Showing papers on "Alkylation published in 1984"
TL;DR: In this paper, α-hydroxy- and α-mercapto-carboxylic acids are condensed with pivalaldehyde to give 2-t-butyl-5-substituted-l, 3-dioxolanones or 1,3-oxathiolanones.
254 citations
TL;DR: In this paper, N-Acetanilid (I, II, III, IV, V, VI, VII, VIII, IX, and IX) in MeCN bei Gegenwart von Pd(OAc)2 nach Verfahren A.
Abstract: Durch Reaktion von N-Acetanilid (I) oder der substituierten N-Acetanilide (IV) bzw. (VI) mit Methyliodid (IIa) bzw. Ethyliodid (IIb) in MeCN bei Gegenwart von Pd(OAc)2 nach Verfahren A) werden die o-Alkylderivate (III), (V) bzw. (VII) erhalten.
239 citations
TL;DR: In this paper, the stereoselectivity of α-alkylation of chiral β-hydroxy ester is discussed and the configuration of the alkylated product was proved chemically.
228 citations
196 citations
TL;DR: On prepare des phosphonamides derivees du benzodiazaphosphole et on effectue l'olefination asymetrique de plusieurs cyclohexanones substituees as discussed by the authors.
Abstract: On prepare des phosphonamides derivees du benzodiazaphosphole et on effectue l'olefination asymetrique de plusieurs cyclohexanones substituees
138 citations
TL;DR: Trans-2,5-Bis(methoxymethyl)- and trans-2.5-bis(methyl)pyrrolidines proved to be excellent chiral auxiliaries for the asymmetric alkylation of the corresponding carboxyamide enolates giving good chemical yield and high stereoselectivity as discussed by the authors.
115 citations
TL;DR: Alkylation de carbonate et d'hydrogeno carbonate de K a l'aide d'α-chlorotoluene du halogenomethane en presence of 18-crown-6, ou de sels de tetraalkyl-ammonium dans le toluene ou le N,N-dimethyl acetamide.
Abstract: Alkylation de carbonate et d'hydrogeno carbonate de K a l'aide d'α-chlorotoluene du halogenomethane en presence de 18-crown-6, ou de sels de tetraalkyl-ammonium dans le toluene ou le N,N-dimethyl acetamide
106 citations
TL;DR: In this paper, a comparison of the isomers produced by toluene disproportionation to produce p -xylene (and benzene) with alkylation to produce ethyltoluene, revealed that with the same catalyst, it is more para-selective than xylene.
106 citations
TL;DR: A stereospecific method is described for the alkylation of acyclic amino acids (alanine and phenylalanine) which proceeds with retention of configuration and involves conversion of the amino acid to the predominantly cis 2-aryl-3-carbobenzyloxy oxazolidinones.
105 citations
TL;DR: Diastereoselective alkylation de lithio enamines obtenues a partir d'α-alkyl β-cetoesters et du (S)-valinate de t-butyle as discussed by the authors.
Abstract: Diastereoselective alkylation de lithio enamines obtenues a partir d'α-alkyl β-cetoesters et du (S)-valinate de t-butyle
TL;DR: In this article, a comparative study of the products of l'alkylation catalytique d'acetates allyliques and the corresponding complexes cationiques (η 3 -allyl) palladium correspondants is presented.
TL;DR: In this article, a general α-alkylation of acyclic ketones is described, which allows the overall enantioselective α-alkylation in good overall yields (44-86%,, 4 steps) and enanti-oselectivities ranging routinely from > 94% ee up to virtually complete asymmetric induction (99.5%ee).
TL;DR: In this article, the reaction of phenol with methanol was carried out over five X-, six Y- and three ZSM-zeolites, in a fixed-bed continuous reactor at 250°C.
TL;DR: Etude des alkylations catalysees par W(CO) 3 (CH 3 CN) 3 des methyl phenyl-5 pentadiene-2,4yl carbonate, acetate de phenyl 1 pentadienes-1,4yle-3 and acetate of phenyl1 pentadiENE-2.4yle a l'aide du malonate de dimethyle as discussed by the authors.
Abstract: Etude des alkylations catalysees par W(CO) 3 (CH 3 CN) 3 des methyl phenyl-5 pentadiene-2,4yl carbonate, acetate de phenyl-1 pentadiene-1,4yle-3 et acetate de phenyl-1 pentadiene-2,4yle a l'aide du malonate de dimethyle
TL;DR: In this paper, a two-step process for alkylation of aldonolactones was described, which is relevant to the synthesis of mycotoxins, including citreoviridin and aurovertin B. The resulting enol ethers are of value as potential substrates for glycosidase enzymes.
TL;DR: T-butylation du phenol, benzenediols, biphenylediol-4,4', furanne, thiophene et methyl-1 indole par le bromure de t-butyle en presence de gel de silice.
Abstract: t-Butylation du phenol, benzenediols, biphenylediol-4,4', furanne, thiophene et methyl-1 indole par le bromure de t-butyle en presence de gel de silice
TL;DR: In this article, les reactions des derives styryl-Q and diphenyl-1,1 vinyl-Q (Q=Bn 3 Sn, HgCl,HgB 2, I, C 6 H 5 SO 2, C 6H 5 SO, C6 H 5 S) avec des halogenures d'alkyl-Hg conduisant a divers alcenes
Abstract: On etudie les reactions des derives styryl-Q et diphenyl-1,1 vinyl-Q (Q=Bn 3 Sn, HgCl, HgB 2 , I, C 6 H 5 SO 2 , C 6 H 5 SO, C 6 H 5 S) avec des halogenures d'alkyl-Hg conduisant a divers alcenes
TL;DR: The nucleophilic hydroxymethylation of aldehydes and ketones has been achieved by the reaction with the (isopropoxydimethylsilyl)methyl Grignard reagent and the subsequent oxidative cleavage of the carbon-silicon bond as discussed by the authors.
01 Jan 1984
TL;DR: In this article, the authors propose an asymmetric synthesis of chiral synthons via Intraannular Chirality Transfer (ICT) and extraannular chirality transfer.
Abstract: I. Prologue 2 II. Selective Enolate Formation 6 A. Introduction 6 B. Determination of Enolate Geometry 12 C. Enolization of Acyclic Carbonyl Derivatives 14 III. Enolate Structure 21 IV. Transition-State Control Elements 23 A. Introduction 23 B. Stereoelectronic Effects 25 C. Steric Effects 29 V. Intraannular Chirality Transfer 30 A. Introduction 30 B. Exocyclic Enolates 31 C. Five-Membered Endocyclic Enolates 37 D. Enolates in the Norbornyl Ring System 45 E. Six-Membered Endocyclic Enolates 50 F. Asymmetric Synthesis of Chiral Synthons via Intraannular Chirality Transfer 73 VI. Chelate-Enforced Intraannular Chirality Transfer 80 A. Introduction 80 B. Asymmetric Synthesis of Chiral Synthons via Chelate-Enforced Intraannular Chirality Transfer . . . . 83 VII. Extraannular Chirality Transfer 93 VIII. Conclusions 100 References 101
TL;DR: The data indicate that benzyne, formed by enzymatic oxidation of 1-aminobenzotriazole, is responsible for inactivation of cytochrome P-450 and chloroperoxidase.
TL;DR: In this article, the reactions of nitrile-stabilized anions are grouped according to the nature of the substituents attached to the carbanion center bearing the n-group, including alkyl, alkenyl, alkynyl, and aryl groups.
Abstract: The utilization of carbanions stabilized by various electron-withdrawing groups to effect carboncarbon bond formation occupies a central position in organic synthesis. This chapter focuses on the reactions of nitrile-stabilized carbanions with an array of carbon electrophiles and updates another chapter along these lines in this series. Subsequent review articles have dealt with various aspects of the chemistry of nitrile-stabilized carbanions. In this review, the reactions of nitrile-stabilized anions are grouped according to the nature of the substituents attached to the carbanion center bearing the nitrile group. These substituents include alkyl, alkenyl, alkynyl, and aryl groups as well as various α-oriented halogen-, oxygen-, nitrogen-, sulfur-, and selenium-containing groups. Notably absent from this survey are the carbanions derived from active methylene compounds bearing two electron-withdrawing groups such as cyanoacetate esters, malononitriles, α-sulfonylnitriles, and α-phosphorylnitriles. Also absent are those carbanions such as Reissert compounds, which are the subject of comprehensive reviews.
The chapter is arbitrarily subdivided into six sections: (1) reactions of alkyl-, aryl-, and heteroaryl-substituted nitriles; (2) reactions of α,β- and β,γ-unsaturated nitriles as well as tolunitriles; (3) reactions of cyanohydrins and their hydroxyl-protected derivatives; (4) reactions of nitriles bearing α-sulfur and α-selenium substituents; (5) reactions of α-(dialkylamino)nitriles; and (6) reactions of α-halonitriles. Within each of these sections, the reactions are further subdivided according to the nature of the electrophile: (1) alkylation reactions employing alkyl halides, alkyl sulfonates, dialkyl sulfates, and epoxides; (2) arylation reactions involving the substitution of hydrogen, halogen, nitro, or alkoxy groups on aryl or heteroaryl substrates; (3) acylation reactions employing carboxylic esters, anhydrides, acid chlorides, dialkyl carbonates, and nitriles; (4) addition reactions involving aldehydes, ketones, imines, alkenes, and alkynes; and (5) Michael-type addition reactions to unsaturated aldehydes, ketones, imines, sulfoxides, sulfones, and nitro compounds. Finally, a section involving cyclization reactions is included for each of the six groups of nitrile-stabilized anions.
Keywords:
addition;
substitution;
nitriles;
anions;
scope;
limitations;
protected cyanohydrins anions;
halonitrile stabilized carbanions;
alkylations;
side reactions;
arylation;
vinylation;
acylation;
Michael acceptors;
ketones;
aldehydes;
Darzens reaction;
olefins;
nitrile stabilized carbanions;
sulfur substituents;
selenium substituents;
(dialkylkylamino)nitriles;
unsaturated nitriles;
experimental procedures
TL;DR: Substituted carbohydrate derivatives (D-gluco, D-manno, and D-galacto) having two free hydroxyl groups were converted into their metal chelates by reaction with sodium hydride and a metal chloride in either oxolane or 1,2-dimethoxyethane and disubstitution was absent.
TL;DR: In this article, the decays of 13C n.m.r. spectra of coal and its reductive methylation and butylation products have been studied by magnetic resonance techniques.
TL;DR: In this paper, the incorporation of hydrophobic vitamin B12 derivatives into the single-compartment vesicles of N,N-didodecyl-Nα-[6-(tyimethylammonio)hexanoyl]-L-alaninamide bromide (N+C5Ala2C12) was found to be primarily concerned with the extent of insolubility of the cobalt complexes in the aqueous bulk phase, while such incorporation into single-walled VB12 derivatives was enhanced by the coordination interaction between the cob
Abstract: The incorporation of hydrophobic vitamin B12 derivatives into the single-compartment vesicles of N,N-didodecyl-Nα-[6-(tyimethylammonio)hexanoyl]-L-alaninamide bromide (N+C5Ala2C12) was found to be primarily concerned with the extent of insolubility of the cobalt complexes in the aqueous bulk phase, while such incorporation into the single-walled vesicles of N,N-ditetradecyl-Nα-[6-(trimethylammonio)hexanoyl]-L-histidinamide bromide (N+C5His2C14) was enhanced by the coordination interaction between the cobalt complex and the imidazolyl group of the lipid. In molecular aggregates formed with hexadecyltrimethylammonium bromide, α-[4-(1,1,3,3-tetramethylbutyl)phenyl]-ω-hydroxypoly(oxyethylene), or N+C5Ala2C12, the alkylation rates of a hydrophobic vitamin B12 with 1-bromo-2-methylpropane and methyl 2-methyl-3-bromopropanoate were much enhanced relative to those in methanol. In the N+C5Ala2C12 vesicle, a two-step mechanism was observed for the alkylation with the latter reagent. The possible origin of such rate...
TL;DR: A series of 5-cyano-6-aryluracils and 2-thiouracils have been prepared and alkylated to 1,3-dialkyluracILS 2a-d and 2alkylthiourACils, 3, 4 and 6, by electrophilic substitution with alkyl halides.
TL;DR: A total synthesis of polyamines was developed using potassium phthalimide as a sole nitrogen source and the alkylation using KF-Celite was extremely useful for the synthesis of spermidine and spermine.
Abstract: A total synthesis of polyamines was developed using potassium phthalimide as a sole nitrogen source. 15N-Enriched phthalimide was prepared almost quantitatively from 15N-enriched ammonium sulfate by a modified method. Key compounds for the synthesis of 15N-enriched spermidine and spermine were 15N-enriched putrescine (I), N-(3-bromopropyl)-phthalimide (II), N-(4-bromobutyl) phthalimide (III), and benzylamine, which were easily prepared in high yields from potassium 15N-enriched phthalimide. Spermidine was synthesized by two alternative methods involving an alkylation of monobenzyloxycarbonyl putrescine with II and a stepwise alkylation of benzylamine with II and III in the presence of KF-Celite. The lattter method allowed the preparation of all seven kinds of various 15N-enriched spermidines with combinations of the three reagents containing 15N or 14N. Spermine was similarly synthesized by an alkylation of N, N'-dibenzylputrescine with II. In these methods, the alkylation using KF-Celite was extremely useful for the synthesis of spermidine and spermine. The present methods were also used to synthesize various other polyamines in high yields.
TL;DR: In this paper, the title reaction in the presence of tetrakis(triphenylphosphine)palladium(0) affords alkylative coupling products in good to excellent yields in 1,2-dichloroethane at room temperature.
Abstract: The title reaction in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(0) affords alkylative coupling products in good to excellent yields in 1,2-dichloroethane at room temperature. This coupling reaction under C(sp2)–O cleavage proceeds stereospecifically. The reaction does not affect a coexisting vinyl sulfide group. This feature enables 1,2- and 1,3-carbonyl transposition with or without alkylation via phenylthio-substituted enol phosphates.