Acylsilane Directed Rh-Catalyzed Arene C–H Alkylation with Maleimides and Visible-Light-Induced Siloxycarbene-Amide Cyclization: [3 + 2] Carbo-Annulation in Ru Catalysis

Abstract

We herein demonstrate the acylsilane-directed Rh-catalyzed arene C−H bond alkylation with maleimides. The resulting derivatives were utilized in visible-light-induced intramolecular siloxycarbene-amide cyclization for the synthesis of new tricyclic γ-lactams. In parallel, we also harnessed the same acylsilane and maleimide units through [3 + 2] carbo-annulation by using Ru-catalysis. A wide range of maleimides and aroylsilanes were used to establish the broadness of these transformations.

Acylsilanes in Transition-Metal-Catalyzed and Photochemical Reactions: Clarifying Product Formation

“…Furthermore, photochemical irradiation of olefin-tethered acylsilanes affords stable cyclopropane adducts, and photochemical irradiation of ester-tethered acylsilanes produces a mixture of structural isomers following 1,2-carbonyl addition of the visible light-induced siloxy carbene to the ester. The discovery that nucleophilic siloxy carbene intermediates can undergo 1,2-carbonyl addition to proximal esters presents further opportunities to exploit siloxy carbene reactivity . Moreover, the 1,2-alkoxy migration that occurred to generate the minor structural isomer described in Figure represents an intriguing transformation that warrants further investigation.…”

Palladium-Catalyzed [3 + 2] Annulation of ortho-Substituted Iodoarenes with Maleimides via a Consecutive Double Heck-type Strategy

“…2-Phenyl-3a,8a-dihydroindeno [1,2-c]pyrrole-1,3,8(2H)-trione (7aa). 15 GP-3 was carried out with 2-iodobenzaldehyde 2a (58 mg, 0.25 mmol), N-phenylmaleimide 6a (53 mg, 0.30 mmol), Pd(OAc) 2 (5.6 mg, 10 mol %, 0.025 mmol), AgOAc (83 mg, 0.50 mmol), NaOAc ( [1,3]dioxole-5-carbaldehyde 2f (69 mg, 0.24 mmol), N-ethylmaleimide 6r (38 mg, 0.30 mmol), Pd(OAc) 2 (5.6 mg, 10 mol %, 0.025 mmol), AgOAc (83 mg, 0.50 mmol), NaOAc (21 mg, 0.25 mmol), and TFA (2 mL) at 100 °C for 6 h in an oil bath. Purification of the crude material by silica gel column chromatography (petroleum ether:ethyl acetate = 70:30 to 65:25) furnished the product 7fr (43 mg, 63%) as a colorless solid.…”

“…13,14 Recently, the research group of Das revealed a strategy for succinimide-fused indane derivatives via Ru-catalyzed [3 + 2] cyclization of acyl silane motifs with maleimides (Scheme 1a(ii)). 15 The research groups of Chatani and Jeganmohan explored a Pd-catalyzed [3 + 2] annulation of maleimides with benzamides and benzoic acids via benzylic C(sp 3 )−H and meta-C(sp 2 )−H bond activation by bis-chelating amino acid ligands in 2021, 2022, and 2023 (Scheme1b). 16,17 Kumar et al unveiled the synthesis of succinimide-fused unsymmetrical 9,10-dihydrophenanthrenes via the Heck strategy using aryl iodides and maleimides in 2020.…”

“…For instance, maleimide motifs have been found in natural products, drugs, and active pharmaceutical intermediates. , In addition, succinimide-fused tricyclic frameworks encompass antihypertensive, hypertensive, anorexic, analgesic, anticonvulsant, and hyperglycemic activities (Figure ). − Due to their significant biological properties and pharmaceutical importance, some notable strategies have been established for attaining such heterocyclic frameworks; for instance, transition metal-catalyzed annulations effectively accomplish such heterotricyclic systems. − Despite the aforementioned notable strategies, there is still enough scope to develop efficient synthetic methodologies to accomplish such heterocyclic products. Mainly, maleimide and its derivatives are highly affordable and simple starting materials; therefore, in recent years, chemists have employed maleimides as leading coupling partners under induced catalytic transformations. − Especially, maleimide-based transition metal-catalyzed C–H activations to construct polycyclic molecules have been developed. − On the other hand, Pd-catalyzed activation of aryl halides and their eventual Heck couplings with olefins were found as one of the promising tools for constructing polycyclic molecules, − which can be extended to maleimides to get polycyclic compounds.…”

“…C{H}-NMR (101 MHz, DMSO-d 6 ) δ 194.4, 174.0, 168.7, 148.5, 135.9, 135.8, 133.0, 131.1, 129.5, 129.1 (2 × C), 128.9 (2 × C), 126.9, 124.3, 54.6, 46.4 ppm. HRMS (ESI): m/z calcd for C 17 H 10 NClNaO 3 + [M + Na] + : 334.0241, found: 334.0231.2-(4-Bromophenyl)-3a,8a-dihydroindeno[1,2-c]pyrrole-1,3,8(2H)-trione (7ai) 15. GP-3 was carried out with 2-iodobenzaldehyde 2a (58 mg, 0.25 mmol), N-(4-bromo)phenylmaleimide 6i (75 mg, 0.30 mmol), Pd(OAc) 2 (5.6 mg, 10 mol %, 0.025 mmol), AgOAc (83 mg, 0.50 mmol), NaOAc (21 mg, 0.25 mmol), and TFA (2 mL) at 100 °C for 6 h in an oil bath.…”