2-[4-(t-butoxycarbonylmethoxy)phenyl]ethanal   、                                                                                      
2-氨基-1-(4-羟基苯基)-1-丙醇盐酸盐                                                                                                                                                              在
                                                                                                                                                                                 
t-butyl 4-[-2-(beta-hydroxy-alpha-methyl-4-hydroxyphenethylamino)ethyl]phenoxyacetate                                                                                                                                  作用下,
                                                                                                                                                                                                                            以The ester 20 (8.18 g, 51%) was obtained as a yellow oil的产率得到t-butyl 4-[-2-(beta-hydroxy-alpha-methyl-4-hydroxyphenethylamino)ethyl]phenoxyacetate