- Morpholine Ketene Aminal as Amide Enolate Surrogate in Iridium-Catalyzed Asymmetric Allylic Alkylation
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Morpholine ketene aminal is employed in iridium-catalyzed asymmetric allylic alkylation reactions as a surrogate for amide enolates to prepare γ,δ-unsaturated β-substituted morpholine amides. Kinetic resolution or, alternatively, stereospecific substitution affords the corresponding products in high enantiomeric excess. The utility of the products generated by this method has been showcased by their further elaboration into amines, ketones, or acyl silanes. A putative catalytic intermediate (η3-allyl)iridium(III) with achiral P,Olefin-ligand was synthetized and characterized for the first time.
- Sempere, Yeshua,Alfke, Jan L.,R?ssler, Simon L.,Carreira, Erick M.
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- Enantioselective Allylation of Alkenyl Boronates Promotes a 1,2-Metalate Rearrangement with 1,3-Diastereocontrol
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Alkenyl boronates add to Ir(π-allyl) intermediates with high enantioselectivity. A 1,2-metalate shift forms a second C-C bond and sets a 1,3-stereochemical relationship. The three-component coupling provides tertiary boronic esters that can undergo multiple additional functionalizations. An extension to trisubstituted olefins sets three contiguous stereocenters.
- Davis, Colton R.,Luvaga, Irungu K.,Ready, Joseph M.
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supporting information
p. 4921 - 4927
(2021/05/04)
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- Formaldehyde N, N-dialkylhydrazones as neutral formyl anion equivalents in iridium-catalyzed asymmetric allylic substitution
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The use of formaldehyde N,N-dialkylhydrazones as neutral C1-nucleophiles in the iridium-catalyzed substitution of allylic carbonates is described for two processes. Kinetic resolution or, alternatively, stereospecific substitution affords configurationally stable α,α-disubstituted aldehyde hydrazones in high enantiomeric excess and yield. This umpolung approach allows for the construction of optically active allylic nitriles and dithiolanes as well as branched α-aryl aldehydes. A catalyst-controlled reaction with Enders' chiral hydrazone derivatives followed by diastereoselective nucleophilic addition to the hydrazone products constitutes a two-step stereodivergent synthesis of chiral amines.
- Breitler, Simon,Carreira, Erick M.
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p. 5296 - 5299
(2015/05/13)
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- Synthesis of enantiopure 1-arylprop-2-en-1-ols and their tert-butyl carbonates
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(Chemical Equation Presented) Enantiomerically pure 1-arylpropenols 8 have been prepared by resolution of the corresponding racemates, using the lipase formulation Novozyme 435. Deprotonation of the latter alcohols with n-BuLi, followed by derivatization with (t- BuO)2CO, afforded the corresponding carbonates 5. Optimization of the process is presented.
- Stambasky, Jan,Malkov, Andrei V.,Kocovsky, Pavel
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supporting information; body text
p. 9148 - 9150
(2009/04/11)
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