76 research outputs found
Ketene 3‐Component Staudinger Reaction (K‐3CSR) to β‐Lactams: A New Entry in the Class of Photoinduced Multicomponent Reactions
No full textThe Staudinger synthesis of β-lactams from imines and ketenes has been conducted photochemically only in very limited cases. Recent advances in the visible light mediated Wolff rearrangement of diazoketones allowed us to perform, for the first time, a 3-component Staudinger reaction, by mixing aldehydes, amines and diazoketones in the dark and switching the light on after imine formation. The new photoinduced reaction parallels the classic methods in terms of efficiency/selectivity and adds to the existing multicomponent approaches for the preparation of combinatorial libraries of compounds. A thorough optimization of the reaction conditions was performed both for the classic two component reaction and for the novel three component version of the photoinduced Staudinger reactio
A novel photoinduced multicomponent reaction to β-lactams: Ketene 3-Component Staudinger Reaction (K-3CSR)
No full textKetene 3-Component Staudinger Reaction (K-3CSR): a novel photoinduced approach to the synthesis of β-lactams
No full textKetene 3-Component Staudinger Reaction (K-3CSR) to β-Lactams: A New Entry in the Class of Photoinduced Multicomponent Reactions
No full textSwitching the Photochromic Activity of Acenaphthylene Derivatives through a Tandem Nucleophile‐Promoted Addition Reaction
No full textNew acenaphthylene-based dithienylethenes have been prepared. Surprisingly they did not show photochromism. However, they readily underwent a tandem addition of a nucleophile and an electrophile, leading to a small library of dearomatized colourless analogues, which, on the contrary, were endowed with photochromic activity. In the absence of the electrophile, the intermediate obtained by C-attack readily aromatizes to give, surprisingly, a final product of direct aromatic nucleophilic substitution, which was not photochromically active
Integrating biocatalysis and multicomponent reactions
No full textWhile often multicomponent reactions (MCR) are used for the diversity-oriented synthesis of racemic (or achiral) molecular entities, this short review describes two alternative approaches for accessing enantiopure products exploiting the power of biocatalysis. Enzymes or microorganisms may be used for preparing enantiopure MCR inputs or for resolving racemic (or achiral) MCR adducts
Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light
No full textSpiro-heterocyclic indolenines are privileged scaffolds widely present in numerous indole alkaloids. Here, we develop a novel approach for the one-pot multistep synthesis of different spiro[indole-isoquinolines]. The protocol proposed involves the visible light mediated oxidation of N-aryl tertiary amines using bromochloroform with the generation of a reactive iminium species, which reacts with an isocyanide and an electron-rich aniline in a three-component Ugi-type reaction to give an α-aminoamidine. This compound might undergo an additional visible light-mediated oxidation to furnish a second iminium intermediate, which acts as electrophile in an intramolecular electrophilic aromatic substitution giving the final spiro-indolenine. The scope of the process has been investigated with respect to all three components. Simple operations, mild conditions, and good yields make this strategy a convenient and sustainable way to obtain novel spiro-indolenine derivatives
Use of biocatalytic chiral bio-based starting material in the Hosomi-Sakurai multicomponent reaction
No full textSynthesis of bio-based heterocycles from levulinic acid using the Ugi multicomponent reaction
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