Water → HCID 53803370, compound

Participants

Reaction Steps

Benzyl-2-bromo-4,4-dimethylpentanoate (20 g) in dry dimethyl sulphoxide (250 ml) was treated with D-alanine methylester hydrochloride (9.33 g), N-methyl morpholine (6.78 g) and tetrabutyl ammonium iodide (24.7 g) at 90° under an atmosphere of argon for 2 days. The reaction mixture was allowed to cool to room temperature, poured into water (500 ml) and the products recovered by extraction into dichloromethane (3×250 ml). The material isolated from the organic extracts was purified by chromatography on silica developed in a gradient of hexane-ether. Elution with 30% ether-hexane afforded benzyl 4,4-dimethylpent-2-enoate (14 g). Elution with 40% ether in hexane afforded the title compound (350 mg) as a gum; (Found: [m+1]+ =322.2022. C18H27N1O4 requires [m+1]+ =322.2018); νmax (film) 1735 cm-1 ; δ(CDCl3) 0.90 (9H, s, C(CH3)3 ); 1.28 (3H, d, J=7 Hz CHCH3); 2.46 and 2.68 (2H, each dd, J=12 and 5 Hz, CH2 (CH3)3); 3.30 (1H, q, J=5 Hz CH-CH3); 3.36 (1H, t, J=5 Hz, CH-CH2); 3.66 (3H, s, OCH3); 5.12 (2H, s, OCH2) and 7.36 (5H, s, C6H5). Elution with 45% ether in hexane afforded benzyl 2-(R)-N-(1-(R)-methoxycarbonylethyl)-amino-4,4-dimethylpentanoate (340 mg); (Found: [m+1]+ =322.2022. C11H27NO4 requires 322.2018); νmax (film) 3360 and 1735 cms-1 ; δ(CDCl3) 0.90 (9H, s, C(CH3)3); 1.28 (3H, d, J=6 Hz, CHCH3 ); 1.44 and 1.72 (2H, each dd, J=5 and 12.5 Hz, CH2); 3.32 (1H, q, J=7 Hz, CHCH3); 3.44 (1H, t, J=6 Hz, CHCH2); 3.69 (3H, s, OCH3), 5.24 (2H, s, OCH2) and 7.36 (5H, m, C6H5).

Provenance & Evidence