ABSTRACT
Electrolysis of the dicarboxylic acid (LVII) in an MeOH-MeONa-(Pt) system and subsequent workup afford the keto acid (LVIII), a precursor of chrysanthemic acid (LVIII), in 86% yield via intramolecular acyloxylation and acid-promoted hydrolysis [139]:
Decarboxylative acetoxylation and methoxylation of a-aminocarboxylic acids proceed smoothly, yielding synthetically useful intermediates. For example, the versatile intermediate (LX) for the synthesis of thienamycine is prepared by electrodecarboxylative acetoxylation of 4-carboxy-2-azetidinone (LIX) in an AcOH-MeCN-AcONa-(Pt) system [134]:
(30)
Electrolysis of N-carbamoylaspartic acid or N-ethoxycarbamoylaspargine in MeOHMeONa-(C) affords the corresponding methoxylated products [140]. A 5-fluorouracil derivative (LXIII), a potent antitumor agent, can be prepared via electrolytic methoxylation of N-acylazacycloalkane-2-carboxylic acids (LXI) in MeOH-MeONa-(C) and subsequent condensation of (LXII) with 2,4-bis-(trimethylsilyl)-5-fluorouracil (TMS-5-FU) [Eq. (31)] [133,141]. Recently, the decarboxylative methoxylation of a-amino acids has been extended to prepare useful chiral building blocks [127-130].
