Action des composes organomagnesiens sur les pyrones-2-VII
作者:P. Lhoste、M. Moreau、J. Dreux
DOI:10.1016/s0040-4020(01)91804-6
日期:1984.1
In the reaction between organomagnesiumcompounds and 2-pyrones, the relative stability of the 6-hydroxy 5,6-dihydro 2H-pyrans and their tautomeric forms (ketols) has no influence on the reaction pathway. When ethylenic ketols are obtained, the corresponding tautomeric dihydropyranols are prepared in a selective way by reaction of nucleophilic reagents on the 3,6-dihydro-2-pyrones. In the other hand
LHOSTE, P.;MOREAU, M.;DREUX, J., TETRAHEDRON, 1984, 40, N 9, 1551-1561
作者:LHOSTE, P.、MOREAU, M.、DREUX, J.
DOI:——
日期:——
Synthesis of 3,6-dihydro-2H-pyran-2-ones via cationic palladium(II) complex-catalyzed tandem [2+2] cycloaddition-allylic rearrangement of ketene with α,β-unsaturated aldehydes and ketones
Treatment of ketene with α,β-unsaturated aldehydes and ketones in the presence of [Pd(dppb)(PhCN)2](BF4)2 leads to the formation of 4-vinyloxetan-2-ones, which rearrange under the conditions to give 3,6-dihydro-2H-pyran-2-ones in a variety of yields, depending on the substituents. Asymmetric induction with up to 57% de has been achieved by using α,β-unsaturated aldehydes bearing an asymmetric carbon