... Novel Heterocycles by Bis Heteroannulation of Oxazolesl A. Hassner* and B. Fischer Department of Chemistry, Bar-Ilan University, Ramat Can 52100, Israel Received July 23, 1990 ... Page 2. 3420 J. Org. Chem., Vol. 56, No. 10, 1991 Scheme I 0 Hassner and Fischer 3 ...