New Entry for Synthesis of N-Acylhydrazones, Pyridazinones, and 1,3,4-Oxadiazin-6-ones from α-Amino Acid Esters

• Published in: Chemical & pharmaceutical bulletin Vol. 55; no. 11; pp. 1652 - 1654
• Main Authors: Yasui, Eiko, Wada, Masao, Takamura, Norio
• Format: Journal Article
• Language: English
• Published: TOKYO The Pharmaceutical Society of Japan 01.11.2007; Pharmaceutical Soc Japan
• Subjects: 1,3,4-oxadiazin-6-one; Acylation; Amino Acids - chemistry; Azo Compounds - chemistry; Chemistry; Chemistry, Medicinal; Chemistry, Multidisciplinary; Esters - chemistry; hydrazone; Hydrazones - chemical synthesis; Life Sciences & Biomedicine; Magnetic Resonance Spectroscopy; Models, Chemical; N-acylhydrazone; Oxazines - chemistry; Oxidation-Reduction; Pharmacology & Pharmacy; Physical Sciences; Pyridazines - chemistry; pyridazinone; Science & Technology; Stereoisomerism; α-diazo ester; alpha-diazo ester; PEPTIDES; DIASTEREOSELECTIVE SYNTHESIS; 1,3,4-oxadiazin-6-one; pyridazinone; DIAZO ESTERS; hydrazone; N-acylhydrazone; DERIVATIVES; CYCLIZATION
• ISSN: 0009-2363; 1347-5223
• DOI: 10.1248/cpb.55.1652

Versatile electrophiles N-acylhydrazones are synthesized via diazotization, reduction, and acylation of α-amino acid esters. Reduction of diazo esters with L-selectride® or tributylphosphine affords the corresponding hydrazones in good yields. Both reducing agents give anti-hydrazones as the major product although the reactivity of each reductant is slightly different. The resulting hydrazones are acylated to give N-acylhydrazones, which are subjected to further reactions to give 1,3,4-oxadiazin-6-ones that serve as useful synthetic intermediates for the Diels–Alder reaction.