Isonitriles 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. 

Naturally occurring marine isonitriles are either sesquiterpenes or diterpenes with one, two, or three isocyano (or isocyano-related) functions. As mentioned previously, it usually is the same carbon that bears the -NC, -NCS, or -NHCHO function. Commonly encountered in sesqui- and diterpenes are... 

A total synthesis of the related ( )-trichoviridin 1671, a naturally occurring epoxy-isonitrile, has also been described [1241]. The dehydration step to afford the O-protected trichoviridin was accomplished with triflic anhydride. 

The trimeric compounds have been cleaved with a variety of neutral ligands [Eq. (41)] (154). With PPh3 the reaction proceeds smoothly, the rate and extent of reaction being dependent on the nature of R (the process occurs more readily when R is aromatic), but with isonitriles species of indeterminate constitution are obtained in addition to lAu C(OR )=NR (CNR")]. The cyclic complexes also underwent stepwise oxidative addition of bromine or iodine to yield (155) mixed gold(I)-gold(III) species, and finally the analogous gold(III) trimers. 

In addition to this broad class of conventional hydrogen bonds, several non-conventional variants also exist in nature [2-7]. For example, hydrogen bonds occur in systems with non-conventional hydrogen acceptors, such as isonitriles [8, 9], carbanions [10, 11], carbenes and silynes [12], n-systems [8, 9, 13]. Non-conventional hydrogen bonds also include those known as hydridic, also termed inverse hydrogen bonds since they are characterised by an inverted polarity [9], that is and a newly characterised... 

To end this part it is worth mentioning lingshuine, a natural produd-like, which actually the result of a Passer-ini reaction that occurred during the extraction process. The acetone extract of the Chinese sponge Axinyssa var-iabilis readed with a natural isonitrile compormd and some free fatty acids to give an inseparable mixture, which was called lingshuine (Xue et al., 2009). 

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