82387-87-9Relevant 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.
Bispalladacycle-catalyzed Michael addition of in situ formed azlactones to enones
Weber, Manuel,Jautze, Sascha,Frey, Wolfgang,Peters, René
supporting information, 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
Synthesis of 1,2,4-Triazolines and triazoles utilizing oxazolones
Saleem, Rahman Shah Zaib,Tepe, Jetze J.
supporting information; experimental part, p. 4330 - 4332 (2010/09/03)
We describe herein a convenient method for the synthesis of 1,2,4-triazolines using oxazolones and azodicarboxylates. Subsequent treatment of these 1,2,4-triazolines with NaOH provides efficient access to the corresponding triazoles.
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.
Cycloaddition Reactions of Mesoionic Oxazolones. Reactions of Δ2-Oxazolin-5-one with Cinnamaldehyde Anils
Sain, Bir,Baruah, J. N.,Sandhu, J. S.
, p. 1511 - 1514 (2007/10/02)
Cinnamaldehyde anils have been reacted with several mesoionic oxazolones.The products thus obtained are α-pyridones and structures of these compounds have been fully established.
