1,721,067 research outputs found
Metal Promoted Cyclocarbonylation Reactions in the Synthesis of Heterocycles
Full text linkOxygen and nitrogen heterocycle systems are found in a vast number of natural substrates and biologically active molecules such as antimycotics, antibiotics, antitumors and antioxidants, in addition to pigments and fluorophores [...
Direct ni mediated synthesis of ketones from acyl bromides and grignard reagents
No full texta catalytic amount of NidppeCl2 converts an acyl bromide directly into ketones at 0 °C in THF in the presence of a Grignard reagent. The described procedure represents a useful way to afford dialkyl, diaryl or alkyl aryl ketones as well as 1,2-diketones. In the adopted reaction conditions double bonds, esters and ketones are unaffected
New syntheses of 2-phenylsulphonylfurans
No full textthe synthesis of 2-phenylsulphonyltetrahydrofuran (1), 2-phenyl sulphonyl-5-methoxy-2,5-dihydrofuran (2) and 2-phenylsulphonylfuran (3) was carried out in very good yields and short reaction times starting from easily available precursors
Synthesis of 3-Alkylideneisoindolin-1-ones via Sonogashira Cyclocarbonylative Reactions of 2-Ethynylbenzamides
Full text linkCyclocarbonylative Sonogashira reactions of ortho-ethynylbenzamides
have been investigated. The process is carried out under CO pressure, in the presence of
a very small amount of PdCl2(PPh3)2 (0.4 mol %) as a catalytic precursor and without
the need for a Cu salt as the co-catalyst. 2-Ethynylbenzamide reacted successfully with
iodoarenes bearing electron-withdrawing and electron-donating groups, giving rise to
different classes of compounds depending on the solvent used. On the contrary, N-(4-
chlorophenyl)-2-ethynylbenzamide afforded exclusively polyfunctionalized isoindolinones
with high stereoselectivity toward (E) isomers
Nickel mediated double bond formation from vic-dibromides and ethyl magnesium bromide
No full textv/c-dibromides are quantitatively converted into alkenes by using a catalytic amount of NidppeCl2, in the presence of two molar equivalents of EtMgBr in THF Stereochemical aspects of the reaction are given
Potentiality and Synthesis of O- and N-Heterocycles: Pd- Catalyzed Cyclocarbonylative Sonogashira Coupling as a Valuable Route to Phthalans, Isochromans, and Isoindolines
No full textOxygen and nitrogen heterocycle systems are found in a vast number of natural substrates and biologically active
molecules. In particular, phthalan, isochroman, and isoindoline scaffolds are present in many classes of products such as antimycotics, antibiotics, antioxidants, pigments, and fluorophores. Therefore several procedure dedicated to the building of such heterocycles have been developed. In this review a detailed analysis of literature data relating to these scaffolds is described. Particular attention has been devoted to their biological and chemical potentiality, and an in-depth investigation into the most important synthetic methods is reported. Cyclocarbonylative Sonogashira coupling of suitable alcohols and amides has been carefully considered, because it represents a valuable and atom-economic route for the construction of alkylidenephthalans, -isochromans, and -isoindolines
Silylcarbocyclisation-desilylation reactions of N-tosyl-2-ethynylaniline: a new protocol for the synthesis of 2-hydroxyindoline derivatives
No full text2-Hydroxyindolines are useful building blocks for the preparation of pharmaceutical and biological-ly active compounds. (1) However, to the best of our knowledge only few synthetic procedures have been developed; most of them are based on the reduction of corresponding lactams or on cy-clisation processes of variously substituted anilines. (2)
We found that β-lactams and β-lactones can be easily obtained from propargyl amides and propargyl alcohols by means of rhodium-catalysed silylcarbocyclisation reactions with dimethylarylsilanes; subsequent treatment with TBAF promotes a desilylation step, consisting in a 1,2-migration of aryl group from the silyl moiety to the adjacent carbon atom. (3) Very recently, we extended our silylcarbocyclisation-desilylation protocol to the preparation of various 4-(arylmethyl) isochroman-3-ones starting from 2-ethynylbenzyl alcohol and arylsilanes with different steric properties. (4)
Here we report that silylcarbocyclisations of N-tosyl-2-ethynylaniline with dimethylarylsilanes, car-ried out with catalytic Rh+[(C7H8)(BPh4)]- (Rhsw, 0.3 mol%) under CO pressure (30 atm) at 100°C, generate (Z)-1-tosyl-3-((dimethylarylsilyl)methylene)indolin-2-ols with good yields (51-68%). These compounds can be submitted to a facile TBAF-promoted desilylation step with migration of the aryl group, affording the corresponding N-tosyl-3-(methylaryl)indolin-2-ols quantitatively and with very high diastereoselectivity (anti > 90%)
Solvated metal atoms mediated intramolecular hydrosilylation and silylformilation of acetylenic compounds: synthesis of silacyclanes
No full textSynthesis and characterization of new chiral oligothiophenes for innovative optoelectronic applications
Full text linkIn recent years, ¶-conjugated polymers and oligomers have found considerable attention as organic semiconductor in the field of optoelectronics; in this field a very important role is played by oligothiophene-based systems.
Their fundamental optical and electrical properties (light absorption and emission, charge transport, exciton transfer, etc.) depend not only on their chemical structure and confor-mation assumed, but also on the supramolecular interactions and nano/mesoscale organi-zation in the solid-state1. Chirality represents a way of controlling supramolecular aggre-gation of these systems: the introduction of chiral groups in their structure can drive them to organize into architectures with chiral geometries, where a perfect alignment between proximate chains is disfavoured with respect to a twisted arrangement. Moreover, non-racemic chiral ¶-conjugated systems can be studied using chiroptical spectroscopic tech-niques, in particular the electronic circular dichroism (ECD), which give access to a range of structural information otherwise not observable with other common spectroscopies. However, more importantly, these compounds may be used as chiral organic semi-conductors in novel optoelectronic applications: circularly polarized light sensors2, OFET able to discriminate enantiomers3, spin filters4, etc.
In light of this, we designed and synthesized a set of new chiral oligothiophenes for the realization of some innovative optoelectronic devices
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