C-H-Alkenylation of Arenes in a One-Pot VNS - Julia-Kocienski Reaction

The Coupling of Carbon and Nitrogen Substituents with Nitroarenes：Vicarious Nucleophilic Substitution of Hydrogen in Nitroarenes

Abstract:

In recent years, nitroarenes have been extensively exploited as green, efficient electrophilic arylation reagents used in a variety of organic syntheses. Transition-metal-free cross-coupling reactions and vicarious nucleophilic substitution (VNS) have become practical and reliable synthetic methods to access momentous func-tionalized organic compounds. Thus, the introduction of various substituents into nitroarenes has attracted considerable attention as important synthetic approach-es due to their simplicity and practicality. In this review, we comprehensively summarize the coupling of several carbon and nitrogen substituents with ni-troarenes via nucleophilic substitution under mild conditions, followed by the ap-plication of these transversions in the construction of carbon and heterocyclic rings.

Introduction of Carbon Substituents into Nitroarenes via Nucleophilic Substitution of Hydrogen: New Developments

Nucleophilic substitution of hydrogen in nitroarenes has become a powerful synthetic tool for functionalization of these important organic substrates, complementary to other modern methods. In this review we present new developments in the area of introduction of alkyl and functionalized alkyl substituents into nitroarene rings via nucleo­philic substitution of hydrogen, followed by application of these processes in the construction of carbo- and heterocyclic rings. Finally, new developments in the investigation of the mechanism of SNArH are summarized.

1 Introduction

2 Alkylation and Haloalkylation

3 Functionalized Carbon Substituents

4 Formation of Carbo- and Heterocyclic Rings

5 Mechanistic Aspects of SNArH

6 Conclusion

Stereoselective Synthesis of Trisubstituted (Z)-Alkenes from Ketones via the Julia-Kocienski Olefination Using 1-Methyl- and 1-tert-Butyl-1H-tetrazol-5-yl Alkyl Sulfones

1-Methyl-1H-tetrazol-5-yl (MT) alkyl sulfones 1b, 3b, and 7b react with various unsymmetrical ketones in the presence of LiHMDS in THF at low temperature to give trisubstituted (Z)-alkenes in good yields stereoselectively (Z/E = 91:9 to 99:1). For sterically less demanding ketones, olefination using t-Bu reagents 1d and 3d generated (Z)-alkenes with higher stereoselectivity (93:7-99:1).