1. At the completion of this work, we became aware that compounds 5 and 7 were disclosed by Boehringer, C. H., Sohn in German Patent 2,318,673 (1974).
2. Chem. Abstr., 82, 57747w (1975).
3. and by E. R. Squibb and Sons, Inc., in Netherlands Application, 7407,111.
4. Boehringer Ingelheim, G. m. b. G., U. S. Patent 3,711,467 (1973).
5. Chem. Abstr., 78, 97729r (1973).