scholarly journals The Synthesis and Reactions of Chiral Sulfonium Ylids

1974 ◽  
Vol 52 (16) ◽  
pp. 2953-2959 ◽  
Author(s):  
Stewart J. Campbell ◽  
D. Darwish
Keyword(s):  
Acetic Anhydride ◽  
Room Temperature ◽  
Dimethyl Sulfate ◽  
Phenyl Isocyanate ◽  
Methyl Sulfate ◽  
Pyramidal Inversion ◽  
Benzoic Anhydride

Treatment of (−)-ethylmethylsulfonium phenacylid, (−)-1, in THF at room temperature with 15 equiv. of benzoic anhydride, acetic anhydride or 1 equiv. phenyl isocyanate produces the corresponding (−)-ethylmethylsulfonium diacylmethylids, (−)-5, (−)-6, and (−)-8. Treatment of (−)-1 with dimethyl sulfate in acetone gives (Z)-(+)-ethylmethyl-α-methoxy-β-styrylsulfonium methyl sulfate, (+)-10. Resolution of (±)-10 via its DBT salt and conversion to perchlorate gives the corresponding vinyl perchlorates (+)- and (−)-13. Under the resolution conditions the ketal perchlorates, (−)- and (+)-ethylmethyl-2,2-dimethoxy-2-phenylethylsulfonium perchlorate, (−)- and (+)-14, are also obtained. The rates of racemization at 50° in benzene of 1, 5, 6, and 8 are 39.7, 55.5, 106, and 79.1 × 10−5 s−1 respectively. The rates of racemization at 50° in methanol of 10, 13, and 14 are 1.93, 2.08, and 5.64 × 10−5 s−1. Racemization is proposed to proceed via pyramidal inversion. The synthetic potential of chiral sulfonium ylids is discussed with respect to their ease of racemization.

Reactions of 1-Phenyl-1,2,3-triazolyllithium Compounds; Formation of Ketenimines, Alkynylamines, and Heterocycles from the Ambident (N-Phenyl)phenylketenimine Anion

1971 ◽  
Vol 49 (11) ◽  
pp. 1792-1798 ◽  
Author(s):  
R. Raap
Keyword(s):  
Methyl Iodide ◽  
Heterocyclic Compound ◽  
Room Temperature ◽  
Dimethyl Sulfate ◽  
Phenyl Isocyanate ◽  
Ambident Anion ◽  
Membered Heterocyclic Compound

At room temperature 1,4-diphenyl-1,2,3-triazolyllithium rapidly undergoes fragmentation to nitrogen and lithium (N-phenyl)phenylketenimine anion 8c, [Formula: see text]. Some of the reactions of this ambident anion have been studied. Reaction of 8c with methyl iodide results in C-methylation to a mixture of (N-phenyl)methylphenylketenimine and 3-methyl-1,3-diphenyl-4-(2′-phenylethylene)-2-phenyliminoazetidine. A six-membered heterocyclic compound, 6-anilino-1,3,5-triphenyluracil, results from the reaction between 8c and phenyl isocyanate. With dimethyl sulfate and methyl chloroformate N-alkylation and N-acylation takes place predominantly, forming N-methyl-N-phenyl-2-phenylethynylamine and N-carbomethoxy-N-phenyl-2-phenylethynylamine respectively. Reaction of 8c with methanol and ethanethiol gives an iminoester and an iminothioester respectively.1-Phenyl-1,2,3-triazolyllithium and 4-methyl-1-phenyl-1,2,3-triazolyllithium undergo fragmentation at somewhat higher temperatures.

New Potential Biologically Active Compounds: Synthesis and Characterization of Urea and Thiourea Derivativpes Bearing 1,2,4-oxadiazole Ring

2020 ◽  
Vol 17 (7) ◽  
pp. 525-534 ◽  
Author(s):  
Nevin Arıkan Ölmez ◽  
Faryal Waseer
Keyword(s):  
Microwave Irradiation ◽  
Room Temperature ◽  
Antimicrobial Activities ◽  
Phenyl Isocyanate ◽  
Single Step ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Active Compounds ◽  
Thiourea Derivatives ◽  
Acyl Chlorides

Background: Urea, thiourea, and 1,2,4-oxadiazole compounds are of great interest due to their different activities such as anti-inflammatory, antiviral, analgesic, fungicidal, herbicidal, diuretic, antihelminthic and antitumor along with antimicrobial activities. Objective: In this work, we provide a new series of potential biologically active compounds containing both 1,2,4-oxadiazole and urea/thiouprea moiety. Materials and Methods: Firstly, 5-chloromethyl-3-aryl-1,2,4-oxadiazoles (3a-j) were synthesized from the reaction of different substituted amidoximes (2a-j) and chloroacetyl chloride in the presence of pyridine by conventional and microwave-assisted methods. In the conventional method, 1,2,4-oxadiazoles were obtained in two steps. O-acylamidoximes obtained in the first step at room temperature were heated in toluene for an average of one hour to obtain 1,2,4-oxadiazoles. The yields varied from 70 to 96 %. 1,2,4-oxadiazoles were obtained under microwave irradiation in a single step in a 90-98 % yield at 160 °C in five minutes. 5-aminomethyl-3-aryl-1,2,4- oxadiazoles (5a-j) were obtained by Gabriel amine synthesis in two steps from corresponding 5-chloromethyl-3- aryl-1,2,4-oxadiazoles. Finally, twenty new urea (6a-j) and thiourea (7a-j) compounds bearing oxadiazole ring were synthesized by reacting 5-aminomethyl-3-aryl-1,2,4-oxadiazoles with phenyl isocyanate and isothiocyanate in tetrahydrofuran (THF) at room temperature with average yields (40-70%). Results and Discussions: An efficient and rapid method for the synthesis of 1,2,4-oxadiazoles from the reaction of amidoximes and acyl halides without using any coupling reagent under microwave irradiation has been developed, and twenty new urea/thiourea compounds bearing 1,2,4-oxadiazole ring have been synthesized and characterized. Conclusion: We have synthesized a new series of urea/thiourea derivatives bearing 1,2,4-oxadiazole ring. Also facile synthesis of 3,5-disubstituted 1,2,4-oxadiazoles from amidoximes and acyl chlorides under microwave irradiation was reported. The compounds were characterized using FTIR, 1H NMR, 13C NMR, and elemental analysis techniques.

Das dynamische Verhalten des 1-Methyl-1-benzothiepinium-Ringsystems/The Dynamic Behaviour of the 1-Methyl-1-benzothiepinium Ring System

1981 ◽  
Vol 36 (8) ◽  
pp. 974-977 ◽  
Author(s):  
Hans Hofmann ◽  
Franz Dickert
Keyword(s):  
Nmr Spectroscopy ◽  
Room Temperature ◽  
Dynamic Behaviour ◽  
Ring System ◽  
Membered Ring ◽  
Ring Inversion ◽  
Methyl Group ◽  
H Nmr ◽  
Pyramidal Inversion ◽  
Mutual Conversion

Abstract By 1H NMR spectroscopy the stereochemistry of the 1-methyl-1-benzothiepinium ring system was investigated both in thermodynamic and kinetic respects. It was shown that in solution a rapid mutual conversion of the boat shaped seven membered ring system with exo-respectively endo-S-methyl group occurs via a ring inversion and not by a pyramidal inversion at the sulfonium ion. At room temperature predominantly the conformation with the exo-S-methyl group is present.

scholarly journals Efficient Synthesis of α-Branched Purine-Based Acyclic Nucleosides: Scopes and Limitations of the Method

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4307
Author(s):  
Jan Frydrych ◽  
Lenka Poštová Slavětínská ◽  
Martin Dračínský ◽  
Zlatko Janeba
Keyword(s):  
Acetic Anhydride ◽  
Room Temperature ◽  
Side Chain ◽  
Efficient Synthesis ◽  
Purine Derivatives ◽  
Aliphatic Side Chain ◽  
Acyclic Nucleosides ◽  
Efficient Route ◽  
High Yields ◽  
Trimethylsilyl Trifluoromethanesulfonate

An efficient route to acylated acyclic nucleosides containing a branched hemiaminal ether moiety is reported via three-component alkylation of N-heterocycle (purine nucleobase) with acetal (cyclic or acyclic, variously branched) and anhydride (preferentially acetic anhydride). The procedure employs cheap and easily available acetals, acetic anhydride, and trimethylsilyl trifluoromethanesulfonate (TMSOTf). The multi-component reaction is carried out in acetonitrile at room temperature for 15 min and provides moderate to high yields (up to 88%) of diverse acyclonucleosides branched at the aliphatic side chain. The procedure exhibits a broad substrate scope of N-heterocycles and acetals, and, in the case of purine derivatives, also excellent regioselectivity, giving almost exclusively N-9 isomers.

scholarly journals A simple and effective preparation of quercetin pentamethyl ether from quercetin

2018 ◽  
Vol 14 ◽  
pp. 3112-3121 ◽  
Author(s):  
Jin Tatsuzaki ◽  
Tomohiko Ohwada ◽  
Yuko Otani ◽  
Reiko Inagi ◽  
Tsutomu Ishikawa
Keyword(s):  
Hydrogen Bonding ◽  
Dimethyl Sulfoxide ◽  
Room Temperature ◽  
Computational Study ◽  
Dimethyl Sulfate ◽  
Intramolecular Hydrogen Bonding ◽  
Single Product ◽  
Oh Groups ◽  
Methylation Product ◽  
Intramolecular Hydrogen

Among the five hydroxy (OH) groups of quercetin (3,5,7,3',4'-pentahydroxyflavone), the OH group at 5 position is the most resistant to methylation due to its strong intramolecular hydrogen bonding with the carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pentamethyl ether efficiently by conventional methylation. Here, we describe a simple and effective per-O-methylation of quercetin with dimethyl sulfate in potassium (or sodium) hydroxide/dimethyl sulfoxide at room temperature for about 2 hours, affording quercetin pentamethyl ether (QPE) quantitatively as a single product. When methyl iodide was used in place of dimethyl sulfate, the C-methylation product 6-methylquercetin pentamethyl ether was also formed. A computational study provided a rationale for the experimental results.

THE ALCOHOLYSIS OF TRIALKYLALKOXYSILANES: PART II. THE PREPARATION AND CHEMISTRY OF METHYL 2,3,4-TRI-O-TRI-METHYLSILYL-α-D-GLUCOPYRANOSIDE

1965 ◽  
Vol 43 (7) ◽  
pp. 2004-2011 ◽  
Author(s):  
D. T Hurst ◽  
A. G. McInnes
Keyword(s):  
Magnetic Resonance ◽  
Acetic Anhydride ◽  
Proton Magnetic Resonance ◽  
Benzoyl Chloride ◽  
Phenyl Isocyanate ◽  
High Yield ◽  
Aqueous Methanol ◽  
Trimethylsilyl Group ◽  
Acidic Catalysts ◽  
Derivatives Of

The trimethylsilyl group on the 6-position of methyl 2,3,4,6-tetra-O-trimethylsilyl-α-D-glucopyranoside is preferentially removed by methanolysis, using basic or acidic catalysts, giving methyl 2,3,4-tri-O-trimethylsilyl-α-D-glucopyranoside in high yield (>80%). Reaction of the latter with acetic anhydride, benzoyl chloride, or phenyl isocyanate produces the corresponding 6-substituted derivatives in quantitative yield. The trimethylsilyl residues from the latter compounds are hydrolyzed by 50% aqueous methanol with the concomitant formation of 6-O-acetyl, 6-O-benzoyl, or 6-carbanilate derivatives of methyl α-D-glucopyranoside in excellent yield. Chemical and proton magnetic resonance (p.m.r.) studies established the structure of methyl 2,3,4-tri-O-trimethylsilyl-α-D-glucopyranoside, and of subsequent derivatives prepared from this compound. Infrared and p.m.r. evidence is offered to support conclusions regarding the conformation of the groups or atoms attached to C6 and C5 of the glucoside residue in some of these compounds.

Room-temperature-adsorption behavior of acetic anhydride on a TiO2(110) surface

2007 ◽  
Vol 601 (8) ◽  
pp. 1822-1830 ◽  
Author(s):  
Hidenori Ashima ◽  
Wang-Jae Chun ◽  
Kiyotaka Asakura
Keyword(s):  
Acetic Anhydride ◽  
Room Temperature ◽  
Adsorption Behavior

TiO2/SO42-, A Convenient and Efficient Catalyst for Desilylation-Acetylation of Trimethylsilyl Ethers with Acetic Anhydride

2003 ◽  
Vol 2003 (2) ◽  
pp. 98-100 ◽  
Author(s):  
Tong-Shou Jin ◽  
Yan-Wei Li ◽  
Guang Sun ◽  
Tong-Shuang Li
Keyword(s):  
Acetic Anhydride ◽  
Rapid Method ◽  
Room Temperature ◽  
Efficient Catalyst ◽  
Trimethylsilyl Ethers

A rapid method for desilylation-acetylation of trimethylsilyl ethers with acetic anhydride catalysed by TiO2/SO42- at room temperature is reported.

scholarly journals Fused Quinoline Heterocycles V. Synthesis of Novel 1,2,3,5,6-Pentaazaaceanthrylene Derivatives

2003 ◽  
Vol 2003 (7) ◽  
pp. 388-389 ◽  
Author(s):  
Ramadan Ahmed Mekheimer ◽  
Essam Khalaf Ahmed ◽  
Hassan Attia El-Fahhama ◽  
Laila Hanafy Kamel ◽  
Dietrich Döpp
Keyword(s):  
Acetic Anhydride ◽  
Room Temperature ◽  
Ring System ◽  
Triethyl Orthoformate ◽  
Primary Amines ◽  
Phenyl Isothiocyanate ◽  
The Novel ◽  
Substituted 1

2,4-Dichloroquinoline-3-carbonitrile (1) with phenylhydrazine in DMF at room temperature gave the 3-amino-4-chloro-1-phenylpyrazolo[4,3- c]quinoline (2). Reaction of 2 with phenyl isothiocyanate afforded the novel fused tetracyclic ring system 1,5-diphenyl-1,5-dihydro-1,2,3,5,6-pentaazaaceanthrylene-4(3 H)-thione (7). Refluxing 2 with excess of a primary amines 8a-d in boiling DMF yielded the corresponding aminopyrazolo[4,3- c]quinolines 9a-d which react with an excess of triethyl orthoformate to furnish 5-substituted 1-phenyl-1,2,3,5,6-pentaaza-aceanthrylenes 11a-d. Reacting 9a with acetic anhydride does not give the expected tetracyclic compound 12, but instead the acetamide 13 is obtained. With triethyl orthoacetate the corresponding iminoester 14 is formed. When compound 14 was refluxed in DMF containing NaH it cyclised to the 4-methyl analogue 12.

Adduct Intermediates in the Side-chain Nitration of 1,4-Dimethylnaphthalene

1972 ◽  
Vol 50 (24) ◽  
pp. 3988-3992 ◽  
Author(s):  
Alfred Fischer ◽  
Alan Leslie Wilkinson
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Acetic Anhydride ◽  
Room Temperature ◽  
Methylene Chloride ◽  
Side Chain ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Naphthyl Acetate

cis and trans isomers of 1,4-dimethyl-4-nitro-1,4-dihydro-1-naphthyl acetate (1) have been isolated from a mixture of 1,4-dimethylnaphthalene and nitric acid in acetic anhydride by quenching at −40°. At room temperature only 1-methyl-4-nitromethylnaphthalene (4) is obtained. The conversion of 1,4-dimethylnaphthalene to 4 and of the cis (1a) and trans (1b) adducts to 4, by nitric acid in acetic anhydride, has been followed by n.m.r. 1,4-Dimethyl-4-nitro-1,4-dihydro-1-naphthyl nitrate (5) appears to be the immediate product from nitration of 1,4-dimethylnaphthalene in acetic anhydride, methylene chloride, or nitromethane. In acetic anhydride 5 is converted into 1. Decomposition of 1 in acetic acid gives 1,4-dimethyl-2-naphthyl acetate and some 4. The formation of 4 in this reaction is suppressed by urea.

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