Prepn: A. P. Roszkowski et al., Science 144, 412 (1964); R. J. Mohrbacher et al., BE 659610; eidem, US 3378566 (1965, 1968 both to McNeil). Stereoisomerism: idem et al., J. Org. Chem. 31, 2141 (1966); S. Abrahamsson, B. Nilsson, ibid. 3631. Structure-activity studies: G. I. Poos et al., J. Med. Chem. 9, 537 (1966). Toxicity data: A. P. Roszkowski, J. Pharmacol. Exp. Ther. 149, 288 (1965).