Synthesis of Lactams via Isocyanide-Based Multicomponent Reactions

Unveiling the Phosphine-Mediated N-Transfer from Azide to Isocyanide en Route to Carbodiimides and 4-Imino-1,3,2-diazaphosphetidines

Intramolecular reactions between isocyano and iminophosphorane functions yield species containing an embedded 1,3,2-diazaphosphetidine ring, as result of the [2 + 2] cycloaddition of the primary reactive product, the cyclic carbodiimide, with a second unit of reactant. DFT studies reveal a first rate-determining step entailing a [2 + 1] cycloaddition involving the isocyanide carbon atom and the P═N double bond, with the further intervention of a dipolar precursor of the intermediate carbodiimide. The 1,3,2-diazaphosphetidine ring of the final products is shown to be hydrolytically and thermally labile.

Ultrasound-assisted diastereoselective green synthesis of spiro-fused-γ-lactams functionalized with an amide bond heterocyclic bioisostere via the Ugi azide/domino process coupled strategy

A series of linked-type 1,5-disubstituted tetrazoles (1,5-DS-Ts) were synthesised via an isocyanide-based multicomponent reaction (IMCR) and used as synthetic platforms to access bound-type polyheterocycles containing an epoxyisoindol-1(6H)-one scaffold under green conditions. This rapid sonochemical synthetic strategy includes a double domino process using an orthogonal heterocyclic input in the Ugi-azide (UA) reaction. DFT calculations and NBO analysis were performed to understand the pseudopericyclic reaction involved in the 1,5-electrocyclization of the UA mechanism.

Copper-Catalyzed Asymmetric Kinugasa/Michael Addition Cascade Reactions for the Synthesis of Chiral Spiro β-Lactams

A mild copper-catalyzed asymmetric Kinugasa/Michael addition cascade process is developed. The reaction of α, β-unsaturated ester-tethered propiolamides with nitrones provides an efficient protocol for the construction of functionalized chiral 2,6-diazaspiro[3.4]octane-1,5-dione products in satisfactory yields and with high enantio- and diastereoselectivities.

Diversifying DNA-Tagged Amines by Isocyanide Multicomponent Reactions for DNA-Encoded Library Synthesis

In DNA-encoded library synthesis, amine-substituted building blocks are prevalent. We explored isocyanide multicomponent reactions to diversify DNA-tagged amines and reported the Ugi-azide reaction with high yields and a good substrate scope. In addition, the Ugi-aza-Wittig reaction and the Ugi-4-center-3-component reaction, which used bifunctional carboxylic acids to provide lactams, were explored. Five-, six-, and seven-membered lactams were synthesized from solid support-coupled DNA-tagged amines and bifunctional building blocks, providing access to structurally diverse scaffolds.

Functional chromophores synthesized via multicomponent Reactions: A review on their use as cell-imaging probes

This review aims to provide a comprehensive overview of recent advancements and applications of fluorescence imaging probes synthesized via MCRs (multicomponent reactions). These probes, also known as functional chromophores, belong to a currently investigated class of fluorophores that are presently being successfully applied in bioimaging experiments, especially in various living cell lineages. We describe some of the MCRs that have been employed in the synthesis of these probes and explore their applications in biological imaging, with an emphasis on cellular imaging. The review also discusses the challenges and future perspectives in the field, particularly considering the potential impact of MCR-based fluorescence imaging probes on advancing this field of research in the coming years. Considering that this area of research is relatively new and nearly a decade has passed since the first publication, this review also provides a historical perspective on this class of fluorophores, highlighting the pioneering works published between 2011 and 2016.

Enantioselective 1,3-Dipolar Cycloadditions of α-Methylene Lactams to Construct Spirocycles

Spirocyclic scaffolds are important motifs due to their potential to bestow favorable effects on pharmaceutical compounds. However, there is a need for efficient methods for their enantioselective construction. We report a method for the asymmetric 1,3-dipolar cycloaddition of diazoacetates or nitrile oxides with α-methylene lactams to prepare chiral spirocyclic heterocycles. The methodology is high yielding (up to 91% yield) and enantioselective (up to 89% ee) for a wide range of N-substituents and 6- and 7-membered ring lactam substrates.

[4 + 2] Annulation of δ-Hydroxy/δ-Sulfonamido-α,β-Unsaturated Ketones with Azlactones for Diastereoselective Synthesis of Highly Substituted 3-Amino-δ-Lactones and 3-Amino-δ-Lactams

The first base-mediated [4 + 2] annulation of δ-hydroxy-α,β-unsaturated ketones with azlactones has been developed, through which 3,4-disubstituted 3-amino-δ-lactones were obtained in good yields and with excellent diastereoselectivities. This approach was also applied to the [4 + 2] annulation of δ-sulfonamido-α,β-unsaturated ketones, which provided a practical protocol for constructing biologically important 3-amino-δ-lactam frameworks.

2-Benzyl-3-morpholino-7-(thiophen-2-yl)-6-(thiophen-2-ylmethyl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one

The new polyheterocyclic compound 2-benzyl-3-morpholino-7-(thiophen-2-yl)-6-(thiophen-2-ylmethyl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one (1) was synthesized via a one-pot process involving an Ugi-Zhu three-component reaction coupled to a cascade aza-Diels-Alder cycloaddition/N-acylation/decarboxylation/dehydration process, using toluene as the solvent, ytterbium (III) triflate as the Lewis acid catalyst, and microwave-dielectric heating to increase the overall yield by up to 73%, while decreasing the reaction time to less than one hour. Product 1 was fully characterized by its physicochemical properties and using spectroscopic techniques (IR, HRMS and NMR).

Amino-Functionalized Multiwall Carbon Nanotubes as Efficient Basic Catalysts for the Formation of γ-Lactams: Synthesis of N-1-Heptenyl-2-Pyrrolidinone

In this work, we prepared a series of N-functionalized carbon nanotubes by means of a process of acylation-amidation of commercial multiwall carbon nanotubes that were previously pre-oxidized with nitric acid. Three different amines, butylamine, N,N-dimethyl ethylenediamine, and ethylenediamine, were used in the process. The characterization of samples by several techniques probed the incorporation of nitrogen atoms to the carbon nanotubes, especially in the case of ethylenediamine. The solids were tested as catalysts in the synthesis of N-1-heptenyl-2-pyrrolidinone, included in the group of a γ-lactams, compounds that show important biological properties. The most active catalyst was that prepared with butylamine, which exhibited the highest S_BET and V_pore values and contained an amount of nitrogen that was intermediate between that of the other two catalysts. A yield of 60% to N-1-heptenyl-2-pyrrolidinone was achieved after 3 h at 120 °C under free-solvent conditions. This catalyst could be used in four consecutive cycles without significant activity loss.

Mechanochemical IMCR and IMCR-post transformation domino strategies: towards the sustainable DOS of dipeptide-like and heterocyclic peptidomimetics

A facile, rapid, sustainable one-pot Diversity Oriented Synthesis of peptidomimetics via mechanochemical IMCR-based domino strategies.

A DFT study of NHC-catalyzed reactions between 2-bromo-2-enals and acylhydrazones: mechanisms, and chemo- and stereoselectivities

The reaction mechanisms and origins of the chemo- and stereoselectivities of NHC-catalyzed [4 + 2] annulation of 2-bromo-2-enals and acylhydrazones.

Formation of amidino-borate derivatives by a multi-component reaction

Cyclohexene reacts with the (Fmes)BH2·SMe2 borane reagent and three molar equivalents of the isonitrile CN-Xyl to give the five membered 1,3-BN heterocyclic product 7 that contains a zwitterionic borata-amidinium moiety and a cyclohexenyl substituent. The analogous five-component coupling between cyclopentene, (Fmes)BH2·SMe2 and CN-Xyl in a 1 : 1 : 3 molar ratio gives the related cyclic amidino-borate derivative 10. The reaction of the (Fmes)BH2 derived frustrated Lewis pair 12, in situ generated or employed as the isolated dimer, reacts with 3 CN-Xyl equivs. at elevated temperature (60 °C) to yield the analogous coupling product 13.

Strategies and methodologies for the construction of spiro-γ-lactams: an update

This review gives an insight into the most recent synthetic methodologies towards spiro-γ-lactams, a class of compounds that are present in a wide range of synthetic bioactive and naturally occurring molecules.