Synthesis of Indolo-1,2-Benzothiazines from Sulfoximines and 3-Diazoindolin-2-imines

A rhodium-catalyzed cascade C-H activation/annulation strategy for the expeditious assembly of pyrrolidinedione-fused 1,2-benzothiazines

A cascade annulation strategy triggered by rhodium(III)-catalyzed C-H activation has been reported for the expeditious assembly of pyrrolidinedione-fused 1,2-benzothiazines from free NH-sulfoximines with maleimides under mild conditions. Without the need for inert atmosphere protection, a broad range of sulfoximines with maleimides were well tolerated, producing diverse fused-thiazine derivatives in moderate to good yields. Additionally, the late-stage transformation of the target product demonstrated the potential synthetic value of this protocol.

Iridium(III)-Catalyzed C-H Cyclization of Sulfoximines with Diazo Meldrum's Acids for the Synthesis of Cyclic Sulfoximines

Iridium(III)-catalyzed C-H cyclization of sulfoximines with diazo Meldrum's acid provided cyclic sulfoximines with a carbonyl group in good to excellent yields. These compounds were easily converted into unsubstituted and arylated sulfoximines. Moreover, the vinyl triflates obtained from the cyclic sulfoximines underwent palladium(II)-catalyzed cross-coupling reactions with a variety of aryl, arylalkynyl, and heteroatom (N and S) nucleophiles, affording a wide range of monosubstituted sulfoximines in high yields.

Rh(III)-Catalyzed [4 + 1] Annulation of Sulfoximines with Maleimides: Access to Benzoisothiazole Spiropyrrolidinediones

Rh(III)-catalyzed synthesis of benzoisothiazole spiropyrrolidinediones using sulfoximine as a directing group under a C-H activation and [4 + 1] annulation strategy with maleimides as a coupling partner is reported. The cyclization reaction was compatible with various substituted sulfoximine and maleimides. The deuterium-labeling studies were performed to investigate the mechanism of the reaction.

Recent Advances in the Synthesis of Cyclic Sulfoximines via C-H Bond Activation

Sulfoximines, a ubiquitous class of structural motifs, are widely present in bioactive molecules and functional materials that have received considerable attention from modern organic chemistry, pharmaceutical industries, and materials science. Sulfoximines have proved to be an effective directing group for C-H functionalization which was widely investigated for the synthesis of cyclic sulfoximines. Within the last decade, great progress has been achieved in the synthesis of cyclic sulfoximines. Thus, this review highlights the recent advances in the synthesis of cyclic sulfoximines via the C-H activation strategy and is classified based on the substrate types.

Annulation-Triggered Denitrogenative Transformations of 2-(5-Iodo-1,2,3-triazolyl)benzoic Acids

The ability of [1,2,3]triazolobenzoxazinones to act as a source of "hidden" diazo group was discovered. These diazo precursors can be easily prepared by the intramolecular cyclization of 2-(5-iodo-1,2,3-triazolyl)benzoic acids. The Cu-catalyzed capture of the hidden diazo group allows for further functionalization through the denitrogenative pathway. The transformations proceed via the formation of either diazoimine or diazoamide intermediates. Novel routes to various anthranilamides as well as thiolated benzoxazinones were developed using the one-pot cyclization/diazo capture procedure.

Rhodium(III)-catalyzed cascade C-H functionalization/annulation of sulfoximines with iodonium ylides for the synthesis of cyclohexanone-1,2-benzothiazines

A highly efficient Rh(III)-catalyzed cascade C-H activation/annulation of sulfoximines with iodonium ylides under metal-oxidant-free conditions has been reported. The fused cyclohexanone-1,2-benzothiazine scaffold is readily achieved with a one-pot process in this reaction. This protocol exhibits good functional group tolerance and moderate to excellent yields. Additionally, the olefination of the target product illustrates the promising usefulness of this strategy.

Rhodium-catalyzed C-H activation/cyclization of aryl sulfoximines with iodonium ylides towards polycyclic 1,2-benzothiazines

The synthesis of 1,2-benzothiazine derivatives through rhodium-catalyzed C-H activation/cyclization of S-aryl sulfoximines with iodonium ylides was developed for the first time. In this report, C-H and N-H bond functionalization was realized towards a series of tricyclic and tetracyclic sulfoximine derivatives with moderate to excellent yields under simple reaction conditions.

Sulfoximines Assisted Rh(III)-Catalyzed C-H Activation/Annulation Cascade to Synthesize Highly Fused Indeno-1,2-benzothiazines

A facile access to highly fused tetracyclic indeno-1,2-benzothiazines has been established via a Rh(III)-catalyzed C-H bond activation and intramolecular annulation cascade between sulfoximides and all-carbon diazo indandiones. This strategy is characterized by the fact that the diazo coupling partners do not require preactivation, along with its high efficiency, broad substrate generality, and facile transformation. Particularly, the highly conjugated tetracyclic products demonstrate good optical properties and can easily enter cells to emit bright fluorescence for live cell imaging.

Rhodium(III)-Catalyzed Sequential C-H Activation and Cyclization from N-Methoxyarylamides and 3-Diazooxindoles for the Synthesis of Isochromenoindolones

An efficient synthetic method for structurally various isochromenoindolones has been demonstrated through Rh(III)-catalyzed C-H activation followed by a cyclization reaction of N-methoxyarylamides with 3-diazooxindoles. The sequential reaction involves the streamlined formation of C-C and C-O bonds in one pot. The present method provides a broad range of isochromenoindolones as a new privileged scaffold in moderate to good yields with the release of methoxyamine and molecular nitrogen and has the benefits of a broad substrate scope and good functional group tolerance.

Recent advances in the synthesis of indole embedded heterocycles with 3-diazoindolin-2-imines

The preparations, reactivity and synthetic applications of 3-diazoindolin-2-imines, a valuable class of α-diazo amidines, are reviewed.

Sulfoximines-Assisted Rh(III)-Catalyzed C-H Activation and Intramolecular Annulation for the Synthesis of Fused Isochromeno-1,2-Benzothiazines Scaffolds under Room Temperature

A mild and facile Cp*Rh(III)-catalyzed C–H activation and intramolecular cascade annulation protocol has been proposed for the furnishing of highly fused isochromeno-1,2-benzothiazines scaffolds using S-phenylsulfoximides and 4-diazoisochroman-3-imine as substrates under room temperature. This method features diverse substituents and functional groups tolerance and relatively mild reaction conditions with moderate to excellent yields. Additionally, retentive configuration of sulfoximides in the conversion has been verified.

Preparation of spiro[imidazolidine-4,3′-indolin]-2′-imines via copper(i)-catalyzed formal [2 + 2 + 1] cycloaddition of 3-diazoindolin-2-imines and triazines

We report a facile and efficient synthesis of spiro[imidazolidine-4,3′-indolin]-2′-imines via a copper(i)-catalyzed cascade reaction of 3-diazoindolin-2-imines with 1,3,5-triazines.

A comprehensive overview of directing groups applied in metal-catalysed C-H functionalisation chemistry

The present review is devoted to summarizing the recent advances (2015-2017) in the field of metal-catalysed group-directed C-H functionalisation. In order to clearly showcase the molecular diversity that can now be accessed by means of directed C-H functionalisation, the whole is organized following the directing groups installed on a substrate. Its aim is to be a comprehensive reference work, where a specific directing group can be easily found, together with the transformations which have been carried out with it. Hence, the primary format of this review is schemes accompanied with a concise explanatory text, in which the directing groups are ordered in sections according to their chemical structure. The schemes feature typical substrates used, the products obtained as well as the required reaction conditions. Importantly, each example is commented on with respect to the most important positive features and drawbacks, on aspects such as selectivity, substrate scope, reaction conditions, directing group removal, and greenness. The targeted readership are both experts in the field of C-H functionalisation chemistry (to provide a comprehensive overview of the progress made in the last years) and, even more so, all organic chemists who want to introduce the C-H functionalisation way of thinking for a design of straightforward, efficient and step-economic synthetic routes towards molecules of interest to them. Accordingly, this review should be of particular interest also for scientists from industrial R&D sector. Hence, the overall goal of this review is to promote the application of C-H functionalisation reactions outside the research groups dedicated to method development and establishing it as a valuable reaction archetype in contemporary R&D, comparable to the role cross-coupling reactions play to date.

Rhodium(iii)-catalyzed annulative coupling between arenes and sulfoxonium ylides via C–H activation

Sulfoxonium ylides acts as a bifunctional C₂-synthon in Rh(iii)-catalyzed redox-neutral annulative coupling with arenes for the synthesis of N-heterocycles and carbocycles.

Cp*Ir(iii)-catalyzed C–H/N–H functionalization of sulfoximines for the synthesis of 1,2-benzothiazines at room temperature

The first Cp*Ir(iii)-catalyzed C–H/N–H bond functionalization of sulfoximines with α-diazocarbonyl compounds has been developed for the synthesis of 1,2-benzothiazines under redox-neutral conditions at room temperature.

Rhodium-catalyzed benzoisothiazole synthesis by tandem annulation reactions of sulfoximines and activated olefins

Rhodium(iii)-catalyzed N-directed ortho C–H activation reactions have been developed for the synthesis of unique heterocyclic benzoisothiazoles.