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9.9.1.3.1.1.2 Method 2: Cyclization of 4-Hydroxybut-2-enenitriles

DOI: 10.1055/sos-SD-009-00244

König, B.Science of Synthesis, (20019204.

On reduction with bis(isobutyl)borane, 4-hydroxybut-2-enenitriles 101 yield the corresponding α,β-unsaturated aldehydes, which cyclize spontaneously on workup to give furans 102 (Scheme 34).[‌175‌] The rearrangements of α-cyanoallyl acetates 103, catalyzed by bis(acetonitrile)palladium(II) chloride or tetrakis(triphenylphosphine)palladium(0), give γ-cyanoallyl acetates 104, which react with sodium hydroxide, diisobutylaluminum hydride, and hydrochloric acid sequentially to provide 3-substituted furans 105 in good overall yield (Scheme 35).[‌175‌] This procedure is also useful for the preparation of 2,3- and 3,4-disubstituted furans.

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