A Novel Synthesis of 4H-1,4-Benzoxazines.
作者:Noriaki KUDO、Satoru FURUTA、Kazuo SATO
DOI:10.1248/cpb.44.1663
日期:——
The reaction of methyl 2-chloro-5-ethoxycarbonylamino-4-fluorobenzoate (4a) and 1-bromo-3, 3-dimethyl-2-butanone (2) in the presence of 2.2 eq of lithium bis(trimethylsilyl)amide afforded the 4H-1, 4-benzoxazine (6a) in good yield instead of the expected 4-oxazolin-2-one (5a). The generality of the reaction and the mechanism are discussed.
反应中,甲基2-氯-5-乙氧基羧酰胺-4-氟苯甲酸酯(4a)与1-溴-3,3-二甲基-2-丁酮(2)在2.2当量的锂双(硅烷基)氨存在下,获得了良好产率的4H-1,4-苯并噁唑啉(6a),而非预期的4-噁唑啉-2-酮(5a)。讨论了该反应的普遍性及其机制。