75553-25-2Relevant articles and documents
Photoenzymatic Synthesis of α-Tertiary Amines by Engineered Flavin-Dependent "ene"-Reductases
Gao, Xin,Turek-Herman, Joshua R.,Choi, Young Joo,Cohen, Ryan D.,Hyster, Todd K.
supporting information, p. 19643 - 19647 (2021/12/01)
α-Tertiary amines are a common motif in pharmaceutically important molecules but are challenging to prepare using asymmetric catalysis. Here, we demonstrate engineered flavin-dependent ‘ene'-reductases (EREDs) can catalyze radical additions into oximes to prepare this motif. Two different EREDs were evolved into competent catalysts for this transformation with high levels of stereoselectivity. Mechanistic studies indicate that the oxime contributes to the enzyme templated charge-transfer complex formed between the substrate and cofactor. These products can be further derivatized to prepare a variety of motifs, highlighting the versatility of ERED photoenzymatic catalysis for organic synthesis.
Photoredox/Nickel-Catalyzed Single-Electron Tsuji–Trost Reaction: Development and Mechanistic Insights
Matsui, Jennifer K.,Gutiérrez-Bonet, álvaro,Rotella, Madeline,Alam, Rauful,Gutierrez, Osvaldo,Molander, Gary A.
supporting information, p. 15847 - 15851 (2018/11/23)
A regioselective, nickel-catalyzed photoredox allylation of secondary, benzyl, and α-alkoxy radical precursors is disclosed. Through this manifold, a variety of linear allylic alcohols and allylated monosaccharides are accessible in high yields under mild reaction conditions. Quantum mechanical calculations [DFT and DLPNO-CCSD(T)] support the mechanistic hypothesis of a Ni0 to NiII oxidative addition pathway followed by radical addition and inner-sphere allylation.
Stereodivergence in the Ireland-Claisen Rearrangement of α-Alkoxy Esters
Podunavac, Ma?a,Lacharity, Jacob J.,Jones, Kerry E.,Zakarian, Armen
, p. 4867 - 4870 (2018/08/24)
A systematic investigation into the Ireland-Claisen rearrangement of α-alkoxy esters is reported. In all cases, the use of KN(SiMe3)2 in toluene gave rearrangement products corresponding to a Z-enolate intermediate with excellent diastereoselectivity, presumably because of chelation control. On the other hand, chelation-controlled enolate formation could be overcome for most substrates through the use of lithium diisopropylamide (LDA) in tetrahydrofuran (THF).
Synthesis of Chiral Tertiary Boronic Esters by Oxime-Directed Catalytic Asymmetric Hydroboration
Shoba, Veronika M.,Thacker, Nathan C.,Bochat, Andrew J.,Takacs, James M.
supporting information, p. 1465 - 1469 (2016/02/12)
Chiral boronic esters are useful intermediates in asymmetric synthesis. We have previously shown that carbonyl-directed catalytic asymmetric hydroboration (CAHB) is an efficient approach to the synthesis of functionalized primary and secondary chiral boronic esters. We now report that the oxime-directed CAHB of alkyl-substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime-containing chiral tertiary boronic esters with yields up to 87 % and enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O-substituted hydroxylamines, the generation of quaternary carbon stereocenters through carbon-carbon coupling reactions, and the preparation of chiral 3,4,4-trisubstituted isoxazolines.
Efficient construction of benzohydrindenones from aryltrienones via domino Nazarov electrocyclization - Electrophilic aromatic substitution
Browder, Cindy C.,Marmsaeter, Fredrik P.,West
, p. 375 - 385 (2007/10/03)
1,4-Dien-3-ones substituted with pendant arylethyl side chains attached at C-1 were readily prepared from substituted dihydrocinnamaldehydes. Treatment with TiCl4 at low temperature effected domino Nazarov electrocyclization - arene trapping within 5 min to give racemic benzohydrindenones in near-quantitative yield and with complete diastereoselectivity.
Highly efficient trapping of the Nazarov intermediate with substituted arenes.
Browder,Marmsaeter,West
, p. 3033 - 3035 (2007/10/03)
1,4-Dien-3-ones bearing pendant arylethyl side chains were readily prepared from substituted dihydrocinnamaldehydes. When treated with TiCl(4) at low temperature, these compounds underwent domino cyclization to give benzohydrindenones in near-quantitative yield and with complete diastereoselectivity. Reaction: see text.
Synthetic studies on the sarcodictyins: Synthesis of fully functionalized cyclization precursors
Ceccarelli, Simona M,Piarulli, Umberto,Gennari, Cesare
, p. 8531 - 8542 (2007/10/03)
A strategy featuring a key retrosynthetic disconnection at the C2-C3 position was applied to the total synthesis of the common diterpenoid tricyclic skeleton of sarcodictyins and eleutherobin. Fully functionalized cyclization precursors were accessed via a brief and convergent route, making use of unprecedented synthetic transformations.
Acyclic Stereoselection in the Ortho Ester Claisen Rearrangement
Daub, G. William,Edwards, James P.,Okada, Carol R.,Allen, Jana Westran,Maxey, Claudia Tata,Wells, Matthew S.,Goldstein, Alexandra S.,Dibley, Michael J.,Wang, Clarence J.,Ostercamp, Daniel P.,Chung, Steven,Cunningham, Paula Shanklin,Berliner, Martin A.
, p. 1976 - 1985 (2007/10/03)
The ortho ester Claisen rearrangement of trisubstituted allylic alcohols exhibits significant levels of diastereoselection. In E allylic alcohols, a 1,3-diaxial interaction develops in the chairlike transition state leading to the anti isomer, rendering the reaction syn selective by a factor of 3-5 to 1. In Z allylic alcohols, the 1,3-diaxial interaction develops in the transition state leading to the syn isomer, generating an anti:syn selectivity of 6-15 to 1. The relative stereochemistry of the syn isomer was confirmed independently by the synthesis of the mycotoxin botryodiplodin.
COPPER(I)-CATALYZED REACTION OF ISOPRENE BROMOHYDRIN WITH ORGANOLITHIUM REAGENT
Araki, Shuki,Butsugan, Yasuo
, p. 185 - 186 (2007/10/02)
The reaction of isoprene bromohydrin (1-bromo-2-methyl-3-buten-2-ol) (1) with ethyl-, propyl- and butyllithium in the presence of copper(I) iodide leads to the exclusive formation of the vinyl group migrated 2-alkyl-4-penten-2-ols (3d-3f), in contrast to
