Acetic Acid → HCID 70686336, compound

Participants

Reaction Steps

To a solution of the above bis-amide 5 (crude, 2.15 g, 0.367 mmol) in anhyd 1,2-dichloroethane (20 mL), propionaldehyde (0.265 mL, 3.67 mmol) and HOAc (0.263 mL, 4.56 mmol) were added at ice-bath temperature while stirring in an atmosphere of argon. Then sodium triacetoxyborohydride (0.779 g, 3.68 mmol) was added in small portions over a 15 min period, resulting reddish suspension was slowly allowed to warm to room temperature and stirred overnight under argon. The reaction was quenched by a slow addition of saturated NaHCO3 (20 mL) at 0° C. The biphasic mixture was stirred for 15 min and extracted with CHCl3 (3×25 mL). The combined organic extracts were washed with water and brine (50 mL each) and then dried over Na2SO4. Solvents were removed in vacuo and the crude product (0.945 g) was subjected purification by preparative RP-HPLC (Sunfire, 5-95% B/10 min). The pure fractions were concentrated in vacuo, the residue was co-evaporated with CH3CN (3×10 mL), and then dried under high vacuum to give 4 (0.281 g, 33%) as a brick-red sticky solid: 1H NMR (CDCl3) characteristic br s at δ 3.64 for poly(ethylene glycol) moiety; RP-HPLC (264 nm) 91% (tR=19.2 min); RP-LC/MS (ESI) m/z 567.4 (M+H)+, 589.4 (M+Na)+ (tR=5.17 min). HRMS (ESI) m/z calculated for C110H218N6O56 (M+2H)2+ 1211.7345, found 1211.7343; calculated for C110H217N6O56Na (M+H+Na)2+ 1222.7254, found 1222.7256; calculated for C110H216N6O56Na2 (M+2Na)2+ 1233.7164, found 1233.7173.

Provenance & Evidence