetonitrile has been developed. The advantages of this method include straightforward operation, lack of odor, good stability, and high purity of the products.     

An Efficient Synthesis of Silyl Dienol Ethers from α, β-Unsaturated Aldehydes and Ketones

α, β-Unsaturated aldehydes and Ketones when reacted with NaBr-Me₃SiCl-Et₃N in DMF at ambient temperature, yield silyl dienol ethers in high yields.     

An Efficient Solid-State Synthesis of N-Aryl-2-phenyldiazenecarboxamides

The subject of organic solid-state synthesis is a fascinating one. It has many advantages such as high efficiency and selectivity, easy separation and purification, mild reaction conditions, and environmental acceptability1. In recent years, this method has been widely used in a variety of organic reactions including substitution2, condensation3, oxidation-reduction4, rearrangement5 and elimination6. However, the solid state reaction using K3Fe(CN)6/KOH to oxidize substituted semicarbazides…     

An Efficient Approach to 6, 7-Disubstituted-lH-quinoxalin-2-ones

A novel approach to the synthesis of 6, 7-disubstituted-1H-quinoxalin-2-ones is described The title compounds were regioselectively prepared by starting from substituted phenylamines and chloroacetyl chloride through the efficient sequence of acylation, nitration, reduction, intramolecular alkylation, and oxidation.     

Application of the Intermolecular α-Amido-alkylation Reaction for the Synthesis of Tertiary Amides and 1-Substituted 2-Acyltetrahydroiso-Quinolines. Synthesis of (±)-Carnegine

Adducts 4 of Schiff bases and 3,4-dihydroisoquinolines with acyl chlorides react with Grignard reagents 5 in an intermolecular α-amidoalkylation reaction to the corresponding tertiary amides or 1-substituted 2-acyltetrahydroisoquinolines.     

Synthesis of (-)-swainsonine and (-)-8-epi-swainsonine by the addition of allenylmetals to chiral α,β-alkoxy sulfinylimines

The asymmetric synthesis of (-)-swainsonine and (-)-8-epi-swainsonine is reported through the addition of either the allenylzinc or the allenyl lithio cyanocuprate reagents derived from [3-(methoxymethoxy)prop-1-ynyl]trimethylsilane to enantiopure α,β-dialkoxy N-tert-butanesulfinylimines derived from d-erythronolactone.     

A Simple and Efficient New Approach to the Total Synthesis of (±)-4-Amino-3-(4-Chlorophenyl)-Butyric Acid (BACLOFEN)

Based on the utilization of a [2+2] cycloaddition reaction between dichloroketene and an appropriated olefin as a key step, we describe a new and simple four step approach to the total synthesis of (±)-4-amino-3-(4-chlorophenyl)-butyric acid (BACLOFEN), a selective GABA_B agonist used as antispastic agent     

Synthesis of β-d-(1→4)-Substituted Trehalose Oligosaccharides

Abstract

Glycosylation of 2,3,6-tri-O-benzyl-α-D-glucopyranosyl 2,3-di-O-benzyl-4,6-O-benzylidene-α-D-glucopyranoside (5) with α-D-glucopyranosyl, α-maltosyl, and α-maltotriosyl bromides 4, 7, and 8 afforded the β-D-(1→4)-substituted trehalose tri-, tetra-, and pentasaccharides 6, 9, and 10 which were fully characterized by ¹H NMR spectroscopy. Deprotection gave the free oligosaccharides 1, 2, and 3.