- Stereoselective Formation of cis-2,3-Dimethylcyclopropanone Hemiacetals from 2-Halo-3-pentanones. - Cycloadditions with Conjugated Diene Systems
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2-Chloro- and 2-bromo-3-pentanone (1,2) react in methanol, ethanol, and 2-propanol with the corresponding sodium alkoxides in a highly stereoselective manner to provide the hemiacetals of cis-2,3-dimethylcyclopropanone (4aα-4cα).The benzoate of 4aα was characterized by an X-ray crystal structure determination. cis-2,3-Dimethylcyclopropanone can be trapped by an aldol type addition with dimethyl malonate.It undergoes a disrotatory retro-electrocyclic ring opening to form a W-configured allylium-2-olate (oxyallyl) 10 which combines with isoprene, (E)-1,3-pentadiene,furan, and 2-methylfuran in highly stereoselective cycloadditions.With methanol and 2,2,2-trifluoroethanol, the 2-alkoxy-3-pentanones are formed.N-Methylpyrrol is oxoalkylated at the 2-position.
- Foehlisch, Baldur,Gehrlach, Eberhard,Stezowski, John J.,Kollat, Petra,Martin, Eveline,Gottstein, Wolfgang
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p. 1661 - 1682
(2007/10/02)
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