Mitomycin Kishi synthesis

In the dosing stages of a synthesis of Mitomycin derivative FR-900482, a densely functionalised intermediate had to be shorn of its robust MOM protector [Scheme 4.250].46S The task was accomplished with trityl tetrafluoroborate under conditions devised some years ago by Kishi and co-workers.466 Lithium tetrafluoroborate in refluxing aqueous acetonitrile has been successfully deployed in the deprotection of a MOM ether in the presence of a benzyl ether [Scheme 4 2511 467... 

Taking into consideration the properties of mitomycins, two total syntheses have been achieved. The synthesis of mitomycin B (217a), reported by Kishi <79MI 80l-0i>, comprises many steps, two of which are not stereoselective. The total yield of 0.2% demonstrates the enormous difficulties in the synthesis of such a highly functionalized molecule. 

The total synthesis of mitomycins by Kishi and co-workers was based on the transannular closure of a benz[b]azocine [11]. This approach has been investig-... 

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