Ketene thioketals synthesis

The use of diphenylcyanomethylphosphine oxide is effective for the synthesis of ( )-a,3-unsaturated nitriles. ° Phosphine oxides can bis used to synthesize a variety of functionalized alkenes, including vinyl ethers (215 equation 51), ° vinyl sulfides (217 equation 52), ° allylic amines (219) and amides (equation 53), " ketene acetals (221 equation 54) and ketene thioketals (223 equation In the examples of a-thio substitution, the alkenes are formed directly. 

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