Keteneおよびその誘導体の研究(第45報) : 2-Alkyl-2-imidazolineとDiketeneとの反応

抄録

Reaction of 2-methyl-(Ia), 2-ethyl-(Ib), and 2-benzyl-2-imidazoline (Ic) with diketene in acetone gave 8-substituted 7-hydroxy-7-methyl-5-oxo-2, 3, 5, 6, 7, 8-hexahydroimidazo[1, 2-α]-pyridine derivatives (8-substituent=H (IIa), CH₃ (IIb), C₆H₅ (IIc)). Treatment of II with conc. H₂SO₄. afforded 8-substituted 7-methyl-5-oxo-2, 3-dihydro-1H-imidazo[1, 2-α]-pyridine derivatives (IIIa, b, c). Each II and III reacted with acetic anhydride to give 8-substituted 1-acetyl-7-methyl-5-oxo-2, 3-dihydro-1H-imidazo[1, 2-α]pyridine derivatives (IVa, b, c). Acetylation of I with ketene in chloroform afforded N-acetates (Va, b, c), which reacted with diketene in acetic acid to give IV and VI.