22887-54-3Relevant academic research and scientific papers
Group-Assisted Purification Chemistry for Asymmetric Mannich-type Reaction of Chiral N-Phosphonyl Imines with Azlactones Leading to Syntheses of α-Quaternary α,β-Diamino Acid Derivatives ?
Zhang, Haowei,Yang, Zhen,Zhao, Brian Nlong,Li, Guigen
, p. 644 - 655 (2018/01/27)
An asymmetric Mannich-type reaction between chiral N-phosphonyl imines and azlactones [oxazol-5(4H)-ones] has been established under convenient conditions at room temperature. The reaction was performed without using any bases, additives, or catalysts to achieve up to excellent chemical yields and diastereoselectivity for 32 examples. The α-quaternary syn-α,β-diamino acid products were purified simply by washing the crude mixtures with cosolvents, following the group-assisted purification chemistry/technology, without involving traditional chromatography or recrystallization methods. The auxiliary can be readily removed and recycled for reuse. The absolute configuration was unambiguously assigned by X-ray structural analysis.
Bronsted acid accelerated Pd-catalyzed direct asymmetric allylic alkylation of azlactones with simple allylic alcohols: A practical access to quaternary allylic amino acid derivatives
Zhou, Hui,Yang, Huameng,Liu, Muwen,Xia, Chungu,Jiang, Gaoxi
, p. 5350 - 5353 (2015/01/09)
A Bronsted acid accelerated Pd-catalyzed asymmetric allylic alkylation of azlactones with simple allylic alcohols under mild reaction conditions has been realized, which provides a direct and readily scalable approach for the synthesis of all-carbon quaternary allylic amino acid derivatives in excellent yields and good enantioselectivities. (Chemical Equation Presented).
Alkynyliodonium salt mediated alkynylation of azlactones: Fast access to Cα-tetrasubstituted α-amino acid derivatives
Finkbeiner, Peter,Weckenmann, Nicole M.,Nachtsheim, Boris J.
supporting information, p. 1326 - 1329 (2014/04/03)
An efficient electrophilic alkynylation of azlactones (oxazol-5(4H)-ones) is developed using alkynyl(phenyl)iodonium salts as the electrophilic alkyne source. After remarkably short reaction times, the desired alkyne functionalized azlactones are obtained in 60-97% yield and can be transformed easily into a variety of quaternary α-amino acid derivatives.
Bispalladacycle-catalyzed Michael addition of in situ formed azlactones to enones
Weber, Manuel,Jautze, Sascha,Frey, Wolfgang,Peters, René
, p. 14792 - 14804 (2013/01/15)
The development and further evolution of the first catalytic asymmetric conjugate additions of azlactones as activated amino acid derivatives to enones is described. Whereas the first-generation approach started from isolated azlactones, in the second-generation approach the azlactones could be generated in situ starting from racemic N-benzoylated amino acids. The third evolution stage could make use of racemic unprotected α-amino acids to directly form highly enantioenriched and diastereomerically pure masked quaternary amino acid products bearing an additional tertiary stereocenter. The step-economic transformations were accomplished by cooperative activation by using a robust planar chiral bis-Pd catalyst, a Br?nsted acid (HOAc or BzOH; Ac=acetyl, Bz=benzoyl), and a Br?nsted base (NaOAc). In particular the second- and third-generation approaches provide a rapid and divergent access to biologically interesting unnatural quaternary amino acid derivatives from inexpensive bulk chemicals. In that way highly enantioenriched acyclic α-amino acids, α-alkyl proline, and α-alkyl pyroglutamic acid derivatives could be prepared in diastereomerically pure form. In addition, a unique way is presented to prepare diastereomerically pure bicyclic dipeptides in just two steps from unprotected tertiary α-amino acids. Flourishing step economy: The evolution of the catalytic asymmetric addition of azlactones to enones is described. The first-generation approach started from isolated azlactones. In the second-generation approach azlactones could be generated in situ from racemic N-benzoylated amino acids. The third evolution stage could directly use racemic unprotected α-amino acids to form a large number of highly enantioenriched quaternary amino acids derivatives (see figure). Copyright
A simple and convenient synthesis of pyrazinones
Sharma, Saikat Das,Gogoi, Pranjal,Konwar, Dilip
, p. 107 - 111 (2007/10/03)
Pyrazinones were synthesized by reacting mesoionic azlactone [2-aryl-4-methyl-Δ2-oxaxolin-5-one] and 1,4-diazabutadienes in good yields at room temperature. Copyright Taylor & Francis Group, LLC.
Au(I)-catalyzed enantioselective 1,3-dipolar cycloadditions of muenchnones with electron-deficient alkenes
Melhado, Asa D.,Luparia, Marco,Toste, F. Dean
, p. 12638 - 12639 (2008/03/14)
The first catalytic enantioselective 1,3-dipolar cycloaddition of muenchnone dipoles with electron-deficent alkenes is described. The reaction is catalyzed by chiral bis(phosphine)gold(I) benzoate complexes and provides Δ1-pyrrolines with excellent regio-, diastereo-, and enantioselectivity. The reaction is proposed to proceed througha 1,3-dipole generated by deprotonation of a gold(I)-activated azlactone. Copyright
Studies on chromone derivatives : An efficient one-pot synthesis of various 3-( N-aroylamino)-3-methyl-4-(4-oxobenzopyran-3-yl)-1-( N,N-dimethylamino)azetidin-2-ones
Boruah, Anima,Prajapati, Dipak,Sandhu, Jagir S.
, p. 1148 - 1151 (2007/10/03)
Chlorosulfonylmethylene(dimethyl)ammonium chloride 1 is found to be a highly reactive cyclodehydrating agent for the one-pot synthesis of various novel 3-(N-aroylamino)-3-methyl-4-(4-oxobenzopyran-3-yl)-1-(N,N-dimethylamino) azetidin-2-ones 5 from N-aroyl
1-Azadienes in Heterocyclic Synthesis. Reaction of 1-N-Alkyl-1-azapenta-1,3-dienes with Mesoionic Oxazolones
Sain, B.,Sandhu, J. S.
, p. 1007 - 1010 (2007/10/02)
1-N-Alkyl-1-azapenta-1,3-dienes 2 smoothly reacted with various mesoionic oxazolones 1 to afford 3,4-dihydro-2-pyridones 3 in excellent yields and there is no evidence for the formation of any products arising from the cycloaddition on the carbon-carbon double bond or on the azomethine function.
GENERATION AND FATE OF FREE RADICALS OF Δ2-OXAZOLIN-5-ONES
Marquez, A.,Chuaqui, C. A.,Rodriguez, H.,Zagal, L.
, p. 2341 - 2346 (2007/10/02)
The reaction of Δ2-oxazolin-5-ones 1a and 1b with nickel peroxid in benzene produces the corresponding 4,4-dehydrodimers 5a and 5b as the main products in yields over 75percent.Under the same conditions, the 2-aryl-4-methyl-Δ2-oxazolin-5-ones 1c, 1d and 1e yield five products.In the case of 1c, the constituents of the product mixture were separated and identified as two 4,4-dehydrodimers (meso and dl pair isomers) 5c and 5c', (40.7percent), 2,4-dehydrodimer 6c (34.9percent), acetylanisoylimide 8c(8.5percent) and anisamide (15.9percent).Adequate mechanistic schemes are discussed to account for the products formed.
