“…Homogeneous catalysts generally show a high catalytic efficiency under mild reaction conditions due to their excellent accessibility leading to a full contact with the substrate molecules. Various transition metal-based catalysts such as Ir [3] , Pd [4] , Fe [5] , Zr [6] were reported for GVL preparation, but Ru-based homogeneous catalysts were extensively investigated for this transformation, which include Ru(CO) 4 I 2 [7] , RuCl 2 (PPh 3 ) 3 [8] , RuHCl(CO)(PPh 3 ) 3 [9] , Ru Ⅱ -BINAP-HCl (BINAP = 2,2 -bis(diphenylphosphino) −1,1binaphthyl) [10] , Ru(acac) 3 /PBu 3 (acac = acetylacetone) [11] , Ru 4 (Cl) 8 ( p -cymene) 4 (L1) 4 Zn 2 [L1 = 4-(diphenylphosphino)benzoic acid] [12] , Ru-(TPPTS) (TPPTS = tris(3-sulfonatophenyl)phosphine, sodium salt) [13] , and Ru-NHC (NHC = N -heterocyclic carbenes) [14] . However, many limitations from complex and expensive ligands, high cost of precious transition metals as active sites, and unrecyclable nature had seriously restricted their applications in LA(EL)-to-GVL transformations in industrial scales.…”