60027-53-4Relevant academic research and scientific papers
Synthesis of α,α-Difluorinated Phosphonate pSer/pThr Mimetics via Rhodium-Catalyzed Asymmetric Hydrogenation of β-Difluorophosphonomethyl α-(Acylamino)acrylates
Chen, Hong-Xue,Kang, Jie,Chang, Rong,Zhang, Yun-Lai,Duan, Hua-Zhen,Li, Yan-Mei,Chen, Yong-Xiang
supporting information, p. 3278 - 3281 (2018/06/11)
A novel and facile synthetic strategy for α,α-difluorinated phosphonate mimetics of phosphoserine/phosphothreonine utilizing rhodium-catalyzed asymmetric hydrogenation was developed. The dehydrogenated substrate β-difluorophosphonomethyl α-(acylamino)acrylates were first prepared from protected serine/threonine followed by asymmetric hydrogenation using the rhodium-DuPhos catalytic system to generate the chiral center(s). These important phosphonate building blocks were successfully incorporated into phosphatase-resistant peptides, which displayed similar inhibition to the 14-3-3 ζ protein as the parent pSer/pThr peptides.
A Five-Step Cascade for the Modular and Regiodefined Synthesis of Naphth[2,1-d]oxazoles
Dinda, Bidyut Kumar,Basak, Shyam,Ghosh, Bidhan,Mal, Dipakranjan
, p. 1235 - 1245 (2016/05/11)
The reaction of 3-nucleofugal phthalides with 2-amidoacrylates is shown to provide a synthesis of densely substituted naphth[2,1-d]oxazoles in good yields. It is proposed to proceed via a five-step cascade which includes phthalide annulation, demethoxycarbonylation, and heterocyclization. The methodology is free from regiochemical ambiguity of the products. In certain cases, the corresponding 2-amidonaphthoquinones are directly formed.
Stereo-controlled asymmetric bioreduction of α,β-dehydroamino acid derivatives
Stueckler, Clemens,Winkler, Christoph K.,Hall, Melanie,Hauer, Bernhard,Bonnekessel, Melanie,Zangger, Klaus,Faber, Kurt
supporting information; experimental part, p. 1169 - 1173 (2011/07/09)
α,β-Dehydroamino acid derivatives proved to be a novel substrate class for ene-reductases from the 'old yellow enzyme' (OYE) family. Whereas N-acylamino substituents were tolerated in the α-position, β-analogues were generally unreactive. For aspartic aci
Facile and selective synthesis of chloronicotinaldehydes by the Vilsmeier reaction
Gangadasu,Narender,Bharath Kumar,Ravinder,Ananda Rao,Ramesh,China Raju,Jayathirtha Rao
, p. 8398 - 8403 (2007/10/03)
Eleven enamides were prepared by adopting different procedures. The various enamides prepared were subjected to Vilsmeier reaction using (i) POCl3/DMF; (ii) diphosgene/DMF; (iii) triphosgene/DMF leading to the formation of various multisubstituted chloronicotinaldehydes. Studies carried out indicate that Vilsmeier reagent concentration and the replacement of POCl3 by diphosgene or triphosgene, provides excellent selectivity and higher yields. Under modified reaction conditions one can get only chloronicotinaldehydes and not the chloropyridines as products. The various advantages in using diphosgene and triphosgene are illustrated. The mechanism of formation of chloronicotinaldehyde was discussed.
A Versatile Chemo-Enzymatic Route to Enantiomerically Pure β-Branched α-Amino Acids
Roff, Geoffrey J.,Lloyd, Richard C.,Turner, Nicholas J.
, p. 4098 - 4099 (2007/10/03)
A series of diastereoisomers of β-methyl-β-phenylalanine analogues 1a?f have been prepared in enantiomerically pure form using a combination of chemo- and biocatalysis. Starting from l-threonine methyl ester 2, a range of β,β-disubstituted didehydroamino
Structure elucidation of Sch 20562, a glucosidic cyclic dehydropeptide lactone: The major component of W-10 antifungal antibiotic
Afonso, Adriano,Hon, Frank,Brambilla, Ray
, p. 383 - 397 (2007/10/03)
A novel bacterium designated as Aeromonas sp. W-10 produces the antibiotic W-10 complex which comprises of two major and several minor components. The two major components from this complex, Sch 20562 (1) and Sch 20561 (1a), are of biological interest in view of their potent antifungal activity. The chemical degradation studies utilized for the assignment of structure 1 for Sch 20562 are described here. Some of the noteworthy diversity of structural features in this glucosidic cyclic dehydrononapeptide lactone 1 are: an N-terminal (D)-β-hydroxymyristyl unit, three D-amino acid units, two (E)-α-aminocrotonyl units, and an O-α-D-glucosyl-N-methyl-L-allo-threonine unit. The structure determination of 1 utilized the selective cleavage of the dehydropeptide units by ozonolysis to form fragments that were sequenced by mass spectrometry. The stereochemistry of the amino acid units were assigned by isolation of the free amino acids from the hydrolysates of the fragments. The stereochemistry of the α-aminocrotonyl units and the glucosidic linkage were assigned by nmr spectroscopy and molecular rotation data.
A Highly Enantioselective Asymmetric Hydrogenation Route to β-(2R,3S)-Methyltryptophan
Hoerrner, R. Scott,Askin, David,Volante, R. P.,Reider, Paul J.
, p. 3455 - 3458 (2007/10/03)
Asymmetric hydrogenation of a protected (Z)-dehydro-β-methyltryptophan derivative 2 with (R,R)-Me-DuPHOS-Rh catalysis was achieved in 97percent ee.Deprotection then afforded (2R,3S)-β-methyltryptophan 1.
Practical synthesis of methyl Z-2-(n-acetylamino) but-2-enoate. An intermediate to D- and L-2-aminobutyric acid
Nugent, William A.,Feaster, John E.
, p. 1617 - 1623 (2007/10/03)
Treatment of inexpensive L- or DL-threonine methyl ester with acetic anhydride and either pyridine or anhydrous sodium acetate at reflux results in dehydration yielding the N,N-diacetamide of the title compound in >80% yield. Monodeacetylation of the diacetamide with 0.1 equiv of triethylamine in methanol affords the title monoacetamido derivative 1 in nearly quantitative yield.
A facile conversion of (Z)-2-alkenoic esters into the (E)-isomers with diphenyl disulfide
Miyata,Shinada,Ninomiya,Naito
, p. 1123 - 1125 (2007/10/02)
Diphenyl disulfide is shown to be an efficient catalyst for the isomerization of (Z)-2-alkenoic esters to (E)-2-alkenoic esters in boiling tetrahydrofuran.
N-Acyl Dehydro-α-amino Acids from N-Formyl Dehydro-α-amino Acid Esters
Schoellkopf, Ulrich,Meyer, Rolf
, p. 1469 - 1475 (2007/10/02)
On treatment with methyl potassioisocyanoacetate (2), aldehydes and ketones 1 give N-anionized N-formyl dehydro-α-amino acid methyl esters 3.Compounds 3 with R1 = CH3, R2 = H is obtained by base induced ring opening of methyl 2-oxazoline-4-carboxylate 5. - Acylation of 3, followed by deformation of the intermediates 6, yields N-acyl dehydro α-amino acid methyl esters 7 which can be hydrolyzed to the N-acyl dehydro α-amino-acids 8.
