133398-24-0Relevant academic research and scientific papers
Enantioselective NiH/Pmrox-Catalyzed 1,2-Reduction of α,β-Unsaturated Ketones
Chen, Fenglin,Zhang, Yao,Yu, Lei,Zhu, Shaolin
, p. 2022 - 2025 (2017/02/15)
The enantioselective 1,2-reduction of α,β-unsaturated ketones was achieved using a NiH catalyst in the presence of pinacolborane. This mild process represents a general method to access a wide variety of structurally diverse α-chiral allylic alcohols in excellent yields and enantioselectivity, as well as very high levels of ambidoselectivity for 1,2- over 1,4-reduction. Furthermore, for reactions on a 10 mmol scale, catalyst loadings as low as 0.5 mol % could be employed to deliver product without any detrimental effect on the yield, enantio-, or ambidoselectivity.
Copper-Catalyzed γ-Selective and Stereospecific Allylic Cross-Coupling with Secondary Alkylboranes
Yasuda, Yuto,Nagao, Kazunori,Shido, Yoshinori,Mori, Seiji,Ohmiya, Hirohisa,Sawamura, Masaya
supporting information, p. 9666 - 9670 (2015/06/30)
The scope of the copper-catalyzed coupling reactions between organoboron compounds and allylic phosphates is expanded significantly by employing triphenylphosphine as a ligand for copper, allowing the use of secondary alkylboron compounds. The reaction proceeds with complete γ-E-selectivity and preferential 1,3-syn stereoselectivity. The reaction of γ-silicon-substituted allylic phosphates affords enantioenriched α-stereogenic allylsilanes.
Reversible 1,3-anti/syn-stereochemical courses in copper-catalyzed γ-selective allyl-alkyl coupling between chiral allylic phosphates and alkylboranes
Nagao, Kazunori,Yokobori, Umi,Makida, Yusuke,Ohmiya, Hirohisa,Sawamura, Masaya
supporting information; scheme or table, p. 8982 - 8987 (2012/07/02)
The stereochemical courses of the copper-catalyzed allyl-alkyl coupling between enantioenriched chiral allylic phosphates and alkylboranes were switchable between 1,3-anti and 1,3-syn selectivities by the choice of solvents and achiral alkoxide bases with different steric demands. The reactions with γ-silylated allylic phosphates allow efficient synthesis of enantioenriched chiral allylsilanes with tertiary or quaternary carbon stereogenic centers. Cyclic and acyclic bimodal participation of alkoxyborane species in an organocopper addition-elimination sequence is proposed to account for the phenomenon of the anti/syn-stereochemical reversal.
Stereoselective synthesis of (Z)- and (E)-allylic silanes by copper- mediated substitution reactions of allylic carbamates with grignard reagents
Smitrovich, Jacqueline H.,Woerpel
, p. 1601 - 1614 (2007/10/03)
Both (Z)- and (E)-allylic silanes were prepared with high stereoselectivity by the copper-mediated substitution of allylic carbamates by organometallic reagents. The reaction of alkylmagnesium reagents with (E)- allylic carbamates provides (Z)-allylic silanes, whereas both alkylmagnesium and alkyllithium reagents react with (Z)-allylic carbamates to afford (E)- allylic silanes. Because Grignard reagents are often more facile to prepare than alkyllithium species, these reagents are the optimal nucleophiles for the synthesis of both (Z)- and (E)-allylic silanes. This method also allows readily available nonracemic allylic carbamates to be converted to chiral, nonracemic (Z)- and (E)-allylic silanes with high stereoselectivity.
Asymmetric synthesis of homoallylic amines and functionalized pyrrolidines via direct amino-crotylation of in situ generated imines
Schaus, Jennifer V,Jain, Nareshkumar,Panek, James S
, p. 10263 - 10274 (2007/10/03)
The asymmetric synthesis of functionalized homoallylic amines and silyl functionalized pyrrolidines through the Lewis acid promoted condensation of chiral (E)-crotylsilanes with sulfonyl imines and in situ generated N-acyl imines is described. We had anticipated that this bond construction could be used in the asymmetric synthesis of the N-terminal amino acid subunit of the nikkomycins. Aryl sulfonyl imines condense with chiral silane reagents in the presence of BF3·OEt2 to form homoallylic arylsulfonyl amines with useful levels of syn selectivity. For cases involving aryl N-acyl imines we have learned that the temperature controls the course of the reaction. For instance, at temperatures of -78°,C or below the major product is the pyrrolidine, while at higher temperatures (-30 to -20°C) the homoallylic amine is produced. For the cases studied, the [3+2]-annulation is limited to aryl imine derivatives, as alkyl- and branched- imines failed to produce the pyrrolidine derivatives: higher reaction temperatures promote the conversion of the annulation product to the homoallylic amines. In double stereodifferentiating reactions with in situ generated imines, good levels of selectivity were achieved in the formation of secondary amines beating syn-anti and syn-syn stereochemical triads. (C) 2000 Elsevier Science Ltd.
Lipase mediated resolution of chiral (E)-vinylsilanes: An improved procedure for the production of (R)- and (S)-(E)-1-trialkylsilyl-1-buten-3-ol derivatives
Sparks,Panek
, p. 4085 - 4088 (2007/10/02)
A crude enzymic extract of Pseudomonas AK in pentane catalyzes the transesterification of chiral (E)-vinylsilanes 1, resulting in the production of highly enantiomerically enriched (R)- and (S)-(E)-1-trialkylsilyl-1-buten-3-ol derivatives (S)-2 and (R)-3.
Synthesis, resolution and absolute stereochemical assignment of C1-oxygenated allylsilanes and C3-oxygenated vinylsilanes
Panek,Sparks
, p. 801 - 816 (2007/10/02)
(R)-O-acetyl mandelic acid has been utilized for the development of a procedure for resolution and absolute stereochemical assignment of C1-oxygenated E-crotylsilanes 1a-c. The procedure is enhanced further by an efficient boron trifluoride etherate catal
