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

The 1,3-dipolar cycloadditions between imidate 1, derived from dimethy laminomalonate and aldehydes 2(a-f), phthalaldehyde 2g, isophthalaldeh yde 2h. 4-chlorophenylisocyanate 9a, ethoxycarbonylisothiocyanate 9d a s 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 reactivi ty in these cycloaddition reactions are rationalized by PM3 MO calcula tions. The stereoselective demethoxycarbonylation of dimethyl 2-oxazol ine-4,4-dicarboxylate 4a is described. The mild hydrolysis of 5-(2-for mylphenyl)-2-oxazoline 4g leads to the formation of a new 3,4-dihydroi soquinoline 8h in quantitative yield. (C) 1997 Elsevier Science Ltd.