Indium-mediated Barbier-type allylation of aldehydes as a convenient method for the highly enantioselective synthesis of homoallylic alcohols
作者:Lacie C. Hirayama、Soya Gamsey、Daniel Knueppel、Derek Steiner、Kelly DeLaTorre、Bakthan Singaram
DOI:10.1016/j.tetlet.2005.01.169
日期:2005.3
enantioselective allylation of both aromatic and aliphatic aldehydes using commercially available (1S,2R)-(+)-2-amino-1,2-diphenylethanol as a chiral auxiliary. Using only two equivalents of allyl bromide, excellent yields and very good to excellent enantioselectivities are obtained. To our knowledge, the enantioselectivities reported herein are the highest obtained for indium-promoted allylations of carbonyl
Synthetically amenable amide derivatives of tosylated-amino acids as organocatalysts for enantioselective allylation of aldehydes: computational rationale for enantioselectivity
作者:Debashis Ghosh、Debashis Sahu、S. Saravanan、Sayed H. R. Abdi、Bishwajit Ganguly、Noor-ul H. Khan、Rukhsana I. Kureshy、Hari C. Bajaj
DOI:10.1039/c3ob27513b
日期:——
A phenylalanine derived chiral amide is developed that serves as an effective organocatalyst for the reaction of allyltrichlorosilane with aryl, hetero-aryl and α,β-unsaturated aldehydes to afford the desired homoallylic alcohols in good yield (up to 90%) and high enantioselectivity (up to 99%). The experimental results and DFT calculations suggest that para substituted aromatic aldehydes as substrate show higher ee in the product than their ortho/meta counterparts. The 1H and 13C NMR spectra study corroborated the calculated results. The chiral organocatalyst can be easily synthesized from optically pure phenylalanine in two simple steps with 90% overall yield.
Indium-Mediated Asymmetric Barbier-Type Allylations: Additions to Aldehydes and Ketones and Mechanistic Investigation of the Organoindium Reagents
作者:Terra D. Haddad、Lacie C. Hirayama、Bakthan Singaram
DOI:10.1021/jo902173j
日期:2010.2.5
indium-mediated additions, solvent plays a major role in determining the nature of the organoindium intermediate and we observed the susceptibility of some allylindium intermediates to hydrolysis in protic solvents. Under our reaction conditions using a polar aprotic solvent, we suggest that an allylindium(III) species is the active allylating intermediate. In addition, we have observed the presence of
我们报告了一种简单,有效且通用的方法,用于在一锅合成中在Barbier型条件下进行芳香族和脂肪族醛和酮的铟介导的对映选择性烯丙基化,可提供非常好的收率的手性醇产品(高达99% )和对映体过量(最高93%)。我们的方法能够耐受各种官能团,例如酯,腈和酚。此外,当使用肉桂基溴化物(> 95/5 anti / syn)时,可以使用更多取代的烯丙基溴,例如巴豆基和肉桂基溴化物,提供中等的对映选择性(分别为72%和56%)和出色的非对映选择性。)。然而,使用巴豆基溴化物时的立体选择性差,并且在我们的方法下,其他官能化的烯丙基溴化物对醇产物的对映选择性低。在这些类型的铟介导的添加物中,溶剂在确定有机铟中间体的性质中起主要作用,我们观察到某些烯丙基铟中间体对质子溶剂水解的敏感性。在使用极性非质子传递溶剂的反应条件下,我们认为烯丙基(III)物种是活性烯丙基化中间体。此外,我们已经观察到整个反应过程中存在
A New Approach to Axially Chiral BipyridineN,N′-Dioxides Bearing Aromatic Substituents and their Use for Catalytic Asymmetric Allylation of Aldehydes with Allyl(trichloro)silane
作者:Asato Kina、Toyoshi Shimada、Tamio Hayashi
DOI:10.1002/adsc.200404054
日期:2004.8
(Rnap,Rpyr)-1 with the aryl Grignard reagents opened a new approach to axiallychiral bipyridine N,N′-dioxides (R)-2 bearing a variety of aryl groups at the 6 and 6′ positions. One of the N,N′-dioxides (R)-2d which is substituted with 3,5-dimethyl-4-methoxy groups was found to be highly catalytically active and enantioselective for the asymmetric allylation of aldehydes with allyl(trichloro)silane. The
as Lewis base catalysts are reported. Lewis bases containing the 3,5-bis(trifluoromethyl)phenyl group were found to be significantly more enantioselective for a wider range of substrates than those bearing aromatic residues that are not strongly electron-deficient in the allylation of aldehydes with allyltrichlorosilane. Also, optically pure 3,3′-dibromo-1,1′-biisoquinoline N,N′-dioxide that has not