Carbon-Carbon Bond Formation by Use of Chloroiodomethane as a C1 Unit. I. Formation of Chloromethyltriphenylphosphonium Iodide, and Its Application for the Wittig Chloromethylenation of Aldehydes and Ketones

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Abstract Chloromethyltriphenylphosphonium iodide has been prepared by the reaction of chloroiodomethane with triphenylphosphine. Upon treatment with potassium t-butoxide in t-butyl alcohol, the phosphonium iodide was converted into chloromethylenetriphenylphosphorane; this in turn was used for the Wittig reaction of aldehydes and ketones into the corresponding chloroolefins of the type RCH=CHCl and RR′C=CHCl in good to moderate yields. The configurations of these chloroolefins were assigned on the basis of NMR spectral studies. Direct conversion of benzaldehyde into phenylacetylene was also achieved using the phosphonium salt and excess potassium t-butoxide.