Obtained from cultures of Penicillium chrysogenum in the absence of side chain precursors: F. R. Batchelor et al., Nature 183, 257 (1959). Synthesis: J. C. Sheehan, K. R. Henery-Logan, J. Am. Chem. Soc. 81, 5838 (1959); 84, 2983 (1962). Intermediate in the manuf of synthetic penicillins: J. C. Sheehan, US 3159617 (1964 to Arthur D. Little). HPLC determn: J. Haginaka, J. Wakai, Anal. Biochem. 158, 146 (1986). Review of prepn: F. M. Huber et al. in Cephalosporins Penicillins: Chem. Biol., E. H. Flynn, Ed. (Academic, New York, 1972) pp 27-73. Review of chemistry: E. J. Vandamme, J. P. Voets, Adv. Appl. Microbiol. 17, 311-369 (1974). General review: G. N. Rolinson, J. Antimicrob. Chemother. 22, 5-14 (1988).