206768-81-2Relevant academic research and scientific papers
The First Catalytic Asymmetric Allylation of Imines with the Tetraallylsilane-TBAF-MeOH System, Using the Chiral Bis-π-allylpalladium Complex
Fernandes, Rodney A.,Yamamoto, Yoshinori
, p. 735 - 738 (2004)
The asymmetric allylation of imines with use of catalytic transition metals with chiral ligands should be a new frontier of the enantioselective C-C bond formation. So far allyltrimethylsilane, allyltrichlorosilane, and allyltrimethoxysilane have been commonly employed with use of either silane activators or dual silane-imine activators. However, tetraallylsilane is untouched in the allylation of aldimines. The first allylation of aldimines with the tetraallylsilane-TBAF-MeOH system with use of the bis-π -allylpalladium catalyst under catalytic, non-Lewis acid, essentially neutral and very mild reaction conditions has been achieved. The reaction is triggered by dual activation/promotion by TBAF and MeOH in which the fluoride anion activates the C-Si bond cleavage and MeOH promotes the facile protonation of intermediate palladium amide. Thus, the synthesis of chiral homoallylamines is achieved in a shorter reaction time and higher yields and enantioselectivities through an efficient, general, and reproducible allylation protocol for imines.
Preparation and application of a polymer-supported chiral π-allylpalladium catalyst for the allylation of imines
Bao, Ming,Nakamura, Hiroyuki,Yamamoto, Yoshinori
, p. 131 - 134 (2000)
The polymer-supported chiral π-allylpalladium catalyst 8 was applied to the asymmetric allylation reaction of imines 9 with allyltributylstannane. The catalyst was very stable and could be reused several times with high catalytic activity, although the enantioselectivity was not necessarily high.
Chiral Bis-π-allylpalladium Complex Catalyzed Asymmetric Allylation of Imines: Enhancement of the Enantioselectivity and Chemical Yield in the Presence of Water
Fernandes, Rodney A.,Stimac, Anton,Yamamoto, Yoshinori
, p. 14133 - 14139 (2003)
The chiral π-allylpalladium complex 2a, prepared from exoethylidenenorpinane 7, catalyzed the allylation of diverse imines with allyltributylstannane in the presence of 1 equiv of water in good to high enantioselectivities. The catalyst prepared from a 1:1 mixture of (E)- and (Z) -7 was found to be consisting of two stereoisomers 2a and 2b in 1.3:1 ratio. On separation, 2a catalyzed the allylation of imines in much higher enantioselectivities than 2b, giving the same major enantiomer and thereby justifying the need to separate 2a free of 2b. We have achieved the highest separation ratio of >400:1 for 2a:2b by repeated recrystallizations. Isomerization of 2b to 2a during recovery of 2a from the filtrates was observed as more of 2a was recovered each time during recrystallization. Although dry THF was the best solvent, we tried various additives and found that addition of one equivalent of water gave the best results with respect to shorter reaction time, higher yields and enantioselectivities. Thus, we have developed a more general, reproducible, robust and a non-Lewis acid catalyzed procedure for catalytic asymmetric allylation of imines under essentially neutral conditions.
Menthane-Based Chloride-Bridged η3-Bis-π-Allylpalladium Chloride Dimers: Catalytic Asymmetric Allylation of Imines
Jha, Amit K.,Fernandes, Rodney A.
, p. 2857 - 2863 (2019/05/15)
Menthane-based η3-bis-π-allylpalladium chloride dimer complexes have been prepared for the first time. They exist as dimeric η3-bis-π-allylpalladium with four chloride bridges. The complexes catalyze the asymmetric allylation of vari
Development of the first menthane-based chiral bis(π-allylpalladium) catalysis: Asymmetric allylation of imines
Fernandes, Rodney A.,Chaudhari, Dipali A.
experimental part, p. 1945 - 1952 (2012/05/20)
A new ethylidene menthane-based chiral π-allylpalladium complex catalyzes the asymmetric allylation of various imines with allyltributylstannane and 1 equiv. of water to give chiral homoallylamines in good yields and enantioselectivities. The reaction was carried out essentially under neutral conditions and displayed a good transfer of chiral information from the menthane skeleton through the formation of a bis(π-allylpalladium) species. This is the first example of menthane-based chiral bis(π-allylpalladium) catalysis. A menthane-based chiral π-allylpalladium-catalyzed asymmetric allylation of various imines has been developed giving chiral homoallylamines in good yields and enantioselectivities. The reaction displays a good transfer of chiral information from the menthane skeleton through the formation of a bis(π-allylpalladium) complex. Copyright
Enantioselective allylation of imines catalyzed by newly developed (-)-β-pinene-based π-allylpalladium catalyst: An efficient synthesis of (R)-α-propylpiperonylamine and (R)-pipecolic acid
Fernandes, Rodney A.,Nallasivam, Jothi L.
, p. 7789 - 7800 (2013/04/23)
A newly developed π-allylpalladium with a (-)-β-pinene framework and an isobutyl side chain catalyzed the enantioselective allylation of imines in good yields and enantioselectivities (20 examples, up to 98% ee). An efficient enantioselective synthesis of the (R)-α-propyl piperonylamine part of DMP 777, a human leukocyte elastase inhibitor and (R)-pipecolic acid have been achieved as a useful application of this methodology. The Royal Society of Chemistry 2012.
Asymmetric allylboration of acyl imines catalyzed by chiral diols
Lou, Sha,Moquist, Philip N.,Schaus, Scott E.
, p. 15398 - 15404 (2008/09/18)
Chiral BINOL-derived diols catalyze the enantioselective asymmetric allylboration of acyl imines. The reaction requires 15 mol % (S)-3,3′-Ph2-BINOL as the catalyst and allyldiisopropoxyborane as the nucleophile. The reaction products are obtained in good yields (75-94%) and high enantiomeric ratios (95:5-99.5:0.5) for aromatic and aliphatic imines. High diastereoselectivities (diastereomeric ratio > 98:2) and enantioselectivities (enantiomeric ratio > 98:2) are obtained in the reactions of acyl imines with crotyldiisopropoxyboranes. This asymmetric transformation is directly applied to the synthesis of Maraviroc, the selective CCR5 antagonist with potent activity against HIV-1 infection. Mechanistic investigations of the allylboration reaction including IR, NMR, and mass spectrometry studies indicate that acyclic boronates are activated by chiral diols via exchange of one of the boronate alkoxy groups with activation of the acyl imine via hydrogen bonding.
