Regioselective Ring Opening of Di-isopropylsilylenes Derived from 1,3-Diols with Alkyl Lithium Reagents
摘要:
The selective alkyl lithium-induced ring opening of 1,3-di-isopropylsilylenes is described. The reaction affords a differentially substituted 1,3-diol bearing a silane that resides at the oxygen in the more sterically demanding position. The reaction can be highly selective with a regiochemical preference up to >50:1 and likely proceeds via an alkoxy-silane intermediate. This intermediate can by trapped by methyl iodide to provide the corresponding silyl methyl ether, wherein the silane again resides at the oxygen in the more sterically demanding position.
Synthesis of Enantiomerically Pure β-Hydroxy Ketones via β-Keto Weinreb Amides by a Condensation/Asymmetric-Hydrogenation/Acylation Sequence
作者:Julian Diehl、Reinhard Brückner
DOI:10.1002/ejoc.201601202
日期:2017.1.10
an ester/amide exchange, and the use of the resulting β-hydroxy amide for the acylation of an organometallic compound. We shortened this route by showing that β-keto Weinreb amides are hydrogenated with up to 99 % ee in the presence of [Me2NH2]+[RuCl(S)-BINAP]2(µ-Cl)3}– (0.5 mol-%) at room temp./5 bar. These Weinreb amides were prepared by seemingly obvious yet unprecedented condensations of lithiated
The Zirconium Alkoxide-Catalyzed Aldol-Tishchenko Reaction of Ketone Aldols
作者:Christoph Schneider、Markus Hansch、Timo Weide
DOI:10.1002/chem.200400951
日期:2005.1
Evaluation of a broad range of metal alkoxides as catalysts and optimization of the reaction protocol led to a modified zirconium alkoxide catalyst with attenuated Lewis acidity and dichloromethane as solvent, which resulted in suppression of the undesired acyl migration to a large extent. Various ketone aldols have been prepared and subjected to the general process, giving rise to a broad range of differently
Stereocontrolled reductive amination of 3-hydroxy ketones
作者:Mansour Haddad、Jérôme Dorbais、Marc Larchevêque
DOI:10.1016/s0040-4039(97)01349-x
日期:1997.8
syn-1,3-Aminoalcohols are synthesized in high diastereomeric excess by reductive amination of 3-hydroxyketones with sodium cyanoborohydride in the presence of benzylamine.
syn -1,3-氨基醇是通过在苄胺存在下用氰基硼氢化钠对3-羟基酮进行还原胺化反应而以非对映异构体过量的方式合成的。
1,3-syn diastereoselective reduction of β-hydroxyketones with diisobutylaluminum hydride and tributyltin hydride
1,3-Syn diastereofacial selectivity (>12 : 1) has been achieved in a facile reduction of β-hydroxyketones with DIBAL-H. Tributyltinhydride also has shown 1,3-syn selectivity.
Stereocontrol in intramolecular hydrosilylation of allyl and homoallyl alcohols: a new approach to the stereoselective synthesis of 1,3-diol skeletons
作者:Kohei. Tamao、Takashi. Nakajima、Ritsuo. Sumiya、Hitoshi. Arai、Noriko. Higuchi、Yoshihiko. Ito
DOI:10.1021/ja00279a097
日期:1986.9
31.30; H, 5.22; N, 36.52. Found: C, 31.34; H, 5.25; N, 36.70. Low-resolution mass spectral analysis showed the expected molecular ion at m / e 345. The infrared spectrum contained a cyano stretching peak at 2180 cm-'. The 31P NMR spectrum consisted of a singlet at -7.8 ppm. Crystals suitable for X-ray analysis were grown by slow evaporation of a solution of 2 in hexane. The structure of 2 is illustrated