摘要：

The reaction of acetylacetone with the Mannich bases prepared from diethyl acetamidomalonate (I) and diethyl 2-(benzyloxycarbonylamino) malonate (VII) respectively resulted in deacetylation and formation of γ-aminoketone derivatives, diethyl 2-acetamido-2-(2-acetylethyl) malonate (IV) and diethyl 2-(2-acetylethyl)-2-(benzyloxycarbonylamino) malonate (IX). Cyclization of (IV) and (IX), followed by the reduction of 3, 4-dihydro-2H-pyrrolenine so obtained, and hydrolysis of its product afforded 5-methylproline. In this reaction, the use of (I) or (VIII) as the starting material gave different intermediates and showed different mode of reaction, affording two kinds of 5-methylproline, sterically isomeric in respect to C-2 and C-5 positions, of m.p. 188° (XVI) and of m.p. 207° (XVI′).

展开