| Number | Name | Date | Kind |
|---|---|---|---|
| 1890916 | Semon | Dec 1932 | |
| 3244517 | Lind | Apr 1966 | |
| 3414618 | Randall | Dec 1968 | |
| 3598592 | Cescon | Aug 1971 | |
| 3634248 | Andress, Jr. | Jan 1972 | |
| 4426475 | Brassat et al. | Jan 1984 | |
| 4440657 | Metro et al. | Apr 1984 |
| Number | Date | Country |
|---|---|---|
| 1123103 | Feb 1962 | DEX |
| Entry |
|---|
| J. E. Kuder, et al., J. Org. Chem. 44, 761 (1979). |
| M. M. Sprung, Chem. Rev., 26, 297 (1940). |
| E. C. Wagner, J. Org. Chem., 19, 1862 (1954). |
| A. R. Katrisky et al., Synthesis, 1990, 341. |