1-(N-Acylamino)alkyltriphenylphosphonium salts as synthetic equivalents of N-acylimines and new effective α-amidoalkylating agents

✍ Scribed by Roman Mazurkiewicz; Agnieszka Październiok-Holewa; Beata Orlińska; Sebastian Stecko

• Publisher: Elsevier Science
• Year: 2009
• Tongue: French
• Weight: 276 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2009.05.101

✦ Synopsis

1-(N-Acylaminoalkyl)triphenylphosphonium salts 2a-f on reaction with DBU in MeCN are transformed into 1-(N-acylaminoalkyl)amidinium salts 3a-f. Amidinium salts 3d-f with a proton at the b-position undergo slow tautomerization into the corresponding enamides 6d-f. The same 1-(N-acylamino)alkyltriphenylphosphonium salts 2d-f in the presence of Hünig's base are transformed directly into the corresponding enamides. Phosphonium salts 2, amidinium salts 3, and enamides 6 react with dialkyl malonates in the presence of DBU to give the corresponding amidoalkylation products. a-Amidoalkylation of dialkyl malonates is not observed in the presence of (i-Pr) 2 EtN, yet proceeds well under these conditions with more acidic nucleophiles, for example, phthalimide or benzyl mercaptan.