References
- Berk , H. C. and Franz , J. E. 1980 . Synthetic Communications , 10 : 189 and references therein
- Glass , R. S. and Smith , D. L. 1974 . J. Org. Chem. , 39 : 372
- Vorlander , D. , Mumme , E. , Sheehan , J. C. and Yang , D-D. H. 1901 . Ber. Dtsch. Chem. Geo. , 80 : 1154 For the preparation 2b 2c the procedure of J. A. C. S. 1958, was utilized. 34, 1647 (was used. For 2a 2d the procedure of