Distinctive reactivity of N-benzylidene-[1,1'-biphenyl]-2-amines under photoredox conditions

• Shrikant D. Tambe,
• Kwan Hong Min,
• Naeem Iqbal and
• Eun Jin Cho

Beilstein J. Org. Chem. 2020, 16, 1335–1342, doi:10.3762/bjoc.16.114

• ), ethers (2e), halogens (2i and 2l) [48][49][50], the medicinally important CF3 group (2m), and acetals (2p) were tolerated under these mild reaction conditions. The substitution pattern of the aryl groups, such as ortho (2c, 2e, and 2k), meta (2m and 2p), and para substitution (2b–2d, 2g, 2i, 2l, 2o, and

• electron density or position of the substituent on the benzylidene moiety. Interestingly, the homocoupling process was highly stereoselective, resulting in the formation of only one diastereomer, probably due to the bulky substitution pattern of the substrates. The structure of the homocoupled 1,2-diamine

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• porphyrin [75] and rhodamine 6G (OD14) [76]. Aryl radicals from aryl halides. Aryl halides are generally more difficult to reduce than aryl diazonium salts (Ered < −1.2 V) [77][78]. However, they are more available and bench-stable. Their reduction potential is dependent on the substitution pattern and on

• fragmentation. N-aminopyridinium salts are also emerging starting materials. Iminyl radical generation Hydroxylamines have emerged as key precursors for iminyl radical generation [128]. Their redox properties can be easily tuned through the substitution pattern of the electrophore. They can be subjected to

• SET. After the reduction, a fragmentation affords the desired amidyl radicals together with the corresponding pyridines. The reduction potential of such species was around −0.75 V vs Ag/Ag+, depending on the substitution pattern. This scaffold was employed recently by the Hong group to achieve an

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• the phenol substrate substitution pattern, and it is therefore difficult to develop general methods for this transformation. This substrate–control bias was successfully outmaneuvered by the development of a copper-based catalytic system operating under aerobic conditions and allowing selective access

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

• Péter Bagi,
• Réka Herbay,
• Nikolett Péczka,
• Zoltán Mucsi,
• István Timári and
• György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

• substituents on the P-heterocyclic core influence the outcome of the isomerization. Methyl group(s) in positon 3 and 4 represents a typical substitution pattern. Thus, the isomerization of 1-phenyl-3-phospholene oxide (5) and 1-phenyl-3,4-dimethyl-3-phospholene oxide (8) was investigated under the optimized

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• last hundred years [1][2][3][4]. Their substitution pattern easily facilitates shift of the absorption from the ultra violet part into the near infrared region while they exhibit huge extinction coefficients [3]. The connection of two nitrogens with an odd number of methine groups results in a positive

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• the solid state [50][51][52][53][54]. Conclusion In summary, we have achieved the synthesis of a series of CPL-active polyheteroaromatic compounds from readily available chiral BINOLs via the O-arylation and subsequent palladium-catalyzed C–H/C–H coupling reaction. The substitution pattern on the

Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

• Alexander Sailer,
• Franziska Ermer,
• Yvonne Kraus,
• Rebekkah Bingham,
• Ferdinand H. Lutter,
• Julia Ahlfeld and
• Oliver Thorn-Seshold

Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

• because of the S/CH2 replacement, we assumed that "mapping" the substitution pattern of indanocine onto a hemithioindigo core should result in a lead structure for tubulin-binding (Z)-HTIs, namely the class of HITubs. The para-hydroxy substitution of indanocine suggested that HTI might be a more desirable

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• populated at 20 °C (see Supporting Information File 1). Calculating the effect of the substitution pattern on the pKa value is problematic [18] and was not attempted here. Figure 2 shows calculated structures and spectra of the neutral forms of simplified models of 4 and 5, with either a pyrollidino or

• (i.e., a 2-bromo-6-methoxy substitution pattern) was found to lower the pKa of the azonium ion such that it fell outside the normal physiological range. The neutral version of this compound nevertheless underwent trans-to-cis photoisomerization in the presence of blue-green light and exhibited slow

Two new aromatic polyketides from a sponge-derived Fusarium

• Mada Triandala Sibero,
• Tao Zhou,
• Keisuke Fukaya,
• Daisuke Urabe,
• Ocky K. Karna Radjasa,
• Agus Sabdono,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2941–2947, doi:10.3762/bjoc.15.289

• . HMBC correlations from an exchangeable proton at δH 12.57 (4-OH) to C3, C4, and C4a were also supportive of the substitution pattern in this benzene ring. Strong correlations from H6 to C8 and C10a implied the meta-relationship of C8 and C10a to C6, and similarly the ortho-relationship of C5 and C7 to

Palladium-catalyzed synthesis and nucleotide pyrophosphatase inhibition of benzo[4,5]furo[3,2-b]indoles

• Hoang Huy Do,
• Saif Ullah,
• Alexander Villinger,
• Joanna Lecka,
• Jean Sévigny,
• Peter Ehlers,
• Jamshed Iqbal and
• Peter Langer

Beilstein J. Org. Chem. 2019, 15, 2830–2839, doi:10.3762/bjoc.15.276

• changes of the substitution pattern allow for a modification of the selectivity and activity of these compounds to these enzymes. Docking studies of h-ENPP1 inhibitors Molecular docking of the most potent compounds 5c and 6a (for ENPP1) and for 6e (exhibiting dual inhibition for both isozymes) were

Design, synthesis and investigation of water-soluble hemi-indigo photoswitches for bioapplications

• Daria V. Berdnikova

Beilstein J. Org. Chem. 2019, 15, 2822–2829, doi:10.3762/bjoc.15.275

• shifted relative to the one of the Z-isomer. Depending on the substitution pattern, the thermal lifetimes of metastable E-isomers at 25 °C vary from hours to days and sometimes even years [12][13][14]. Remarkably, for sterically hindered hemi-indigo derivatives, thermal lifetimes of the metastable states

• high importance for biological applications. Herein, the synthesis and adjustment of the substitution pattern of hemi-indigo derivatives for the efficient photoswitching in aqueous medium are described. Detailed characterization of the photoinduced isomerization of hemi-indigo derivatives in water is

• in the presence of the co-solvent. The comparison with the reported data on Z-1a [13] and related hemi-indigo derivatives containing a 4-amino group in the phenyl ring [13] allowed to conclude that this substitution pattern is unfavorable for photoswitching in aqueous medium. Thus, a higher content

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• well as on the electronic substitution pattern of the alkynone. While electron-donating groups furnish α-pyrones as main products, electron-withdrawing groups predominantly give the corresponding 1H-pyridines. Both heterocycle classes fluoresce in solution and in the solid state. In particular

• in solution and in the solid state. While the absorption behavior is not affected by the substitution pattern the emission maxima are shifted bathochromically with increasing acceptor strength. The same trend manifests for the solid-state emission. For α-pyrones the photophysical properties are

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• substitution pattern of this biaryl moiety, a broad spectrum of efficacies for CXCR3 can be obtained, i.e., from antagonists to partial agonists and full agonists (Figure 1C) [24]. Meta and para-substitution yields antagonists (exemplified by 1a,b), while ortho-substitution with halogen atoms provides agonists

• atom of 1e. These calculations indicate that CXCR3 agonism is more likely to be associated with the cis-isomer than with the trans-isomer in our designed azobenzenes. Synthesis of azobenzene analogues and exploration of substitution pattern on the outer aromatic ring In addition to unsubstituted

• azobenzene analogue 2a, we explored the substitution pattern of the outer aromatic ring with chlorine atoms in the ortho, meta and para-position (compounds 2b–d, respectively) to also assess the possibility of agonism provided by a halogen bond. Compound 2e, which contains a bromine atom in the ortho

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• compounds were nonemissive. The Stokes shift of the OFs of nonoxidized DAEs was always ca. 6000 cm−1, independent of the substitution pattern. For comparison, this value was much lower than the Stokes shift of the OF of compound 6 (10,700 cm−1) [4]. The Stokes shift of the CFs of oxidized DAEs varied

Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

• Chenxia Zhang,
• Kaori Morinaka,
• Mahmut Kose,
• Takashi Ubukata and
• Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

• the terminal phenyl groups on the photochromic properties, compounds with methoxy groups or cyano groups at the para-position of the phenyl groups were also synthesized. To avoid the generation of isomers with a substitution pattern by Huisgen cyclization, the same substituents were introduced to both

Isolation and characterisation of irinans, androstane-type withanolides from Physalis peruviana L.

• Annika Stein,
• Dave Compera,
• Bianka Karge,
• Mark Brönstrup and
• Jakob Franke

Beilstein J. Org. Chem. 2019, 15, 2003–2012, doi:10.3762/bjoc.15.196

• (δH 3.37 (H-6)), and a tertiary alcohol at C-14 (δC 80.9 ppm). COSY correlations supported by HMBC analysis (Figure 2A) revealed an intact ABCD ring system with a substitution pattern identical to 4β-hydroxywithanolide E (1). Only a single, striking difference was noted: C-17 was shifted from 87.8 to

• identities of 22–28%, indicating that no P450 enzymes of these clans exist in P. peruviana. Although enzymes with similar catalytic activity might have evolved convergently in plants, the different substitution pattern in the side chain suggests that a side-chain cleavage mechanism distinct from mammals is

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• study 3,6-dihydroxyphthalimide derivatives as aromatic diols to construct functionalized O6-corona[3]arene[3]tetrazins. Being different from terephthalate in terms of substitution pattern, we envisioned that the phthalimide unit would flip freely owing to the less steric hindrance. In addition, N

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• synthesis of the target materials is schemed in Figure 4. To introduce the selected substitution pattern, 2,3-dimethylpyrrole 1 is first synthesized through a Trofimov reaction in a one-pot two-step reaction [29]. The condensation of the aforementioned pyrrole on para-iodobenzoyl chloride affords the

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• demonstrated, mechanochemical reactions usually give a more balanced substitution pattern for the randomly substituted derivatives [12]. In CDP preparations almost the same reaction conditions are used, but 1,2-propylene oxide is replaced with epichlorohydrin [13][14][15][16]. The disadvantage of this reaction

Fluorine-containing substituents: metabolism of the α,α-difluoroethyl thioether motif

• Andrea Rodil,
• Alexandra M. Z. Slawin,
• Nawaf Al-Maharik,
• Ren Tomita and
• David O’Hagan

Beilstein J. Org. Chem. 2019, 15, 1441–1447, doi:10.3762/bjoc.15.144

• not possible due to the low levels recovered, 1H and 19F NMR for this metabolite showed an intact -OCF2CH3 motif, as well as a para-substitution pattern, which suggested the identity of 4-(1,1-difluoroethoxy)phenol (16). Conclusion In conclusion, we have explored Cunninghamella elegans fungal

Efficient resolution of racemic crown-shaped cyclotriveratrylene derivatives and isolation and characterization of the intermediate saddle isomer

• Sven Götz,
• Andreas Schneider and
• Arne Lützen

Beilstein J. Org. Chem. 2019, 15, 1339–1346, doi:10.3762/bjoc.15.133

• ][51][52][53][54][55][56][57] we were intrigued by the class of chiral CTVs. This is especially true for derivative 1 (Scheme 2) due to its interesting trifold substitution pattern with an almost orthogonal orientation of the functional groups which make it an ideal precursor for the synthesis of other

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• substitution pattern at the phenyl moiety (Figure 2A). The small library of compounds enabled a better understanding of the structural factors determining the antiviral activity versus the cytotoxic one, with the major effect found for substituents at the para-position [23]. Eventually, this work allowed the

An improved synthesis of adefovir and related analogues

• David J. Jones,
• Eileen M. O’Leary and
• Timothy P. O’Sullivan

Beilstein J. Org. Chem. 2019, 15, 801–810, doi:10.3762/bjoc.15.77

• tetrabutylammonium salt of adenine facilitates alkylations in solvents other than DMF. Additionally, we have investigated how regioselectivity is affected by the substitution pattern of the nucleobase. Finally, this chemistry was successfully applied to the synthesis of several new adefovir analogues, highlighting

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• ]. Several reliable approaches to produce cyclopropanols have been reported in the literature (Scheme 1) [6] but a number of challenges still exist particularly for the stereoselective preparation of cyclopropanols of high structural complexity and substitution pattern. Since the first synthesis of

• organometallic species. The presence of a bulky substituent (alkyl or aryl) at the opposite face at the C3 position might equally be important as it might induce an additional steric parameter leading to a potentially more selective carbometalation reaction. The substitution pattern on the double bond needs to

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• very challenging to prepare due to the fact that in addition to regioisomers, pseudoenantiomers are unavoidably formed that have the same substitution pattern, but mirror-image relationship between the arrangements of substituents [19]. This phenomenon has an amplified effect in applications which are

• reversed-phase HPLC method (reaction 8, Figure 4). With reactions 6, 7 and 8 all the possible regioisomers of 6A-monoazido-6X-monotosyl-β-CD were prepared and due to their different HPLC retention times, they can be used as reference compounds to evaluate the substitution pattern in stepwise hetero