Claims
- 1. A process for the preparation of a compound of the formula ##STR31## wherein K is a protective group selected from the group consisting ##STR32## n is 2 or 3, the wavy line means the group may have either isomeric form or is a mixture thereof and R.sub.2 is selected from the group consisting of methyl, phenyl, tolyl and xylyl, comprising reacting a compound of the formula ##STR33## with acetic anhydride in the presence of a strong acid, then with an acid hydrolysis agent to obtain a compound of the formula ##STR34## selectively blocking the 3-oxo function with a diol, a thiol or a dithiol of the formula HO--(CH.sub.2).sub.n --OH, HO--(CH.sub.2).sub.n --SH or HS--(CH.sub.2).sub.n --SH,
- wherein n is defined as above to obtain a compound of the formula ##STR35## wherein K is defined as above, reacting the latter with a compound of the formula
- Hal.sub.3 C--CO.sub.2 R
- wherein Hal is chlorine or bromine and R is selected from the group consisting of alkyl of 1 to 6 carbon atoms, aralkyl or 7 to 15 carbon atoms and a silylated group, in the presence of zinc and a Lewis acid, to obtain a compound of the formula ##STR36## reacting the latter in the presence of a base with an alkali metal sulfinate of the formula
- R.sub.2 SO.sub.2 Q
- wherein R.sub.2 is defined as above and Q is an alkali metal, to obtain a compound of the formula ##STR37## in which R, R.sub.2 and K are defined as above, reacting the latter with a halogenation agent in the presence of a base, saponifying and decarboxylating the product to obtain a compound of the formula ##STR38## in which Hal.sub.1 is halogen, reacting the latter with formaldehyde in the presence of a base to obtain the compound of formula XI.
- 2. The process of claim 1 wherein the strong acid in the presence of which the acetic anhydride is reacted on the compound of formula II is p-toluene sulfonic acid, the acid hydrolysis agent is formic acid, the blocking agent of the 3-oxo function is ethane dithiol in the presence of a catalytic quantity of concentrated hydrobromic or hydrochloric acid and the Lewis acid is titanium tetrachloride.
- 3. The process of claim 1 wherein the alkali metal sulfinate is sodium toluene sulfinate and the halogenation agent is sodium hypochlorite or sodium hypobromite.
- 4. The process of claim 1 further comprising opening the epoxide function of the compound of formula XI in a basic medium and in the presence of R.sub.1 O ions, in which R.sub.1 is acyl of 1 to 8 carbon atoms to obtain a compound of the formula ##STR39## the 3-oxo function of which is deprotected to obtain the compound of formula A ##STR40##
- 5. The process of claim 4, wherein the opening of the epoxide is carried out in the presence of acetate ions.
- 6. The process of claim 1, further reacting the compound of formula XI with an alkali metal halide to obtain a compound of the formula ##STR41## in which Hal.sub.2 is chlorine, bromine or iodine and K is defined as in claim 1, subjecting the latter to the action of an acyloxylation agent in an alkaline medium to obtain the compound of formula XII as defined in claim 4 and then the synthesis is continued as described in claim 4.
- 7. The process of claim 6 wherein the alkali metal halide is lithium bromide and the acyloxylation agent is potassium acetate.
Priority Claims (1)
Number |
Date |
Country |
Kind |
91 06202 |
May 1991 |
FRX |
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PRIOR APPLICATION
This application is a division of U.S. patent application Ser. No. 885,150 filed May 18, 1992, now U.S. Pat. No. 4,187,273.
US Referenced Citations (1)
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Name |
Date |
Kind |
4189430 |
Shephard |
Feb 1980 |
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Divisions (1)
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Number |
Date |
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Parent |
885150 |
May 1992 |
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