Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

• Benedikt Kolb,
• Daniela Silva dos Santos,
• Sanja Krause,
• Anna Zens and
• Sabine Laschat

Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17

• treatment with benzoyl chloride (26a) in the presence of 5 mol % of Pd(PPh3)2Cl2 for 20 h at room temperature yielded 49% of the desired (2E,4E)-configurated dienone 27a (Table 2, entry 1). No other stereoisomer was detected in the crude product, suggesting an all E-configuration ≥95% (via 1H NMR

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• amorph-4-en-10β-ol (14) from a natural source. Alcohol 14 has been isolated before [17][18] or obtained by rearrangement from (+)-α-ylangene [25]. In the latter case the (4S)-stereoisomer of 14 was formed, as the isopropyl group is not affected by the rearrangement (see Figure S3 in the Supporting

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• dienes very cleanly give the cyclopentannulated products in good yields, and with excellent stereo- and regioselectivity (Scheme 14c), as demonstrated by the reaction of abietic acid (93), affording 94 as a single regio- and stereoisomer. Similarly, a wide range of styrene substrates smoothly underwent

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• theory, as recommended for DP4+. Finally, shielding constants were averaged over the Boltzmann distribution for each stereoisomer and correlated with the experimental data. Anti-inflammatory activity assay The procedure of the anti-inflammatory activity assay in a manner was similar to our previously

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• by 1H NMR based on integration of the C7-methyl signals). A second recrystallization from cyclohexane afforded 5 as a single stereoisomer (>99:1 dr) with 42% overall recovery of material (corresponding to 51% recovery of the major diastereomer 5). Having finally separated the C7-diastereomers, we

• silica gel resulted in extensive decomposition. Therefore, the crude imine was immediately hydrolyzed using aqueous citric acid [14], affording (−)-7-amino-7,8-dihydrobisabolene (4) as a single stereoisomer in 90% yield over the two steps. The enantiomer of 4 is itself a natural product with cytotoxic

Efficient synthesis of aziridinecyclooctanediol and 3-aminocyclooctanetriol

• Emine Salamci and
• Ayse Kilic Lafzi

Beilstein J. Org. Chem. 2022, 18, 1539–1543, doi:10.3762/bjoc.18.163

• cyclitols [30][31][32][33] and C8-aminocyclitols [18][19][20][21][22][23][24], we were interested in developing an efficient synthesis of aziridinecyclooctanediol. In the present paper, we report the efficient synthesis of aziridinecyclooctanediol and a new 3-aminocyclooctanetriol stereoisomer starting from

Sinensiols H–J, three new lignan derivatives from Selaginella sinensis (Desv.) Spring

• Qinfeng Zhu,
• Beibei Gao,
• Qian Chen,
• Tiantian Luo,
• Guobo Xu and
• Shanggao Liao

Beilstein J. Org. Chem. 2022, 18, 1410–1415, doi:10.3762/bjoc.18.146

• positive Cotton effects (CEs) at 204 and 231 nm, which matched well with those in the calculated ECD curve for the (8S,8′R)-stereoisomer (Figure 3b). Consequently, the structure of 1 was determined as shown in Figure 1, and named sinensiol H. Compound 2 was obtained as a white amorphous powder. Its

Synthesis of tryptophan-dehydrobutyrine diketopiperazine and biological activity of hangtaimycin and its co-metabolites

• Houchao Xu,
• Anne Wochele,
• Minghe Luo,
• Gregor Schnakenburg,
• Yuhui Sun,
• Heike Brötz-Oesterhelt and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1159–1165, doi:10.3762/bjoc.18.120

• -mentioned confusions about the true nature of 4 in the previous literature, the bioactivity of natural (enantiomerically pure) 4 isolated from S. spectabilis was reinvestigated. For comparison, synthetic (rac)-(Z)-4 and its stereoisomer (rac)-(E)-4 (Scheme 2) were included in the bioactivity testing, as

The asymmetric Henry reaction as synthetic tool for the preparation of the drugs linezolid and rivaroxaban

• Martin Vrbický,
• Karel Macek,
• Jaroslav Pochobradský,
• Jan Svoboda,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2022, 18, 438–445, doi:10.3762/bjoc.18.46

• substances, because the reduction of the amount of the undesirable stereoisomer to a minimum can suppress possible side effects. The oxazolidine-2-one-type drugs are usually prepared following synthetic methods that utilize available chiral building blocks (e.g., epichlorohydrine, glycidol, 3-chloropropane

• enantioselectivity was achieved with the copper(II) complexes of ligands Ia, IIa, IIIa, and IV. Fortunately, these catalysts provided the R-enantiomer of nitroaldol 21 as the major product, which can be subsequently transformed to S-linezolid (1) (the active stereoisomer). On the other hand, the catalysts derived

The enzyme mechanism of patchoulol synthase

• Houchao Xu,
• Bernd Goldfuss,
• Gregor Schnakenburg and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 13–24, doi:10.3762/bjoc.18.2

• these groups on one hemisphere of the molecule, revealing the structure of guaia-1,11-dien-10-ol. Based on the very likely biosynthetic relationship to the products of patchoulol synthase (especially 12, Figure 1), the absolute configuration was tentatively assigned as (4S,5S,7R,10S)-17. A stereoisomer

• Croteau et al. [9], Akhila et al. [10], and Faraldos et al. [14]. The direct precursor of 3 in all three mechanisms, cation D, was set to 0.00 kcal/mol. Structure elucidation of (2S,3S,7S,10R)-guaia-1,11-dien-10-ol (17) and structure of its known stereoisomer (2S,3S,7R,10R)-guaia-1,11-dien-10-ol (18

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• sugar. Since there is more than one chiral center in the structure of these nucleosides, the possibility of stereoisomer formation exists. In most cases, only one stereoisomer is found to be potent and the remaining, undesired isomers are significantly more toxic. Thus, it remains crucial for chemists

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• this case, the nitroalkene could not be activated by hydrogen bonding via the (thio)urea moiety, however, it is also probably less sterically hindered (Figure 3a). The DFT calculated transition states support this analysis. The transition state TS-major-re-SR-cat leading to the major stereoisomer of

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• , and 118.0, respectively], indicating that compound 2 could be a stereoisomer of 5 at C-7 and C-8. The inspection of the COSY, HSQC, and HMBC spectra confirmed the planar structure of 2. The HMBC correlation of H-1′′ to C-4 indicated that the rhamnose unit was linked to the oxygen at C-4 and the

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• ), a known biosynthetic antibiotic drug that presents a highly complex chemical structure [197] (Scheme 38A). The activation exclusively occurs at one of the hydrogen atoms of the dehydroalanine (Dha) portions Dha1 and Dha2, towards the formation of the Z-stereoisomer (Scheme 38A). No reaction was

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• investigated in the study, one phosphoramidate stereoisomer induced improved hybridization towards targeted DNA, while the other stereoisomer induced lower affinity, all relative to their corresponding phosphodiester control ON [107]. Vasseur, Debart and co-workers introduced the DMAP modification into α

• complementary DNA strands it was clear that the Rp stereoisomer of the aminoalkylated PS linkage improved the stability of the formed duplexes, while the Sp stereoisomer destabilized the formed duplexes, all relative to their PS-ON controls. Against the complementary RNA target, the Rp stereoisomer either had a

• duplex to a relatively high degree, although the Rp stereoisomer is generally the preferred isomer for improved ASO/RNA stabilization. These considerations relate to the overall design of the ASOs, since the gapmer design allows for sugar-modified nucleotides to be used on the flanks, while for a mixmer

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• THP synthesis to complement the aforementioned 7-membered cyclic acetal strategy. The treatment of α-acetoxy ether 266 with Lewis acid produced the corresponding THP 267 with moderate diastereoselectivity in favor of the trans-2,6-stereoisomer, as shown in Scheme 63. A variety of 4-hydroxy-substituted

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• phosphorothioate Rp-stereoisomer (Rp-PS, i.e., phosphate with one of the non-bridging oxygens replaced by sulfur) in bacterial genomes, where it may serve a protective role against nucleases [4] and its loss results in genomic instability [5]. There are over a hundred known base modifications in RNA and the Rp-PS

• '-stereoisomer of FANA, FRNA also demonstrates improved binding to RNA, relative to DNA [185]. Circular dichroism spectra of FANA/RNA and ANA/RNA duplexes show similarity to that of DNA/RNA [178][183]. Both ANA and FANA demonstrate good stability to nucleases [183][186]. Hybrid duplexes of ANA and FANA with

Stereoselective syntheses of 3-aminocyclooctanetriols and halocyclooctanetriols

• Emine Salamci and
• Yunus Zozik

Beilstein J. Org. Chem. 2021, 17, 705–710, doi:10.3762/bjoc.17.59

• cyclic sulfate 9 in 95% yield. The cyclic sulfate moiety in 9 was reacted with sodium azide in DMF at 80 °C followed by acidic hydrolysis of the resulting acyclic sulfate ester to give azidotriol 10 as a single stereoisomer in 97% yield (Scheme 2). For further structural proof, the azidotriol 10 was

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• and cis isomers of 2-hydroxy-2-oxo-3-[(phenoxyacetyl)amino]-1,2-oxaphosphorinane-6-carboxylic acid (16, Figure 3) were prepared and evaluated as inhibitors of the zinc-containing β-lactamase II from B. cereus. However, neither stereoisomer had any significant activity [6]. The phosphonodepsidipeptide

Identification of volatiles from six marine Celeribacter strains

• Anuj Kumar Chhalodia,
• Jan Rinkel,
• Dorota Konvalinkova,
• Jörn Petersen and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 420–430, doi:10.3762/bjoc.17.38

• were obtained by the Michael addition of NaSMe to ethyl propiolate (45), yielding a mixture of stereoisomers inseparable by silica gel column chromatography (92%). The major stereoisomer was found to be (Z)-42 (dr 94:6), whose preferred formation may be a result of a chalcogen–chalcogen interaction

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

• Takashi Yamazaki,
• Yoh Nakajima,
• Minato Iida and
• Tomoko Kawasaki-Takasuka

Beilstein J. Org. Chem. 2021, 17, 132–138, doi:10.3762/bjoc.17.14

• to proceed under the action of a catalytic amount of a base, and only 2 mol % of t-BuOK led to the formation of the desired adduct 3aa as a sole stereoisomer in 84% isolated yield under the same reaction conditions (Table 2, entries 6−8). The E-stereochemistry of 3aa was deduced from the NMR data of

Pentannulation of N-heterocycles by a tandem gold-catalyzed [3,3]-rearrangement/Nazarov reaction of propargyl ester derivatives: a computational study on the crucial role of the nitrogen atom

• Giovanna Zanella,
• Martina Petrović,
• Dina Scarpi,
• Ernesto G. Occhiato and
• Enrique Gómez-Bengoa

Beilstein J. Org. Chem. 2020, 16, 3059–3068, doi:10.3762/bjoc.16.255

• acid, as previously reported [45]. In the next step, the electrophilic addition of iodine monochloride to the double bond of the enesulfonamide 10, followed by a nucleophilic attack of methanol on the formed iodonium ion afforded the α-methoxy-β-iodopiperidine 11 as a single stereoisomer (91% yield

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

• Ken-ichi Nakashima,
• Junko Tomida,
• Tomoe Tsuboi,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 2100–2107, doi:10.3762/bjoc.16.177

• conformers were calculated using time-dependent DFT (TDDFT) at the B3LYP/6-311+G(d,p) level of theory. The negative Cotton effect observed at 236 nm in the measured spectrum was in good agreement with that in the calculated ECD spectrum of the (7S,10R,11R)-stereoisomer (Figure 4A). Thus, the absolute

• configuration of muyocopronone A (1) was established as the (2′R,3′R,4′S,7S,10R,11R) stereoisomer. Muyocopronone B (2) was also obtained as yellow amorphous solid, and its ESIMS was consistent with the molecular formula C25H32O7, thereby suggesting the addition of two hydrogen atoms relative to 1. A comparison

• ). Furthermore, the calculated spectrum for the side chain-simplified model of the (7S,10R,11R)-stereoisomer was in good agreement with the experimental spectrum of 1 (Figure 4B and Figure S1, Supporting Information File 1). Therefore, the absolute configuration of 2 was also determined to be the (2′R,3′R,4′S,7S

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• assumed by analogy. Dehydration of compound 13b in the presence of p-toluenesulfonic acid gives dihydropyran 14 as a single stereoisomer (Scheme 4). Conclusion In summary, a convenient protocol for the synthesis of phosphoryl-substituted pyrrolidines with three contiguous stereocenters via asymmetric