Methyl-4,6-O-benzyliden-2-deoxy-2-methyl-α-D-altropyranosid   、                                                                                      alkaline earth salt of/the/ methylsulfuric acid                                                                                                                                                              在
                                                                                                                                                                                 sodium hydride                                                                                                                                  作用下,
                                                                                                                                                                                                                            以85%的产率得到(4aR,6S,7S,8S,8aS)-6-methoxy-7-methyl-2-phenyl-8-phenylmethoxy-4,4a,6,7,8,8a-hexahydropyrano[3,2-d][1,3]dioxine