- Catalytic Enantioselective Direct Aldol Addition of Aryl Ketones to α-Fluorinated Ketones
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The catalytic enantioselective synthesis of α-fluorinated chiral tertiary alcohols from (hetero)aryl methyl ketones is described. The use of a bifunctional iminophosphorane (BIMP) superbase was found to facilitate direct aldol addition by providing the strong Br?nsted basicity required for rapid aryl enolate formation. The new synthetic protocol is easy to perform and tolerates a broad range of functionalities and heterocycles with high enantioselectivity (up to >99:1 e.r.). Multi-gram scalability has been demonstrated along with catalyst recovery and recycling. 1H NMR studies identified a 1400-fold rate enhancement under BIMP catalysis, compared to the prior state-of-the-art catalytic system. The utility of the aldol products has been highlighted with the synthesis of various enantioenriched building blocks and heterocycles, including 1,3-aminoalcohol, 1,3-diol, oxetane, and isoxazoline derivatives.
- Barber, David M.,Dixon, Darren J.,Thomson, Connor J.
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supporting information
p. 5359 - 5364
(2020/02/28)
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- Bifunctional iminophosphorane organocatalysts for enantioselective synthesis: Application to the ketimine nitro-Mannich reaction
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The design, synthesis, and development of a new class of modular, strongly basic, and tunable bifunctional Bronsted base/H-bond-donor organocatalysts are reported. These catalysts incorporate a triaryliminophosphorane as the Bronsted basic moiety and are readily synthesized via a last step Staudinger reaction of a chiral organoazide and a triarylphosphine. Their application to the first general enantioselective organocatalytic nitro-Mannich reaction of nitromethane to unactivated ketone-derived imines allows the enantioselective construction of β-nitroamines possessing a fully substituted carbon atom. The reaction is amenable to multigram scale-up, and the products are useful for the synthesis of enantiopure 1,2-diamine and α-amino acid derivatives.
- Nunez, Marta G.,Farley, Alistair J. M.,Dixon, Darren J.
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supporting information
p. 16348 - 16351
(2013/12/04)
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- An efficient synthesis of N-Boc-D-diphenylalanine from a chiral azirdine-2-carboxylate
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N-Boc-D-diphenylalanine was prepared from a commercially available aziridine-2(S)-carboxylate through alkylation, regiospecific aziridine ring opening, and benzylic deoxygenation followed by oxidation in 57% overall yield.
- Chang, Jae-Won,Ha, Hyun-Joon,Park, Chan Sun,Kim, Min Sung,Lee, Won Koo
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p. 1143 - 1148
(2007/10/03)
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- Stereocontrolled Conversion of L-Serine into a Series of Valuable Unnatural α-Amino Acids
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Stereocontrolled synthesis of (2R,3S)- and (2R,3R)-phenylserine, (R)-3,3-diphenylserine and (R)-3,3-diphenylalanine are described.
- Koskinen, Ari M. P.,Hassila, Heikki,Myllymaeki, Vesa T.,Rissanen, Karl
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p. 5619 - 5622
(2007/10/02)
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- Synthesis of N-BOC-D-Diphenylalanine from L-Serine Methyl Ester Hydrochloride
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A convenient six step synthesis of N-BOC-D-diphenylalanine from L-serine methyl ester hydrochloride is described.The preparation of a novel chiral auxiliary, an oxazolidinone derived from D-diphenylalaninol, is also described.
- Sibi, Mukund P.,Deshpande, Prasad K.,Loggia, Anthony J. La,Christensen, James W.
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p. 8961 - 8964
(2007/10/02)
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