A New Cycloaddition Profile for ortho-Quinone Methides: Photoredox-Catalyzed [6+4] Cycloadditions for Synthesis of Benzo[b]cyclopenta[e]oxepines

Visible-light-induced [6+4] cycloaddition reactions of ortho-quinone methides have been developed. The reaction of ortho-quinone methides with pentafulvenes in the presence of a thioxanthylium photoredox catalyst afforded benzo[b]cyclopenta[e]oxepines. The present reaction...

3 Ruthenium-Catalyzed Azide–Alkyne Cycloaddition (RuAAC)

Under ruthenium catalysis, 1,5-disubstituted 1,2,3-triazoles can be accessed with high selectivity from terminal alkynes and organic azides via a ruthenium-catalyzed azide–alkyne cycloaddition (RuAAC) reaction. These conditions also allow the use of internal alkynes, providing access to 1,4,5-trisubstituted 1,2,3-triazoles. This chapter reviews the scope and limitations of the RuAAC reaction, as well as selected applications. A brief mention of azide–alkyne cycloaddition reactions catalyzed by other metals is also included.

Asymmetric Synthesis of Isoxazole and Trifluoromethyl‐Containing 3,2’‐Pyrrolidinyl Dispirooxindoles via Squaramide‐Catalysed [3 + 2] Cycloaddition Reactions

A highly efficient squaramide‐catalysed asymmetric domino Michael/Mannich [3 + 2] cycloaddition of 3‐methyl‐4‐nitro‐5‐ isatylidenyl‐isoxazoles and N‐2,2,2‐trifluoroethylisatin ketimines was developed. A new class of complex and skeletondiversified isoxazole and trifluoromethyl‐containing 3,2’‐pyrrolidinyl...

2.4 CuAAC in Carbohydrate Conjugation

Copper(I)-catalyzed azide–alkyne cycloaddition reactions (CuAAC), as a versatile, reliable, and modular strategy, have been widely investigated in the area of glycoscience during the last 20 years. Herein, we presented a brief overview of CuAAC click approaches for easy access to diverse simple and complex triazole-appended carbohydrate-containing molecular architectures. Both intermolecular and intramolecular CuAAC conjugation of glycosylated azides and terminal alkynes have been widely employed for the regioselective triazole-forming reaction under standard click conditions.