A study of the photochemical behavior of terarylenes containing allomaltol and pyrazole fragments

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2022, 18, 588–596, doi:10.3762/bjoc.18.61

• (Scheme 1D). In contrast to the previously described phototransformation of analogously substituted oxazolones 9, in the considered case, the photoreaction proceeds exclusively as a contraction of the pyranone ring, while 6π-electrocyclization of the hexatriene system was not observed. Results and

Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore

• Esteban P. Urriolabeitia,
• Pablo Sánchez,
• Alexandra Pop,
• Cristian Silvestru,
• Eduardo Laga,
• Ana I. Jiménez and
• Carlos Cativiela

Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98

• Chemistry Centre, Departament of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Str. Arany Janos 11, RO-400028 Cluj−Napoca, Romania 10.3762/bjoc.16.98 Abstract The stereoselective synthesis of truxillic bis-amino esters from polyfunctional oxazolones is reported. The

• reaction of 4-((Z)-arylidene)-2-(E)-styryl-5(4H)-oxazolones 2 with Pd(OAc)2 resulted in ortho-palladation and the formation of a dinuclear open-book complexes 3 with carboxylate bridges, where the Pd atom is C^N bonded to the oxazolone. In 3 the two exocyclic C=C bonds of the oxazolone are in a face-to

• complexes 4. Treatment of 4 with CO in a MeOH/NCMe mixture promoted the methoxycarbonylation of the palladated carbon and the release of the corresponding ortho-functionalized 1,3-diaminotruxillic bis-amino esters 5 as single isomers. Keywords: amino acids; C–H activation; Kaede protein; oxazolones

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• . Thus, a three-component condensation of a series of fluorinated benzaldehydes 50a–h, N-acetyl- or N-benzoylglycine 51a or 51b, respectively, and an excess of acetic anhydride in the presence of sodium acetate afforded the oxazolones 52a–h. The subsequent reductive ring cleavage of 52a–h without

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• . Intermediary diacid was first esterified with diazomethane, then the isopropylidene acetal was hydrolyzed, and diester saponification gave N-Boc-protected compound (2S,3R)-35. Via ketopinic acid functionalized 2(3H)-oxazolones When oxazolone 36 derived from (R)-(−)-ketopinic acid was reacted with bromine and

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• reaction with 5-(4H)-oxazolones in the presence of triethylamine formed 4-(2-phosphonioethyl)-5(4H)-oxazolones 116. The oxazolone ring opening with methanol and subsequent deprotonation with sodium methoxide converted phosphonium salt 116 into phosphorous ylide 117, which underwent an intramolecular Wittig

• reaction that eventually led to pyrroline derivatives 118 (Scheme 67) [79]. Gelmi et al. also conducted a number of syntheses of pyrrole derivatives 120 from vinylphosphonium bromide 8 and protonated 5-(4H)-oxazolones 119 (Scheme 68, R3 = H) as well as the so-called münchnones 119 (Scheme 68, R3 = Me). The

• reaction yields for the protonated oxazolones were ca. 40% and 48–53% in the reactions involving münchnones (Scheme 68) [80]. In 2007 Alizadeh et al. described an interesting reaction of α,β-di(alkoxycarbonyl)vinylphosphonium salts with the carboxylate anion. The reaction of triphenylphosphine with dialkyl

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• oxazolones and pyrazinediones [150][153][154], which are found alongside thioamides in these molecules (Figure 11). These post-translational modifications are critical for copper binding but the mechanisms of these heterocyclisation steps have not yet been determined for any pathway, despite the

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• published [73]. This study shows that α’-oxyenones are very efficient key enoate equivalents in Brønsted base-catalyzed asymmetric conjugate addition of a range of soft nucleophiles such as α-substituted oxindoles, cyanoesters, oxazolones, azlactones and thiazolones to afford the corresponding

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• : asymmetric catalysis; DFT; 1,3-dipolar cycloaddition; gold catalysis; NICS; NTR; oxazolones; prolines; Introduction The synthesis of α-amino acids employing an α-amino carbonyl template constitutes the most straightforward route to introduce the α-side chain [1]. As a valid example, oxazol-5-(4H)-ones

• described in a preliminary communication [28] concerning the catalytic activity of complexes 3 and 4 in the 1,3-DC of oxazolones with electrophilic alkenes. Here, a deep DFT analysis and the application of other computational experiments (NRT, NICS) were compared to the experimentally observed results in

• order to clarify the enantio- and anomalous regioselectivity. Results and Discussion Initially, the synthesis of oxazolones 5 was accomplished under mild reaction conditions by mixing N-acyl-α-amino acid derivatives in the presence of dehydrating agents such as carbodiimides [2][3][4][5]. Gold(I