Rhodium-Catalyzed Reaction of Sulfoxonium Ylides and Anthranils toward Indoloindolones via a (4 + 1) Annulation

Abstract

A rhodium-catalyzed annulation between aroyl sulfoxonium ylides and anthranils has been developed to synthesize 10H-indolo­[1,2-a]­indol-10-one derivatives. This reaction started with an unpredented (4 + 1) annulation toward N-(2-formylphenyl) indolones, proceeding with the sequential ortho-amination of the C–H bond in aroyl sulfoxonium ylides by anthranils and the insertion of N–H to carbene. Finally, the Aldol condensation constructed the second indole ring. This procedure features the formation of two C–N bonds and one CC bond in one pot.

Bi(OTf)3‐Mediated (4+1) Annulation of α‐Sulfonyl o‐Hydroxyacetophenones with α‐Hydroxy Arylketones to Access Sulfonyl 2‐Aroylbenzofurans

“…The initial study commenced with the treatment of αsulfonyl o-hydroxyacetophenone 2 a (Ar=Ph, 870 mg, 3.0 mmol, prepared from CuBr 2 -mediated α-bromination of o-hydroxyacetophenone 1 a followed by nucleophilic substitution of the resulting α-bromo-o-hydroxyacetophenone with TolSO 2 Na) and α-hydroxy phenylketone 3 a (Ar'=Ph; 420 mg, 3.1 mmol). First, using Bi(OTf) 3 (20 mol%), a 72% yield of 4 a was obtained in the presence of MeNO 2 (5 mL) at 25°C for 10 h (Table 1, entry 1). With these results in mind, the optimal reaction time was studied by using 20 mol% Bi(OTf) 3 as the promoter and 5 mL of MeNO 2 as the solvent.…”

“…The Xiao group summarized and analysed the elegant synthetic applications of the (4 + 1) annulation reaction. [1] Recently, a number of transition metal-catalysed methods (e. g., with Rh(III), [2][3][4][5][6][7] Au-(I), [8][9] Re(I) [10] and Ir(III) [11] ) have emerged as (4 + 1) annulation routes to provide a structurally diverse range of molecules. The use of other promoters, including organophosphines, [12][13][14] organoamines [15] and K 2 CO 3 , has been reported.…”

Iridium‐Catalyzed [4+2] Annulations of β‐Keto Sulfoxonium Ylides and o‐Phenylenediamines: Mild and Facile Synthesis of Quinoxaline Derivatives

“…In particular, those compounds have been approved as a forceful and universal synthetic tool for the organic chemists, owing to fruitful chemistries of both the sulfoxonium ylides and carbonyl moieties. While, the reported cyclization reactions of β‐keto sulfoxonium ylides via metal‐carbene intermediates process mainly include the following categories: 1) As one carbon synthons participates in ( n + 1, n = 4, 5, 6, 7) annulation reaction (Scheme a) . 2) Be known as two carbon synthons mediates ( n + 2, n = 3, 4) cyclization reaction (Scheme a) .…”

Anthranils: versatile building blocks in the construction of C–N bonds and N-heterocycles

“…In 2019, a Rh(III)-catalysed C-H amination/annulation protocol of aroyl sulfoxonium ylides 54 and anthranils has been developed for the synthesis of 10H-indolo[1,2-a]indol-10-one derivatives 55 (Scheme 19). 27 This transformation was initiated by an ortho-C-H amination of α-aroyl sulfoxonium ylides with anthranils to generate 54d. Subsequently, the insertion of the N-H bond to the in situ-formed Rh carbene species 54f led to an unprecedented [4 + 1] annulation toward N-(2-formylphenyl) indolones 54h.…”