Page 1. Tetrahedron Letters,Vol.27,No.49,pp 6005-6008,1986 0040-4039/86 $3.00 + .OO Printed in Great Britain ... MR UskokoviC and G. Grethe, "The Cinchona Alkaloids" in The Alkaloids, Vol. XIV, ed. RHF Manske, Academic Press, New York, 1973, p. 181. ...