“…Moreover, chitosan, a chiral polysaccharide, has been used as an efficient catalyst for enantioselective syntheses that result in the creation of asymmetric products with chiral center(s) [21,22,23,24,25]. Previously, while using chitosan [9,11], we suffered from some disadvantages of this catalyst namely, that it afforded low yields of products in many of the investigated reactions and it could not easily be recycled because of its high hygroscopicity, leading it to form gels. Herein, we successfully overcome the drawbacks of chitosan and enhance its catalytic activity via heterogeneous grafting with 4-vinyl-pyridine (VP) [26] (Scheme 1), thereby producing a basic, recyclable, eco-friendly biocatalyst that could be used efficiently in Michael additions, especially when a stronger basic catalyst than chitosan, is required.…”