Triflic Anhydride-Mediated Approach to Furo[3,2-b]furans from Diacetonide Protected Furanoses

Trifluoromethanesulfonic anhydride (Tf2O) exhibits excellent reactivity as an electrophile, serving as a highly versatile reagent in diverse chemical transformations. Herein, we report an operationally simple, efficient, unique, and practical one-step strategy for synthesizing diverse valuable structures bearing furo[3,2-b]furans core leveraging Tf2O's promoted reactivity of nitriles with diacetonide protected furanose. Furthermore, we demonstrate the potential of furo[3,2-b]furan as a precursor for complex structures through 1,3-dipolar cycloaddition.

Recent Advances in Palladium-Catalyzed Oxidative Couplings in the Synthesis/Functionalization of Cyclic Scaffolds Using Molecular Oxygen as the Sole Oxidant

Over the past years, Pd(II)-catalyzed oxidative couplings have enabled the construction of molecular scaffolds with high structural diversity via C–C, C–N and C–O bond-forming reactions. In contrast to the use of stoichiometric amounts of more common oxidants, such as metal salts (Cu and Ag) and benzoquinone derivatives, the use of molecular oxygen for the direct or indirect regeneration of Pd(II) species presents itself as a more viable alternative in terms of economy and sustainability. In this review, we describe recent advances on the development of Pd-catalyzed oxidative cyclizations/functionalizations, where molecular oxygen plays a pivotal role as the sole stoichiometric oxidant.

1 Introduction

2 Oxidative C–C and C–Nu Coupling

2.1 Intramolecular Oxidative C–Nu Heterocyclization Reactions

2.1.1 C–H Activation

2.1.2 Wacker/Aza-Wacker-Type Cyclization

2.1.3 Tandem Wacker/Aza-Wacker and Cyclization/Cross-Coupling Reactions

2.2 Intermolecular Oxidative C–Nu Heterocoupling Reactions

2.3 Intramolecular Oxidative (C–C) Carbocyclization Reactions

2.4 Intermolecular Oxidative C–C Coupling Reactions

2.4.1 Cyclization Reactions

2.4.2 Cross-Coupling Reactions

2.4.3 Homo-Coupling Reactions

3 Aerobic Dehydrogenative Coupling/Functionalization

4 Oxidative C–H Functionalization

5 Summary

Intramolecular Palladium-Catalyzed Oxidative Amination of Furans: Synthesis of Functionalized Indoles

Unconventional modification of palladium-catalyzed oxidative amination where a furan ring serves as a masked olefin is described. The designed chemical process provides 2-(2-acylvinyl)indole derivatives with up to a 93% yield and excellent E-selectivity. A highly reactive α,β-unsaturated carbonyl moiety of the obtained compounds allows for accessing various heteroaromatic scaffolds through simple synthetic procedures.

Aerobic oxidative α-arylation of furans with boronic acids via Pd(ii)-catalyzed C–C bond cleavage of primary furfuryl alcohols: sustainable access to arylfurans

Aerobic oxidative α-arylation of furans with boronic acids via Pd(ii)-catalyzed C–C bond cleavage of primary furfuryl alcohol provides sustainable access to arylfurans.