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Direct Umpolung Morita-Baylis-Hillman like α-Functionalization of Enones via Enolonium Species

Shlomy Arava, Sourav K. Santra, Gulab K. Pathe, Raja Kapanaiah, Alex M. Szpilman*

*Department of Chemical Sciences, Ariel University, Ariel 4070000, Israel, Email:

S. Arava, S. K. Santra, G. K. Pathe, R. Kapanaiah, A. M. Szpilman, Angew. Chem. Int. Ed., 2000, 59, 15171-15175.

DOI: 10.1002/anie.202005286

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The hypervalent iodine reagent PIDA in combination with a nucleophilic amine (DABCO or pyridine) induces α-functionalization of enones via umpolung of Morita-Baylis-Hillman type intermediates. Depending on the presence of additional nucleophiles, α-chloro-enones, 1,2-diketones and α-tosyloxy-enones can be obtained.

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General Procedure for preparation of α-tosyl-enones

In an oven dried 50 mL round bottom flask 1-arylprop-2-en-1-one 1 (0.7 mmol) and freshly distilled dry acetonitrile (8 ml) were placed under an argon atmosphere. To that solution (diacetoxyiodo)benzene (2.1 mmol, 3.0 equivalents) and pyridinium p-toluenesulfonate (PPTS) (2.45 mmol, 3.5 equivalents) were added and the reaction mixture was stirred for overnight (14-16 hours) at room temperature. Then triethylamine (4.2 mmol, 6 equivalents) was added and stirred for another 2 hours at room temperature. The reaction mixture was concentrated on rotavapor under reduced pressure. The concentrated reaction mixture was quenched by the addition of H2O (5 mL) and then extracted with CH2Cl2 (315 mL). The combined organic extracts were dried over anhydrous Na2SO4.The crude product was purified by silica gel column chroromatography (10 → 15% EtOAc in hexane) to afford the corresponding products.

2-Fluoroenones via an Umpolung Morita-Baylis-Hillman Reaction of Enones

S. Maity, A. M. Szpilman, Org. Lett., 2023, 25, 1218-1222.

1,2-diketones, protected enols, Morita-Baylis-Hillman reaction, PIDA

ID: J54-Y2023