【Task】
The invention relates to a method of synthesizing a compound or a salt thereof of Formula 1, Fukoshirudona the formula H-A-R 1 of formula 2 under the catalytic action of transferable enzymes and fucose _(A and R ₁ are the following acceptor or a method of reacting a salt thereof, the compound of formula 1 ', used in the human milk oligosaccharides production, human milk oligosaccharides method and Fukoshirudona of).

(Or A is lactosyl moiety, a carbohydrate linker consisting of at least one monosaccharide unit selected lactosylation moiety and glucose, galactose, from N- acetylglucosamine, fucose and N- acetyl-neuraminic acid, R ₁ is the following is one of the anomeric protecting group _[a) -OR 2 (R 2 is a protecting group removable by catalytic _{hydrogenolysis), b) -SR 3 (R} 3 is optionally substituted alkyl, an optionally substituted aryl or optionally substituted benzyl), c) -NH-C ( R ") = C (R ') 2 (R' is -CN independently, -COOH, -COO- alkyl, -CO- alkyl, -CONH ₂ , -CONH- alkyl or -CON _(alkyl) one at either electron-withdrawing group selected from _2, two R 'groups bonded to _-CO- (CH 2) 2-4 -CO- a forming and replaced by the two R 'groups are bonded to that carbon atom and the 5- to 7-membered ring of the cycloalkane-1,3-dione (any methylene group optionally one or two alkyl groups in said dione ) forms a, R "is H or alkyl)], X-is guanosine phosphatonin chill portion, lactose moiety, azido, fluoride, optionally substituted phenoxy group, optionally substituted pyridinyloxy group, an optionally substituted of formula the a 3- oxo - furanyloxy group selection, 1,3,5-triazinyl group of the formula B, which is optionally substituted, from the base of 4-methylumbelliferyl group and formula D of the formula C (R or _a is H or alkyl independently, two adjacent _{R a} groups are ₌ C (R b) 2 group _{(R b} is H or alkyl independently) represented by, _{R c} is alkoxy independently amino is selected from alkylamino and dialkylamino, _{R d-is} H, alkyl and _{-C (= O) R e (} R e is OH, alkoxy, amino, alkylamino, dialkylamino, hydrazino, alkyl hydrazino, dialkyl hydrazino or selected from trialkyl hydrazino)))
.BACKGROUND