The Regioselective Mono-deprotection of 1,3-Dioxa-2,2-(di-tert-butyl)-2-silacyclohexanes with BF3·SMe2
摘要:
The selective mono-deprotection of di-tert-butylsilylene ethers prepared from substituted 1,3-pentanediols and 2,4-hexanediols has been achieved with BF3.SMe2. The reaction conditions are compatible with esters, allyl ethers, and TIPS ethers. The resulting di-tert-butylfluorosilyl ethers are stable to various conditions including low pH aqueous solutions and silica gel chromatography; the di-tert-butylfluorosilyl ethers are readily cleaved with HF-pyridine. Substrate stereochemistry and conformation influences the efficiency of the deprotection, while the deprotection regiochemistry is consistent with coordination of boron to the sterically more accessible oxygen prior to intramolecular delivery of fluoride.
A flexible synthesis of C33-C39 polyketide region of apratoxin: Synthesis of natural and unnatural analogues
作者:Arnaud Gilles、Jean Martinez、Florine Cavelier
DOI:10.1016/j.crci.2010.09.002
日期:2011.5
Résumés Anglais Français A flexible synthesis sequence toward the synthesis of the polyketide region of apratoxin has been developed. The common step of the synthesis is a crotylation reaction. Stereospecific aldolisation, sulfate ring opening or Jacobsen HKR is also highlighted. This synthetic scheme led to the synthesis of several analogues. These examples raise the possibility of synthesising numerous analogues of this portion of apratoxins. Then, together with our supported strategy to synthesise the oxazoline analogue of apratoxin A, this paper opens the possibility to provide easily oxoapratoxin analogues for future SAR studies of this potent antitumoral compound. Un schéma de synthèse flexible a été développé en vue de la synthèse de la région polycétidique de l’apratoxine. L’étape clé commune de ces synthèses est une réaction de crotylation. Une réaction d’aldolisation stéréospécifique, une ouverture d’un cycle sulfate ainsi qu’une réaction de résolution cinétique par hydrolyse ont également été utilisées. Ce schéma synthétique a conduit à la synthèse de plusieurs analogues. Les différents exemples décrits ici démontrent la possibilité d’intégrer d’autres modifications dans cette portion des apratoxines. Ainsi, avec notre stratégie supportée de synthèse de l’analogue oxazoline de l’apratoxine A, ce travail peut conduire à une synthèse aisée d’analogues de l’oxoapratoxine, dans la perspective de futures études de relation structure–activité de ce composé aux propriétés anti-tumorales.
Ruthenium–BINAP catalysedhydrogenation of 1,3-diketones gives 1,3-diols with extremely high diastereo- and enantio-selectivity.
钌–BINAP催化的1,3-二酮加氢生成1,3-二醇,具有极高的非对映选择性和对映选择性。
The Regioselective Mono-deprotection of 1,3-Dioxa-2,2-(di-<i>tert</i>-butyl)-2-silacyclohexanes with BF<sub>3</sub>·SMe<sub>2</sub>
作者:Ming Yu、Brian L. Pagenkopf
DOI:10.1021/jo025624x
日期:2002.6.1
The selective mono-deprotection of di-tert-butylsilylene ethers prepared from substituted 1,3-pentanediols and 2,4-hexanediols has been achieved with BF3.SMe2. The reaction conditions are compatible with esters, allyl ethers, and TIPS ethers. The resulting di-tert-butylfluorosilyl ethers are stable to various conditions including low pH aqueous solutions and silica gel chromatography; the di-tert-butylfluorosilyl ethers are readily cleaved with HF-pyridine. Substrate stereochemistry and conformation influences the efficiency of the deprotection, while the deprotection regiochemistry is consistent with coordination of boron to the sterically more accessible oxygen prior to intramolecular delivery of fluoride.
Enzyme-Catalyzed Kinetic Resolution of 1,3-anti-Diol Monoesters – Efficient Preparation of Enantiomerically Highly Enriched and Unsymmetrically Substituted 1,3-anti-Diols
作者:Florian Jakob、Christoph Schneider
DOI:10.1002/ejoc.200700096
日期:2007.6
3-anti-diol monoesters which have been obtained through a zirconium-catalyzed aldol-Tishchenko reaction. The product 1,3-anti-diol diesters were formed in yields close to 50 % and >98 % ee. Separation from the unreactive enantiomers and subsequent hydrolysis furnished both enantiomers of unsymmetricallysubstituted 1,3-anti-diols in high optical purities. Alternatively, the kinetic resolution process can