Axisonitriles, naturally occurring

Isonitriles are stable, often naturally occurring, compounds that contain a divalent carbon. An example is axisonitrile-3, which can be isolated from a species of sponge and possesses anti-malarial activity. Write a resonance form for axisonitrile-3 that satisfies the octet rule. Don t forget to include formal charges. 

A total synthesis of the sesquiterpenoids (-)-axamide-4 1663 and (—)-axisonitrile-4 1664, affording both natural products, has been accomplished in eleven steps [1233]. From the view of a chemist, it is remarkable that both the isocyanide and its chemical precursor molecule formamide are naturally occurring. The transformation of (—)-axamide-4 into (—)-axisonitrile-4 is carried out with p-tosyl chloride in 94% yield. 

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See also in sourсe #XX -- [ ]

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