Triethylamine → (3aR-cis)-(+)-3,3a,8,8a-Tetrahydro-2H-indeno[1,2-d]oxazol-2-one

Participants

Reaction Conditions

Reaction Steps

(1R,2S)-cis-1-amino-2-indanol (0.980 g, 6.569 mmol) was placed in a round-bottomed flask and a dry Ar atmosphere was established. Dry CH2Cl2 (50 mL) and Et3N (1.9 mL, 13.63 mmol) were added, and the resulting solution was cooled to −60° C. On addition of triphosgene (0.64 g, 2.157 mmol), the cooling bath was removed, and the reaction was allowed to warm to 20° C. over one hour. The reaction was then poured into CH2Cl2 (100 mL) and H2O (50 mL) and the aqueous phase was extracted with CH2Cl2 (3×100 mL). After drying with MgSO4, the organic layer was evaporated under reduced pressure to give (3aR-cis)-3,3a,8,8a-tetrahydro-2H-indeno[1,2-d]-oxazol-2-one, (R)-24 (1.15 g, quantitative) as white crystals, which was of sufficient purity for the next step in the reaction sequence. An analytical sample was recrystallized from CH2Cl2/hexanes. mp 205.5-206.5° C.; [Ghosh et al. (1992) J. Chem. Soc. Chem. Commun. 1673-1674 for enantiomer mp 205° C.]; [α]25D=+107.7 (c 1.25, CHCl3); [Id. for enantiomer [α]25D=−79.4 (c 1.4, CHCl3)]. IR (KBr) 3255, 1752, 1707 cm−1; 1H NMR (acetone-d6) δ 7.24-7.43 (4H, m), 5.39 (1H, t, J=7.5 Hz), 5.21 (1H, d, J=7.0 Hz), 3.42 (1H, dd, J=17.7, 6.2 Hz), 3.20 (1H, d, J=17.9 Hz), 2.90 (1H, br s); 13C NMR (acetone-d6) δ 159.1, 142.5, 141.0, 129.7, 128.3, 126.2, 125.8, 80.8, 61.7, 39.3; HRMS (FAB+) m/z: calcd for C10H9NO2+H, 176.0771; found, 176.0681.

Provenance & Evidence