Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• compound [100]. Several later reports claim the detection of “eudesma-5,7(11)-diene”, a name assigned to CAS number 869998-21-0, but neither a structure is shown nor a reference to previous work is given in these reports, leaving doubt about the stereostructure the authors of this work had in mind [101

• planar structure of 56 was concluded by Pliva and Šorm [128]. After the absolute configuration of 61 was solved [129], the full stereostructure of 56 became known. No total synthesis and no NMR data are available for 56. β-Guaiene is one of the main constituents of the essential oil from Achillea

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• concluded that (+)-69 must have (3R)-stereochemistry and they had completed a formal total synthesis of the Zeeck−Taylor [2][21] stereostructure for inthomycin C ((+)-3). To remove any doubt, Stille cross-coupling of 48 with (+)-69 was performed under Ryu’s conditions [50] to give the desired product (+)-11

• enyne (−)-82b (Scheme 10) [22]. Hence, this new total synthesis has claimed to reinstate the originally formulated Zeeck–Taylor (3R)-stereostructure [2][21] for inthomycin C ((+)-3), R. J. K. Taylor’s total synthesis (Scheme 6) and disputes Ryu and Hatakeyama’s (3S)-stereochemical revision of inthomycin

• expected alcohol (−)-140 was obtained in 93% ee and 72% yield. Compound (−)-140 was further transformed to the corresponding Mosher's esters and their NMR and X-ray crystallographic data were well-matched with the (R)-stereostructure of (−)-140 [77][78]. The hydroxy group of (−)-140 was protected as

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• structure for compounds 3b, 8a,b, and 23a, and the RR–SS structure for congener 23b. In order to get a better insight into the stereochemistry of compounds 23a and 23b, we calculated their refined stereostructure by means of DFT geometry optimization in a DCM solution. As a result, one minimal energy

A new member of the fusaricidin family – structure elucidation and synthesis of fusaricidin E

• Marcel Reimann,
• Louis P. Sandjo,
• Luis Antelo,
• Eckhard Thines,
• Isabella Siepe and
• Till Opatz

Beilstein J. Org. Chem. 2017, 13, 1430–1438, doi:10.3762/bjoc.13.140

• was performed with extensive NMR spectroscopy and tandem mass spectrometry. The full stereostructure of the major component, fusaricidin E, could be confirmed by total synthesis. It included a macrolactamization approach combined with a late stage attachment of the GHPD side chain which was

A new and expeditious synthesis of all enantiomerically pure stereoisomers of rosaprostol, an antiulcer drug

• Wiesława Perlikowska,
• Remigiusz Żurawiński and
• Marian Mikołajczyk

Beilstein J. Org. Chem. 2016, 12, 2234–2239, doi:10.3762/bjoc.12.215

• stereostructure–bioactivity relationship in biologically active compounds [18][19], including selected prostanoids [20][21][22], we decided to synthesize all four rosaprostol stereoisomers 1a–d in enantiomerically pure form (Figure 2). The two rosaprostol stereoisomers 1c and 1d have an absolute configuration at

Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

• Reji Thomas and
• Nobuyuki Tamaoki

Beilstein J. Org. Chem. 2016, 12, 2211–2215, doi:10.3762/bjoc.12.212

• Single crystal X-ray diffraction has been used as one of the common methods for the unambiguous determination of the absolute stereostructure of chiral molecules. However, this method is limited to molecules containing heavy atoms or to molecules with the possibility of functionalization with heavy

• elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i.e., defunctionalization of its precursor of known stereostructure with bromine

• substitution (S-(−)-(E)-1). A reductive debromination of S-(−)-(E)-1 results in formation of one of the enantiomers of (E)-2. Using a combination of HPLC and CD spectroscopy we could safely assign the stereostructure of one of the enantiomers of (E)-2, the reduced product R-(−)-(E)-1. Keywords: azobenzene

Synthesis of a tricyclic lactam via Beckmann rearrangement and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha,
• Ongolu Ravikumar and
• Jadab Majhi

Beilstein J. Org. Chem. 2015, 11, 1503–1508, doi:10.3762/bjoc.11.163

• towards BR (Scheme 6). The stereostructure of the oxime 11b has been determined by single crystal X-ray diffraction data (Figure 2) [33]. Allylation of lactam 12 in the presence of NaH/allyl bromide in dry DMF gave the allyl derivative 2 in 80% yield. Finally, the RRM of compound 2 was accomplished with G

Design and synthesis of fused polycycles via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Ongolu Ravikumar

Beilstein J. Org. Chem. 2015, 11, 1259–1264, doi:10.3762/bjoc.11.140

• with allylmagnesium bromide to produce 1,2-addition product 4. A molecular model of compound 3 reveals that its exo-face is more accessible for Grignard addition than the endo-face. Also, the X-ray structure of compound 5 indicates the stereostructure of 4. Further, the diol 4 was treated with four

• equivalents of allyl bromide in the presence of an excess amount of NaH to generate the mono-O-allyl compound 5 and surprisingly the di-O-allyl compound was not formed. The stereostructure of 5 has been established on the basis of single-crystal X-ray diffraction studies [29] and it shows the steric hindrance

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• single crystals of this derivative, the assignment of its exact stereostructure (syn- or anti-epoxide) must remain tentative. Since many other epoxidations take place with retention of the original double bond configuration, we assume that the anti-configuration is more probable in the present case as

Decandrinin, an unprecedented C₉-spiro-fused 7,8-seco-ent-abietane from the Godavari mangrove Ceriops decandra

• Hui Wang,
• Min-Yi Li,
• Félix Zongwe Katele,
• Tirumani Satyanandamurty,
• Jun Wu and
• Gerhard Bringmann

Beilstein J. Org. Chem. 2014, 10, 276–281, doi:10.3762/bjoc.10.23

• isolation and structural elucidation of an unprecedented C9-spiro-fused 7,8-seco-ent-abietane, named decandrinin (1) (Figure 1), from the bark of an Indian mangrove, C. decandra, collected in the estuary of Godavari, Andhra Pradesh. The absolute stereostructure of 1 was established by HRMS (ESI), extensive

Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of ¹³C chemical shifts

• Simone Di Micco,
• Angela Zampella,
• Maria Valeria D’Auria,
• Carmen Festa,
• Simona De Marino,
• Raffaele Riccio,
• Craig P. Butts and
• Giuseppe Bifulco

Beilstein J. Org. Chem. 2013, 9, 2940–2949, doi:10.3762/bjoc.9.331

• . Plakilactone H was used as a template to set up the potential application of a combined approach of quantitative NMR-derived interproton distances and QM calculations of 13C chemical shifts in defining the stereostructure of highly flexible chemical scaffolds. The two independent methodologies agree and

Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• two halogen atoms are apparently correct, the given stereochemistry is disputable, since no unambiguous stereostructure assignment was performed. It is surprising that the d,l-diastereomer of 61 furnishes the same iodine addition product as the meso-compound, as claimed by the authors [33]. Turning to

Asymmetric one-pot sequential Friedel–Crafts-type alkylation and α-oxyamination catalyzed by a peptide and an enzyme

• Kengo Akagawa,
• Ryota Umezawa and
• Kazuaki Kudo

Beilstein J. Org. Chem. 2012, 8, 1333–1337, doi:10.3762/bjoc.8.152

• of the second-step α-oxyamination was determined mainly by the stereostructure of the peptide catalyst rather than by the chirality of the intermediate 3. Finally, other substrates were tested in the present one-pot sequential reaction system (Table 2). Several substituted indoles gave the products

• aqueous media, and mild reaction conditions for enzymatic reactions, various types of new sequential reactions can be expected for producing highly functionalized compounds. Oxygen-functionalized indole compounds. Resin-supported peptide catalyst. Effect of the stereostructure of the peptide catalyst. One

Efficient syntheses of 25,26-dihydrodictyostatin and 25,26-dihydro-6-epi-dictyostatin, two potent new microtubule-stabilizing agents

• María Jiménez,
• Wei Zhu,
• Andreas Vogt,
• Billy W. Day and
• Dennis P. Curran

Beilstein J. Org. Chem. 2011, 7, 1372–1378, doi:10.3762/bjoc.7.161

• by Pettit and coworkers [5][6], its complete stereostructure was proposed by Paterson and Wright in 2004 [7]. The structure assignment phase was finalized in 2004 when total syntheses by Paterson and our group confirmed the assignment [8][9]. The two synthetic samples of dictyostatin provided

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• ]. This synthesis was important in establishing the absolute stereostructure of the natural product. Subsequently, numerous synthetic approaches to related core THF arrays have been reported. Total synthesis of parviflorin Parviflorin (153), a relatively rare C35 adjacent bis-THF acetogenin, was isolated