Sequential Diimination, Staudinger [2 + 2] Ketene–Imine Cycloaddition, and Ring-Closing Metathesis (RCM) Reactions: In Route to Bis(4-spiro-fused-β-lactams)-Based Macrocycles

Abstract

Based on sequential organic transformations, that is, diimine formation, Staudinger [2 + 2] ketene–imine cycloaddition, and ring-closing metathesis (RCM) reactions, the synthesis with full structural identification including NMR and HRMS spectral data along with single X-ray diffraction analysis (for anti 7b, anti 8b, syn 9a, and anti 9b) of the first syn/anti bis-4-spiro-β-lactams-based azacrown ethers (7a,b–9a,b) is reported.

Stereoselective synthesis of β-lactams: recent examples

“…Multicomponent cycloaddition reactions have been the most widely employed methods in order to obtain β-lactam derivatives, highlighting the synthesis based on the Staudinger ketene-imine cycloaddition. 2,28–33 This section discusses selected recent examples of metal-free stereoselective cycloaddition syntheses of β-lactams.…”

Variable-Sized bis(4-spiro-fused-β-lactam)-Based Unsaturated Macrocycles: Synthesis and Characterization

“…Among azaheterocyclic ring systems, C3 and C4 spiro-fused βlactams (azetidin-2-one) (Figure 1) 1−4 are uniquely important for their presence in a family of marine natural products, e.g., chartellines and chartelamides, 5 for their prominence in synthetic chemistry as versatile building blocks in the synthesis of α/β-amino acids, 6 alkaloids, 7 heterocycles, 8 toxoids, and other relevant molecular structures 9 and for their medicinal chemistry in synthesis of many biologically vital materials that behave as β-turn mimetics, 10 enzyme inhibitors, 11 and precursors of α,α-disubstituted β-amino acids, 12 as well as their biological activities including antibacterial agents, 13 active against HIV-1 and plasmodium, 14 along with cholesterol absorption inhibitors. 15 In the light of their remarkable structural, chemical, and biological properties and applications, much attention has been devoted by our research group for demonstrating more complexed materials, 16 that is, bis-4-spiro-β-lactams containing unsaturated macrocycles (Figure 2).…”

“…In the light of their remarkable structural, chemical, and biological properties and applications, much attention has been devoted by our research group for demonstrating more complexed materials, 16 that is, bis-4-spiro-β-lactams containing unsaturated macrocycles ( Figure 2 ).…”

Syntheses and Applications of Indol-2-ylidene-Ligated Ruthenium-Based Olefin Metathesis Catalysts

“…Olefin metathesis is one of the most important catalytic reactions for the formation of new CC bonds . Over the past three decades, olefin metathesis polymerization, macrocyclization, and ethenolysis reactions have been developed in industry and academia. Ru-based olefin metathesis catalysts are well-defined molecular systems and exhibit significant reactivities .…”