Stereospecific C-N bond cleavage of 4-silylated 1,2-thiazetidine 1,1- dioxides with EtAlCl2 or AlCl3: Formation of (E)-vinylsulfonamides

Article abstract of DOI:10.1248/cpb.46.757

Monosilylation of 1,2-thiazetidine 1,1-dioxides (β-sultams) 3 gave (3R*, 4S*)-4-monosilyl-β-sultams 4 stereoselectively. Disilylated β- sultams 5 were obtained by the use of trimethylsilyl chloride. Treatment of 4-monosilyl-β-sultams 4 with EtAlCl₂ caused stereospecific C-N bond cleavage owing to β-cation stabilization of the silicon group to provide (E)-vinylsulfonamides (E)-7. (E)-α-Silylstyrylsulfonamides (E)-7j - l were generated in the reaction of 4,4-disilyl-β-sultams 5 with EtAlCl₂. Reaction of 4-silyl-β-sultams with AlCl₃ afforded N-dealkylated (E)- vinylsulfonamides in good yields. Reaction of (E)-α-silylstyrylsulfonamide (E)-10 with benzaldehyde in the presence of tetrabutylammonium fluoride and BF₃·Et₂O provided the allylic alcohol (E)-12.

Full text of DOI:10.1248/cpb.46.757

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