KRP-105

We described the practical synthesis of β-acyl glucuronide from allyl 2,3,4-tri-(O-allyloxycarbonyl)-D-glucuronate (5) mediated by 1-chloro-N,N,2-trimethyl-1-propenylamine (TMCE).A wide range of bulky carboxylic acids (aryl carboxylic acids or tertiary-carbon-linked carboxylic acids) were employed to give the corresponding β-acyl glucuronate in good yields.The side products of this reaction are only N,N-dimethylisobutyramide and HCl.As the resulting acyl glucuronates show sufficient solubility to organic solvent, it can be easily purified by conventional silica gel column chromatog. and/or crystallization, even in multigram quantities.The allyloxycarbonyl group and allyl group are cleanly removed by Pd(0), and thus the protocol can provide multigram quantities of β-acyl glucuronides with high purity.