Method for preparing a fatty acid derivative

1. A method for manufacturing a fatty acid derivative represented by formula (I):

wherein X 1 is

wherein R1 is a protecting group for hydroxy group;

Y 1 is

wherein R2 is a protecting group for hydroxy group;

Z 1 is

wherein R3 is a protecting group for hydroxy group, provided that at least one of X 1 , Y 1 and Z 1 is

A is —CH 3 , —CH 2 OH, —COCH 2 OH, —COOH or a salt, ether, ester or amide thereof;

B is a single bond, —CH 2 —, —CH 2 —CH 2 —, —CH═CH— or —C≡C—, —CH 2 —CH 2 —CH 2 —, —CH═CH—CH 2 —, —CH 2 —CH═CH—, —C≡C—CH 2 — or —CH 2 —C≡C—;

Ra is bivalent saturated or unsaturated lower-medium aliphatic hydrocarbon group, which is unsubstituted or substituted by halogen atom, lower alkyl, lower alkoxy, oxo, aryl or heterocyclic group, provided that one or more carbon atoms of the aliphatic hydrocarbon group may optionally be replaced with oxygen, nitrogen or sulfur atom; and

Rb is hydrogen atom; saturated or unsaturated lower-medium aliphatic hydrocarbon group which is unsubstituted or substituted by a halogen, oxo, hydroxy, lower alkoxy, lower alkanoyloxy, cyclo(lower)alkyl, cyclo(lower)alkyloxy, aryl, aryloxy, heterocyclic or heterocyclic oxy;

cyclo(lower)alkyl; cyclo(lower)alkyloxy; aryl; aryloxy; heterocyclic; or heterocyclic oxy, which comprises the step of, reacting a compound of formula (II):

wherein, X 2 is the same as X 1 except for when X 1 is

X 2 is

Y 2 is the same as Y 1 except for when Y 1 is

Y 2 is

Z 2 is the same as Z 1 except for when Z 1 is

Z 2 is

provided that at least one of X 2 , Y 2 and Z 2 is

and, A, B, Ra and Rb are the same as above;

with a co-oxidizer under the presence of an azaadamantane-N-oxyl compound.

2. The method of claim 1 , wherein A is —COOH or a salt, ester or amide thereof.

3. The method of claim 1 , wherein the azaadamantane-N-oxyl compound is 2-azaadamantane-N-oxyl.

4. The method of claim 1 , wherein the azaadamantane-N-oxyl compound is 1-methyl-2-azaadamantane-N-oxyl.

5. The method of claim 1 , wherein the azaadamantane-N-oxyl compound is 2-hydroxy-2-azaadamantane.

6. The method of claim 1 , wherein the azaadamantane-N-oxyl compound is 2-hydroxy-1-methyl-2-azaadamantane.