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 Efficcient Method for α—Alkylation of γ—Butyrolactone

This paper provides a simple ,convenient and mild condition method for α-alkylation of γ-Butyrolactone,Three types of (E)-α-alkenyl-γ-Butyrolactone compounds were synthesized by condensation of corresponding aldehydes and γ-Butyrolactone,suing MeONa and EtONa as base, Then the α-alkyl-γ-Butyrolactone were gained by redcing the former alkenyl compounds through catalytic transfer hydrogenation under Pd/C catalyst with sodium hypophoshite at room temperature.     

Reduction and Reductive Alkylation of α-tert-Butylthio Carbonyl Compounds. An Efficient Method for Stepwise α-Alkylation of Esters,Nitriles and Ketones Via the α-Tert-Butylthio Derivatives

An efficient and generally applicable method for stepwise α-alkylatton of esters, nitriles, and ketones via the α-tert-butylthio derivatives is described. The method involves reductive-protonation and reductive-alkylation of α-alkylthio α,α-bis-alkylated carbonyl compounds which are prepared by stepwise alkylation of the corresponding simple α-alkylthio carbonyl precursors. The reduction is conveniently performed by use of stoichiometric amounts of a dissolving metal, particularly lithium, affording correspondingly the α-mono-and the α,α-bis-alkylated carbonyl compounds in good yields.     

An Efficient Synthesis of 4,4-Dimethyl 5-Methylene-γ-Butyrolactone

Cis^1a and -trans^1b Caronaldehyde acids are crucial intermediates for the synthesis of highly potent photostable pyrethroids like deltamethrin^1c and NRDC-182^1d. Recently these intermediates have been obtained by a total synthetic approach from 3, 4-dihydro-4, 4-dimethyl (2H)-pyran-2(one), know as DDP ^1b. The latter is prepared by a zeolite catalysed thermal rearrangement of 4, 4-dimethyl 5-methuylene-γ-butyrolactone (4). The lactone (4) is thus an important intermediate in the total synthtic sequence leading to potent pyrethroids.     

An Efficient and Convenient Cyclization Method for the Synthesis of Flavans

Flavansrefertoalargegroupofnaturallyoccurringcompoundspossessinga2-phenyl-chromannucleus.Naturallyoccurringflavansexhibitanumberofimportantbiologicalactivitieswhichifexploitedproperly,mayleadtovaluablenewdrugsoragrochemicals'.Inflavansynthesis,thekeystepistoconstructthe3,4-dihydrobenzopyranring-Variousmethodshavebeendevelopedfortheringformation,butmostoftheminvolvemultiplestepsandgivelowoverallyields2.Inthispaper,BF3wasusedforthefirsttimeasanefficientcatalysttoformthepyranringfroml,3-diaryIp…     

Efficient Method for The Synthesis of α-Amidophosphonates via the Michaelis-Arbuzov Reaction

Abstract

A new series of modified α-amidophosphonates (or β-ketophosphonate) was synthesized by an efficient method, starting from aminoesters and chloroacetyl chloride. We have established that chloroacetyl chloride is a suitable reagent allowing the introduction a halogen moiety for the Arbuzov reaction. The α-amidophosphonates were prepared in two steps (acetylation, phosphorylation).

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

An Efficient Solid State Method for Deoximation under Mild Conditions

In recent years, organic reactions conducted in solid state have received increasing attention1 due to short reaction time, mild reaction conditions, excellent selectivity and solvent-free feature. On the other hand, recovery of ketone and aldehyde from o…     

An Efficient Way for Glycosylation of Spirostanol

Using thioglycosides as donors, trimethylsilyl trifluoromethanesulfonate (TMSOTf) and N-iodosuccinimide(NIS) as promoter, a modified procedure for the glycosylation of spirostanol was developed. A series of saponins were synthesized in mild condition with excellent yields.     

An Efficient Synthesis of Heterocyclic Substituted Ureidoalkylphosphonates

Inarecentreport',a-aminoalkylphosphonateswithpyrazoIemoietyshowedverygoodinhibitoryeffectsagainstplantvirus.Inaddition,a-aminoalkylphosphonicacidsserveforinhibitingenZymeactivity,bacterialgrowthandinagrochemistryasantifungalagents,herbicidesandplantregulators'.Thereforeconsideringthewideapplicationsofsuchcompoundsandthebioactivitiesofheterocycliccompoundsandureaderivatives,wedesignedtosynthesizealargevarietyofheterocyclicsubstitutedureidoalkylphosphonates3.Thereportedmethodforsynthesisofsubst…     

Photoactive Chiral Metal-Organic Frameworks for Light-Driven Asymmetric α-Alkylation of Aldehydes

Chiral metal-organic frameworks (MOFs) with porous and tunable nature show promise as heterogeneous asymmetric catalysts. Through incorporating the stereoselective organocatalyst l- or d-pyrrolidin-2-ylimidazole (PYI) and a triphenylamine photoredox group into a single framework, we have developed two enantiomeric MOFs, Zn-PYI1 and Zn-PYI2, to prompt the asymmetric α-alkylation of aliphatic aldehydes in a heterogeneous manner. The strong reductive excited state of the triphenylamaine moiety within these MOFs initiated a photoinduced electron transfer, rendering an active intermediate for the α-alkylation. The chiral PYI moieties acted as cooperative organocatalytic active sites to drive the asymmetric catalysis with significant stereoselectivity. Control experiments using the lanthanide-based metal-organic frameworks Ho-TCA and MOF-150, assembled from 4,4',4″-nitrilotribenzoic acid, as catalysts suggested that both the photosensitizer triphenylamine moiety and the chiral organocatalyst d-/l-PYI moiety were necessary for the light-driven α-alkylation reactions. Further investigations demonstrated that the integration of both photocatalyst and asymmetric organocatalyst into a single MOF makes the enantioselection superior to that of simply mixing the corresponding MOFs with the chiral adduct. The easy availability, excellent stereoselectivity, great separability, and individual components fixed with their well-defined porous and repeating structures make the MOF a versatile platform for a new type of tandem catalyst and cooperative catalyst.     

An Efficient Synthetic Method of Nordihydroguaiaretic Acid（NDGA）

Nordihydroguaiaretic acid(NDGA)has been synthesized in nine steps from piperonal using Stobbe condensation as the key step with high yield.By this approach,five relative natural products were obtained.     

A simple and convenient method for direct α-chlorination of ketones with ammonium chloride and Oxone~

When ketones were treated with ammonium chloride and Oxone~ in MeOH at room temperature,a directα-chlorination of ketones was occurred and a series of the corresponding a-chloroketones were obtained in moderate to good yields after 24 h.In this reaction,ammonium chloride was used as the source of chlorine and Oxone~ was used as an oxidant.This method was simple, convenient and providing a novel procedure for preparation of a-chloroketones.     

Reactions of α-Formyl-α-Chlorcyclonones and γ-Butyrolactone with S-Trirnethylsilyl Ester of Dialkyldithiophosphoric Acid

Abstract

α-Formyl-α-chlorsubstituted cyclonones or α-formyl-α-chlor-γ-butyrolactone react with O,O-diizopropyltrimethylsilyldithiophosphate to give adducts which rearrange thermaly to α- dithiophos phoryl contained β-dicarbonic compounds.     

An Efficient and Novel Method for the Synthesis of β-Aroylpropionic Acids Under Solvent-Free Conditions

Abstract

A simple and rapid reaction of succinic anhydride with aromatic hydrocarbons is described. The reaction is conducted under Friedel–Crafts conditions in the absence of solvent at room temperature using aluminium chloride as catalyst.     

An Efficient Method for The Preparation of w,w′-bis-Urethane Protected Arginine Derivatives

Fmoc-Arg^{w, w′}(Boc)₂-OH and Boc-Arg^{w, w′}(Cbz)₂-OH were prepared in two steps: Guanylation of Cu(II)-ornithine complex at N^δ with N, N′bis-urethane protected derivatives of 1-guanylpyrazole, followed by N^α-protection using either 9-fluorenylmethyl succinimidylcarbonate or di-t-butyl-dicarbonate in the presence of EDTA. The overall yields of these products (2 steps) were 65% and 73%.     

Synthesis of Optically Active β-Alkyl-α-methylene-γ-butyro- lactones from Enantioselective Biotransformation of Nitriles, an Unusual Inversion of Enantioselectivity

ＩｎｔｒｏｄｕｃｔｉｏｎＢｉｏｔｒａｎｓｆｏｒｍａｔｉｏｎｓｏｆｎｉｔｒｉｌｅｓ ,ｅｉｔｈｅｒｔｈｒｏｕｇｈａｎｉｔｒｉ ｌａｓｅ ｃａｔａｌｙｚｅｄｄｉｒｅｃｔｃｏｎｖｅｒｓｉｏｎｔｏｔｈｅｃａｒｂｏｘｙｌｉｃａｃｉｄｓｏｒｖｉａａｎｉｔｒｉｌｅｈｙｄｒａｔａｓｅ ｃａｔａｌｙｚｅｄｈｙｄｒａｔｉｏｎｔｏｔｈｅａｍｉｄｅｓｆｏｌｌｏｗｅｄｂｙｔｈｅｈｙｄｒｏｌｙｓｉｓｔｏｔｈｅａｃｉｄｓｍｅｄｉａｔｅｄｂｙａｎａｍｉｄａｓｅ ,ｈａｖｅｐｒｏｖｉｄｅｄａｕｓｅｆｕｌａｎｄｅｎｖｉｒｏｎｍｅｎｔａｌ…     

Studies on Reactivity of Pyridinium Chlorochromate — Iodine System: An Efficient Method for Converting Enol Silyl Ethers into α-Iodo Ketones

A new synthesis of α-iodo carbonyl derivatives is described. They are obtained, in very high yields, through an original and efficient procedure, by reaction of enol silyl ethers with I₂-PCC system.     

Tween-20: An Efficient Catalyst for One-Pot Synthesis of α-Aminophosphonates in Aqueous Media

Abstract

A green one-pot three-component synthesis has been developed for α-aminophosphonates by condensation of aldehydes, amines, and diethylphosphite by using nonionic surfactant Tween-20 as catalyst in aqueous media. The results showed that this synthetic route for α-aminophosphonates takes just 25–60 min for completion at 60 °C and affords 64%–91% yields depending on the nature of the amine substrates. The major advantages of this novel method are green reaction conditions with water as solvent, simple workup, less reaction times, and high to moderate yields.