| Number | Name | Date | Kind | 
|---|---|---|---|
| 4306076 | Nelson | Dec 1981 | 
| Number | Date | Country | 
|---|---|---|
| 2424908 | Feb 1979 | FRX | 
| 2014143 | Aug 1979 | GBX | 
| Entry | 
|---|
| Morton et al, "J. Organic Chem.", vol. 44 (1979) p. 2880. | 
| Aristoff et al, "J. Organic Chem.", vol. 48 (1983) 5341. | 
| Crossley, "Tetrahedron Letters" (1971) p. 3327. | 
| Corey et al, "Tetrahedron Letters" (1973) p. 3091. | 
| Kojima et al, "Tetrahedron Letters" (1978) p. 3743. | 
| Shibasaki et al, "Tetrahedron Letters" (1979) p. 433. |