(2R,3S,4aR,6R,7R,8aS)-2-(hydroxymethyl)-6-(phenylsulfonylmethyl)octahydropyrano[3,2-b]pyran-3,7-diol benzylidene acetal   、                                                                                      
乙酸酐                                                                                                                                                              在
                                                                                                                                                                                 
吡啶                                                                                                                                  作用下,
                                                                                                                                                                                                                            以96%的产率得到(2R,3R,4aS,6R,7S,8aR)-7-hydroxy-6-(hydroxymethyl)-2-(phenylsulfonylmethyl)octahydropyrano[3,2-b]pyran-3-yl acetate benzylidene acetal