Construction of functionalized spiro 1,4-benzoxazine oxindole derivatives via domino Mannich-alkylation of α-halocarbonyl compounds with imines

Expedient, regioselective C-H chalcogenation of 3,4-dihydro-1,4-benzoxazines using a palladium-copper catalyst

The palladium-catalysed regioselective C-H chalcogenation of benzoxazines with disulfides and diselenides in air has been described. In this protocol, palladium acetate serves as the catalyst in conjunction with copper as an oxidizing agent. Through this approach, a wide array of sulfenylation and selenylation reactions of benzomorpholines have been effected, yielding results ranging from good to excellent. Thus, the established procedure demonstrates superb regioselectivity and a strong tolerance towards various functional groups and is suitable for gram-scale synthesis. Additionally, this synthetic approach offers a practical and convenient pathway for late-stage functionalization leading to the Rosenmund-von Braun reaction.

Substrate-Controlled Product Divergence in Iron(III)-Catalyzed Reactions of Propargylic Alcohols: Easy Access to Spiro-indenyl 1,4-Benzoxazines and 2-(2,2-Diarylvinyl)quinoxalines

We report herein unprecedented cascade reactions of O-propargyl-N-tosyl-amino phenols with 10 mol% FeCl₃ in DCE at room temperature for 0.67-3 h to form spiro-indenyl 1,4-benzoxazines with 38-89 % yield. Replacing the substrates' oxygen atom by a N-tosylimine group followed by treatment with the same catalyst and solvent at 80 °C produced 2-(2,2-diarylvinyl)quinoxalines in 12-20 h with up to 62 % yield. Mechanistic understanding provided an insight into the transformations. The use of simple substrates and an environmentally benign low-cost catalyst, broad substrate scope and tolerance of diverse functional groups makes the methodology inherently attractive.

Stereoselective Domino Reactions in the Synthesis of Spiro Compounds

This review summarizes the latest developments in asymmetric domino reactions, with the emphasis on the preparation of spiro compounds. Discussions on the stereoselectivity of the transformations, the reaction mechanisms, the rationalization of the stereochemical outcome, and the applications of domino reactions to the synthesis of biologically active molecules and natural products are included when appropriate.

1 Introduction

2 Asymmetric Domino Reactions

2.1 Domino Reactions Initiated by Michael Reactions

2.2 Domino Reactions Initiated by Mannich Reactions

2.3 Domino Reactions Initiated by Knoevenagel Reactions

2.4 Domino Reactions Initiated by Cycloaddition Reactions

2.5 Domino Reactions Initiated by Metal Insertion

2.6 Other Mechanisms

3 Conclusion

Synthesis and antifungal activities of novel polyheterocyclic spirooxindole derivatives

A series of spirooxindole tetrahydrofuran derivatives were obtained in moderate to good yields via base-mediated cascade [3+2] double Michael reactions under mild conditions. Their antifungal effects on selected five target phytopathogenic fungi were investigated, and their structure antifungal activity relationships were also discussed.