Chemical structure and synthesis of FA-BA esters. The detailed procedure as well as NMR spectral data are shown in Supplementary text S1. DMAD, dimethylazodicarboxylate; DIC, N,N′-diisopropylcarbodiimide; DMAP, dimethylaminopyridine; Et3N, triethylamine; LiI, lithium iodide; THF, tetrahydrofuran; TPP, triphenylphospine; PhCF3, benzotrifluoride; BA, bile acid; FA, fatty acid.