“…In the same year, Martin et al, reported the first total synthesis of the (+)-8-epi-xanthatin starting from the commercially available ester in 14 steps with overall yield of 5.5% [ 86 ]. In 2008, Shishido et al, completed the enantioselective total synthesis of xanthatin by the construction of the vinyl functionality at C1 and the exo-methylene at C11 via the syn-elimination of selenoxides from an optically pure cis-fused bicyclic lactone, and then, they reported an enantioselective total synthesis of 8-epi-xanthatin ( 2 ) by developing a synthetic route without the stoichiometric selenium reagents in 2012 [ 87 , 88 ]. In 2012, Tang et al, developed a method to synthesize the enantiopure γ-butyrolactones via a controllable Wagner–Meerwein-type dyotropic rearrangement of cis-β-lactones and successfully applied it to prepare a number of xanthanolides [ 89 ].…”