Rhodium‐Catalyzed Oxidative Annulation of Sulfoximines and Alkynes as an Approach to 1,2‐Benzothiazines

Abstract

Revitalization by oxygen: A rhodium(III)-catalyzed oxidative CH/NH activation/annulation sequence provided access to a variety of substituted 1,2-benzothiazine derivatives from readily available NH-sulfoximines and alkynes (see scheme; Cp*=C5 Me5 ). The oxidation system consisted of molecular oxygen in combination with a catalytic amount of Fe(OAc)2 .

General Catalytic Methylation of Amines with Formic Acid under Mild Reaction Conditions

“…The chelation‐assisted C–H activation approach has emerged as a powerful strategy for the cleavage and functionalization of inert C–H bonds and attracted considerable interest in recent years 11. Triazene,12 nitroso,13 sulfoximine,14 P=O bonds,15 and unsaturated C–C bonds16 have been explored as effective directing groups (DG) to assist selective C–H bond functionalization and employed in a variety of reactions.…”

Ruthenium‐Catalyzed Alkenylation of Arenes with Alkynes or Alkenes by 1,2,3‐Triazole‐Directed C–H Activation

“…The chelation-assisted C-H activation approach has emerged as a powerful strategy for the cleavage and functionalization of inert C-H bonds and attracted considerable interest in recent years. [11] Triazene, [12] nitroso, [13] sulfoximine, [14] P=O bonds, [15] and unsaturated C-C bonds [16] have been explored as effective directing groups (DG) to assist selective C-H bond functionalization and employed in a variety of reactions.…”

Rhodium(III)‐Catalyzed Selective ortho‐Olefinations of N‐Acyl and N‐Aroyl Sulfoximines by CH Bond Activation

“…Making use of the directing power of the sulfoximidoyl group, we recently reported the direct conversion of NH ‐sulfoximines into 1,2‐benzothiazines by rhodium‐catalyzed CH/NH insertions of alkynes [Eq. (4)] 7. The process was well suited to the synthesis of such heterocycles; however, the sulfoximidoyl moiety, which is often a desired functional group for either a specific property8 or a subsequent targeted derivatization, was not retained 9.…”

“…(4)]. [7] The process was well suited to the synthesis of such heterocycles; however, the sulfoximidoyl moiety, which is often a desired functional group for either a specific property [8] or a subsequent targeted derivatization, was not retained. [9] Herein, we disclose two unprecedented oxidative sulfoximine olefinations [Eqs.…”

“…A mechanistic proposal for the rhodium-catalyzed ortho-olefination, based on previously reported related catalysis, [3,6,7,10] is shown in Scheme 2. Most likely, the catalytic cycle is initiated by cationic rhodium(III) complex A, which is formed from [RhCp*Cl 2 ] 2 with the aid of the silver salt.…”