Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

• (TXA2) synthetase inhibition [10], antinociceptive [11], histone deacetylase inhibition [12], α-glucosidase inhibition [13] , tyrosinase inhibition [14], allelochemical [15], anticonvulsant [16], antioxidant [17], antiplatelet aggregation [18], anti-inflammatory [19], and UV absorption [20]. Cinnamic

Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts

• Valentina Benazzi,
• Arianna Bini,
• Ilaria Bertuol,
• Mariangela Novello,
• Federica Baldi,
• Matteo Hoch,
• Alvise Perosa and
• Stefano Protti

Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84

• via hydrothermal treatments have an amorphous structure. The optical properties of the prepared CDs were thus investigated by UV–vis absorption spectroscopy. The obtained spectra (Figure 1) showed three main absorption bands located at 225–235 nm (assigned to, according to the literature, the π–π

• predominant band located at 350 nm, CDs synthesized from glucose and bass scales show a significant absorption at around 260 nm and 300 nm, respectively [33][34][35]. A different UV–vis spectrum was obtained for the Blackberries-derived nitrogen-doped material, which showed a main absorption at 330 nm, with a

Synthesis of pyrrolo[3,2-d]pyrimidine-2,4(3H)-diones by domino C–N coupling/hydroamination reactions

• Ruben Manuel Figueira de Abreu,
• Robin Tiedemann,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2025, 21, 1010–1017, doi:10.3762/bjoc.21.82

• Abstract A variety of pyrrolo[3,2-d]pyrimidine-2,4(3H)-diones were prepared by a combination of Sonogashira reaction and subsequent cyclization by domino C–N coupling/hydroamination reaction. The optical properties (UV–vis absorption and fluorescence) depend on the substitution pattern of the compounds

• ]pyrimidine-2,4(3H)-diones 4 were investigated by steady-state absorption and photoluminescence spectroscopy (Figure 2, Table 2). The wavelength and intensity of absorption and emission depended on the substitution pattern. The methyl-substituted compound 4a showed one broad absorption band at ≈290 nm. A

• similar absorption feature, but slightly bathochromically shifted, was observed for the thienyl-substituted derivative 4m. The strongly electron-donating N,N-dimethylaminophenyl group (products 4k,l) resulted in segmentation into two absorption bands accompanied by a strongly red-shifted lower energy

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

• , there is a lack of understanding of why the absorption and photoluminescence of D3 symmetrical triphenylmethyl radicals are so weak in the visible spectrum. While it is understood that the functionalization with donor moieties breaks the D3 symmetry, the ϕ varies greatly among different donors and also

• . Only at temperatures as low as 90 K, the monoradical is stable, allowing recording of the absorption and emission spectra [30]. Symmetrical halogenation of the triphenylmethyl (or trityl) unit increases stability of the molecule, compared to the parent unsubstituted trityl radical first reported by

• –LUMO energy gaps are identical and their respective transitions exhibit identical transition dipole moments [19][32][33]. For the |D1⟩ transition these two degenerate transitions mix in an out-of-phase fashion leading to the observed weak absorption at 544 nm (see Figure 1b and c). When looking at the

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• absorption profile in the visible region, ii) a long lifetime of the excited states, and iii) balanced redox potentials in both the ground and excited states [7]. In 2018, Zeitler and her collaborators conducted an innovative and in-depth study on modulating the photochemical properties of a family of donor

• 6a, we observed a blue-shifted absorption profile due to the break of the conjugation in sulfur-based acceptors. Compounds 4a and 6a presented a similar absorption profile, while molecule 5a showed a red-shifted spectrum tailing up to the visible region (Figure 2a). The lack of a significant charge

• electron-withdrawing group [31]. Additionally, it is possible that the mobility of core 4 contributes to this behavior, as evidenced by the observation that the DE is not present in the more rigid structures 5a and 6a. In this compound, we did not observe changes in the absorption profile during the

Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters

• Lewis McGhie,
• Hannah M. Kortman,
• Jenna Rumpf,
• Peter H. Seeberger and
• John J. Molloy

Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69

• solvent had a profound effect on reactivity with more Lewis-basic solvents suppressing reactivity (Table 1, entries 4 and 5 vs entries 6 and 7), indicating p-orbital availability plays a prominent role [56][57]. A control reaction (Table 1, entry 8), in combination with UV–vis absorption studies (see

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• examples. Azobenzene and its derivatives show two characteristic absorption bands, namely a π→π* transition around 330 nm and an n→π* one around 450 nm, respectively [22]. The molecule can populate the thermodynamically metastable Z isomer by addressing these transitions in the thermally stable E form. The

• relative position of the absorption bands in the azobenzene derivatives depends on the substitution pattern on the aromatic rings, which can act as a handle to affect the absorption properties of the compound class [3]. For instance, push–pull systems or the introduction of tetra-ortho substituents were

• reported to either bathochromically shift the UV–vis absorption spectrum or lead to a better separation of the n→π* bands of the two photoisomers and allow for visible-light-responsive switches [23][24][25][26]. In recent years, heteroaryl azobenzene derivatives have revealed superior properties to

4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Luc Van Meervelt,
• Do Thi Thao and
• Nguyen Minh Thong

Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65

• interactions of these derivatives with the enzyme inducible nitric oxide synthase (iNOS), compared to dexamethasone used as a reference. Furthermore, ADMET (absorption, distribution, metabolism, excretion, and toxicity) predictions were performed to assess their drug-likeness and pharmacokinetic properties

• prediction of drug-like properties, in silico evaluations of ADMET (absorption, distribution, metabolism, excretion, and toxicity) characteristics of all potential drug candidates were conducted using the pkCSM online tool [28]. The resulting data are presented in Table 3. The absorption capability of the

• examined molecules was assessed via two key parameters: Caco-2 membrane permeability and intestinal absorption. Caco-2 membrane permeability is widely recognized as a critical indicator of a compound's ability to permeate biological membranes, in which permeability is measured in log Papp. A log Papp value

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• incorporating larger heteroatoms in the bridge moiety, we anticipate a bathochromic shift that would facilitate absorption match with the solar emission spectrum. Results and Discussion Synthesis The library of new heterocyclic NBD molecules synthesized and investigated in this study is presented in Scheme 1

• . Photoswitching The photoswitching of the NBDs to corresponding QCs was monitored by UV–vis and 1H NMR spectroscopy. With increasing electronegativity of the bridge-atom, a slight bathochromic shift in the absorption spectra of the parent NBD precursors O-NBD1 and N-NBD1 was found (Figure 2a and 2c). For the

• comparison with the data obtained for C-NBD1 we refer to previous literature studies [40]. As with C-NBD1, clean conversion of O-NBD1 into the corresponding O-QC1 was observed upon irradiation at 275 nm. The absorption maximum at λmax = 278 nm decreased, correlating with a simultaneous increase in the

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• . HPLC traces were recorded with UV absorption by 260 nm. Structure-guided approach for engineering the (non-covalent) fluorescent light-up aptamer Pepper into its covalent counterpart [11]. a) Secondary structure of the Pepper aptamer [12]; b) chemical structure of the fluorophore HBC530 [7]; c) three

Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• fluorination on the electronic features of phenacene molecules. F8-Phenacenes were conveniently synthesized by the Mallory photoreaction of the corresponding fluorinated diarylethenes as the key step. Upon fluorination on the phenacene cores, the absorption and fluorescence bands of the F8-phenacenes in CHCl3

• systematically red-shifted by ca. 3–5 nm compared to those of the corresponding parent phenacenes. The vibrational progressions of the absorption and fluorescence bands were little affected by the fluorination in the solution phase. In the solid state, the absorption band of F8-phenacenes appeared in the similar

• common organic solvents. Therefore, the crude 18 was subjected to the Mallory photoreaction without purification. Photoirradiation of diarylethene 18 was performed in the presence of a catalytic amount of I2 in refluxing toluene to afford F87PHEN which was isolated by sublimation under vacuum. Absorption

Asymmetric synthesis of fluorinated derivatives of aromatic and γ-branched amino acids via a chiral Ni(II) complex

• Maurizio Iannuzzi,
• Thomas Hohmann,
• Michael Dyrks,
• Kilian Haoues,
• Katarzyna Salamon-Krokosz and
• Beate Koksch

Beilstein J. Org. Chem. 2025, 21, 659–669, doi:10.3762/bjoc.21.52

• (HREIMS) were measured on a MAT 711 (Varian MAT, Bremen, Germany). Electron energy for EI was set to 70 eV. Infrared spectra (IR) were measured on an ALPHA II (Bruker, Billerica, USA) spectrometer. Characteristic absorption bands are given in wave numbers (cm−1). Qualitative thin-layer chromatography (TLC

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• ; ALFRED PASIEKA/SCIENCE PHOTO LIBRARY, No. 585105259. This content is not subject to CC BY 4.0. a. Photoredox catalytic cycles; b. absorption spectrum of photosensitizers. Therapeutic window indicates the most appropriate wavelength range to apply irradiation for biological applications. Graph

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• devices, can differ and this requires further studies. Photophysical properties Absorption and emission spectra of ANTH and 9,10-ANTH(BnF)2 are shown in Figure 1. The maximum λabs and λem values for ANTH and the 9,10-disubstituted ANTH derivatives are shown in Table 1. The maximum λem of 9,10-ANTH(BnF)2

• photoproducts were insoluble resulting in decreased concentration of 9,10-ANTH(BnF)2 in the irradiated solution or new photoproducts had similar absorption features. To identify the photoproducts in the irradiated solutions of ANTH and 9,10-ANTH(BnF)2, complementary NMR analyses were carried out (Figures S6 and

• = 13.63 Hz, 2F), −140.67 (m, 2F), −151.7 (t, J = 21.8 Hz, 1F), −162.68 (m, 2F); 1H NMR (δ/ppm): 8.23 (m, 4H), 7.45 (m, 4H); EIMS (m/z): [M]+ calcd for 610.0402; found, 610.100. Absorption and emission spectroscopy Absorption spectra were collected under aerobic conditions in cyclohexane. Measurements were

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• with the Schmidt criteria for topochemical cycloaddition. Additionally, two other bimane derivatives with different substitution patterns were synthesized and investigated. Our findings suggest that functionalizing bimanes to redshift their absorption maxima into the visible-light spectrum provides a

• extinction coefficient (6100 M−1 cm−1) compared to Me2B (4700 M−1 cm−1) at their λmax values of 403 nm and 394 nm in DCM, respectively [19]. This difference in light absorption is further exacerbated by the fact that the irradiation wavelength is not aligned with the λmax of Me2B. Calculating from the

• between these bonds is outside the acceptable range (4.2 Å) [24]. This finding, along with the re-examination of several previously synthesized bimane compounds, suggests that substituting the bimane chromophore with groups that sufficiently redshift the absorption maximum could result in a wide range of

Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction

• Thomas Brandt,
• Pascal Lentes,
• Jeremy Rudtke,
• Michael Hösgen,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36

• particular to gain insight into the effects of different substituents on UV spectra and switching behavior. For the determination of the n–π*-absorption maxima of the E and Z isomers 250 µM solutions of each compound in acetonitrile were prepared and measured at 25 °C. All compounds (4, 7–14, 17, 19–21, 23

• measurements revealed that the absorption maxima of the n–π*-transitions of the Z isomers of 13 and 21 (392–398 nm) are almost independent of solvent and pH, while the n–π*-transitions of the E isomers at ≈515 nm are significantly shifted to shorter wavelengths (Δλmax = 10–20 nm) in water (Table 7). At the

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• research. Keywords: light-mediated synthesis; mechanochemistry; photomechanochemistry; Introduction Light-mediated synthetic methodologies have significantly transformed contemporary organic chemistry by enabling a broad array of previously unattainable transformations [1]. In fact, the absorption of a

• the absorption spectrum of reagents and ensure that the emission spectrum of the light source used overlaps (at least to some extent) with it (Figure 1). The Stark–Einstein law, sometimes referred to as the law of photochemical equivalence, asserts that the absorption of light is a quantum process

Identification and removal of a cryptic impurity in pomalidomide-PEG based PROTAC

• Bingnan Wang,
• Yong Lu and
• Chuo Chen

Beilstein J. Org. Chem. 2025, 21, 407–411, doi:10.3762/bjoc.21.28

• of 5 using the same sequence of reactions starting from 3-fluorophthalic anhydride instead of 1. Indeed, 5 is a white solid without UV absorption around 410 nm (Figure 2). The formation of 6 originated from nucleophilic acyl substitution to displace the glutarimide in 1 by 2. Interestingly, this side

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• (0.84) Å, H···O = 1.79 (1.83) Å, and N···O = 2.513 (2.518) Å, angle N–H–O 140.4° (138.0°). The electronic absorption spectra of compounds 7a,b and 8a,b in acetonitrile have long wavelength bands in the region of 425–432 nm (Table 2). They exhibit dual-maxima fluorescence at 476–530 nm with normal and

• sensitivity of in situ obtained complexes 9 and 10 with CN− to different cations. It appeared that the addition of an equivalent amount of Hg(ClO4)2 to an acetonitrile solution selectively and completely restores the initial absorption and fluorescence spectra (Scheme 3). Thus, the obtained compounds

• spectrometer. Electronic absorption spectra were obtained on a Varian Cary 100 spectrophotometer. Emission spectra were recorded on a Varian Cary Eclipse spectrofluorimeter. Acetonitrile of spectroscopic grade (Aldrich), previously purified by distillation, and tetra-n-butylammonium salts (TBAX: F, Cl, Br, I

Synthesis of new condensed naphthoquinone, pyran and pyrimidine furancarboxylates

• Kirill A. Gomonov,
• Vasilii V. Pelipko,
• Igor A. Litvinov,
• Ilya A. Pilipenko,
• Anna M. Stepanova,
• Nikolai A. Lapatin,
• Ruslan I. Baichurin and
• Sergei V. Makarenko

Beilstein J. Org. Chem. 2025, 21, 340–347, doi:10.3762/bjoc.21.24

• IR spectra of compounds 5a–6d containing an alkoxyfuropyran fragment shows that in the case of methyl esters 5a, 6a, and 6c the absorption band of the alkoxycarbonyl function is shifted to a lower frequency region (1714–1721 cm−1), while ethyl esters 5b, 6b, and 6d are characterized by higher

• . In turn, in the IR spectra (KBr) of compounds 7a–f, absorption bands of the ester fragment in the region of 1714–1750 cm−1 and absorption bands of the carbonyl group of the amide fragment in the region of 1674–1688 cm−1 are observed, which suggests the existence of these compounds in the solid phase

• expands the possibilities of further transformation and obtaining new compounds on their basis. Experimental General information IR spectra were recorded on a Shimadzu IRPrestige-21 FT-IR spectrometer for samples in KBr pellets over 400–4000 cm−1 range. The electronic absorption spectra were recorded on a

Antibiofilm and cytotoxic metabolites from the entomopathogenic fungus Samsoniella aurantia

• Rita Toshe,
• Syeda J. Khalid,
• Blondelle Matio Kemkuignou,
• Esteban Charria-Girón,
• Paul Eckhardt,
• Birthe Sandargo,
• Kunlapat Nuchthien,
• J. Jennifer Luangsa-ard,
• Till Opatz,
• Hedda Schrey,
• Sherif S. Ebada and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 327–339, doi:10.3762/bjoc.21.23

• ]+ (calculated 446.1962). The UV–vis spectrum of 1 (Figure S3, Supporting Information File 1) revealed a prominent absorption peak (λmax) at 434 nm in the visible region reflected by being yellow-colored and suggesting the presence of an extended conjugated π-system in its structure. The 1H NMR and 1H–1H COSY

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• own a large span of colors depending on the nature of the metal and the ligands but also on the various oxidation states these compounds can attain. This property results on the absorption of a visible-light photon complementary to the observed color and has been extensively exploited in photoredox

• and a given substrate or a sacrificial species. In the case of the metal-based complexes, the absorption band associated to the metal-to-ligand charge transfer (MLCT) is generally addressed even though other types of excitations like ligand-to-metal charge transfer, ligand- and metal-based excitation

• excitations (MC), which are governed by the ligand field splitting, an effect that increases for larger and more diffuse orbitals, and by the energy of the ligand’s π* orbitals. This interplay between relativistic effects, ligand field strength, and ligand orbital energy ultimately determines the absorption

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• radical cations and dications of linear and angular [3]naphthylenes, consisting of fused aromatic naphthalenoid and antiaromatic cyclobutadienoid moieties and containing different degrees of paratropicity. Electronic absorption and vibrational Raman spectroscopies were used to describe the more relevant

• dication is associated to the appearance of a global diatropic ring current which stabilizes the whole molecule. On the contrary, 22+ can be better viewed as two segregated radical cations with slight, but high enough, local diatropic character in each. Here, we use electronic UV–vis–NIR absorption and

• give rise to two naphthylene-centered cations located at both sides of the molecule. The connection path would be partially interrupted by the angular topology, thus accounting for the more similar redox potentials. Electronic spectroscopy The UV–vis–NIR electronic absorption spectra of the neutral and

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

• Islam S. Marae,
• Jingyun Tan,
• Rengo Yoshioka,
• Zakaria Ziadi,
• Eugene Khaskin,
• Serhii Vasylevskyi,
• Ryota Kabe,
• Xiushang Xu and
• Akimitsu Narita

Beilstein J. Org. Chem. 2025, 21, 270–276, doi:10.3762/bjoc.21.19

• properties were investigated by UV–vis absorption and fluorescence spectroscopy in compassion to pristine BPP and its oxidation product, benzo[rst]pentaphene-5,8-dione (BPP-dione). BPP-OiPr exhibited a significantly enhanced photoluminescence quantum yield (PLQY), reaching 73% in comparison to pristine BPP

• (13%). BPP-dione, when compared to the parent BPP, also displayed improved absorption and emission from the first excited singlet (S1) state with a PLQY of 62% and an intramolecular charge-transfer character. The rod-like nano- to microcrystals as well as longer wires of these BPPs were also revealed

• optimized by density functional theory (DFT) calculations (Figure S2 in Supporting Information File 1). The optoelectronic properties of BPP-OiPr 3 and BPP-dione 4 were initially investigated by UV–vis absorption spectroscopy in comparison with BPP 2 (Figure 2a). BPP 2 and BPP-OiPr 3 displayed similar and

Three-component reactions of conjugated dienes, CH acids and formaldehyde under diffusion mixing conditions

• Dmitry E. Shybanov,
• Maxim E. Kukushkin,
• Eugene V. Babaev,
• Nikolai V. Zyk and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 262–269, doi:10.3762/bjoc.21.18

• reactions that proceed through the formation of formaldehyde condensation products (Scheme 1). Previously, we have proposed a convenient diffusion mixing technique for multicomponent reactions based on the absorption of volatile reagent vapors by a mixture containing the remaining reaction components. This

• (Table 1, entries 11 and 13). Apparently, an increase in the surface area of the reaction solution promoted more efficient absorption of CH2O molecules, which accelerated the condensation reaction. The reaction of formaldehyde and diketone 1 in chloroform and acetonitrile predominantly led to diketo

• absence of ʟ-proline was carried out under otherwise identical conditions in the same apparatus (Table 1, entries 9 and 10), the significant difference in the conversion of compound 1 could not be explained only by the evaporation and absorption processes of CH2O. Apparently, the reaction rate also played