Synthesis of Functionalized γ-Lactone via Sakurai <i>exo</i>-Cyclization/Rearrangement of 3,3-Bis(silyl) Enol Ester with a Tethered Acetal
作者:Zhiping Yin、Zengjin Liu、Zhenggang Huang、Yang Chu、Zhiwen Chu、Jia Hu、Lu Gao、Zhenlei Song
DOI:10.1021/acs.orglett.5b00437
日期:2015.3.20
functionalized γ-lactones has been developed involving Sakurai exo-cyclization/rearrangement of 3,3-bis(silyl) enolesters with a tethered acetal. While the steric and electronic effects of geminal bis(silane) favor the desired Sakurai pathway, the methoxy species formed in the deprotection step also facilitates both cyclization and rearrangement. The synthetic value of this approach has been demonstrated by efficiently
Eine flexible Synthese von 4-Oxobutansäure- methylestern und deren Derivaten
作者:Thomas Kunz、Agnes Janowitz、Hans-Ulrich Reißig
DOI:10.1055/s-1990-26783
日期:——
A Flexible Synthesis of Methyl 4-Oxobutanoates and Their Derivatives Ring cleavage of several methyl 2-trimethylsiloxycyclopropanecarboxylates 3 provides rather sensitive methyl 4-oxobutanoates (ß-formyl esters) 4 in excellent yields. Siloxycyclopropanes 3 are easily available either directly from the corresponding silyl enol ethers 2 and methyl diazoacetate or by alkylation of deprotonated cyclopropanes 3. A highly efficient one-pot procedure affords methyl 4,4-dimethoxybutanoates 5, which can be converted into protected 4-hydroxybutanals 7 and 8 by standard methods.
A convenient synthesis of naturally occurring quinizarins
作者:Bruno Simoneau、Paul Brassard
DOI:10.1016/s0040-4020(01)85881-6
日期:1988.1
A general and regiospecific method for the preparation of quinizarins involves the cycloaddition of electron-rich dienes. Advantageous syntheses of several natural products, 2-methylquinizarin, islandicin, digitopurpone, erythroglaucin, 5-0-methylislandicin and 8-0-methyl-digitopurpone illustrate this procedure. A structure attributed to ventinone B is incorrect and 1,4,8-trihydroxy-6-methylanthraquinone
The Synthesis of Highly Functionalized Naphthalene Derivatives
作者:Simon J. Teague、Gregory P. Roth
DOI:10.1055/s-1986-31667
日期:——
Condensation of the α-lithio derivative of 3-substituted 4,4-dialkoxybutanoates, butanenitriles, and butanamides with methoxy-activated aromatic aldehydes, followed by treatment with refluxing dilute sulfuric acid gives rise to substituted naphthalene products. In this manner, 2,6,7-tri- and 2,3,6,7-tetrasubstituted naphthalenes are synthesized in high yields on a multigrarn scale.