A Convenient Baylis-Hillman Synthesis of 3-Substituted 2H-1-Benzothiopyrans

Abstract

Reaction of 2,2"-dithiodibenzaldehyde 1 with activated alkenes 2a-g in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) affords, in one step, 3-substituted 2H-1-benzopyrans 6a-g in yields of up to 67%.

Key words

heterocycles - thiochromenes - 2H-1-benzothiopyrans - Baylis-Hillman methodology

References

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13

The splitting of this methylene proton signal, attributed to allylic coupling to the 4-H nucleus, is supported by a weak cross-peak in the COSY spectrum; however, no splitting of the 4-H signal was observed. In the 1-D spectrum of compound 6d, the splitting was not resolved but coupling between the methylene and 4-H protons was evident in the COSY spectrum.