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

Subrata Maity and Alex M. Szpilman*

*Department of Chemical Sciences, Ariel University, Ariel 4070000, Israel, Email: Szpilmanariel.ac.il

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

DOI: 10.1021/acs.orglett.3c00313


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Abstract

A formal enone-α-H to F substitution provides 2-fluoroenones in a single step from ubiquitous enones in good yield. The reaction is applicable to a wide range of aromatic and alkenyl enones and is carried out at room temperature using HF-pyridine complex as the fluoride source. The reaction takes place through a rare umpolung Morita-Baylis-Hillman-type mechanism.


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proposed mechanism



General procedure for the Umpolung MBH Fluorination Reaction:

To a stirring solution of 1-(Naphthalen-2-yl) prop-2-en-1-one 1 (0.100 g, 0.548 mmol) in a Falcon tube (Teflon coated) in dry acetonitrile (4 mL) at 25 C was added DABCO (0.092 g, 0.823 mmol, 1.5 eq) under a nitrogen atmosphere. The mixture was stirred at the same temperature for 5 minutes under a nitrogen atmosphere. Then 2-Iodosyl-1,3-dimethylbenzene (0.217 g, 0.877 mmol, 1.6 equiv.) and Py9HF (0.247 mL, 2.74 mmol, 5 equiv.) were added to the reaction mixture sequentially. The resulting homogeneous mixture was stirred at the same temperature and monitored by TLC. On completion (14-18 hours), triethyl amine (0.765 mL, 5.485 mmol, 10 equiv.) was added to the reaction mixture and stirred for another 3 hr at the same temperature. Solvent was evaporated under reduced pressure and the crude residue was purified by silica gel (230-400) flash chromatography usingto afford the desired product.


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

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


Key Words

fluoroalkenes, Morita-Baylis-Hillman reaction, hypervalent iodine reagents


ID: J54-Y2023