77 research outputs found
L’ influenza del grado di insaturazione sulle macrociclizzazioni: sintesi di diarileptanoidi ciclici
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Last decade of unconventional methodologies for the synthesis of substituted benzofurans
No full textThis review describes the progress of the last decade on the synthesis of substituted benzofurans, which are useful scaffolds for the synthesis of numerous natural products and pharmaceuticals. In particular, new intramolecular and intermolecular C–C and/or C–O bond-forming processes, with transition-metal catalysis or metal-free are summarized. (1) Introduction. (2) Ring generation via intramolecular cyclization. (2.1) C7a–O bond formation: (route a). (2.2) O–C2 bond formation: (route b). (2.3) C2–C3 bond formation: (route c). (2.4) C3–C3a bond formation: (route d). (3) Ring generation via intermolecular cyclization. (3.1) C7a-O and C3–C3a bond formation (route a + d). (3.2) O–C2 and C2–C3 bond formation: (route b + c). (3.3) O–C2 and C3–C3a bond formation: (route b + d). (4) Benzannulation. (5) Conclusion
Regio- and diastereoselective organo-zinc promoted arylation of trans 2,3- diaryloxiranes by arylboronic acids: stereoselective access to trans 2,3-diphenyl- 2,3-dihydrobenzofuran.
No full textA chemical/computational approach to the determination of absolute configuration of flexible and transparent molecules: aliphatic diols as a case study
No full text(Graph Presented) By reacting flexible and optically transparent in UV-vis molecules such as 1,2-, syn- and anti-1,3-diols, 1,3-sulfanylalcohols of known absolute configuration (AC) with fluorenone dimethyl acetal, the corresponding ketals are obtained. They are conformationally well-defined (only one conformer in most cases) compounds exhibiting medium-high optical rotation (OR) values, which are independent of the solvent, and electronic circular dichroism (ECD) spectra, which show several (up to five) Cotton effects in the 350-200 nm range due to valence shell π→π* transitions. These features allow simulation of the chiroptical properties of these compounds at the TDDFT/B3LYP/6-31G* level of theory to obtain, using the known ACs of these compounds, a satisfactory reproduction of the OR values (sign and order of magnitude; quantitatively, the predicted values are twice the experimental ones), and a more than satisfactory reproduction of the ECD spectra (sign, intensity, and position of the lowest-energy four Cotton effects) for all the compounds studied. Therefore, this approach can be used to assign the AC of such flexible molecules, in particular, syn-1,3-diols, which are important substrates in organic synthesis and for which nonempirical methods of AC assignment have not been devised so far. Furthermore, since the fluorene chromophore leads to the presence of several Cotton effects from, say, 350 to 200 nm, their correct simulation of sign, intensity, and position is a guarantee of the correct assignment of AC: in this way, ECD spectroscopy gains the same advantages of VCD spectroscopy, that is, the need of reproducing many ECD bands and then a solid guarantee of a correct AC assignment. © 2008 American Chemical Society
Recent Advances in Synthetic Strategies to 2,3-Dihydrobenzofurans
No full textThis review gives an overview on recent developments in methods for the construction of compounds with the 2,3-dihydrobenzo furan core in the period 2012 to 2019. Interest in 2,3-dihydrobenzofurans is constantly increasing. The methods are divided into intermolecular and intramolecular approaches. Intermolecular approaches are subdivided according to the parent intermediate for the key reaction, while intermolecular approaches are subdivided according by which bond is formed in the key reaction. The transformation of benzofurans to dihydrobenzofurans and other miscellaneous methods are also discussed. Approaches useful for the synthesis of natural products are emphasized. 1 Introduction 2 Intermolecular Approaches 2.1 o -Quinone Methides and o -Quinones 2.2 p -Quinone Methides and p -Quinones 2.3 Nitrogen-Containing Phenols and Quinones 2.4 o -Hydroxyphenylcarbonyl Derivatives and Phenols 2.5 Miscellaneous 3 Intramolecular Approaches 3.1 O-C2 Bond Forming 3.2 C2-C3 Bond Forming 3.3 C3-Aryl Bond Forming 3.4 O-Aryl Bond Forming 4 From BF to DHB 5 Rearrangements and Aromatizations
Radical resveratrol dimerization to dihydrobenzofuran system by NIS
No full textInterest of organic chemistry in biomimetic synthesis is constantly increasing in order to obtain bioactive natural products in steps and atoms economy. In the light of these, during iodination of resveratrol as starting material to obtain natural compounds, unexpectedly, an interesting by-product
was obtained. In fact, in addition to iodinated resveratrol NMR signals showed the presence of a
compound with a 2,3-dihydrobenzofuran motif. The only explanation for this event is the radical
generation on resveratrol by NIS, used as iodinating agent. Oxidation of the phenol moiety can generate a hypothetical phenoxyl radical, that leads to dimerization, affording to a 2,3-
dihydrobenzofuran moiety. Therefore, formation of radical and subsequently dimerization, as naturally occurs, makes this strategy as a new biomimetic synthesis of resveratrol dimer. Herein, we
present our study performed to optimize the 2,3-dihydrobenzofuran formation conditions and to identify the structure of the obtained compound.
Methylation and dehalogenation reactions confirmed the formation of the permethylated (±)-e viniferi
From trans 2,3-diaryloxiranes to trans 2,3-diaryl-2,3-dihydrobenzofurans:toward the synthesis of ε-Viniferin and Gnetin C
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A Convergent Preparation of the C1-C13 Fragment of Amphotericin B from a Single Chiral Precursor
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