Prepn from pyrrolidine + 1,4-dichloro-2-butyne: Maier, DE 896810 (1953 to BASF); Reppe et al., Ann. 596, 79 (1955); Biel, DiPierro, J. Am. Chem. Soc. 80, 4609 (1958). Review of chemical and biological studies: Karlen, Acta Pharm. Suec. 1970, 169-200; see also Kolla, Obvintseva, Farmakol. Toksikol. 36, 736-745 (1973).