Method of synthesis of chitosan derivatives and uses thereof

A method for the preparation of a cross-linked chitosan comprising the following steps:

• a) providing a chitosan and leaving the said chitosan to swell in a solvent;
• b) acylating-b) acylating the amino groups of said chitosan with an acrylic compound of Formula (I):
• wherein R1 is an a halogen or any other leaving group that upon removal, ensures acylation of an amino group;
• R2, R3 and R4 are independently selected from H, optionally substituted C1-C6 alkyl, optionally substituted C2-C6 alkenyl, optionally substituted alkynyl, optionally substituted C3-C8-cycloalkyl, optionally substituted C4-C8 cycloalkenyl, optionally substituted C5-C8 cycloalkynyl, optionally substituted heterocycloalkyl, optionally substituted aryl, optionally substituted heteroaryl and optionally substituted aryl C1-C6 alkyl;
• wherein the term “substituted” refers to groups substituted with from 1 to 5 substituents selected from the group consisting of halogen, —COOR′, —NR′R″, ═O, —OR′, —COR′, —CONR′R″, —SR′, —SO3R′, —SO2NR′R″, —SOR″, —SO2R′, —NO2, or —CN;
• or R1 and R2 or R1 and R3, or R1 and R4 together form 4-24 membered aryl, heteroaryl, cycloalkyl or heterocycloalkyl;
• c) reacting the acylation product of step b) in the presence of a base, wherein step c) is carried out in an aprotic solvent or using the base as a solvent;
• and
• d) purifying the cross-linked chitosan obtained from step c).