A Convenient Synthesis Method for Methylenomycin B and Its Application to Methylenomycin A

Abstract

A convenient synthesis method for methylenomycin B and its homolog, methylenomycin A, has been developed. Methylenomycin B, 2, 3-dimethyl-5-methylene-2-cyclopentenone (3) was synthesized: i) by methylation of Mannich derivative prepared from morpholine and 2, 3-dimethyl-2-cyclopentenone (5) or ii) by treatment of formalin with sodio derivatives of 2, 3-dimethyl-5-formyl-2-cyclopentenone (7a) and 2, 3-dimethyl-5-ethoxalyl-2-cyclopentenone (7b), both of which were easily prepared from 5 and ethyl formate or ethyl oxalate. 2, 3-Dimethyl-2, 3-epoxy-5- methylenecyclopentanone (2) was similarly prepared from the epoxide compound of 5 and ethyl oxalate. The bioassay of methylenomycin B and its related compounds against bacteria (B. subtilis, S. aureus, Ps. aeruginosa and E. coli) was also conducted. Methylenomycin A (1) and its desepoxy compound (17) were also prepared from 4-carboxy-2, 3-dimethyl-2-cyclopentenone (15) in the same procedure as described above.