Synthesis and reactions of α-fluoro-α-amino amides

N-((S)-1-Phenylethyl)halofluoroethanamides have been investigated as precursors to N-protected α-fluoro-α-amino amides by nucleophilic displacement of halide with nitrogen nucleophiles such as potassium phthalimide, sodium succinimide, sodium glutarimide, trimethylamine and sodium azide. With single diastereoisomers of the iodofluoroethanamide, clean inversion of configuration occurs at room temperature, but subsequent epimerisation may occur as a result of the liberated iodide. The α-fluoro-α-amino amides made underwent a wide variety of reactions depending on conditions, but in many cases the carbon-fluorine bond was compromised. However, reacting trimethylamine and N-((S)-1-phenylethyl)iodofluoroethanamide gave the corresponding α-fluorobetaine amide, and subsequent acidic hydrolysis led to α-fluorobetaine as the first example of an ‘unprotected’ α-fluoroamino acid.     

Synthesis of 5-alkyl-5-aryl-γ-lactams from 1-aryl-substituted nitroalkanes and methyl acrylate via Michael addition and reductive lactamization

A general method for accessing 5-alkyl-5-aryl-γ-lactams has been developed using readily available aryl bromides, nitroalkanes, and methyl acrylate as the starting materials. The palladium-catalyzed arylation of nitroalkanes gave the 1-aryl-substituted nitroalkanes, which underwent the DBU-mediated Michael addition with methyl acrylate at room temperature to afford the methyl 4-aryl-4-nitroalkanoates. The latter were then subjected to the nitro reduction using NaBH₄–NiCl₂·6H₂O in MeOH at 0 °C to furnish, after treatment with aqueous K₂CO₃ at room temperature, the 5-alkyl-5-aryl-γ-lactams in good to excellent overall yields. Selected examples of N-alkylation of the γ-lactams were also illustrated.     

Selective synthesis of α-fluoro-β-keto- and α-fluoro-β-aminophosphonates via electrophilic fluorination by selectfluor

A series of α-mono- and α,α-difluoro-β-ketophosphonates were synthesized in moderate to good yields with excellent selectivities via electrophilic fluorination by Selectfluor. Subsequently, synthetic potential of the obtained α-monofluoro-β-ketophosphonates was demonstrated by their application in synthesis of α-monofluoro-β-aminophosphonates, useful building blocks in the preparation of phosphapeptides.     

Acetals of lactams and acid amides. 73. Synthesis and some properties of derivatives of 6-nitro-γ-carboline

We have developed two synthesis routes for 4-amino derivatives of 6-nitro--carbolines: 1) consecutive conversion of 1,2-dimethyl-3-formyl-5-nitroindole to the 3-cyano derivative, condensation of the latter with DMF diethyl acetal, and cyclization of the enamine formed in this case with ammonia and benzylamine; 2) N-oxidation of 9-substituted 6-nitro--carbolines, transformation of N-oxides to the corresponding -carbolin-4-ones, from which the target compounds are obtained through the 4-chloro derivatives.For Communication 72, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 502–505, April, 1992.     

Synthesis of α-fluoro-β-amino acids via the Reformatsky reaction of chiral N-tert-butylsulfinylimines with ethyl bromofluoroacetate

Treatment of chiral N-tert-butyl sulfinylimines with ethyl bromofluoroacetate in the presence of activated Zn dust in THF afforded the α-fluoro- β-amino acid derivatives in good yields(70-86%) and moderate diastereoselectivity(66:34-92:8).     

Asymmetric Synthesis. XVIII. Stereocontrolled Synthesis of α-Substituted-2-furfurylamines via Chiral Intermediates

The stereocontrolled synthesis of (R)-α-alkyl-2-fur furylamines (5), using (-)-2-hydroxypinan-3-one (1) as a chiral auxiliary, had been studied. The e. e values of (5) were 91.4->98%, which determined by capillary GC (stationary phase: Chirasil-Val).     

Synthesis of α-Methylene-γ-Lactones via Cr and Sn Complexes of β-Carbethoxy and β-Nitrile Allyl Bromides

The synthesis of some α-methylene-γ-lactones employing allylic Cr and Sn complexes is described.     

Synthesis of indenoindene-fused α-methylene-γ-butyrolactones via a tandem intra- and intermolecular Friedel-Crafts reaction

An efficient synthesis of indenoindene-fused α-methylene-γ-butyrolactones was carried out via a tandem intra- and intermolecular Friedel-Crafts reaction from the spiro-lactone, which can be easily prepared from ninhydrin by indium-mediated Barbier reaction of cinnamyl bromide.     

On-Surface Synthesis of One-Dimensional Carbon-Based Nanostructures via C−X and C−H Activation Reactions

The past decades have witnessed the emergence of low-dimensional carbon-based nanostructures owing to their unique properties and various subsequent applications. It is of fundamental importance to explore ways to achieve atomically precise fabrication of these interesting structures. The newly developed on-surface synthesis approach provides an efficient strategy for this challenging issue, demonstrating the potential of atomically precise preparation of low-dimensional nanostructures. Up to now, the formation of various surface nanostructures, especially carbon-based ones, such as graphene nanoribbons (GNRs), kinds of organic (organometallic) chains and films, have been achieved via on-surface synthesis strategy, in which in-depth understanding of the reaction mechanism has also been explored. This review article will provide a general overview on the formation of one-dimensional carbon-based nanostructures via on-surface synthesis method. In this review, only a part of the on-surface chemical reactions (specifically, C−X (X=Cl, Br, I) and C−H activation reactions) under ultra-high vacuum conditions will be covered.     

Highly Deoxygenated Sugars. II. Synthesis of Chiral Cyclopentenes via Novel Carbocyclization of C‐4 Branched Deoxysugars

Tri‐O‐acetyl‐d‐glucal (1) was converted via Ferrier type II rearrangement with high α‐selectivity to 2,3‐unsaturated methyl glycosides 2a and 2b using ferric chloride as the catalyst. Palladium induced allylic substitution with sodium tert‐butylacetoacetate as a nucleophile leads to C‐4 branched sugars. Subsequent hydrogenation followed by treatment with trifluoroacetic acid affords the highly functionalized chiral cyclopentene derivative 5a as a versatile chiral building block for cyclopentanoids.     

Synthesis and conversions of metallocycles. 9. Synthesis of polycyclic aluminocyclopentanes with the participation of (η5-C5H5)2ZrCl2

The Cp₂ZrCl₂-catalyzed (Cp=⁵-C₅H₅) stereoselective cyclometalation of norbornenes and norbornadienes with AlEt₃ was carried out. It led in one stage to the preparation of polycyclic aluminocyclopentanes (ACP). It was shown that the ACP synthesized can be converted into polycyclic thiophanes under the action of elementary sulfur.For previous communication, see [1].Institute of Chemistry, Bashkir Scientific Center, Ural Branch, Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 386–391, February, 1992.     

Synthesis of phosphinic acids on the basis of hypophosphites: IV. Synthesis of pseudo-γ-glutamylglycine and its enantiomers

A new method for construction of pseudopeptide molecules is proposed, exemplified by the synthesis of [3-amino-3-(hydroxycarbonyl)propyl][2-(hydroxycabonyl)ethyl]phosphinic acid (I) (pseudo--glutamylglycine), starting from ammonium hypophosphite. Enzymatic synthesis using immobilized penicillamidase allowed preparation of the enantiomers of acid I.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1273–1278.Original Russian Text Copyright © 2004 by Ragulin.For communication III, see [1].This revised version was published online in April 2005 with a corrected cover date.     

Generation and cyclization of α-diazocarbothioimidates. Synthesis and structure of derivatives of 5-mercapto-1,2,3-triazole

The reaction of 5-amino-1,2,3-thiadiazol-4-carbothioamides with methyl iodide basically generates -diazo-S-methylthioimidates and -carbothioimidolates. It is shown that the reactivity of the latter increases when either alkyl or aryl substituents are introduced at the nitrogen atom of the carbothioamide groupTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 979–984, July, 1992.     

Synthesis of C‐3 Branched Allyl and Pentadienyl Glucosamines via Radical Coupling of Sugar‐Thionocarbonates

Abstract

The intermolecular AIBN‐promoted free radical reaction of glucosamine thionocarbonates as radical donors, and allyl or pentadienyl‐tributyltin reagents gave the expected C‐3 branched sugar derivatives in good yield and with total equatorial selectivity.     

Synthesis of structurally diversified BINOLs and NOBINs via palladium-catalyzed C–H arylation with diazoquinones

Privileged biaryl frameworks, BINOL and NOBIN, were efficiently constructed with sole 1-DNQs as arylation reagents under one set of reaction conditions. The judicious selection of palladium-catalytic system plays a pivotal role in the excellent selectivities. This transformation accommodated fairly broad substrate generality for both 2-naphthol and N-Boc-2-naphthylamine and afforded the structurally diversified BINOLs and NOBIN derivatives in high efficiency. Notably, the bromosubstituents which cannot survive in conventional palladium-catalyzed reactions were well-compatible with this set of conditions, providing an effective handle for further enriching the library of BINOLs and NOBINs. Preliminary attempts on the asymmetric variant of this reaction were also performed with up to 80:20 er for BINOLs synthesis.     

Synthesis of LiNbO_3 via a hydrothermal route and characterization

Lithium niobate (LiNbO3) crystal, used in many optical fields, has been of great interest for fundamental science and applications in optics for many years due to its excellent ferroelectric properties such as piezoelectricity, pyroelectrical, electro-optical, photorefractive and nonlinear-optical properties. Several methods for synthesizing lithium niobate crystal have been reported, for instance Czochralski growth, top seeded solution growth (TSSG), liquid phase epitaxy, laser deposition, …     

Molecular design of multitarget neuroprotectors 2. Synthesis and bioactivity of carbazole—γ-carboline conjugates

Russian Chemical Bulletin - Earlier unknown conjugates of carbazoles and γ-carbolines were obtained by the reaction of 3,6-substituted 9-oxiranylmethylcarbazoles and 2,8-substituted...