Diisopropylamine → (4R,5R)-4,5-Dimethyl-(R)-3-(toluene-4-sulfinylamino)-octanoic Acid tert-butyl Ester

Participants

Reaction Conditions

Reaction Steps

Butyl lithium (26.3 mL, 42.04 mmol) was added to a solution of diisopropylamine (4.6 g, 45.6 mmol) in dry THF (40 mL) under nitrogen at 0° C. and stirred for 20 minutes. The solution was cooled to −78° C. followed by the addition of t-butyl acetate (4.1 g, 35.0 mmol) and stirred at that temperature for 45 minutes. Chlorotitanium triisopropoxide (9.4 g, 36.2 mmol) was added dropwise and stirring was continued for 30 minutes at −78° C. A −50° C. solution of 4-methyl-benzenesulfinic acid ((2R,3R)-2,3-dimethyl-hexylidene)-amide (3.1 g, 11.7 mmol) in dry THF (10 mL) was added to the reaction and the resulting mixture was stirred at −78° C. for 4 hours. The reaction was quenched with a saturated solution of NaH2PO4 and extracted into ethyl acetate. The solution was dried over MgSO4 and concentrated. The resulting residue was chromatographed on silica, eluting with 15% ethyl acetate in hexane to give the titled compound (2.4 g, 53.9% yield) as white solid: 1H NMR (400 MHz, CDCl3) δ ppm 0.9 (m, 6 H) 1.0 (d, J=6.6 Hz, 3 H) 1.1 (m, 1 H) 1.3 (m, 2 H) 1.4 (m, 9 H) 1.5 (m, 2 H) 2.4 (s, 3 H) 2.6 (m, 2H) 3.8 (m, 1 H) 4.4 (d, J=10.0 Hz, 1 H) 7.3 (d, J=8.1 Hz, 2 H) 7.6 (d, J=8.1 Hz, 2 H). MS, m/z (relative intensity): 382 [M+1H, 100%], 326 [M+1H—C(CH3)3, 50%].

Provenance & Evidence