An Easy, Stereoselective Synthesis of Hexahydroisoindol‐4‐ones under Phosphine Catalysis

Abstract

International audienceA new synthetic approach to hexahydroisoindol-4-ones is reported, based on the formal [3+2] cyclization reaction between N-arylsulfonylimines and cyclic conjugated dienes, under phosphine catalysis. Key substrates are 3-vinylcyclohex-2-enones with electron-withdrawing substituents (ester, amido, cyano, phosphoryl and keto groups) on the exocyclic double bond, which afford the three atom synthons for the construction of the pyrroline ring. Total syn stereoselectivity is observed in these annulations. The scope of the reaction has been demonstrated and mechanistic issues are considered, based on deuteration experiments and DFT calculations

Phosphine‐Catalyzed Rauhut–Currier Domino Reaction: A Facile Strategy for the Construction of Carbocyclic Spirooxindoles Skeletons

“…According to the experimental results and previous studies, [12,13,15] we proposed a possible mechanism that can help to account for the formation of carbocyclic spirooxindoles in this domino reaction (Scheme 4). According to the experimental results and previous studies, [12,13,15] we proposed a possible mechanism that can help to account for the formation of carbocyclic spirooxindoles in this domino reaction (Scheme 4).…”

“…To demonstrate the versatility of the product, we explored the important transformation of the cycloadduct trans-3 k. Compound 4 was finally accessed after removal of the tert- PBu 3 dioxane 105 8 65 11 [c] PBu 3 CHCl 3 rt 9 57 12 [d] PBu 3 CHCl 3 rt 8 75 13 [d] PBu 3 CHCl 3 60 6 91 14 [d] PBu 3 CHCl 3 40 6 83 15 [e] PBu 3 CHCl 3 60 6 90 16 [d,f] PBu 3 CHCl 3 60 6 89 17 [d,g] PBu 3 According to the experimental results and previous studies, [12,13,15] we proposed a possible mechanism that can help to account for the formation of carbocyclic spirooxindoles in this domino reaction (Scheme 4). Nucleophilic addition of phosphine to the dieneone double bond of 1 gave intermediate I, which subsequently underwent intermolecular conjugate addition to the 3' position of 2 to give intermediate II.…”

“…The reaction proceeded smoothly and afforded the desired product in moderate yield. Various solvents, such as DMF, CH 2 Cl 2 , ClCH 2 CH 2 Cl, and dioxane were scanned, but no better results could be obtained ( [14][15][16][17]. In the screening of phosphine catalysts, the more nucleophilic catalyst PMe 3 led to lower yield, and no product was obtained when using less nucleophilic catalysts, such as PPh 3 , PPh 2 Et, LBBA-1, LBBA-2 ( Table 1, entries [1][2][3][4][5][6].…”

PPh3‐Catalyzed Ring‐Expansion Reactions of Sulfamate‐Derived Cyclic Imines with Acetylenedicarboxylates

“…The reaction is operationally simple, proceeds smoothly under very mild reaction conditions, and provides various sulfamate-fused benzo [g]A C H T U N G T R E N N U N G [1,2,3]oxathiazocine-4,5-dicarboxylate 2,2-dioxide derivatives in moderate to excellent yields. Further efforts to expand the scope of phosphine-catalyzed reactions of sulfamate-derived cyclic imines are underway.…”

“…[1] Among various phosphine-catalyzed reactions, the annulation reactions of electron-deficient olefins, allenes, and alkynes with activated imines [2] have received much attention due to their extensive application in the synthesis of various useful nitrogen-containing heterocycles [3] and natural products. [4] Compared with electron-deficient olefins and allenes, alkynes were seldom used in annulation reactions with imines, and only a few examples have been reported.…”