Science of Synthesis

Aggarwal, V.; Richardson, J., Science of Synthesis, (2004) 27, 93.

Reaction of electron-deficient alkynes or electron-deficient alkenes bearing leaving groups in the β-position, with sulfoxonium ylides affords dimethylsulfoxonium alk-2-enylides (see Section ‌27.1.2.1.2.6‌). In the presence of a second equivalent of base the dimethylsulfoxonium alk-2-enylides cyclize to afford 1λ4-thiopyran 1-oxides, e.g. dimethylsulfoxonium methylide (‌52‌) reacts with 1,3-diphenylprop-2-yn-1-one (‌233‌) to give dimethylsulfoxonium 4-oxo-2,4-diphenylbut-2-enylide (‌234‌) which cyclizes with dimethylsulfoxonium methylide as base to give 1λ4-thiopyran 1-oxide ‌235‌ (‌Scheme 112‌).[‌276‌]

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References

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• 8.Meeeee-Meee, (8888) 8/8e, 888.
• 8.Meeeee-Meee, (8888) M 88-8, 8888.