Claims
- 1. A method for preparing a compound in pure crystalline form having a melting point within the range of from about 196.5.degree. to about 198.degree. C., having the structure ##STR28## which comprises treating a lactone of the structure ##STR29## with a strong base and then an acid to form the corresponding tetrahydroxy acid of the structure ##STR30## lactonizing by treating the resulting tetrahydroxy acid with acid to form the triol of structure ##STR31## reacting the triol with a silyl chloride protecting agent in the presence of an amine base to form the bis-silyl ether of the structure ##STR32## reacting the bis-silyl ether with 2,2-dimethylbutyryl chloride in the presence of dimethylamino pyridine and pyridine to form the acylated bis-silyl ether of the structure ##STR33## and treating the acylated bis-silyl ether with hydrofluoric acid in the presence of pyridine to form ##STR34##
- 2. The method as defined in claim 1 wherein the silyl chloride protecting agent is tertiary-butyldimethylsilyl chloride, trimethylsilyl chloride, tertiary-butyldiphenylsilyl chloride, triethylsilyl chloride or phenyldimethylsilyl chloride.
- 3. The method as defined in claim 1 wherien the amine base is imidazole, triethylamine, ethyldiisopropylamine or N,N-dimethylaniline.
- 4. The method as defined in claim 1 wherein the silyl chloride protecting agent is tertiary-butyldimethylsilyl chloride and the amine base is imidazole.
Parent Case Info
This is a continuation of application Ser. No. 431,263, filed Nov. 3, 1989, now abandoned, which is a division of application Ser. No. 316,203 filed Feb. 27, 1989, now abandoned.
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
4444784 |
Hoffman et al. |
Apr 1984 |
|
4581345 |
Wyvratt, Jr. |
Apr 1986 |
|
4733003 |
Ide et al. |
Mar 1988 |
|
4845237 |
DeCamp et al. |
Jul 1989 |
|
Divisions (1)
|
Number |
Date |
Country |
Parent |
316203 |
Feb 1989 |
|
Continuations (1)
|
Number |
Date |
Country |
Parent |
431263 |
Nov 1989 |
|