Chemoselective TBS deprotection of primary alcohols by means of pyridinium tribromide (Py·Br3) in MeOH
摘要:
A catalytic amount of pyridinium tribromide (Py center dot Br(3)) in MeOH chemoselectively deprotects primary TBS ethers in the presence of a Variety of other protecting and common functional groups in modest to excellent yields when performed at 0 degrees C. (C) 2008 Elsevier Ltd. All rights reserved.
One-pot sequential cross-metathesis/hydride reduction: highly stereoselective synthesis of primary (E)-allylic alcohols from terminal olefins
作者:Tapas Paul、Gopal Sirasani、Rodrigo B. Andrade
DOI:10.1016/j.tetlet.2008.03.132
日期:2008.5
Several di- and trisubstituted primary (E)-allylic alcohols have been prepared from the corresponding terminal olefins in a highly stereoselective manner (>20:1 E/Z) by sequencing olefin cross-metathesis (CM) with hydride reduction (DIBAL-H) in good yields utilizing only commercially available reagents in a one-pot fashion. The method is a reliable alternative to the direct CM of terminal olefins with
通过以氢化物还原法对烯烃交叉复分解(CM)进行测序(DIBAL-H),从相应的末端烯烃以高度立体选择性的方式(> 20:1 E / Z)制备了几种二和三取代的伯(E)烯丙基醇。)仅使用一锅法仅使用市售试剂即可获得高收率)。该方法是端烯与烯丙醇直接CM的可靠替代方法,后者并不总是立体选择性的,而是高度依赖底物的。
A Short and Efficient Synthesis of (-)-Diospongin A
作者:Janine Cossy、Cyril Bressy、Florent Allais
DOI:10.1055/s-2006-956485
日期:2006.12
The synthesis of (-)-diospongin A has been achieved from benzaldehyde in six steps with an overall yield of 29%.
Regiochemical Control in the Metal-Catalyzed Transposition of Allylic Silyl Ethers
作者:Eric C. Hansen、Daesung Lee
DOI:10.1021/ja0620639
日期:2006.6.1
A novel mode of regiochemical control over the allylic [1,3]-transposition of silyloxy groups catalyzed by Re2O7 has been developed. This strategy relies on a cis-oriented vinyl boronate, generated from the Alder-ene reaction of homoallylic silyl ethers and alkynyl boronates, to trap out the allylic hydroxyl group. The resulting cyclic boronic acids are excellent partners for cross-coupling reactions
The enantioselective allylation of an aromatic aldehyde to give a chiral homoallylic alcohol was employed as the key step in the syntheses of a flobufen metabolite and dapoxetine. In the former case, the homoallylic alcohol moiety (99 % ee) was converted into a five-membered lactone ring with good preservation of the optical purity, and the target compound, a flobufen metabolite, was obtained in 95 % ee
芳醛对映选择性烯丙基化得到手性高烯丙醇被用作氟布芬代谢物和达泊西汀合成的关键步骤。在前一种情况下,高烯丙醇部分 (99% ee) 转化为五元内酯环,光学纯度保持良好,目标化合物氟布芬代谢物以 95% ee 获得。在后一种情况下,高烯丙醇部分 (97% ee) 经过几个步骤转化为 3-氨基丙醇部分。在合成过程中,观察到光学纯度逐渐降低,目标化合物达泊西汀以 85% ee 获得。
Discovery of a Practical Direct O<sub>2</sub>-Coupled Wacker Oxidation with Pd[(−)-sparteine]Cl<sub>2</sub>
作者:Candace N. Cornell、Matthew S. Sigman
DOI:10.1021/ol061662h
日期:2006.8.1
The discovery of a direct O-2-coupled Wacker oxidation with use of balloon pressure of O-2 and low catalyst loading is described. Use of (-)-sparteine as a ligand on Pd prevents olefin isomerization and leads to selective formation of methyl ketones from terminal olefins in good yields. Oxidation of enantiomerically enriched substrates is reported with no observed racemization.