Application of 1-tert-butoxy-3-[(trimethylsilyl)oxy]buta-1,3-diene in the preparation of functionalized .beta.-hydroxycyclohexanone derivatives, including valuable precursors of daunomycinone analogs
Application of 1-tert-butoxy-3-[(trimethylsilyl)oxy]buta-1,3-diene in the preparation of functionalized .beta.-hydroxycyclohexanone derivatives, including valuable precursors of daunomycinone analogs
Chiral Hetero Diels−Alder Products by Enantioselective and Diastereoselective Zirconium Catalysis. Scope, Limitation, Mechanism, and Application to the Concise Synthesis of (+)-Prelactone C and (+)-9-Deoxygoniopypyrone
enantioselectivities in the reaction with 4-methyl Danishefsky's diene. This is the first example of catalyticasymmetric trans-selective hetero Diels-Alderreactions of aldehydes. Furthermore, asymmetric HDA reactions with 4-benzyloxy Danishefsky's dienes were conducted to afford 2,3-cis-pyranone derivatives in high selectivities. Isolation of an intermediate of this asymmetric hetero Diels-Alderreaction indicated
Catalytic asymmetric aza Diels–Alder reactions of hydrazones using a chiral zirconium catalyst
作者:Yasuhiro Yamashita、Yumiko Mizuki、Shū Kobayashi
DOI:10.1016/j.tetlet.2005.01.111
日期:2005.3
Catalyticasymmetric aza Diels–Alderreactions of acylhydrazones with Danishefsky’s dienes have been developed. A chiral zirconium complex derived from zirconium propoxide and 3,3′,6,6′-I4BINOL was found to be effective in this reaction, and the desired optically active 2,3-dihydro-4-pyridone derivatives were obtained with high enantioselectivities. Asymmetric formal synthesis of a natural product
[reaction: see text] The first catalytic, asymmetric 2,3-trans-selective heteroDiels-Alderreaction has been developed. The reactions of aldehydes with Danishefsky'sdienes proceeded smoothly to afford the pyranone derivatives in high yields with high trans-selectivities and enantioselectivities in the presence of a chiral zirconium complex, which was prepared from zirconium tert-butoxide and (R)-3
ANTHRACYCLINES. CYCLOADDITIONS OF 9-CHLORO-10-HYDROXY-1,4-ANTHRAQUINONE WITH VARIOUS BUTA-1,3-DIENES
作者:Nand L. Agarwal、Hans W. Scheeren
DOI:10.1246/cl.1982.1057
日期:1982.7.5
4-anthraquinone (10) affords an efficient, regiospecific access in two steps to tetracyclic ketones (12–14) which have been investigated as intermediates for the synthesis of anthracycline derivatives. Butadienes with a less asymmetric II-electron distribution than 9 give lower regiospecificity in cycloadditions with 10. Depending on the substituents in the used butadiene, the obtained cycloadducts are
tethered by heavier Group 14 elements (Si or Ge) were synthesized. These possess an intramolecularly transannular pπ–σ* interaction between the boron center and the tethered Si/Ge atom, which allows the precise tuning of their Lewisacidity. The Lewisacidity was investigated by the ligand‐exchange reaction rate and IR measurements with the help of theoretical calculation. The synthesized borates exhibited