Dimethylamine → HCID 22506064, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of 13.00 g (28.98 mmol) of enantiomerically-enriched tetrahydrobenzothiepine-1,1-dioxide ((4R,5R)-XXV) in 73 mL of dimethylamine (2.0 M in THF, 146 mmol) in a Parr Reactor was added ca. 20 mL of neat dimethylamine. The mixture was sealed and stirred at 110° C. overnight, and cooled to ambient temperature. The excess dimethylamine was evaporated. The crude oil was dissolved in 200 mL of ethyl acetate and washed with 100 mL of water, dried over MgSO4 and concentrated in vacuo. Purification on a silica gel column (Waters Prep 500) using 20% ethyl acetate/hexane gave 12.43 g (90.5%) of the enantiomerically-enriched 7-(dimethylamino)tetrahydrobenzothiepine-1,1-dioxide ((4R,5R)-XXVI) as a colorless solid: 1H NMR (CDCl3) d 0.87-0.93 (m, 6H), 1.10-1.68 (m, 12H), 2.17-2.25 (m, 1H), 2.81 (s, 6H), 2.99 (d, J=15.3 Hz, 1H), 3.15 (d, J=15.3 Hz, 1H), 3.84 (s, 3H), 4.11 (d, J=7.5 Hz, 1H), 5.49 (s, 1H), 5.99 (d, J=2.4 Hz, 1H), 6.51 (dd, J=8.7 Hz, 2.4 Hz, 1H), 6.94 (d, J=8.7 Hz, 2H), 7.42 (d, J=8.4 Hz, 2H), 7.90 (d, J=8.7 Hz, 1H). The product was determined to have 78% e.e. by chiral HPLC on a Chiralpak AD column using 5% ethanol/hexane as the eluent. Recrystallization of this solid from ethyl acetate/hexane gave 1.70 g of the racemic product. The remaining solution was concentrated and recrystallized to give 9.8 g of colorless solid. Enantiomeric excess of this solid was determined by chiral HPLC on a Chiralpak AD column using 5% ethanol/hexane as the eluent. It showed to have 96% e.e with the first eluting peak as the major product.

Provenance & Evidence