Ylide compounds 1,3-thiazole derivatives

Phosphonium ylides 66 attack 1,2,4-dithiazole derivatives 65 (Y = 0, S) mainly at the S-S bond to give intermediates 67, which can either afford thiazoline derivatives 68 or react further, with a second ylide molecule 66 at the C=Y bond, to finally yield new thiazole and dithiole derivatives 69 and 70. Compounds 70 are predominant in this mixture (yields > 50%). They are oxidized into known dithiole derivatives 71 (Scheme 8) <1993MI33, 1994PS105, 1995PS63, 1999PS393>. 

Thiazole A -oxides, A -imides, and A -ylides are formally betaines derived from A -hydroxy-, A -amino-, and A -alkyl-azolium compounds. Where the cation is involved, reactivity is similar to that of thiazolium ions. 

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