Wyniki wyszukiwania dla: Mauro Pineschi

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Boron Reagents and Catalysts for the Functionalization of Strained Heterocycles

Mauro Pineschi

Advanced Synthesis & Catalysis > 363 > 9 > 2325 - 2339

The particular nature of boron compounds allows an ample modularity of their properties ranging from Lewis acids, C‐nucleophiles, B‐nucleophiles, or even conjunctive reagents for new synthetic manipulations. Moreover, the increasing demand for functionalized boron derivatives for pharmaceutical or material science applications requires the development of new synthetic methods for boron introduction...

artykuł

The Binomial Copper‐Catalysis and Asymmetric Ring Opening of Strained Heterocycles: Past and Future Challenges

Mauro Pineschi

European Journal of Organic Chemistry > 2020 > 18 > 2643 - 2649

This minireview is focused on the use of chiral copper‐catalysts for the asymmetric ring opening of unsaturated strained heterocycles. Starting from the activity of my research group in Pisa over the years a report of the recent literature in this field is provided. From a mechanistic point of view the ring‐opening reactions of unsaturated strained heterocycles with organometallic reagents are a sort...

artykuł

Front Cover: The Binomial Copper‐Catalysis and Asymmetric Ring Opening of Strained Heterocycles: Past and Future Challenges (Eur. J. Org. Chem. 18/2020)

Mauro Pineschi

European Journal of Organic Chemistry > 2020 > 18 > 2641 - 2641

The Front Cover shows how chiral copper catalysts promote in a unique way the asymmetric ring‐opening reactions of strained heterocycles. The coordination of the copper catalyst with the unsaturation adjacent to the heteroatom serving as leaving group triggers a variety of ring openings by changing the nucleophile bound to copper. A variety of chiral non‐racemic building blocks can be efficiently...

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Direct enantioselective vinylogous Mannich‐type reactions of acyclic enals: New experimental insights into the E/Z‐dilemma

Michela Vargiu, Lucilla Favero, Andrea Menichetti, Valeria Di Bussolo, więcej

Chirality > 31 > 7 > 522 - 533

The direct heterofunctionalization of acyclic α,β‐unsaturated aldehydes with N‐acylquinolinium ions contemplating the formation of two stereocentres is studied using dienamine catalysis. This work gives some new experimental insights on the remote stereocontrol in dienamine catalysis using unbiased aliphatic systems and large electrophiles, pointing to a (Z)‐preference of the reactive configuration...

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Organocatalytic alkylation of carbohydrate‐containing aldehydes with dihydroquinoline N,O‐acetals: Absolute configuration of 1,2‐dihydroquinolines

Andrea Menichetti, Francesco Berti, Lorenzo Guazzelli, Lucilla Favero, więcej

Chirality > 31 > 2 > 127 - 137

The direct catalytic α‐amidoalkylation of dihydroquinolines with aldehydes bearing oxygen functionalities at different positions in a Mannich‐type reaction has been studied. β‐Alkoxy‐aldehyde 1d gave high enantioselectivity, albeit with an inherently poor diastereoselectivity, while the use of α‐alkoxy aldehydes 1c was detrimental also to enantioselectivity. Mannich‐type reactions have been studied...

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Synthesis of bicyclic tetrahydropyridine enamides and enecarbamates by hetero-Cope rearrangement of nitroso cycloadducts

Francesco Berti, Andrea Menichetti, Valeria Bussolo, Lucilla Favero, więcej

Chemistry of Heterocyclic Compounds > 2018 > 54 > 4 > 458-468

The hetero-Cope rearrangement reactions of inverse carbamate and amide nitroso Diels–Alder cycloadducts with 1,2-dihydropyridines to give novel tetrahydropyridine enamides and enecarbamates have been studied in detail identifying optimal reaction conditions. The possibility to obtain tetrahydropyridine enamides and carbamates containing a free OH at the C-4 position is restricted to only particular...

artykuł

Copper-Catalyzed Perkin–Acyl-Mannich Reaction of Acetic Anhydride with Pyridine: Expeditious Entry to Unconventional Piperidines

Stefano Crotti, Francesco Berti, Mauro Pineschi

Organic Letters > 2011 > 13 > 19 > 5152 - 5155

artykuł

Copper‐catalyzed divergent kinetic resolution of racemic allylic substrates

Mauro Pineschi, Valeria DI Bussolo, Paolo Crotti

Chirality > 23 > 9 > 703 - 710

When a racemic mixture is fully consumed the products may still be enantiomerically enriched. In particular, the regiodivergent kinetic resolution is a process in which a single chiral catalyst or reagent reacts with a racemic substrate to form regioisomers possessing an opposite configuration on the newly‐formed stereogenic centers. This review reports the major advances in the field of the copper‐catalyzed...

artykuł

Stereodivergent synthesis of diastereoisomeric carba analogs of glycal‐derived vinyl epoxides: A new access to carbasugars

Ileana Frau, Valeria DI Bussolo, Lucilla Favero, Mauro Pineschi, więcej

Chirality > 23 > 9 > 820 - 826

A convenient method for the stereoselective synthesis of diasteroisomeric vinyl epoxides (−)‐2α and (−)‐2β, the carba analogs of D‐galactal and D‐allal‐derived vinyl epoxides 1αand 1β, has been elaborated starting from tri‐O‐acetyl‐D‐glucal. The key step of this synthesis is an application of the known Claisen thermal rearrangement of a glucal derivative, the vinyl allyl ether (+)‐3b, which allows...

artykuł

Synthesis of carba analogs of 6-O-(benzyl)-d-allal- and -d-galactal-derived allyl epoxides and evaluation of the regio- and stereoselective behavior in nucleophilic addition reactions

Valeria Di Bussolo, Ileana Frau, Lorenzo Checchia, Lucilla Favero, więcej

Tetrahedron > 2011 > 67 > 25 > 4696-4709

The new racemic diastereoisomeric epoxides 6α and 6β, the carba analogs of the corresponding d-galactal- and d-allal-derived allyl epoxides have been synthesized and their regio- and stereoselective behavior examined in addition reactions with model O-, C-, N-, and S-nucleophiles. The results have indicated that epoxide 6β has a pronounced tendency toward anti-1,2-addition, whereas epoxide 6α shows...

artykuł

BACE1 inhibitory activities of enantiomerically pure, variously substituted N-(3-(4-benzhydrylpiperazin-1-yl)-2-hydroxypropyl) arylsulfonamides

Simone Bertini, Elisa Ghilardi, Valentina Asso, Carlotta Granchi, więcej

Bioorganic & Medicinal Chemistry > 2010 > 18 > 22 > 7991-7996

β-Secretase (BACE1) has been widely recognized as one of the possible therapeutic targets for the treatment of Alzheimer’s disease. In this paper, we report the synthesis and the BACE1 inhibitory activity of new, variously substituted N-(3-(4-benzhydrylpiperazin-1-yl)-2-hydroxypropyl) arylsulfonamides. Each enantiomeric form was separately evaluated in BACE1 inhibition assays and IC ₅₀ values...

artykuł

Copper-promoted rearrangement of 1,3-cyclohexadiene-acylnitroso cycloadducts

Stefano Crotti, Ferruccio Bertolini, Franco Macchia, Mauro Pineschi

Tetrahedron Letters > 2010 > 51 > 17 > 2284-2286

The ring opening of [2.2.2]-acylnitroso cycloadducts was obtained for the first time by means of a cationic rearrangement promoted by Cu(OTf) ₂ –PPh ₃ under homogeneous and polymer-supported conditions.

artykuł

Regioselective Copper-Catalyzed Alkylation of [2.2.2]-Acylnitroso Cycloadducts: Remarkable Effect of the Halide of Grignard Reagents

Stefano Crotti, Ferruccio Bertolini, Valeria di Bussolo, Mauro Pineschi

Organic Letters > 2010 > 12 > 8 > 1828 - 1830

artykuł

Aminolysis of glycal-derived allyl epoxides and activated aziridines. Effects of the absence of coordination processes on the regio- and stereoselectivity

Valeria Di Bussolo, Lorenzo Checchia, Maria Rosaria Romano, Lucilla Favero, więcej

Tetrahedron > 2010 > 66 > 3 > 689-697

The addition of primary and secondary aliphatic amines to glycal-derived allyl epoxides is completely 1,2-regio- and anti-stereoselective, whereas mixtures of the corresponding anti-1,2- [3–N-(substituted-amino) glycals] and anti-1,4-addition products (N-glycosyl amines) are obtained with N-(mesyl)-aziridines. In this way, structural moieties, otherwise difficult to synthesize, are obtained by means...

artykuł

Nickel-Catalyzed Borylative Ring Opening of Vinyl Epoxides and Aziridines

Stefano Crotti, Ferruccio Bertolini, Franco Macchia, Mauro Pineschi

Organic Letters > 2009 > 11 > 16 > 3762 - 3765

artykuł

A practical regioselective ring-opening of activated aziridines with organoalanes

Ferruccio Bertolini, Simon Woodward, Stefano Crotti, Mauro Pineschi

Tetrahedron Letters > 2009 > 50 > 31 > 4515-4518

The regioselective ring-opening of N-protected 2-phenylaziridines is accomplished by the addition of organoalanes in dichloromethane. With this simple method it is possible to introduce alkyl, alkenyl and alkynyl substituents at the benzylic position of the phenylaziridine to give the corresponding β-phenyl-β-substituted amines, as useful precursors for intramolecular hydroaminations, in high yields.

artykuł

Regio- and Stereoselective Ring Opening of Enantiomerically Enriched 2-Aryl Oxetanes and 2-Aryl Azetidines with Aryl Borates

Ferruccio Bertolini, Stefano Crotti, Valeria Di Bussolo, Franco Macchia, więcej

The Journal of Organic Chemistry > 2008 > 73 > 22 > 8998 - 9007

artykuł

Synthesis of diastereoisomeric 6-deoxy-d-allal- and 6-deoxy-d-galactal-derived allyl epoxides and examination of the regio- and stereoselectivity in nucleophilic addition reactions. Comparison with the corresponding 6-O-functionalized allyl epoxides

Valeria Di Bussolo, Lucilla Favero, Maria Rosaria Romano, Mauro Pineschi, więcej

Tetrahedron > 2008 > 64 > 35 > 8188-8201

The new 6-deoxy-d-allal- and 6-deoxy-d-galactal-derived allyl epoxides 8α and 8β have been stereoselectively prepared and their behaviour as glycosyl donors in addition reactions with nucleophiles examined and compared with that of the corresponding 6-OR (R=Bn, Tr) substituted epoxides. The completely stereoselective substrate-dependent glycosylation process found in the reaction of 8α and 8β with...