3-[(4-{[(3R)-1-(tert-butoxycarbonyl)piperidin-3-yl]oxy}phenyl)carbonyl]-2-butylindolizine-7-carboxylic acid   、                                                                                      
methyl N-propan-2-ylglycinate hydrochloride   、                                                                                      
N,N-二异丙基乙胺   、                                                                                      
2-(1H-Benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate                                                                                                                                                                                                                                                                                                          以0.62 g of tert-butyl (3R)-3-[4-({2-butyl-7-[(2-methoxy-2-oxoethyl)(propan-2-yl)carbamoyl]indolizin-3-yl}carbonyl)phenoxy]-piperidine-1-carboxylate is obtained in the form of a yellow gum的产率得到tert-butyl (3R)-3-[4-({2-butyl-7-[(2-methoxy-2-oxoethyl)(propan-2-yl)carbamoyl]indolizin-3-yl}carbonyl)phenoxy]piperidine-1-carboxylate