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18.2.16.4.1.5.1 By Reaction with Tetrabutylammonium Cyanate

DOI: 10.1055/sos-SD-118-00330

Braverman, S.; Cherkinsky, M.Science of Synthesis Knowledge Updates, (20143265.

Alkyl isocyanates 60 are prepared in good to excellent yields by treatment of primary, secondary, and tertiary alcohols, thiols, or trimethylsilyl ethers with tetrabutylammonium cyanate/triphenylphosphine/2,3-dichloro-5,6-dicyanobenzo-1,4-quinone in acetonitrile under mild and neutral reaction conditions.[‌169‌] Employing a 1:1:1:1 ratio of substrate to reagents in acetonitrile at room temperature immediately produces the corresponding isocyanates 60 in nearly quantitative yields (Scheme 67). This method is highly selective for conversion of primary alcohols into alkyl isocyanates in the presence of secondary and tertiary alcohols, thiols, and trimethylsilyl ethers. For example, in a binary mixture of 3-phenylpropan-1-ol and octan-2-ol, the primary alcohol is completely converted into its isocyanate, but the secondary alcohol remains intact. With the small modification of carrying out the reaction in refluxing acetonitrile, the same protocol can be successfully applied to the preparation of alkyl isocyanates from tetrahydropyran-2-yl ethers (Scheme 67).[‌170‌] The reagent system of tetrabutylammonium cyanate and 2,4,6-trichloro[1,3,5]tri­azine in acetonitrile also produces alkyl isocyanates in good yields from primary, secondary, and tertiary alcohols, thiols, or trimethylsilyl ethers.[‌171‌]

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