Formaldehyde → (3S,8S)-3-[4-(3,4-Dichloro-benzyloxy)-phenyl]-7-((S)-1-phenyl-propyl)-2,3,6,7,8,9-hexahydro-[1,4]dioxino[2,3-g]isoquinoline-8-carboxylic acid methyl ester

Participants

Reaction Steps

(S)-3-{(S)-2-[4-(3,4-Dichloro-benzyloxy)-phenyl]-2,3-dihydro-benzo[1,4]dioxin-6-yl}-2-((S)-1-phenyl-propylamino)-propionic acid methyl ester (893 mg) was dissolved in 80 mL dry dioxane and 133 mg paraformaldehyde and 20 mL trifluoroacetic acid were added. The reaction stirred 12 h at rt, then 66 mg more paraformaldehyde was added while stirring at rt. After 3 h aqueous NaHCO3 was added until a pH of 7 was achieved, then the mixture was extracted with EtOAc. The organic extract was washed with brine and dried over Na2SO4 and evaporated. The residue was purified by silica gel flash chromatography (9:1 to 8:2 hexanes/EtOAc) to give 872 mg desired product after drying. 1H NMR (400 MHz, acetone-d6): 7.72 (d, 1H), 7.62 (d, 1H), 7.51-7.43 (m, 3H), 7.38-7.25 (m, 5H), 7.10 (m, 2H), 6.67 (s, 1H), 6.60 (s, 1H), 5.20 (s, 2H), 5.09 (m, 1H), 4.30 (m, 1H), 4.13 (m, 2H), 3.99 (m, 1H), 3.92 (m, 1H), 3.59 (m, 1H), 3.52 (s, 3H), 2.96-2.78 (m, 2H), 2.16 (m, 1H), 1.68 (m, 1H), 0.65 (t, 3H).

Provenance & Evidence