Heterocyclic compounds Communication 60. Synthetic anesthetics XXI synthesis of esters of the α-forms of 1-alkenyl-2.5-dimethyl-4-piperidinols

Russian Chemical Bulletin -     

α-hydroaxyalkyl(benzyl)furozans and α-hydroxyalkyl(benzyl)furoxans synthesis and reactivity

A general and simple preparative method for the synthesis of -hydroxyalky(benzyl)furazan and -furoxan derivatives is proposed, The method involves reduction of acyl or ethoxycarbonyl substituents in these heterocyclic compounds with NaBH₄ in ethanol. Based on the alcohols thus prepared, a number of previously unknown functional derivatives (-nitroxyalkyl--haloalkyl-, and -azidoalkylfurazans and -furoxans) have been synthesized.Translated fromInvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7. pp, 1782–1788, July, 1996.     

Study of the enantioselectivity of the CAL-B-catalysed transesterification of α-substituted α-propylmethanols and α-substituted benzyl alcohols

A study of the enantioselectivity exhibited by the lipase B from Candida antarctica in the transesterification of different α-substituted α-propylmethanols with vinyl acetate is shown. The best results are obtained when the large-sized (L) substituent of the alcohol is either a phenyl group or more especially a cyclohexyl group, although the reaction rates are lower than when linear or slightly branched groups are present. It is also found that ramification at the β-position of the L substituent has a deleterious effect on both lipase activity and enantioselectivity. Moreover, some α-substituted benzyl alcohols bearing medium-sized (M) substituents larger than an ethyl and smaller than a propyl group are resolved by means of this methodology with moderate-good enantioselectivities (E=46–57) and similar reaction rates.     

Oxidation of benzyl alcohols with difluoro(aryl)-λ-bromane: formation of benzyl fluoromethyl ethers via oxidative rearrangement

Oxidative rearrangement of benzyl alcohols with difluoro(p-trifluoromethylphenyl)-λ³-bromane (5 × 10⁻² M) in chloroform at room temperature afforded aryl fluoromethyl ethers selectively in good yields, probably via 1,2-shift of aryl groups from benzylic carbon to oxygen atoms.     

Iron porphyrins-catalysed oxidation of α-alkyl substituted mono and dimethoxylated benzyl alcohols

The mechanisms of oxidation of a series of a-alkyl substituted mono and dimethoxylated benzyl alcohols catalysed by mesotetrakis(4-N-methylpyridynium)porphyrin iron (III) chloride (FeTMPyPCl) and meso-tetrakis(4-sulfonatophenyl)porphyrin iron (III) chloride (FeTSPPCl) in aqueous solution with KHSO₅ as oxygen atom donor and by meso-tetrakis(pentafluorophenyl)-porphyrin iron (III) chloride (FeTPFPPCl) in dichloromethane employing iodosylbenzene as oxidant have been investigated. In the highly polar aqueous medium an electron transfer mechanism is operating. With FeTMPyPCl, which is a much more efficient catalyst than FeTSPPCl due to the presence of stronger electron withdrawing substituents, formation of side-chain oxidation products accompanies generation of nuclear oxidation products. In the low polar solvent dichloromethane, two competing mechanism have been suggested: hydrogen atom transfer and formation of a complex between the active species iron-oxo porphyrin radical cation and the substrate.      

Synthesis of α-alkyl- and α,α-dialkyl-β-phenyltryptamines

A new method was developed for the synthesis of -alkyl- and ,-dialkyl--phenyltryptamines based on alkylation of nitroalkanes with -phenyl-nor-gramine.     

Asymmetric synthesis of α-alkyl-α-hydroxy-γ-butyrolactones

A new enantioselective approach to α-alkyl-α-hydroxy-γ-butyrolactones employing (1R,2S)-ephedrine-derived chiral allyl morpholinones as starting materials is described.     

Novel α-methyl(benzyl)deoxyvasicinones

A method was developed to prepare -methyl(benzyl)deoxyvasicinones by alkylation of -hydroxy- methylidenedeoxyvasicinone. It has been shown that the reaction proceeds anomalously through a deformylation step.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 407–409, September–October, 2004.     

Novel Phosphonoacetic Acid Derivatives.Synthesis of N-(Ethoxycarbonylmethylphosphonyl)-α-Amino Esters and-α-Amino Phosphonic Acid Esters and Their Bioactivities

PhopendcaCulopA)anditsanalog.PhoSP~cedd(PAA,havboknOWntohavPOtentantiviIalaCtivityagainStviruses,withetw~exvirustwIndIIcoV-I,HSVap['].~r,PAAaPpearStohavahightwforbOnthaIhaypeitsuseinhumans[21,wh~PFAhas~eddricallya~HSVIndHSV-if'l.Here,wedesgnedndSynthesiredanUmberofnewderiv~s(DOfPAAwiththendofpotenhatinitSboactivity~endnigtokicdri,atthesamtiIntostiInulatetheactivityofatnineddsorndnoPhoSPhoulcottyPhOSPhonyation.Intbenew~theNedofamineddsoraminPhoSPhotheotwasbonantoghatomor…     

Stereocontrolled Synthesis of (E)-β,γ-Unsaturated Esters via Palladium-Catalyzed Cross-Coupling of (E)-Alkenylboronic Acids with α-Bromoacetic Esters

The cross-coupling reaction of trans-alkenylboronic acids with a-bromoacetic esters was firstly studied. It was found that using Pd(OAc)2 as catalyst, a bulky electron-rich phospine, (2-dicyclohexylphospino-biphenyl) as ligand, the reaction can be readily accomplished to give specific (E)-b,g-unsaturated esters in high yields.     

Synthesis of optically active α-(allenyl)- and α-substituted-α-(allenyl)glycines

The synthesis of various types of optically active α-(allenylsilane-containing)glycines via a chirality-transferring ester-enolate Claisen rearrangement of α-acyloxy-α-alkynylsilanes is described. The conversion of the rearranged products into the optically active silicon-free α-(allenyl)- and α-substituted-α-(allenyl)glycines was achieved by the removal of the Me₂PhSi- or TMS group from the allene terminus.     

Dehydrochlorination of trichloro(α,β-dichlorophenethyl)-silane and of trichloro[α-chloro-α-(chloromethyl)benzyl]silane

Summary The general character of the rearrangement undergone by ,-dichloroalkyltrichlorosilanes in the course of their dehydrochlorination by means of aluminum chloride was confirmed by reference to a new example of the reaction.     

New Synthesis of α-Bromo-α,β-Unsaturated Esters

A synthesis of α-bromo-α,β-unsaturated esters 2 from tert-butyl α-(trimethylsilyl)-α-bromoacetate (1) and carbonyl compounds is described.     

Metallation of benzyl selenides and of α-aryl selenoacetals. Scope and limitations.

α-Metallo benzylselenides and α-metallo selenoacetals derived from aromatic aldehydes have been conveniently prepared by metallation of the corresponding carbon acids. KDA in THF proved among the various basic systems tested, the most efficient.α-Metallo benzylselenides and α-metallo selenoacetals derived from aromatic aldehydes have been conveniently prepared by metallation with KDA of the corresponding carbon acids. These reactions have been used for the synthesis of arylalkanes, including those bearing a trialkylated benzylic carbon, from aromatic aldehydes.     

Synthesis and free-radical polymerization of methyl α(p-substituted benzyl)acrylates

Methyl α-p-chlorobenzylacrylate and methyl α-p-methoxybenzylacrylate were synthesized from dimethylmalonate by well known organic reactions. Both monomers were polymerized by a free-radical mechanism in benzene and their ceiling temperature determined. Comparison of the ceiling temperatures with that of methyl α-benzylacrylate seems to indicate that the differences in entropic factor for the polymerization of methyl α(p-substituted benzyl)acrylates might be related to the differences in ceiling temperatures.