Abstract
Palladium-catalysed decarboxylative carbonylation of 3-tosyl-5-vinyloxazolidin-2-ones 5 occurs at atmospheric pressure to give 1-tosyl-3,6-dihydro-1H -pyridin-2-ones 6 . The reaction proceeds with no loss of enantiopurity and detosylation with sodium naphthalenide gives the title compounds in good yields.
Key words
carbonylation - catalysis - palladium - cyclisation - lactams
References
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12 Gas chromatography analysis [138 °C, β-dextrin 120 column (20 m × 0.25 mm)] of (6R )-3,6-dihydro-6-isopropyl-1H -pyridin-2-one (6R )-2a , formed by the direct carbonylation of (4R )-1a , showed a single peak (t
R 36.963 min). Likewise, analysis of (6R )-2a formed by deprotection of the N -tosylpiperidinone (4R )-6a also showed only one peak (t
R 36.703 min), as did the analysis of the (S )-N -H lactam (6S )-2a (t
R 37.856 min). Analysis of a 1:4 mixture of the enantiomers, (6R )-2a /(6S )-2a showed two peaks in a 1:4 ratio (37.747 min; 38.590 min).
