TMAF-Catalyzed Conjugate Addition of Oxazolidinone and Thiols

Abstract

TMAF (Me₄NF) is a useful catalyst for the conjugate ­addition of oxazolidinone and thiols to a range of Michael acceptors including esters, ketones, nitroolefins and cinnamaldehyde.

Key words

ammonium fluoride - catalysis - Michael addition - oxazolidinone - thiols

References

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11

General Procedure and Representative Data for the Reaction of Oxazolidinone with Acyclic Enones. To a solution of type 4 chalcone (1 mmol) and oxazolidinone 1a (378 mg, 4 mmol) in anhyd MeCN (2 mL) was added dry Me₄NF (19 mg, 0.2 mmol) in one portion. After stirring of the resulting pale yellow solution for 3 d, H₂O and Et₂O (3 mL each) were added, followed by the addition of few drops of aq HCl 1 mol L^-1 and a spatula of NaCl. After stirring the biphasic system for 5 min, the two phases were separated, the aqueous layer was extracted two times with Et₂O. The organic layer was dried over MgSO₄, concentrated and purified by flash chromatography, eluting with cyclohexane-EtOAc (1:1).
3- N -Oxazolidinyl-1-( p -F-phenyl)-3-phenylpropan-1-one ( 5a): white solid; yield 173 mg, 55%; mp 135 °C. IR (CHCl₃): ν = 1747, 1685 cm^-1. ¹H NMR (200 MHz, CDCl₃, 25 °C): δ = 3.47 (quint, J = 8.6 Hz, 1 H), 3.51 (dd, J = 6.3, 16.4 Hz, 1 H), 3.55 (quint, J = 8.6 Hz, 1 H), 4.05 (dd, J = 8.6, 16.4 Hz, 1 H), 4.24 (quint, J = 8.6 Hz, 2 H), 5.29 (dd, J = 6.3, 8.6 Hz, 1 H), 7.03-7.18 (m, 2 H), 7.25-7.44 (m, 5 H), 7.91-8.05 (m, 2 H). ¹³C NMR (50 MHz, CDCl₃, 25 °C): δ = 40.4, 43.4, 54.6, 62.0, 115.6, 116.1, 127.3, 128.3, 128.9, 130.8, 131.0, 132.7, 132.8, 138.4, 157.7, 163.4, 168.4, 195.5. LRMS: m/z (%) = 313 (2) [M⁺], 225 (66), 131 (29), 123 (base), 103 (53), 95 (85), 77 (30). Anal. Calcd for C₁₈H₁₆FNO₃ (313.33): C, 69.00; H, 5.15; N, 4.47; Found C, 69.05; H, 5.21; N, 4.48.