A NEW ROUTE TO 2-OXAZOLINES, BIS-OXAZOLINES, AND 2-IMIDAZOLINE-5-ONES FROM IMIDATES USING SOLVENT-FREE CYCLOADDITIONS - SYNTHESIS, CHEMICAL PROPERTIES, AND PM3 MO CALCULATIONS

摘要

The 1,3-dipolar cycloadditions between imidate 1, derived from dimethylaminomalonate and aldehydes 2(a-f), phthalaldehyde 2g, isophthalaldehyde 2h. 4-chlorophenylisocyanate 9a, ethoxycarbonylisothiocyanate 9d as dipolarophiles proceeds regioselectively in good yield using solvent-free conditions. Synthesis of ortho and meta-bis-(2'-oxazoline-5'-yl)benzenes 6g, 6h are also reported. The regiochemistry and the reactivity in these cycloaddition reactions are rationalized by PM3 MO calculations. The stereoselective demethoxycarbonylation of dimethyl 2-oxazoline-4,4-dicarboxylate 4a is described. The mild hydrolysis of 5-(2-formylphenyl)-2-oxazoline 4g leads to the formation of a new 3,4-dihydroisoquinoline 8h in quantitative yield. (C) 1997 Elsevier Science Ltd. [References: 44]