stepwise and concerted cycloaddition reactions is in mechanistic chemistry. ’ Whereas stepwise processes can often be proven by lack of stereospecifity or by trapping intermediates, 2 it is generally difficult to find unequivocal evidence for concerted processes. Stepwise cycloadditions of neutral components proceed via dipolar or diradical intermediates, which can usually not be generated spec...

Bio-derived furoic acids and their derivatives are unexpectedly reactive dienes in aqueous Diels–Alder cycloadditions with maleimides.

The first synthesis of 2-iodoynamides is described as well as the first [2+2] cycloadditions of ketene with iodo alkynes.

The [3+2] cycloadditions of N-methyl derivatives of unsaturated imides with various nitrile oxides to yield new bridged isoxazoline derivatives with potential biological activity is described.

3. Synthetic Applications 1746 3.1. Pericyclic Reactions 1747 3.1.1. Diels−Alder Cycloadditions 1747 3.1.2. Dipolar Cycloadditions 1749 3.1.3. Ene Reactions 1750 3.1.4. Claisen Rearrangements 1750 3.2. Radical Cyclizations 1750 3.3. Transition-Metal-Catalyzed Cyclizations 1753 3.4. Ring-Closing Metathesis 1754 3.5. Electrophilic Cyclizations 1755 3.6. Other Cyclizations 1756 4. Biochemical and ...

We provide a comprehensive account of the 1,3-dipolar cycloaddition reactions of azomethine ylides with carbonyl dipolarophiles. Many different azomethine ylides have been studied, including stabilized and non-stabilized ylides. Of the carbonyl dipolarophiles, aldehydes including formaldehyde are the most studied, although there are now examples of cycloadditions with ketones, ketenes and carbo...

meldrum's acid, 2'5-diphenyl-1'3-dioxane-4'6-dione, was produced by [2+2] cycloadditions of the (chlorocarbony1)phenylketene with benzaldehyde. acid hydrolysis of the meldrum's acid regenerated benzaldehyde and also yielded phenylacetic acid as the final product

Abstract The one‐bond nucleophilic reactivities of seven cyclic α‐diazo carbonyl compounds in dichloromethane were determined by analyzing the kinetics their reactions with benzhydrylium ions (one‐bond reference electrophiles) at 20 °C according to Mayr‐Patz equation. Though not calibrated for pericyclic reactions, identified nucleophilicities also reflect relative 1,3‐dipolar cycloadditions di...

Nature creates an intriguing array of molecular architectures that has attracted extensive investigations on natural product identification, origin, biological activities, and chemical synthesis. In particular, biosynthetic studies have inspired elegant biomimetic total synthesis of natural products. Herein, we report biomimetic syntheses of the natural products brosimones A and B featuring mul...