14618-12-3Relevant academic research and scientific papers
General access to C-centered radicals: Combining a bioinspired photocatalyst with boronic acids in aqueous media
Bloom, Steven,Chilamari, Maheshwerreddy,Immel, Jacob R.
, p. 12727 - 12737 (2020/11/18)
Carbon-centered radicals are indispensable building blocks for modern synthetic chemistry. In recent years, visible light photoredox catalysis has become a promising avenue to access C-centered radicals from a broad array of latent functional groups, including boronic acids. Herein, we present an aqueous protocol wherein water features a starring role to help transform aliphatic, aromatic, and heteroaromatic boronic acids to C-centered radicals with a bioinspired flavin photocatalyst. These radicals are used to deliver a diverse pool of alkylated products, including three pharmaceutically relevant compounds, via open-shell conjugate addition to disparate Michael acceptors. The mechanism of the reaction is investigated by computational studies, deuterium labeling, radical-trapping experiments, and spectroscopic analysis.
Preparation method and application of chiral spiro aminophosphine ligand with substituent at 3-position of pyridine ring
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Paragraph 0057-0060; 0064, (2020/02/14)
The invention relates to a preparation method and application of a chiral spiro aminophosphine ligand with a substituent at the 3-position of a pyridine ring. The chiral spiro aminophosphine ligand isa compound shown as a formula 1, or a racemate or an op
Unnatural α-amino ethyl esters from diethyl malonate or ethyl β-bromo-α-hydroxyiminocarboxylate
Coutant, Eloi P.,Hervin, Vincent,Gagnot, Glwadys,Ford, Candice,Baatallah, Racha,Janin, Yves L.
supporting information, p. 2853 - 2860 (2018/11/26)
We have explored here the scope of the age-old diethyl malonate-based accesses to α-amino esters involving Knoevenagel condensations of diethyl malonate on aldehydes, reductions of the resulting alkylidenemalonates, the preparation of the corresponding α-hydroxyimino esters and their final reduction. This synthetic pathway turned out to be general although some unexpected limitations were encountered. The synthetic modifications of some of the intermediates - using Suzuki-Miyaura coupling or cycloadditions - before undertaking the oximation step - provided accesses to further α-amino esters. Moreover, other pathways to α-hydroxyimino esters were explored including an attempt to improve the cycloadditions between ethyl β-bromo-α-hydroxyiminocarboxylate and various alkylfuranes.
IMIDAZOPYRAZINE DERIVATIVES, PROCESS FOR PREPARATION THEREOF, AND THEIR USES AS LUCIFERINS
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Page/Page column 59-60, (2018/11/22)
The present invention is in the field of bioluminescence in biology and/or medicine. In particular, the invention provides imidazopyrazine derivatives, processes for preparation thereof, and their uses as luciferins.
Fe(HSO4)3 : An efficient, heterogeneous and reusable catalyst for C-alkylation of β-dicarbonyl compounds
Khafajeh, Samaneh,Akhlaghinia, Batool,Rezazadeh, Soodabeh,Eshghi, Hossein
, p. 1903 - 1912 (2015/02/05)
Fe(HSO4)3(FHS) was used as an efficient catalyst for the heterogeneous addition of a series of benzylic and allylic alcohols to various β-dicarbonyl compounds, which afforded moderate to excellent yields of C-alkylated products in 1,2-dichloroethane. In comparison with the previous methods, the present research surprisingly exhibited higher reaction yields without formation of any by-products which could be formed by self-condensation of alcohols. Moreover, the catalyst can be readily recovered and reused up to five times with almost maintained reactivity and yields.
Asymmetric conjugate 1,4-addition of arylboronic acids to α,β-unsaturated esters catalyzed by rhodium(I)/(S)-binap
Sakuma, Satoshi,Sakai, Masaaki,Itooka, Ryoh,Miyaura, Noria
, p. 5951 - 5955 (2007/10/03)
Arylboronic acids underwent the conjugate 1,4-addition to α,β-unsaturated esters to give β-aryl esters in high yields in the presence of a rhodium(I) catalyst. The addition of arylboronic acids to isopropyl crotonate resulted in high yields and high enantioselectivity exceeding 90% ee in the presence of 3 mol % of Rh(acac)(C2H4)2 and (S)-binap at 100 °C. The rhodium/(S)-binap complex provided (R)-3-phenylbutanoate in the addition of phenylboronic acid to benzyl crotonate. The effects on the enantioselectivity of chiral phosphine ligands, rhodium precursors, and substituents on α,β-unsaturated esters are discussed, as well as the mechanistic aspect of the catalytic cycle.
Mixed Dialkylaluminum Chlorides and Mixed Trimethylorganoaluminates in Chemoselective 1,4 Addition Reactions to Alkylidene Malonic Acid Diethyl Ester
Maas, Steffen,Kunz, Horst
, p. 396 - 403 (2007/10/03)
Mixed alkyl-methyl- and aryl-methylorganoaluminum chlorides 6 were formed by reaction of methylaluminum dichloride with organolithium or Grignard compounds and used for chemoselective 1,4 addition of higher alkyl, aryl, alkenyl and alkinyl groups to alkylidine malonic esters 1 and 2. As an alternative, mixed trimethylorganoaluminates 7 can also be applied for these Michael addition reactions. For conjugate addition of alkenyl groups to alkylidene malonates 1 and 2, alkenyl diisopropylalanes 10 obtained from alkynes and diisopropylaluminum hydride proved the most efficient reagents. Using these novel mixed organoaluminum compounds, β-branched malonic (carboxylic) acid derivatives 3c, 8, 9 and 11 were obtained in good yields. The method offers a general access to β-branched carboxylic derivatives of quite diverse structure not dependent on the commercial availability of the organoluminum chlorides.
Conjugate addition of dialkylaluminum chlorides to alkylidenemalonic acid derivatives
Maas, Steffen,Stamm, Armin,Kunz, Horst
, p. 1792 - 1798 (2007/10/03)
Complete regioselectivity is achieved in conjugate addition reactions of dialkylaluminum chlorides with alkylidenemalonic esters, alkylidenecyanoacetates, and alkylidenemalonodinitrile to give β-branched carboxylic acid derivatives. Sterically demanding products containing quaternary carbon atoms are obtained in good yields. In the case of diethylaluminum chloride, accompanying reductions of the substrates can be suppressed by application of boron trifluoride as an assisting Lewis acid.
Use of the Nonionic Superbase P(MeNCH2CH2)3N in the Selective Monoalkylation of Active-Methylene Compounds
Arumugam, Subramaniam,McLeod, Dale,Verkade, John G.
, p. 3677 - 3679 (2007/10/03)
The symmetric active-methylene compounds CH2(CO2Et)2 and CH2[C(O)Me]2 are selectively monoalkylated in the presence of 1.1 equiv of a variety of alkyl halides and 1 equiv of the nonionic Superbase P(MeNCH2CH2)2N in 85-98% yields in 30 min at room temperature. The unsymmetrical active-methylene compound EtO2CCH2C(O)Me is selectively monoalkylated under the same conditions, except for the temperature, which is 0 °C, in 59-88% yields. The observation of selective C- rather than O-alkylation is rationalized in terms of the formation of an enolate whose negatively charged oxygen is sterically protected by a nearby HP(MeNCH2CH2)2N+ counterion in a tight ion pair.
Specific Features of Reactions of Butyl- and Phenylacetylenes with CH-Acids
Badanyan,Chobanyan,Tirakyan,Danielyan
, p. 17 - 20 (2007/10/03)
The reactions of butyl- and phenylacetylenes with cyanoacetic, malonic, and acetoacetic esters and acetylacetone in a polar solvent in the presence of mercuric acetate were studied. Intramolecular cyclization of unsaturated dicarbonyl compounds formed at
