Method for preparing cyclic compounds
View Patent ↗The present invention provides a method for preparing a β-lactam compound of the following Formula (3), which comprises the step of reacting a compound of the following Formula (1) with a trialkyl phosphite represented by the formula (R 5 O) 3 P (wherein R 5 represents an ethyl group, etc.) in an amount of 2 to 5 moles per mole of the compound and the step of heating the resulting reaction mixture in a diluent, wherein said method is characterized by having the step of completely removing unreacted trialkyl phosphite from the reaction mixture prior to the step of heating. (wherein X represents S, etc., Y represents N, etc., n represents 0 or 1, R 1 represents an optionally substituted alkyl group containing 1 to 10 carbon atoms, etc., R 2 and R 3 each represent an optionally substituted alkyl or heterocyclic group, etc., and R 4 represents an alkenyloxy group containing 1 to 6 carbon atoms, etc., provided that R 1 and R 2 may together form a β-lactam ring, etc.)
1. A method for preparing a cyclic compound of Formula (3-1),
wherein X represents CH2, O or S, n represents 0 or 1, R 3 represents an alkyl group containing 1 to 6 carbon atoms, an alkenyl group containing 1 to 6 carbon atoms, a phenyl group, a heterocyclic group or a heteroylmethyl group, R 4 represents an alkoxycarbonyl group containing 1 to 6 carbon atoms, a haloalkoxycarbonyl group containing 1 to 6 carbon atoms or an alkenyloxycarbonyl group containing 1 to 6 carbon atoms, and R 6 represents a hydroxyalkyl group whose hydroxy moiety is protected with a protecting group, which comprises the following steps:
a step of reacting a compound of Formula (1-1),
wherein X, n, R 3 , R 4 and R 6 are as defined above, with a triethyl phosphite in an amount of 2 to 5 moles per mole of the compound to obtain a reaction mixture containing a compound of Formula (2-1),
wherein X, n, R 3 , R 4 and R 6 are as defined above; and R 5 is ethyl;
a step of removing unreacted triethyl phosphite from the reaction mixture including reducing the internal pressure of the vessel holding the reaction mixture to 0.7 kPa or below and heating the vessel at 75° C. to 80° C. to distill off the triethyl phosphite remaining in the reaction mixture; and
a step of heating the resulting mixture in a diluent.
2. The method for preparing a cyclic compound according to claim 1 , wherein the step of removing unreacted trialkyl phosphite from the reaction mixture comprises reducing the internal pressure of the vessel holding the reaction mixture to 0.7 to 2 kPa and heating the vessel at 50° C. to 75° C. to distill off low-boiling products, followed by reducing the internal pressure of the vessel to 0.7 kPa or below and heating at 75° C. to 80° C. to distill off the trialkyl phosphite remaining in the reaction mixture.