Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase

• Sanaz Ahmadipour,
• Alice J. C. Wahart,
• Jonathan P. Dolan,
• Laura Beswick,
• Chris S. Hawes,
• Robert A. Field and
• Gavin J. Miller

Beilstein J. Org. Chem. 2022, 18, 1379–1384, doi:10.3762/bjoc.18.142

• accepted. Evaluation of GDP 6-chloro-6-deoxy-ᴅ-mannose suggests that the ligand can bind to GMD, but that targeting inhibitive S-alkylation of an sp3-hybridised C6 electrophilic probe is ineffective here. a) Proposed oxidative pathway for provision of GDP-ManA 5 from GDP-Man 1, C6 stereochemistry of 3 is

Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants

• Karan Malhotra and
• Jakob Franke

Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135

• foenum-graecum; Pp: Paris polyphylla; Dz: Dioscorea zingiberensis) [35][66]. B) Formation of the defence compound ellarinacin (15) in bread wheat [26]. Stereochemistry of ellarinacin (15) is shown as published. C) Biosynthesis of the key intermediate melianol (21) in the pathway to the limonoid limonin

• (18) [29]. The stereochemistry is shown as published. List of characterised plant cytochrome P450 monooxygenases (CYPs) modifying triterpenoids or steroids. Supporting Information Supporting Information File 242: High-quality version of the phylogenetic tree shown in Figure 2 with tip labels

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• of IS5 and 10ab-v2 are also considered with all possible isomers and are listed in Figures S5 and S6, and Table S2 (Supporting Information File 1). It is noticeable that the IS5 and 10ab-v2 are formed via the reaction between 4a/4a’ and 9b (CH3NH2) without any changes in stereochemistry. The

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• , and plants, have the ability to produce homo- or heterodimeric natural products, which enables rapid structural diversification from simple monomers [1]. Often, the dimerized products exhibit significant biological activities due to the increased functional group density or complex stereochemistry, as

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• stereochemistry of the reactions was clearly elucidated and a rational reaction mechanism was proposed. The reactions have the advantages of using readily available reagents, mild reaction conditions, good yields, and high diastereoselectivity, and have potential synthetic applications in organic and medicinal

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• determine the stereochemistry at C-7 and C-10 of compounds 4 and 5. Since both 4 and 5, as mentioned above, are respective racemic mixtures, chiral-phase HPLC was then applied to separate each of them (see Figures S2 and S5 in Supporting Information File 1). As expected, new (+)-maninsigin D [(+)-4, 0.8 mg

• from isoprene units rather than by the much more common routes to aromatics involving acetate or shikimate [37]. In addition, the absolute stereochemistry of (+)-1 was unambiguously elucidated by TDDFT-ECD calculations, and the complete structure of 2 was confirmed for the first time by X-ray

Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

• Shao-Cong Zhan,
• Ren-Jie Fang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

• '-indolines] 2a–h, in which the two phenyl groups exist in cis-position. This result clearly indicated that this reaction has a similar outcome of stereochemistry. Based on the success of the four-component reaction through in situ generation of dienes and dienophiles, we further considered whether more

Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• the water addition occurs on the C3' carbocation, which is generated by one electron transfer to the ferric iron from the C3' radical intermediate (carbocation mechanism in Scheme 9). Notably, in this last step, the stereochemistry of the hydroxylation reaction is regulated by the enzyme to be the R

Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold

• Anastasia Vepreva,
• Alexander S. Bunev,
• Andrey Yu. Kudinov,
• Grigory Kantin,
• Mikhail Krasavin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55

• diastereomer 2a is indicative of a sequence of concerted processes with an unambiguous stereochemistry control at each step where stereogenic centers are formed. Dibenzoazulenodipyrroles 2 have a pronounced three-dimensional character which make this chemotype promising as probe for protein–protein

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• stereochemistry in the Ir-catalyzed allylic substitution reactions. In 2016, Billingsley and co-workers disclosed the total synthesis of (−)-indolactam V (6), a nanomolar agonist of protein kinase C (Scheme 3) [12]. The authors applied an intramolecular SEAr reaction of 4-substituted indole derivative to

Organocatalytic asymmetric nitroso aldol reaction of α-substituted malonamates

• Ekta Gupta,
• Narendra Kumar Vaishanv,
• Sandeep Kumar,
• Raja Krishnan Purshottam,
• Ruchir Kant and
• Kishor Mohanan

Beilstein J. Org. Chem. 2022, 18, 217–224, doi:10.3762/bjoc.18.25

• , and alkyl at the para-position of the phenyl ring and the corresponding oxyaminated products were obtained in excellent yields and good enantioselectivities (4a–f). The single crystal X-ray analysis of the product 4a established the absolute stereochemistry which was found to be S (Figure 1) [62

Synthesis and bioactivity of pyrrole-conjugated phosphopeptides

• Qiuxin Zhang,
• Weiyi Tan and
• Bing Xu

Beilstein J. Org. Chem. 2022, 18, 159–166, doi:10.3762/bjoc.18.17

• spacer in the molecular structure. As the enantiomers of 2g and 2h, respectively, 3a and 3b offer an opportunity to assess the effects of stereochemistry of the pyrrole-capped phosphopeptides. Substituting the ᴅ-phosphotyrosine (py) in 2g and 2h, by ᴅ-phosphoserine (ps), affords 4a and 4b, respectively

Chemical and chemoenzymatic routes to bridged homoarabinofuranosylpyrimidines: Bicyclic AZT analogues

• Sandeep Kumar,
• Jyotirmoy Maity,
• Banty Kumar,
• Sumit Kumar and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2022, 18, 95–101, doi:10.3762/bjoc.18.10

• % yields, respectively (Scheme 5). The overall yields of the synthesis of nucleosides 9a and 9b starting from diacetone ᴅ-glucofuranose following the classical chemical pathway were found to be 24.2 and 24.4%, respectively. The stereochemistry at the C5′ carbon in bicyclic homonucleosides 9a,b was

• ′ proton resonating at δ 4.15 with the C6 proton of the nucleobase resonating at δ 7.67 (see Supporting Information File 1). Based on this analysis of the spatial arrangement of the groups attached at the C5′ chiral centre, the stereochemistry of this carbon centre was assigned to be (R) for both of these

• nucleosides. The study of NOESY NMR spectral data of compound 9a enabled us to assign the stereochemistry at the C5′ chiral centre in the compound as (R). Following this trend, we assigned the same stereochemistry for the C5′ centre of nucleoside 9b. Interestingly, we noticed that the stereochemistry of the

Efficient and regioselective synthesis of dihydroxy-substituted 2-aminocyclooctane-1-carboxylic acid and its bicyclic derivatives

• İlknur Polat,
• Selçuk Eşsiz,
• Uğur Bozkaya and
• Emine Salamci

Beilstein J. Org. Chem. 2022, 18, 77–85, doi:10.3762/bjoc.18.7

• -functional theory (DFT) computations were used to explain the reaction mechanism for the ring opening of the epoxide and the formation of five-membered lactones. The stereochemistry of the synthesized compounds was determined by 1D and 2D NMR spectroscopy. The configuration of methyl 6-hydroxy-9-oxo-8

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• -hydroxynaphthoquinomethanes [110]. These reactions were carried out by method A described above, and the stereochemistry was attributed to the E-isomer (Scheme 19). Conclusion Compounds containing the 1,2-naphthoquinone scaffold represent a class of natural and synthetic substances with important biological activities and

Total synthesis of the O-antigen repeating unit of Providencia stuartii O49 serotype through linear and one-pot assemblies

• Tanmoy Halder and
• Somnath Yadav

Beilstein J. Org. Chem. 2021, 17, 2915–2921, doi:10.3762/bjoc.17.199

• -methoxyphenyl glycoside form 1 was synthesized through a linear [1 + (1 + 1 = 2)] strategy. The target trisaccharide was synthesized as its p-methoxyphenyl glycoside that offered the unaltered stereochemistry of the sugar at the reducing end to mimic the glycosidic linkage of the natural polysaccharide. The

Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation

• Lukáš Ďurina,
• Anna Ďurinová,
• František Trejtnar,
• Ľuboš Janotka,
• Lucia Messingerová,
• Jana Doháňošová,
• Ján Moncol and
• Róbert Fischer

Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188

• desired epoxide 5 in an acceptable 70% yield with excellent stereoselectivity as the sole syn isomer (dr > 95:5). It is worth noting that a small quantity of pyridine was added to prevent unwanted acid-catalyzed epoxide hydrolysis [31]. The stereochemistry of 5 was assigned later after pyrrolidine ring

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

• nucleic acid components. Therefore, it was assumed until recently that effective inhibition of the metabolic enzyme is only possible by ᴅ-nucleoside analogues, which have the stereochemistry of natural nucleosides. This was proved to be untrue when the antiviral activity of 1,3-oxathiolane nucleosides

• nucleoside analogues. The enantiomerically pure 1,3-oxathiolane core has been an important building block in precursors that result in a defined stereochemistry of the resultant nucleoside product after N-glycosylation. Dynamic kinetic resolution (DKR) is a processes that interconverts a racemic mixture into

• in the presence of levamisole, which gave an improved overall yield of 52 of up to 67%. In this approach, the required stereochemistry of the thioacetal compound was created, so that the coupling with a nucleobase in a further step determines the stereochemistry of the attaching nucleobase at the

Ligand-dependent stereoselective Suzuki–Miyaura cross-coupling reactions of β-enamido triflates

• Tomáš Chvojka,
• Athanasios Markos,
• Svatava Voltrová,
• Radek Pohl and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 2657–2662, doi:10.3762/bjoc.17.179

• gel. A moderate loss of stereochemistry was observed only in cases of bulky ortho-substitution of either arylboronic acid or vinyl triflate (2ad, 2da, and 2dd). Alkylboronic acids were found to be unreactive even after prolonged reaction time (1a with n-hexylboronic acid, 60 h, rt). Next, conditions

• -trifluoromethylphenyl group which gave enamides 3da (2da/3da, 20:80) and 3dd (2dd/3dd, <1:99). It is worth mentioning that the reaction of vinyl triflate 1c with 3-methoxyphenylboronic acid led to full decomposition of the starting material. The stereochemistry of the double bond in compounds 2 and 3 was determined by

Solvent-free synthesis of enantioenriched β-silyl nitroalkanes under organocatalytic conditions

• Akhil K. Dubey and
• Raghunath Chowdhury

Beilstein J. Org. Chem. 2021, 17, 2642–2649, doi:10.3762/bjoc.17.177

• catalyst VIII led to ent-4 in 25% yield and 95% ee (Scheme 4). This observation confirmed that the presence of the β-silyl group in the enones played a key role in the high reactivity under the optimized reaction conditions. The stereochemistry of the silicon-substituted chiral center in compound ent-3k

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

• Dušan Đ. Škorić,
• Olivera R. Klisurić,
• Dimitar S. Jakimov,
• Marija N. Sakač and
• János J. Csanádi

Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174

• , TMSOTf proved to be the most efficient. High yields of the desired tetrazole compounds with no lactam byproduct were obtained. The molecular structure and stereochemistry of newly synthesized tetrazoles was established by detailed NMR analysis. For compounds 13 and 14, the structure was established by

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• example of the use of conjugation to drive an α-ketol rearrangement. This study elegantly illustrates the synthetic power of α-ketol rearrangements, whose suprafacial migration ensured that the α-ketol moiety present in the target product 31 was installed with correct stereochemistry. Taking inspiration

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• vinyl triflates 4a–c with a predominant formation of Z-isomers as product of an anti-addition of TfOH to the acetylene bond (Scheme 3). E/Z-Stereochemistry of compounds 4a–c was determined by H,F-NOESY correlation between vinyl proton (>C=CH–) and the CF3 group from the TfO substituent (see Supporting

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• the desired stereochemistry inversion at the C5’ carbon. Treatment with excess NaH furnished a terminal epoxide derivative which after the sequential treatment with benzyl bromide and reduction with LiAlH4 afforded alcohol 102 (81% yield from 95). The free secondary alcohol was then protected as TBS

• derivative in 80% yield. The TBS protecting group was removed under acidic conditions to give secondary alcohol 93 (85%). Afterwards, the 5,6-dihydro-α-pyrone functionality was constructed by applying a cross-metathesis protocol and the stereochemistry at C6’ was inverted with (E)-p-methoxycinnamic acid (17

• ) via a Mitsunobu esterification. The resulting product 106 contained all the correct stereochemistry, which after removal of the benzyl protection, provided the target molecule brevipolide M (13) as a colorless oil. Sabitha’s strategy to brevipolide M and N (13, 14) Following the previous success

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• selectivity of α-stereochemistry was primarily due to the strong directing effect of the neighboring benzyl ether group with the Hg(OAc)2. When cyclic mercuric halide 8 was treated with NaBH4 and oxygen (O2) in DMF oxidative demercuration takes place to give alcohol 10 in quantitative yield (Scheme 4). The

• (II)-salt-catalyzed rearrangement to produce 2,3-disubstituted-2,3-dihydropyranone derivatives 136. The stereochemistry of substituents at 2,3-positions of 2,3-dihydropyranone 136 was controlled by cis- and trans-configuration of the epoxide of starting materials (Scheme 40) [96]. Several unsaturated

• catalytic Hg(II)-salt-induced cyclization. Yamamoto and co-workers published the intermolecular cyclization of alkynyl-carboxylic acid 153 to produce 6-membered morpholine type ring compound 154 and compound 155 [103]. The stereochemistry of the chiral amino acid was not conserved in the cyclized product