A convenient route to heteronaphthacenes

Heteronaphthacenes 1 were prepared in two steps from 1,3-dihydrobenzo[c]thiophene 2,2-dioxide ( 4 ) and dienophiles 2 via convenient high-temperature Diels-Alder reactions.     

A convenient route to new phenyltetrahydroindolizines

Synthesis of new 6-(4-chlorophenyl)-5,6,7,8-tetrahydroindolizines was achieved starting from 4-amino-3-(4-chlorophenyl)butyric acid (Baclofen). The chemical pathway, involving a Clauson-Kaas reaction and a subsequent cyclization, led to an iminium salt whose reactivity was studied.     

A convenient semisynthetic route to hypericin

Summary A semisynthetic route to produce hypericin was established usingCortex frangulae as the starting point. The emodin isolated from it easily and in good yield was reduced to emodin anthrone by means of SnCl₂. The latter was reacted via a known oxidative dimerization and photocyclization reaction into hypericin.

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Ein bequemer semisynthetischer Zugang zu Hypericin

Zusammenfassung Eine semisynthetische Route zur Darstellung von Hypericin unter Verwendung vonCortex frangulae als Ausgangsmaterial wurde erarbeitet. Das daraus einfach und in guten Ausbeuten isolierte Emodin wurde mit Hilfe von SnCl₂ zu Emodinanthron reduziert. Letzteres wurde dann über eine bekannte oxidative Dimerisierung und Photocyclisierung zu Hypericin umgesetzt.

     

Miniemulsion cross-linking: A convenient route to hollow polymeric nanocapsule with a liquid core

Miniemulsion stabilized by poly(2-(dimethylamino) ethyl methacrylate)-block-poly(butyl methylacrylate) (PDMAEMA-b-PBMA) diblock copolymers has been used as liquid templates for the synthesis of polymer nanocapsules via quaternization cross-linking of PDMAEMA segments of the copolymer by 1,2-bis(2-iodoethoxy)ethane (BIEE) crosslinkers. PDMAEMA-b-PBMAs here as a stabilizer in miniemulsion with different molecular weights led to a size variation in diameters of nanocapsules, demonstrating the capsules have potential design capability of this technique. The solution behavior of the capsules has been also investigated in this paper.     

A convenient route to new Cyclopentadienyldinitrosyltungsten compounds

[C₅H₅W(NO)₂CO]PF₆ has been prepared and shown to be a useful precursor for a variety of new cationic and neutral tungsten nitrosyl compounds.     

A convenient route to cyano derivatives of benzonaphthyridines

A smooth synthesis of benzo[c][1,5]naphthyridine-6-carbonitrile and benzo[h][1,6]naphthyridine-5-carbonitrile, starting from benzonaphthyridine N-oxides, is achieved by treatment with trimethylsilane carbonitrile (Me3SiCN) in CH2Cl2 at 0–5 °C. The resulting nitriles are then hydrolyzed to the corresponding acids by boiling in aqueous alkali.     

A simple and convenient route to 11-desoxyprostaglandins

A high yield, four-step route to the key prostaglandin intermediate 4 is described which should make 11-desoxyprostaglandins and their analogs more readily accessible. Procedure provided for the highly versatile 5-benzyloxymethylcyclopentadiene-nitroethylene adduct (1) would enable the preparation of PGA₂, the Corey prostaglandin intermediate and syn-7-benzyloxymethylnorbornenone that is related to all the primary prostaglandins.     

A general and convenient route to oxazolyl ligands

A diverse range of chiral and achiral oxazolyl ligands, which have many applications including catalysis and luminescent devices, are synthesized simply in three steps from readily available and inexpensive phenol and amino alcohol starting materials. The method can be applied to ligands with electron-donating/-withdrawing and sterically demanding/undemanding substituents, and can conveniently be scaled up to >25 g of product.     

O-ethyl thiocarbamates. A convenient route to 2-aryliminoimidazolidines

The reaction of N-aryl thionocarbamates and ethylenediamine lead to the corresponding 2-arylimino-imidazolidines, whose structure in pharmacology is well known. But, the behaviour of the N-alkyl thionocarbamates is quite different under operative conditions and these compounds afford with ethylenediamine, to 2-(2′-aminoethylamino)-Δ²-imidazoline, according to a mechanism which is discussed.     

A convenient route to diazepines by intramolecular cyclisation of carbonylazides

The appropriate substituted carbonylazides I treated with warm acetic acid give the corresponding acetamide IV or the cyclic lactam VI . This is a convenient route to 10,11-Dihydro-5H-pyrrolo[1,2-a][1,4]-benzodiazepin-11-one and 10,11-Dihydro-4H-thieno[2,3-e]pyrrolo[1,2-a][1,4]diazepin-10-one.     

Synthesis of the dysiherbaine tetrahydropyran core utilizing improved tethered aminohydroxylation conditions

A concise stereoselective route to the dysiherbaine tetrahydropyran core was achieved in nine steps and 39% overall yield. Donohoe’s improved tethered aminohydroxylation conditions were employed to concurrently install the amino and alcohol groups and construct the tetrahydropyran ring, which features four contiguous cis-stereocenters.     

Synthesis of the dysiherbaine tetrahydropyran core employing a tethered aminohydroxylation reaction

A stereocontrolled and scalable synthesis of an advanced intermediate of the dysiherbaine tetrahydropyran core has been achieved in 11 steps and 27% overall yield. The key feature of this synthetic approach is the application of the Donohoe tethered aminohydroxylation reaction to install the amino diol and establish the four contiguous syn stereocenters on the tetrahydropyran ring.     

A concise route to the macrocyclic core of the rakicidins

An efficient synthesis of the macrolactone core of the rakicidins is described. The rakicidins are cytotoxic lipopeptides with interesting cancer cell selectivities including HIF-1-independent hypoxia-selective cytotoxicity and anti-invasive activity. Access to the core may now allow establishment of preliminary SAR and exploration of routes to several members of rakicidins.     

A convenient route to prepare isodicyclopentadiene—precursor of 1,5-dihydro-pentalene

A new route to prepare tricyclo[5.2.1.0^2,6]deca-2,4-diene (isodicyclopentadiene) was developed. This new route passes through a brominated (5-bromotricyclo[5.2.1.0^2,6]dec-3-ene) derivative obtained from tricycle[5.2.1.0^2,6]dec-3-ene (8,9-dihydrodicyclopentadiene) and NBS with a good yield. The complete assignment of protons and carbons on nuclear magnetic resonance spectra was done for dicyclopentadiene and the chemically transformed compounds by 2D NMR techniques.     

A concise route to the core pentasaccharide of N-linked glycoproteins

A concise preparation of the common pentasaccharide core of the N-linked glycoproteins is described. The reducing end glycal is functionalized at the level of chitobiose, which is then β-mannosylated using Crich's direct coupling protocol. Deprotection of the branching mannose residue, and di-α-mannosylation complete the synthesis.