PURPOSE: To obtain a compd. in a high yield which is useful as an intermediate of β-lactam antibiotics, obtd. by the reaction of a cephem-carboxylate compd. with a lanthanide complex.
CONSTITUTION: A compd. expressed by formula I (X is a halogen or acetoxy; R1 is H or an org. residue; R2 is a carboxy protecting group; (n) is 0 or 1) is reacted with a lanthanide complex (e.g. samarium complex) in a solvent (e.g. THF) at -100°C as a solvent refluxing temp. for several minutes to one day. The obtd. reaction mixture is cooled with a protonic solvent (e.g. water) to obtain a compd. expressed by formula II. The compd. expressed by formula II is exemplified by methyl-7B-benzoylamino-3-methylenecepham-4-carboxylate. The lanthanide complex is used by 0.1 to 4 mole equiv.
IRARIA KANDEIAANI
ANJIERO BEDESUKI
