One Pot Synthesis of Spirocycles and Cyclopropa[b]pyrans by Alkenylation-Rearrangement of Cyclopropenes
Alejandro Puet1, Eleonora Giona1, Gema Domínguez1
1Department of Chemistry and Biochemistry, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities Urbanización Montepríncipe, 28660 Boadilla del Monte, Madrid, Spain.
Abstract:
A one pot alkenylation followed by a stereoselective Alder-ene cycloisomerization of cyclopropenes give (aza)spiro[2.4]heptanes and spiro[2.5]octanes in high yields. Total trans diastereoselectivity is achieved for spiro[2.4]heptanes if the cyclopropene is monosubstituted in C3. When an α,β-unsaturatedcarbonyl-containing bromide is used, an alternative cyclization takes place giving cyclopenta[c]cyclopropa[b]pyrans.
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