Science of Synthesis

Markó, I. E.; Pospíšil, J., Science of Synthesis, (2010) 47, 156.

Finally, it has been shown that simple alkyl benzothiazol-2-yl sulfones (BT-sulfones) can react at low temperatures with lactones (‌Scheme 43‌).[‌178‌] This coupling, which has to be carried out under Barbier-type conditions, leads smoothly to the desired benzothiazol-2-yl sulfone hemiacetal.[‌178‌,‌179‌] Under these conditions, the desired benzothiazol-2-yl sulfone hemiacetal is formed cleanly and the final alkene is then produced upon warming the mixture to room temperature, albeit in low yields. Interestingly, if the hemiacetal adduct is trapped at low temperature with a proton source, the desired alkene could be formed in 66% yield (over two steps) by treating the isolated intermediate with 1,8-diazabicyclo[5.4.0]undec-7-ene.

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References