efficient cross aldol additions between different ketones and between ketones and aldehydes, in good to excellent yields with high syn-stereoselectivities. As an extension, direct Claisencondensation between methyl esters was also promoted by TiCl4/Bu3N with 0.05 equiv of TMSOTf co-catalyst.
的TiCl 4 /卜3 Ñ进行不同酮类之间和酮和醛,在良好的以高优异的产率之间高效交叉醛醇添加顺-stereoselectivities。此外,TiCl 4 / Bu 3 N与0.05当量的TMSOTf助催化剂还促进了甲酯之间的直接Claisen缩合反应。
Stereoseletive Reduction of<i>β</i>-Hydroxy Ketones to 1,3-Diols with the Aid of a Terphenylboronic Acid
作者:Hiroshi Yamashita、Koichi Narasaka
DOI:10.1246/cl.1996.539
日期:1996.7
stereoselective reduction of acyclic and cyclic β-hydroxy ketones. The terphenylboronic acid 1 and acyclic β-hydroxy ketones 2 are converted to the corresponding boronates by azeotropic removal of water. The resulting boronates are treated in situ with reducing reagents to give syn 1,3-diols 3 almost exclusively. Anti α-substituted β-hydroxy ketones 8 are also reduced to give anti, anti 1,3-diol 9 stereoselectively
REGIOSELECTIVE MONOALKYLATION OF KETONES VIA THEIR MANGANESE ENOLATES: 2-BENZYL-6-METHYLCYCLOHEXANONE FROM 2-METHYLCYCLOHEXANONE
作者:Cahiez, Gérard、Chau, François、Blanchot, Bernard、Yli-Kauhaluoma, Jari、Danheiser, Rick L.
DOI:10.15227/orgsyn.076.0239
日期:——
1,3-versus 1,2-Asymmetric induction in the reduction of β-hydroxy ketones by intramolecular hydrosilylation
作者:Saeed Anwar、Gavin Bradley、Anthony P. Davis
DOI:10.1039/p19910001383
日期:——
The role of 1,2-asymmetric induction has been investigated in the 1,3-anti-selective reduction of beta-hydroxy ketones via intramolecular hydrosilylation. For the alpha-methyl beta-hydroxy ketones 2a, 3a, the effect of the alpha-substituent is negligible except that it appears to reinforce 1,3-asymmetric induction. For the alpha-ethyl beta-hydroxy ketones 2b, 3b, 1,3-asymmetric induction is dominant but not overwhelming. The super-acid TfOH2+ B(OTf)4- has been used as a catalyst for the hydrosilylation giving, in one case, an improved result when compared with previous methodology.
Direct, practical, and powerful crossed aldol additions between ketones and ketones or aldehydes utilizing environmentally benign TiCl4–Bu3N reagent
benign method is advantageous from a green chemical viewpoint with regard to yield, substrates variation, reagent availability, and simple procedures. This method was applied to a short step formal synthesis of (R)-muscone, a natural macrocyclic musk.