Highly Chemoselective Baylis−Hillman and Aldol Reactions of 2<i>H</i>-Thiopyran-4(3<i>H</i>)-one Using Tertiary Amine Catalysts in Aqueous Media
作者:Bagher Eftekhari-Sis、Ali Akbari、Klaus Harms
DOI:10.1021/ol101883g
日期:2010.10.15
Baylis−Hillman (BH) reaction of 2H-thiopyran-4(3H)-one is investigated, and surprisingly, the reaction of 2H-thiopyran-4(3H)-one with aldehydes in the presence of different tertiary amines shows excellent chemo- and regioselectivity in water. At room temperature, DBU affords BH adducts, but with DABCO, aldol products were obtained. In the case of DABCO, Et3N, or DMAP, domino aldol−rearrangement reactions occurred
Switching the Reactivity of Dihydrothiopyran-4-one with Aldehydes by Aqueous Organocatalysis: Baylis–Hillman, Aldol, or Aldol Condensation Reactions
作者:M. Saeed Abaee、Mohammad M. Mojtahedi、Ghasem F. Pasha、Elahe Akbarzadeh、Abbas Shockravi、A. Wahid Mesbah、Werner Massa
DOI:10.1021/ol202145w
日期:2011.10.7
An aqueous medium containing catalytic amounts of a tertiary amine was employed to direct the chemoselectivity of the reaction of aldehydes with 1a. With DBU, 2 was formed at room temperature as a rare exemplary of Baylis–Hillman reactions in heterocyclic enones. DABCO alternated the pathway toward an aldol reaction to form syn/anti mixtures of 3 with the syn isomers being the major products. With
3-substituted thiopyran-4-ones is reported for the first time via aldol condensation of various aromatic aldehydes with dihydrothiopyran-4-one derivatives under very mild conditions using magnesiumbromide diethyl etherate and triethyl-amine. The products were characterized based on spectroscopic and X-ray diffraction experiments.