Parent compound of a series of potent analgetics. Synthesis: Kanematsu et al., J. Am. Chem. Soc. 90, 1064 (1968); Kanematsu et al., J. Med. Chem. 12, 405 (1969). Review of derivative syntheses and pharmacology: May, Sargent, “Morphine and its Modifications”, in Analgetics, G. de Stevens, Ed. (Academic Press, New York, 1965) pp 145-171.