Arynes isocyanides

Yoshida et al. have disclosed a MCR involving arynes, isocyanides, and alkynyl bromides, which affords o-iminobromoarenes 71 through the intermediacy of a bromine ate complex. Interestingly, these anthors also found that cychc ethers are able to participate in this process instead... 

F. Sha, X. Huang, A multicomponent reaction of arynes, isocyanides, and terminal alkynes highly chemo- and regioselective synthesis of polysubstituted pyridines and isoquinolines, Angew. Chem. Int. Ed. 48 (2009) 3458-3461. 

It has been shown that, in the presence of lithium diethylamide at —70 °C, bromoben-zoic acids form arynes which may react with arylacetonitriles to yield, predominantly, 2-cyanobenzoic acids. The reaction of alkyl and aryl isocyanides with benzyne may yield benzamide derivatives, showing their ability to act as charge-reversed equivalents to isocyanates. The generation and cyclization of a benzyne-tethered alkyllithium have been reported, and lead to a convenient synthetic route for 4-substituted indans. ... 

Addition reactions of the Si-Si cr-bonds of disilanes 121, 131, and 133 to the C=C bonds of various arynes were found to be promoted by a palladium-1,1,3,3-tetramethylbutyl isocyanide complex. Diverse 1,2-disilylated arenes 130, 132, and 134 were obtained from five-membered and benzo-condensed six-membered cyclic disilanes (Equations 21-23). The H, 13C, and z9Si NMR spectroscopic data as well as X-ray crystallographic analysis were used to confirm the above structures <20050M156>. 

Chapters on the rearrangements of cyanides, diazo and diazonium compounds, and acetylenes have appeared in books in this series in 1970 and 1978. Chapters on arynes(1983) and isocyanides (1983) have also appeared. This chapter aims to update these earlier works to the end of 1992. 

Palladium-catalyzed reactions of arynes with isocyanides also afford the corresponding [2+2+1] cycloaddition products [67]. For instance, reaction of triflate 55 with isocyanide 160 leads to fluorenimine (161), which can be hydrolysed to fluorenone (154) (Scheme 45). 

An intramolecular pericyclization reaction provides either di- or trisub-stituted pyridines in good yields (Scheme 14) (13EJ02537). Arynes were generated from 2-(trimethylsilyl)phenyltriflate and combined with isocyanides and 3-bromopropyne in one-pot. CsF was the best source of fluoride to provide the benzyne, but yields of the pyridine were low imtil CSCO3 was added. The rate of benzyne formation was modulated with a cosolvent of MeCN and toluene and the ratio of precursors was tweaked. With the optimized conditions, the reaction was shown to be fairly robust in the face... 

H. Yoshida, H. Fukushima, T. Morishita, J. Ohshita, A. Kunai, Three-component coupling using arynes and isocyanides straightforward access to benzo-annulated nitrogen or oxygen heterocycles. Tetrahedron 63 (2007) 4793—4805. 

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