Diisopropyl tartrate modified (E)-γ-[(cyclohexyloxy)dimethylsilyl-allylboronate, a chiral reagent for the stereoselective synthesis of anti 1,2-diols via the formal α-hydroxyallylation of aldehydes
作者:William R. Roush、Paul T. Gover、Xiaofa Lin
DOI:10.1016/s0040-4039(00)97299-x
日期:1990.1
An enantioselective synthesis of anti 1,2-diols via the reactions of aldehydes and the tartrateestermodified γ(alkoxysilyl)allylboronate2 has been developed. This method is most effective in double asymmetric reactions with chiral aldehydes.
Reaction of γ,γ-Dialkoxyallylic Zirconium Species with Aldehyde as Protected Acryloyl Anion
作者:Azusa Sato、Hisanaka Ito、Takeo Taguchi
DOI:10.1021/jo991107b
日期:2000.2.1
4,5-Diisopropyl-<i>B</i>-[(<i>E</i>)-[(3‘-menthofuryl)dimethylsilyl]allyl]-1,3,2- dioxaborolane, an Improved Chiral Reagent for the Anti α-Hydroxyallylation of Aldehydes: Application to the Enantioselective Synthesis of (−)-Swainsonine
作者:J. A. Hunt、William R. Roush
DOI:10.1021/jo961840s
日期:1997.2.1
Diisopropyl tartrate-modified (E)-[gamma-(furyldimethylsilyl)allyl]boronates 10 and 11 were designed for the enantioselective synthesis of substituted anti-3,4-dihydroxy-1-butenes 9 via the anti-alpha-hydroxyallylation of aldehydes. The reactions of aldehydes with 10 and 11 provided furyldimethylsilyl-substituted anti-1,2-silanols 12 and 13 with good enantioselectivity (74-82% ee), and the silanols were oxidized to the corresponding anti-1,2-diols 9 by a modified Fleming-Tamao oxidation protocol. The high reactivity of the (menthofuryl)silane unit toward electrophilic substitution allowed complete protodesilylation of menthofuryl-substituted silanols 13 and subsequent oxidation to diols 9 in a one-pot operation without competing protodesilylation of the allylsilane unit. However, a two-step protocol was required for the protodesilylation-oxidation of the less reactive 2-(5-methyl)-asymmetric reactions with three chiral aldehydes 23-35 (80 to >92% de, with the exception of the mismatched reactions with aldehyde 25, which were essentially unselective). However, [[[2-(5-methylfuryl)]dimethylsilyl]ally]boronate 10 could only be synthesized in less than or equal to 15% yield, and oxidations of the 2-(5-methylfuryl)-substituted silanols 12 were lower-yielding than oxidations of the corresponding menthofuryl-substituted silanols 13. Thus diisopropyl tartrate-modified (E)-[gamma-[(menthofuryl)dimethylsilyl]ally]boronate 11 proved to be the more useful of the two reagents. As a demonstration of the utility of 11 in the synthesis of polyhydroxylated natural products, this new reagent was used in a brief and highly stereoselective synthesis of the naturally occurring alkaloid (-)-swainsonine (42).
Diisopropyl tartrate-modified (E)-γ-[(menthofuryl)dimethylsilyl]-allyl boronate, an improved chiral reagent for the anti α-hydroxyallylation of aldehydes. Application to the enantioselective synthesis of (−)-swainsonine
作者:J.A. Hunt、William R. Roush
DOI:10.1016/0040-4039(94)02295-m
日期:1995.1
An enantioselective synthesis of anti 1,2-diols via the reactions of aldehydes and the tartrate ester-modified (E)-gamma-(menthofurylsilyl)allylboronate 5 has been developed. This methodology is applied to a brief, enantioselective synthesis of (-)-swainsonine.