Stereospecific synthesis of polyfunctionalized carbacephams induced by titanocene(III) chloride.
Enantiomerically pure N-substituted epoxyalkene-2-azetidinones reacted with titanocene monochloride to give stereospecifically polyfunctionalized bicyclic beta-lactams. Four isomeric epoxyaldehydes 2 reacted with TiCp2Cl to give exclusively the respective carbacephams 7 while under the same reaction conditions the epoxyesters 1, which are more hindered for an intramolecular addition, gave the cyclization products 6 (only two isomers) and/or the elimination products 5 (all isomers).
Ruano
Gema
G
Departamento de Química Orgánica, Universidad de Salamanca, E-37008 Salamanca, Spain.
Martiáñez
Justo
J
Grande
Manuel
M
Anaya
Josefa
J
D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D002511:Cephalosporins / Q000138:chemical synthesis*; D004852:Epoxy Compounds / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry*
D000447:Aldehydes; D002511:Cephalosporins; D004852:Epoxy Compounds; C026739:carbacephems; D014025:Titanium; C039460:titanium trichloride