Lawesson's reagent → HCID 86727632, compound

Participants

Reaction Steps

A solution of (R)-2-(7-bromo-3-oxo-2,3-dihydro-benzo[1,4]oxazin-4-yl)-propionic acid ethyl ester (80 g, 244 mmol) and Lawesson's reagent (59.1 g, 146 mmol) in toluene (900 mL) was heated at reflux for 3 h then cooled to ambient temperature. The solvent was removed in vacuo and the residue was purified by chromatography on silica gel (eluting with 5-10% EtOAc in petroleum ether) to give (R)-2-(7-bromo-3-thioxo-2,3-dihydro-benzo[1,4]oxazin-4-yl)-propionic acid ethyl ester (60 g, 71%) as a yellow liquid. 1H NMR (400 MHz, CDCl3): δ 7.20 (s, 1H), 7.12 (d, J=8.8 Hz, 1H), 6.77 (d, J=8.8 Hz, 1H), 6.70 (m, 1H), 4.99-4.88 (m, 2H), 4.23-4.15 (m, 2H), 1.57 (d, J=7.2 Hz, 3H), 1.16 (t, J=7.2 Hz, 3H). SFC (Table 1, Method 30) Rt=2.902 min.; [α]D20=20.79 (C=0.002 g/mL in methanol).

Provenance & Evidence