The stereocontrolled total synthesis of altohyrtin A/spongistatin 1: the CD-spiroacetal segment
作者:Ian Paterson、Mark J. Coster、David Y.-K. Chen、Karl R. Gibson、Debra J. Wallace
DOI:10.1039/b504148a
日期:——
Stereocontrolled syntheses of the C16-C28 CD-spiroacetal subunit of altohyrtin A/spongistatin1 , relying on kinetic and thermodynamic control of the spiroacetal formation, are described. The kinetic control approach resulted in a slight preference (60 : 40) for the desired spiroacetal isomer. The thermodynamic approach allowed ready access to the desired spiroacetal by acid-promoted equilibration
依赖于螺缩醛形成的动力学和热力学控制,描述了altohyrtin A /海绵抑素1的C16-C28 CD-螺缩醛亚基的立体控制合成。动力学控制方法导致所希望的螺缩醛异构体稍微偏爱(60∶40)。通过热力学方法,可以通过酸促进的平衡,C23差向异构体的色谱分离以及不希望的异构体重新达到平衡条件,从而容易地获得所需的螺缩醛。这种可扩展的合成序列提供了数克的,因此能够成功完成altohyrtin A /海绵体抑素1的总合成,如本系列文章的第4部分所报道。
Acyclic stereoselection. 20. High diastereofacial selectivity in the stannic chloride mediated reactions of allylsilanes with chiral α- and β-alkoxy aldehydes.
作者:Syun-ichi Kiyooka、Clayton H Heathcock
DOI:10.1016/s0040-4039(00)94002-4
日期:1983.1
Stannic chloride is an effective catalyst for the reaction of allylsilanes with chiralα- and β-alkoxyaldehydes. In the case of α-alkoxy aldehyde 1, the diastereofacial preference is outstanding (>35:1). With β- alkoxy aldehydes 5 and 6, selectivity is lower, but still quite acceptable (7–12:1).
Addition of Allylindium Reagents to Aldehydes Substituted at C<sub>α</sub> or C<sub>β</sub> with Heteroatomic Functional Groups. Analysis of the Modulation in Diastereoselectivity Attainable in Aqueous, Organic, and Mixed Solvent Systems
作者:Leo A. Paquette、Thomas M. Mitzel
DOI:10.1021/ja953682c
日期:1996.1.1
The stereochemical course of indium-promoted allylations to alpha- and beta-oxy aldehydes has been investigated in solvents ranging from anhydrous THF to pure H2O. The free hydroxyl derivatives react with excellent diastereofacial control to give significantly heightened levels of syn-1,2-diols and anti-1,3-diols. Relative reactivities were determined in the alpha-series, and the hydroxy aldehyde proved to be the most reactive substrate. This reactivity ordering suggests that the selectivity stems from chelated intermediates. The rate acceleration observed in water can be heightened by initial acidification. Indeed, the indium-promoted allylation reaction mixtures become increasingly acidic on their own. Preliminary attention has been accorded to salt effects, and tetraethylammonium bromide was found to exhibit a positive synergistic effect on product distribution. Finally, mechanistic considerations are presented in order to allow for assessment of the status of these unprecedented developments at this stage of advancement of the field.
Dramatic effects of oxygen substituents on 1,3-asymmetric induction in additions of allyltriphenylstannane to .beta.-alkoxy aldehydes: a chemical and spectroscopic investigation
作者:Gary E. Keck、Stephen Castellino、Michael R. Wiley
DOI:10.1021/jo00376a097
日期:1986.12
REETZ, M. T.;KESSELER, K.;JUNG, A., TETRAHEDRON LETT., 1984, 25, N 7, 729-732