Copper-Mediated Domino Cyclization/Trifluoromethylation of Propargylic N-Hydroxylamines: Synthesis of 4-Trifluoromethyl-4-isoxazolines

Lewis-Acid-Catalyzed Reductive Hydroalkoxylation of Propargylic N-Hydroxylamines Gives Stereoselective Access to Isoxazolidines

Lewis-acid-catalyzed 5-endo-dig reductive hydroalkoxylation cascade on propargylic N-hydroxylamine gave expedient, stereoselective access to isoxazolidine derivatives. The developed method provides a new approach toward the synthesis of isoxazolidine, a biologically privileged scaffold. The synthetic potential of the developed methodology was demonstrated by synthesizing 1,3-aminoalcohol, 4-aminotetrahydropyran, and sedamine natural products.

Facile access to [1,2]-oxazine derivatives via annulations of aminoxy-tethered 1,7-enynes

An efficient approach for the highly diastereoselective construction of functionalized cyclopenta[d][1,2]oxazines via sequential oxyamination and Pauson-Khand reaction of readily accessible propargylic alcohols has been developed. Furthermore, the ring closing metathesis of these N-O linked 1,7-enynes afforded vinylated-[1,2]oxazines in good yields. The reduction of the N-O bond of the obtained cyclopenta[d][1,2]oxazine is accomplished to access cyclopentenone-based amino alcohols.

Fluorination and fluoroalkylation of alkenes/alkynes to construct fluoro-containing heterocycles

This review summarize the established strategies through fluorination and fluoroalkylation of alkenes/alkynes for constructing fluoro-containing heterocycles. Reaction scopes, mechanisms and some shortcomings are also discussed.

Perfluoroalkylation of Thiosulfonates: Synthesis of Perfluoroalkyl Sulfides

A practical synthesis of perfluoroalkyl sulfides is described. The method employs stable and readily accessible thiosulfonates as new electrophiles with commercial nucleophilic perfluoroalkylating reagents. The mild reaction conditions allow access to a wide variety of both aryl- and alkyl-substituted perfluoroalkyl sulfides amenable to pharmaceutical development. Furthermore, the reaction operation is straightforward, odorless, does not produce toxic wastes, and, therefore should appeal to practitioners in industrial-scale productions.

Cu(II)-Catalyzed Oxidative Trifluoromethylation of Indoles with KF as the Base

This paper offers an efficient copper-catalyzed oxidative trifluoromethylation of indoles with low-cost CF3SO2Na via C–H activation. Notably, the use of a base is crucial for the trifluoromethylation of indoles. This reaction proceeds efficiently in good to excellent yields and is tolerance of a broad range of functional groups. Furthermore, melatonin, a medicine for sleep disorders, is converted to its 2-CF3 analogue in 68% yield. Studies of possible reaction pathways suggest that this reaction proceeds through a radical process.

5-Endo-dig cyclizations in organic syntheses

The favorability of ring closure reactions as per Baldwin rules has gained immense importance recently. This is evident from the current literature such as research articles, reviews, and books that have been published in this area. This review covers the recent applications of 5-endo-dig cyclization in organic synthesis focusing in the last two decades. A variety of 5-membered heterocycles as well as carbocycles could be synthesized via 5-endo-dig cyclization reactions. The important applications of 5-endo-dig cyclization in organic synthesis covering different aspects have been summarized in this review.

Synthesis of 2-(Trifluoromethyl)indoles via Domino Trifluoromethylation/Cyclization of 2-Alkynylanilines

A new method for the synthesis of 2-(trifluoromethyl)indoles using easily accessible 2-alkynylanilines and a well-established fluoroform-derived CuCF₃ reagent is described. This method utilizes a domino trifluoromethylation/cyclization strategy to construct the indole cores with no ambiguity of the CF₃ position. The intriguing 3-formyl-2-(trifluoromethyl)indoles can also be synthesized by this protocol, which are useful intermediates for the preparation of trifluoromethylated drug analogues. The ultimate CF₃ source is the inexpensive industrial byproduct fluoroform.

Domino cyclization/trifluoromethylation of 2-alkynylanilines using fluoroform-derived CuCF3: synthesis of 3-(trifluoromethyl)indoles

A domino cyclization/trifluoromethylation strategy for the construction of indole cores with concomitant installation of a CF₃ group is described.