反应详情

Intermediates of formula 3 are prepared using methods known in the art. See for example U.S. Pat. No. 3,974,275 to Bossert et al., incorporated fully herein by reference. Additionally, certain intermediates of formula 3 are commercially available, e.g., methyl β-aminocrotonate. Under Claisen reaction conditions, acetone is reacted with methyl propionate in the presence of sodium ethoxide, followed by protonation with dilute HCl, to yield 2,4-hexadione (13). The resulting diketone is then oxidized to 3-oxopentanoic acid (14) by treatment with I2 or Cl2 in aqueous NaOH. The resulting acid is esterified with methanol to yield methyl 3-oxopentanoate (15). The ester is then heated with ammonia, removing water during the reaction to yield methyl 3-aminopent-2-eneoate (3).