- Catalytic Asymmetric Synthesis of Unprotected β2-Amino Acids
-
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
-
supporting information
p. 3312 - 3317
(2021/04/07)
-
- Palladium-Catalyzed α-Arylation of Carboxylic Acids and Secondary Amides via a Traceless Protecting Strategy
-
A novel traceless protecting strategy is presented for the long-standing challenge of conducting the palladium-catalyzed α-arylation of carboxylic aids and secondary amides with aryl halides. Both of the presented coupling processes occur with a variety of carboxylic acids and amides and with a variety of aryl bromides containing a broad range of functional groups, including base-sensitive functionality like acyl, alkoxycarbonyl, nitro, cyano, and even hydroxyl groups. Five commercial drugs were prepared through this method in one step in 81-96% yield. Gram-scale synthesis of medication Naproxen and Flurbiprofen with low palladium loading further highlights the practical value of this method.
- He, Zhi-Tao,Hartwig, John F.
-
supporting information
p. 11749 - 11753
(2019/08/26)
-
- One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride
-
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
-
p. 2647 - 2656
(2007/10/03)
-
- 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
-
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
-
p. 8997 - 8999
(2007/10/03)
-
- One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride
-
Functionalized 3-hydroxymaleic anhydrides were prepared by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride.
- Ullah, Ehsan,Langer, Peter
-
p. 2782 - 2784
(2007/10/03)
-
- α-SILYL TRIMETHYLSILYLESTERS FROM ALIPHATIC CARBOXYLIC ACID DIANIONS
-
The synthesis of α-silyl trimethylsilyl esters from aliphatic carboxylic acid dianions is reported.The results indicate kinetic and thermodynamic control of silylation of acid dianions.
- Bellassoued, M.,Dubois, J. E.,Bertounesque, E.
-
p. 263 - 266
(2007/10/02)
-
- Reactions of Trialkylsilyl Trifluoromethanesulfonates, II. - Synthesis of O-Alkyl-O-(trialkylsilyl)ketene Acetals and 2-(Trialkylsilyl)carboxylates
-
Alkyl carboxylates 2 are silylated by trialkylsilyl triflates 1 in the presence of triethylamine (3) to yield ketene acetals 4.In reactions of the esters 6 mixtures of ketene acetals 7 and at the α-carbon silylated esters 8 are obtained.Ethanoic acid esters and lactones are doubly silylated to give the products 11, 12, and 15, respectively.Under suitable conditions silylation of the esters 10 gives rise to the 2-trimethylsilylethanoic acid esters 13.The thermodynamically more stable products are obtained.Product distributions depend on the structure of the esters and the silylating agents 1.
- Emde, Herbert,Simchen, Gerhard
-
p. 816 - 834
(2007/10/02)
-
