Concerning the Synthesis of the Elusive <i>anti,anti</i>-Dipropionate Stereotriad via the Crotylation of β-Hydroxy α-Methyl Aldehydes with (<i>Z</i>)-Crotyltrifluorosilane. Application to the Synthesis of the C(7)−C(16) Segment of Zincophorin
作者:Sherry R. Chemler、William R. Roush
DOI:10.1021/jo980387c
日期:1998.6.1
Stereochemically divergent pathways for the allylation and crotylation reactions of anti- and syn-β-hydroxy-α-methyl aldehydes with allyl- and crotyltrifluorosilanes
作者:Sherry R. Chemler、William R. Roush
DOI:10.1016/s0040-4039(99)00730-3
日期:1999.6
Allylation and crotylation reactions of 2,3-anti-beta-hydroxy-alpha-methyl aldehydes 10 and 11 with allyl and crotyltrifluorosilanes 2, 8 and 9 proceed with high selectivity via the bicyclic chelated transition states 3 and 30. In contrast, analogous allylation and crotylation reactions of the 2,3-syn-beta-hydroxy-alpha-methyl aldehydes 12 and 13 with 2, 8 and 9 are generally less selective and proceed preferentially by way of the normal Zimmerman-Traxler transition states 6 and 32. (C) 1999 Elsevier Science Ltd. All rights reserved.
Stereochemistry of the Allylation and Crotylation Reactions of α-Methyl-β-hydroxy Aldehydes with Allyl- and Crotyltrifluorosilanes. Synthesis of <i>anti,anti</i>-Dipropionate Stereotriads and Stereodivergent Pathways for the Reactions with 2,3-<i>anti-</i> and 2,3-<i>syn</i>-α-Methyl-β-hydroxy Aldehydes
作者:Sherry R. Chemler、William R. Roush
DOI:10.1021/jo0267908
日期:2003.2.1
experiments performed with beta-hydroxy aldehydes 37a (anti) and the corresponding p-methoxybenzyl (PMB) ether 48, and between aldehyde 39 (syn) and the PMB ether 90, established that the 2,3-anti-beta-hydroxy aldehydes react predominantly through bicyclic transition states while the 2,3-syn aldehydes react predominantly through conventional Zimmerman-Traxler transition states. NMR studies established that