We previously reported that cyclic ?-silyloxy-�-hydroxy-a-diazoesters (e.g. 1  , R=OEt) fragment when treated with Lewis acids to provide tethered aldehyde ynoate products (e.g. 2  , R=OEt). Similarly, cyclic ?-silyloxy-�-hydroxy-a-diazoketones (e.g. 1  , R= Alkyl, Aryl, N-Cbz-Aminoacids) also fragment efficiently to provide aldehyde tethered ynone products in good overall yield (e.g. 2  , R= Alkyl, Aryl, N-Cbz-Aminoacids).We have recently focused our attention on applying this ring fragmentation methodology to the synthesis of medium sized ring systems. We prepared diazo bicycle [4.4.0] decane (3  , X = CH2) as a fragmentation precursor and this compound productively fragmented into ten member cyclodec-5-yne-1, 4-dione (4  , X = CH2) in good yield upon treatment with one equivalent of tin tetrachloride. We will report our current results in making medium sized cyclic-2-alkynones (4  , X = CH2) as well as medium sized 2-ynlactones (4  , X = O), a common structural key feature in many natural products, by this ring fragmentation method.

Macrocycles through fragmentation of fused bicyclic ring systems

244th National Meeting (2012)

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