Intramolecular cycloadditions between cyclobutadiene and olefins can provide highly functionalized cyclobutene-containing products. The outcome of the reaction depends on the nature of the tether connecting the two reactive partners in the cycloaddition. Electronically unactivated olefins attached to cyclobutadiene through a three-atom, heteroatom-containing tether yield successfully the desire...

Staudinger reactions of Cy2BN3 with tri-substituted phosphines (R3P) yielded the boron-nitrogen-phosphorus linked systems Cy2BN=PR3 (R = Et, (t)Bu, Cy, Ph) (1a-1d respectively). Similarly, reaction of (C6F5)2BN3 with the phosphines P(t)Bu3, PPh3, Ph2PC≡CPh and Ph2PC≡CPPh2 yielded (C6F5)2BN=PR3 (2a-d respectively). In contrast, the reaction of (C6F5)2BN3 with Ph2P-C≡Cp-tol in the presence of exc...

New reactions and reagents that allow for multiple bond-forming events per synthetic operation are required to achieve structural complexity and thus value with step-, time-, cost-, and waste-economy. Here we report a new class of reagents that function like tetramethyleneethane (TME), allowing for back-to-back [4 + 2] cycloadditions, thereby amplifying the complexity-increasing benefits of Die...

This review is an endeavor to highlight the progress in the inverse-electron-demand hetero-Diels-Alder reactions of 1-oxa-1,3-butadienes in recent years. The huge number of examples of 1-oxadienes cycloadditions found in the literature clearly demonstrates the incessant importance of this transformation in pyran ring synthesis. This type of reaction is today one of the most important methods fo...

Natural products and their signature fragments are an enduring resource for identifying biological modulators. A number of biologically active alkaloids, such as strychnofoline and isorhynchophylline (Fig. 1), feature spiroindolizidine oxindoles. This fragment is considered ‘privileged’ for potential therapeutic investigation and there is much interest in developing expedient synthesis of such ...

The Front Cover illustrates how multicomponent reactions offer dreamlike opportunities for the conversion of biobased scaffold 5-Hydroxymethylfurfural (HMF) towards complex structures, and ammonium acetate acts as a mild catalyst such [4+2+1] cycloadditions acid-sensitive substrates. This “enchanted” cover, sponsored by INSA Lyon, was designed Lyon artist Adrien Demingeon (https://www.instagram...

Abstract This review updates the field of enantioselective indium-catalyzed transformations all types since 2012. It shows that asymmetric indium catalysis, suits growing demand for greener processes, offers a real opportunity to replace toxic metals in near future. 1 Introduction 2 Allylations, Propargylations, and Allenylations Carbonyl Compounds Derivatives 2.1 Allylations 2.2 Propargylation...

[2+2] Cycloadditions of methylene exo-glycal derivatives with chlorosulfonyl isocyanate and dichloroketene were studied in detail, investigating the effect carbohydrate moiety, protecting groups as well reaction temperature on yields transformations. These reactions gave new anomeric spiro-β-lactam spiro-cyclobutanone derivatives, whose structure was established by 1D 2D NMR MS experiments. The...