methyl (1S,5S,7R)-6,8-dioxa-3-azabicyclo[3.2.1]octane-7-exo-carboxylate 、
(1S,5S,7R)-3-[(1S,5S,7R)-3-((1S,5S,7R)-3-Benzyl-6,8-dioxa-3-aza-bicyclo[3.2.1]octane-7-carbonyl)-6,8-dioxa-3-aza-bicyclo[3.2.1]octane-7-carbonyl]-6,8-dioxa-3-aza-bicyclo[3.2.1]octane-7-carboxylic acid 在
N,N-二异丙基乙胺 、 N-[(dimethylamino)-3-oxo-1H-1,2,3-triazolo[4,5-b]pyridin-1-yl-methylene]-N-methylmethanaminium hexafluorophosphate 作用下,
以
N,N-二甲基甲酰胺 为溶剂,
以50%的产率得到methyl (1S,5S,7R)-3-[(1S,5S,7R)-3-[(1S,5S,7R)-3-[(1S,5S,7R)-3-benzyl-6,8-dioxa-3-azabicyclo[3.2.1]octane-7-carbonyl]-6,8-dioxa-3-azabicyclo[3.2.1]octane-7-carbonyl]-6,8-dioxa-3-azabicyclo[3.2.1]octane-7-carbonyl]-6,8-dioxa-3-azabicyclo[3.2.1]octane-7-carboxylate