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[摘要]：A novel, stereospecific route to allenes is described. The approach proceeds via a retro-ene reaction, initiated by lithium aluminium hydride mediated cleavage of benzothiazole from the respective (chiral) 2-benzothiazolyl propargyl sulfone precursors. As such, allenes in up to 92% yield are formed under evolution of sulfur dioxide at ambient temperature. Furthermore, a new and mild way to generate E-a, b-unsaturated ketones has been discovered. These substrates are formed in around 50% yield by treating 2-benzothiazolyl propargyl sulfides with hydrogen peroxide and a catalytic amount of ammonium molybdate at room temperature. In the course of this research it was also found that treatment of 2-benzothiazolyl propargyl sulfones with sodium borohydride led to reduction of the triple bond exclusively to the Z-double bond. |
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