Activated nitriles in heterocyclic synthesis. A novel synthesis of pyrazine derivatives

A novel synthesis of pyrazine derivatives from the reaction of α-tosyloximinonitriles with several active methylene enaminonitrile derivatives is reported. The reaction sequence is discussed.     

2,5,8,11-Tetraboronic ester perylenediimides: a next generation building block for dye-stuff synthesis

Via an unprecedentedly reported ruthenium catalyzed reaction, an efficient and straightforward method was developed for the synthesis of 2,5,8,11-tetraboronate perylenediimide derivatives. A possible reaction mechanism is proposed. The synthesis of 2,5,8,11-tetra-iodo and tetra-amino perylenediimides derivatives is also reported.     

Amide-Assisted Rearrangement of Hydroxyarylformimidoyl Chloride to Diarylurea

A novel amide-assisted rearrangement reaction of hydroxybenzimidoyl chloride has been established for the efficient synthesis of 1,3-diphenylurea derivatives. A variety of electronically and sterically different 1,3-diphenylurea derivatives can be obtained in good to excellent yields, and a proposed reaction mechanism is also presented.     

固定化脯氨酸及其衍生物用于催化不对称有机合成

脯氨酸及其衍生物作为有机手性催化剂,在不对称有机合成中得到广泛应用。该类催化剂具有结构简单、来源丰富和选择性高等优点,但仍存在催化剂用量大、难以回收以及无法重复利用等不足。近年来,随着固定化技术的发展,固定化脯氨酸及其衍生物受到广泛关注。固定化脯氨酸及其衍生物催化剂可以简化不对称催化中产物的分离过程,实现催化剂的便利回收与循环使用。本文综述了固定化脯氨酸及其衍生物的制备及在催化不对称有机合成(如Aldol反应、Michael加成反应、Mannich反应等)中的研究进展。     

Stereoselective diversity-oriented solution and solid-phase synthesis of tetrahydroquinoline-based polycyclic derivatives

A diversity-oriented solution and solid-phase synthesis of tetrahydroquinoline-based tricyclic derivatives has been achieved from enantiomerically pure, natural product-like bicyclic scaffold. The solution synthesis of enantiopure bicyclic scaffold was developed by asymmetric hetero Michael reaction. Our approach for the synthesis of polycyclic derivatives utilized regio- and stereoselective hetero Michael reaction and ring-closing metathesis as key steps in solution and on solid phase.     

Preparation of N-phenyl-substituted quinolinium derivatives labeled with tritium by chemonuclear synthesis

A chemonuclear method of synthesis is proposed for obtaining difficultly available phenyl-substituted derivatives of quinoline labeled with tritium. The ion-molecule reaction of free phenyl cations, generated on β-decay of tritium, with the nucleophilic centers of heterocyclic compounds is the basis of the synthesis. The onium derivatives synthesized possess significant inhibitory antimicrobial activity and are promising for a detailed study of the reaction mechanisms and metabolic processes using radioactive indicators.     

Simple and one-pot protocol for synthesis of indene-spiro-oxindoles involving tandem Prins and Friedel-Crafts reactions

[reaction: see text] A simple and one-pot protocol for the synthesis of indene-spiro-oxindole derivatives via TiCl4-mediated reaction between 1,1-diarylethylenes and isatin derivatives involving construction of two carbon-carbon bonds through tandem Prins and intramolecular Friedel-Crafts (PFC) reactions has been described. A plausible mechanism for this transformation is also presented.     

Synthesis of alpha-amino acid derivatives and amines via activation of simple alkyl halides by zinc in water

A method for the synthesis of alpha-amino acid derivatives and amines is developed via a zinc-mediated conjugate addition reaction of alkyl halides to alpha-phthalimidoacrylate derivatives and nucleophilic addition to imines in the presence of NH4Cl in water. No reaction was observed in the absence of water.     

Regiodivergent synthesis of functionalized indene derivatives via Pt-catalyzed Rautenstrauch reaction of propargyl carbonates

A regiodivergent synthesis of functionalized indene derivatives from a Pt-catalyzed Rautenstrauch reaction of propargyl carbonate is described. A one-pot Rautenstrauch/Tsuji-Trost reaction delivering 2-indanones was realized efficiently using this methodology.     

Functional derivatives of thiophene. XV.β-Thienylhydrazine derivatives in the synthesis of thieno[3,2-b]pyrroles

A new preparative method for the synthesis of thieno[3,2-b]pyrrole derivatives by condensation of ß-thienylhydrazine derivatives with diverse carbonyl compounds under the conditions of the Fischer reaction is described.     

Stereoselective synthesis of C-substituted morpholine derivatives using reductive etherification reaction: total synthesis of chelonin C

A general strategy is developed for the stereoselective synthesis of C-substituted morpholine derivatives using intramolecular reductive etherification reaction. The method is extended to the first stereoselective total synthesis of (±)-chelonin C.     

Iridium-catalyzed allylic vinylation and asymmetric allylic amination reactions with o-aminostyrenes

An Ir-catalyzed allylic vinylation reaction of allyl carbonates with o-aminostyrene derivatives has been realized, providing skipped (Z,E)-diene derivatives. With (E)-but-2-ene-1,4-diyl dimethyl dicarbonate as the substrate, an efficient enantioselective synthesis of 1-benzazepine derivatives via an Ir-catalyzed domino allylic vinylation/intramolecular allylic amination reaction has been developed. Mechanistic studies of the allylic vinylation reaction have been carried out, and the results suggest that the leaving group of the allylic precursor plays a key role in directing the reaction pathway. Screening of various allylic precursors showed that Ir-catalyzed reactions of allyl diethyl phosphates with o-aminostyrene derivatives proceed via an allylic amination pathway. A subsequent ring-closing metathesis (RCM) reaction of the amination products led to a series of enantiomerically enriched 1,2-dihydroquinoline derivatives. Their utility is indicated by an asymmetric total synthesis of (-)-angustureine.     

A novel synthesis of benzofuran and related compounds. I. The vilsmeier reaction of phenoxyacetonitriles

A novel synthesis of 2-benzofurancarboxylic acid derivatives by the Vilsmeier reaction of phenoxyacetonitriles is described.     

The reduction ring-opening reaction of imidazoline

A new reduction ring-opening reaction of 2-imidazoline with sodium borohydride is reported, and the effect of reaction condition on the yield, reaction mechanism and the use of the new reaction in synthesis of ethylenediamine derivatives are discussed. A new method for the preparation of unsymmetrical substituted ethylenediamine via the reduction ring-opening reaction of imidazoline is provided.     

Selective Lewis acid catalyzed transformation (gamma-butyrolactone versus cyclopropane) of 2-methoxy-4-benzyltetrahydrofuran derivatives. Efficient synthesis of lignan lactones

[reaction: see text]. A short synthesis of lactone lignans exploiting a three-component coupling strategy is presented using a new Lewis acid catalyzed ring-opening/cyclization reaction of 2-methoxytetrahydrofuran derivatives 4 leading to gamma-butyrolactones as a key step. By simply changing the reaction conditions, it was possible, from the same substrates 4, to obtain selectively cyclopropane derivatives.     

Synthesis of polyhydroquinoline derivatives through unsymmetric Hantzsch reaction using organocatalysts

A novel and green approach for efficient and rapid synthesis of polyhydroquinoline derivatives via unsymmetric Hantzsch reaction using organocatalysts at room temperature was reported. The process is a simple, environmentally friendly, rapid, and high yielding reaction for the synthesis of polyhydroquinoline derivatives. The catalytic efficiency of various small organocatalysts such as l-proline, trans-4-hydroxy-l-proline, l-thiaproline, dl-phenylglycine, and (−)-cinchonidine was studied under aqueous, organic, and solvent free conditions.     

A simple and efficient approach for the synthesis of 2-aminated quinazoline derivatives via metal free oxidative annulation

A simple and efficient approach for the synthesis of 2-aminoquinazoline derivatives in moderate to good yields. This reaction employs mild reaction conditions, is metal-free and utilizes readily available starting materials making it a more viable reaction for scale up synthesis and ligand diversity. Notably, this methodology allows for the synthesis of 2-aminoquinazolines using a free amine or cyclic amine enabling structural diversity and good atom economy.     

Convergent integration of two self-labor domino sequences: a novel method for the synthesis of oxazole derivatives from methyl ketones and benzoins

A highly efficient method for the synthesis of oxazole derivatives from methyl ketones, benzoins and ammonium acetate has been established via a novel strategy-convergent integration of two self-labor domino sequences. Owing to the simple and readily available starting materials, mild reaction conditions, facile operation, and the high bioactivity of oxazole derivatives, this reaction promises diverse applications in medical chemistry. Additionally, this reaction could provide an efficient example for self-labor synthesis strategy of organic compounds.     

Synthesis of derivatives of oxazolidin-5-ones

A method has been developed for the synthesis of derivatives of oxazolidin-5-one by the reaction of the corresponding N-benzyloxycarbonylaminoacid with formaldehyde in the presence of formic acid. Yields of derivatives of 3-benzyloxycarbonyloxazolidin-5-one increase with increased molecular weight of the initial compound. For the synthesis of 3-benzyloxycarbonyl-4-benzyloxazolidin-5-one the proposed method gives a higher yield than previously known methods. The reaction mechanism is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–117, January, 1993.     

Efficient synthesis of α-aryl serine derivatives via three-component reactions of aryldiazoacetates,anilines and formaldehyde

A three-component reaction based on trapping of ammonium ylides with formaldehyde was first reported. This reaction offers a new strategy for the synthesis of α-aryl serine derivatives and can be extended to the preparation of α-aryl threonine derivatives. Synthetic application of the three component reaction for the preparation of hydroquinoxaline derivative was also demonstrated.