- Catalytic Asymmetric Synthesis of Unprotected β2-Amino Acids
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We report here a scalable, catalytic one-pot approach to enantiopure and unmodified β2-amino acids. A newly developed confined imidodiphosphorimidate (IDPi) catalyzes a broadly applicable reaction of diverse bis-silyl ketene acetals with a silylated aminomethyl ether, followed by hydrolytic workup, to give free β2-amino acids in high yields, purity, and enantioselectivity. Importantly, both aromatic and aliphatic β2-amino acids can be obtained using this method. Mechanistic studies are consistent with the aminomethylation to proceed via silylium-based asymmetric counteranion-directed catalysis (Si-ACDC) and a transition state to explain the enantioselectivity is suggested on the basis of density functional theory calculation.
- Zhu, Chendan,Mandrelli, Francesca,Zhou, Hui,Maji, Rajat,List, Benjamin
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supporting information
p. 3312 - 3317
(2021/04/07)
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- One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride
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Functionalized 3-hydroxymaleic anhydrides were prepared by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride.
- Rotzoll, Sven,Ullah, Ehsan,G?rls, Helmar,Fischer, Christine,Langer, Peter
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p. 2647 - 2656
(2007/10/03)
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- Synthesis of 7,8-benzo-9-aza-4-oxabicyclo[3.3.1]nonan-3-ones by sequential 'condensation-iodolactonization' reactions of 1,1-bis(trimethylsilyloxy)ketene acetals with isoquinolines
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Functionalized 7,8-benzo-9-aza-4-oxabicyclo[3.3.1]nonan-3-ones were prepared by regio- and diastereoselective condensation of 1,1-bis(silyloxy) ketene acetals with isoquinolinium salts and subsequent regioselective and stereospecific iodolactonization.
- Ullah, Ehsan,Rotzoll, Sven,Schmidt, Andreas,Michalik, Dirk,Langer, Peter
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p. 8997 - 8999
(2007/10/03)
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- One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride
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Functionalized 3-hydroxymaleic anhydrides were prepared by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride.
- Ullah, Ehsan,Langer, Peter
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p. 2782 - 2784
(2007/10/03)
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- Synthesis of α-fluorocarbonyl compounds
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Process for preparing an organic compound of the formula R2 R2 CFC(O)R3, which process comprises contacting and reacting in a reaction mixture which includes an inert solvent, at a temperature of -40° C. to -100° C., ROF and STR1 R is polyfluoroperhaloalkyl of 1-6 carbon atoms or FOCF2 ; R1 is hydrocarbyl of 1-6 carbon atoms; each R2 is selected from H, alkyl of 1-17 carbon atoms, cycloalkyl of 3-6 carbon atoms, aryl, heteroaryl and such alkyl, cycloalkyl, aryl and heteroaryl substituted by halogen or alkoxy of 1-6 carbon atoms; R3 is selected from H, alkyl and haloalkyl of 1-16 carbon atoms, cycloalkyl of 3-10 carbon atoms, aryl and haloaryl, OSi(R1)3, OH, NH2, alkoxy of 1-6 carbon atoms, aryloxy, NHR1 and NR12 wherein R1 is alkyl of 1-6 carbon atoms, N-arylamino and nitrogen or sulfur heterocyclic of 4-5 carbon atoms; R3 and one R2 taken together is a diradical which with the C=C group is carbocyclic, heterocyclic or haloheterocyclic, and recovering from the reaction mixture the compound of the formula R2 R2 CFC(O)R3.
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