Formation of a benzothiazine via the reaction of ortho-halo sulfoximines with copper salts

Abstract

The formation of an interesting benzothiazine from the reaction of S-(o-halophenyl)-S-methyl sulfoximines in the presence of copper salts is reported. The overall yield is 27% over three steps from commercially available 2-halothioanisoles in the best case. The product's structure was confirmed by spectroscopic and X-ray crystal analysis. The benzothiazine shows fluorescent properties.

o-Silylaryl Triflates: A Journey of Kobayashi Aryne Precursors

“…In contrast, the employment of 2-halobenzamides containing either the absence of N -substituent or N , N -dimethyl group did not observe any desired products. In a study carried out by Harmata et al on the preparation of benzofused benzothiazines from o -halo sulfoximines, they also reported Pd-catalyzed annulation examples, albeit in low yields . Recently, Meng, Xu, and co-workers achieved a Pd-catalyzed decarbonylative annulation of phthalimides 10-91 with o -silylaryl triflates, affording phenanthridinones 10-92 with good functional group tolerance (Scheme b) .…”

One-Pot Synthesis of Iodo-Dibenzothiazines from 2-Biaryl Sulfides

“…However, methods for the construction of cyclic sulfoximine frameworks are rather limited. Several studies have focused on the synthesis of bicyclic sulfoximine derivatives, such as benzothiazines and benzoisothiazines . To the best of our knowledge, the synthesis of polycyclic sulfoximine derivatives has been documented in very limited reports .…”

Rhodium(III)-CatalyzedOrthoHalogenations ofN-Acylsulfoximines and Synthetic Applications toward Functionalized Sulfoximine Derivatives

“…Following our interest in sulfoximine chemistry with reports on rhodium-catalyzed C–H bond activations for annulations, olefinations, and hydroarylations, we felt challenged to develop a catalytic process for ortho halogenations of such compounds . Here, we describe brominations and iodinations of sulfoximines leading to products, which can subsequently be functionalized to give alkynylated derivatives and sulfoximidoyl-based heterocycles with potential for further synthetic applications …”

“…Finally, a few transformations of the products were explored. As shown by Harmata et al, N -unprotected ortho halo-substituted sulfoximines can undergo cross-coupling reactions, but commonly, product mixtures were obtained rendering the yields of the individual products only moderate to good. , In contrast, applying the N -acetyl-protected derivatives obtained by the aforementioned rhodium catalysis (Schemes and ) in analogous transformations led to defined target structures in very good yields. For example, Sonogashira-type cross-couplings of ortho -bromo and ortho- iodo sulfoximines 3a and 4a with terminal alkynes 5a and 5b gave the corresponding alkynylated products 6a and 6b in up to 95% yield (Scheme ).…”

“…Palladium-catalyzed Suzuki coupling reactions of 4a with boronic acids 7 under basic conditions in MeCN/H 2 O afforded arylated products 8 , which could be N -deacetylated and oxidatively cyclized , to give benzothiazines 9 in good overall yields (Scheme ). Although few such heterocycles have been reported before, ,, the approach reported here is attractive because it allows access to a wide range of derivatives from a single readily available key intermediate ( 4a ).…”