Coumarin analog. Prepn: M. R. Hadler, R. S. Shadbolt, DE 2424806; eidem, US 3957824 (1975, 1976 to Ward, Blenkinsop & Co.); eidem; J. Chem. Soc. Perkin Trans. 1 1976, 1190. Anticoagulant activity: M. R. Hadler, R. S. Shadbolt, Nature 253, 275 (1975). Field trials: B. D. Rennison, A. C. Dubock, J. Hyg. 80, 77 (1978); F. P. Rowe et al., ibid. 81, 197 (1978). Efficacy and toxicity: L. Yuet-Ming, Malays. Agric. J. 52, 1 (1980).