1. S. Iseda, Bull. Chem. Soc. Jpn.,30, 6 (1957).
2. A. Masakazu and T. Kawasaki, Tetrahedron Lett., 12 (1969).
3. V. B. Kuvaev, V. I. Glyzin, G. S. Glyzina, and A. I. Ban'kovskii, Rast. Res.,8, No. 3, 367 (1972).
4. E. S. Bate-Smith and J. B. Harborne, Nature (London),198, 4887 (1963).
5. K. F. Blinova and N. I. Kalyupanova, Khim. Prirodn. Soedin., 535 (1974).