Enantioselective Total Synthesis of (-)-Clavosolide A and B
作者:Jung-Beom Son、Si-Nae Kim、Na-Yeong Kim、Min-Ho Hwang、Won-Sun Lee、Duck-Hyung Lee
DOI:10.5012/bkcs.2010.31.03.653
日期:2010.3.20
Enantioselective total synthesis of (-)-clavosolide A and B was reported in full including the synthesis of proposed structure of (-)-clavosoldie A (1), revised structure of (-)-clavosoldie A (5), and revised structure of (-)-clavosoldie B (6). The relative and absolute stereochemistries of the natural products were confirmed unambiguously by comparing the optical rotation values and $^1H$ and $^13}C$ NMR spectra of them.
完全报道了(-)-clavosolide A和B的对映选择性全合成,包括所提出的(-)-clavosolide A (1)结构的合成、修订后的(-)-clavosolide A (5)结构的合成以及修订后的(-)-clavosolide B (6)结构的合成。通过比较其旋光值和$^1H$及$^13}C$核磁共振谱,明确证实了这些天然产物的相对和绝对立体化学。
SELECTIVE ALLYLATIONS OF α,β-UNSATURATED ACETALS WITH ALLYLSILANES IN THE PRESENCE OF LEWIS ACID
作者:Akira Hosomi、Masahiko Endo、Hideki Sakurai
DOI:10.1246/cl.1978.499
日期:1978.5.5
The reaction of allylsilanes with α,β-unsaturated acetals in the presence of titanium tetrachloride afforded diallylated compounds, while monoallylated compounds were obtained selectively by the reaction promoted by aluminum trichloride or boron trifluoride–ether complex.
A New Method for the Preparation of δ-Alkoxy-α,β-unsaturated Aldehydes and Polyenals
作者:Akihiko Ishida、Teruaki Mukaiyama
DOI:10.1246/bcsj.50.1161
日期:1977.5
TiCl4 and also in the coexistence of TiCl4 and Ti(OiPr)4 to give δ-alkoxy-α,β-unsaturated aldehydes (3–5) in good yields. In the presence of 1,8-diazabicyclo[5.4.0] undec-7-ene or 1,5-diazabicyclo[4.3.0]non-5-ene and molecular sieves 3A or 4A, the elimination reaction of δ-alkoxyl group of α,β-unsaturated aldehydes (3–5) proceeds smoothly to afford the corresponding polyenals in good yields.
α,β-Unsaturated aldehyde acetals add :CCl2 (obtained in accordance with Makosza procedure) to form gem-dichlorocyclopropanecarboxaldehyde acetals (1) in high yields when the ratio of reactants is no less than 1:4. The addition of :CCl2 to polyunsaturated aldehyde acetals in the above conditions proceeds regioselectively at double bonds enriched by electrons. Compounds 1 are reduced by sodium in liquid
The Michael Reaction of Silyl Enol Ethers with α,β-Unsaturated Eetones and Acetals in the Presence of Titanium Tetraalkoxide and Titanium Tetrachloride
Silyl enol ethers react with α,β-unsaturated ketones and esters in the presence of TiCl4 or in the coexistence of TiCl4 and Ti(Oi-Pr)4 to give 1,5-dicarbonyl compounds in good yields. The reactions of acetals derived from α,β-unsaturated ketones with silyl enol ethers in the coexistence of TiCl4 and Ti(Oi-Pr)4, followed by successive addition of 1,2-ethanedithiol, give the Michael products, δ-keto