Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• produces the diester 4.12 with an inversion of the configuration of the chiral carbon atom. Then, 4.12 was hydrolyzed in the presence of KOH to produce 4.10. The installation of the phosphocholine group was achieved following two schemes: a) Starting from the diol 4.10 (Figure 4C), tritylation and

• deprotection of diol with HCl, the aryl ether glycerol 10.3. The protection of the sn-2 position with a benzyl group was achieved by a classical tritylation of the primary alcohol, benzylation of the secondary alcohol and removing the trityl protecting group. The low yield of this three-step sequence is due to

• , both enantiomers were reported. For the control of the chirality in position 2 of glycerol, (S)-solketal (17.1) was used as starting material to prepare first the hexadecylglycerol (R)-17.2 which was converted to its enantiomer following a five-step sequence (Figure 17A). First, tritylation and

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• -bis(trimethylsilyl)acetamide [34], simultaneous tritylation of N9 and the N2 atoms was achieved using 4,4'-dimethoxytrityl chloride in pyridine. The obtained derivative 4 was amenable to nitrile reduction using diisobutylaluminium hydride (DIBAL-H) in dichloromethane at −78 °C, followed by workup with

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

• by 5'-tritylation. In the case of guanosine, this strategy for 2'-OH methylation was unsuccessful, owing again to undesired methylation at the nucleobase. Instead, the 5'-O-monomethoxytrityl derivative of N2-isobutyrylguanosine was treated with diazomethane in dimethylformamide in the presence of tin

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• that acceptable yields could be achieved under the highly reactive conditions involving two equivalents LDA and one equivalent 5. The silyl protecting groups were then removed with TBAF giving compound 11 in 99% yield. Tritylation of 11 with DMTrCl gave 12, which was phosphitylated with reagents 13 and

• protections, which contained a tertiary butyl carbamate moiety, were not completely stable under the acidic conditions needed for de-tritylation in each synthetic cycle. Once the protection was lost, in the coupling step, incoming phosphoramidites would react with the free amino groups, and branched ODNs

6’-Fluoro[4.3.0]bicyclo nucleic acid: synthesis, biophysical properties and molecular dynamics simulations

• Sibylle Frei,
• Andrei Istrate and
• Christian J. Leumann

Beilstein J. Org. Chem. 2018, 14, 3088–3097, doi:10.3762/bjoc.14.288

• . The relative configuration at C(5’) could be assigned by 1H,1H-ROESY experiments (Supporting Information File 1). Tritylation of allylic alcohol 8 with 4,4-dimethoxytrityl chloride (DMTr-Cl) afforded intermediate 9 which was subsequently phosphitylated with 2-cyanoethyl N,N

• of the nucleobase was partially removed. As a consequence an additional benzoylation step was needed to obtain the allylic alcohol 14 in high yields. Verification of the configuration at C(5’) was again accomplished by 1H,1H-ROESY experiments (Supporting Information File 1). Tritylation of the

Phosphoramidite building blocks with protected nitroxides for the synthesis of spin-labeled DNA and RNA

• Timo Weinrich,
• Eva A. Jaumann,
• Ute M. Scheffer,
• Thomas F. Prisner and
• Michael W. Göbel

Beilstein J. Org. Chem. 2018, 14, 1563–1569, doi:10.3762/bjoc.14.133

• 6-chloro derivative 13 as starting material, easily accessible from deoxyadenosine via enzymatic deamination, acetylation [37] and chlorination. This compound reacted cleanly and yielded 67% of the TEMPO conjugate 14. After deacetylation (15) and tritylation (16), amidite building block 7 was

• similar way as 13 by enzymatic deamination of adenosine, acetylation [46] and chlorination. A clean reaction with amino-TEMPO compound 10 then produced 78% of compound 18. Ester hydrolysis (19) and tritylation afforded 20 which was silylated with 1.8 equiv of TBS chloride. Although the 3’-silylated and

Mechanochemistry of nucleosides, nucleotides and related materials

• Olga Eguaogie,
• Joseph S. Vyle,
• Patrick F. Conlon,
• Manuela A. Gîlea and
• Yipei Liang

Beilstein J. Org. Chem. 2018, 14, 955–970, doi:10.3762/bjoc.14.81

• -fluorouracil (5FU) and nucleoside analogue prodrugs subject to mechanochemical co-crystal or polymorph transformation. Nucleoside tritylation effected by hand grinding in a heated mortar and pestle. Persilylation of ribonucleoside hydroxy groups (and in situ acylation of cytidine) in a MBM. Nucleoside amine

An efficient synthesis of 1,6-anhydro-N-acetylmuramic acid from N-acetylglucosamine

• Matthew B. Calvert,
• Christoph Mayer and
• Alexander Titz

Beilstein J. Org. Chem. 2017, 13, 2631–2636, doi:10.3762/bjoc.13.261

• regioisomers, out of which the desired anhydroMurNAc derivative 1 could only be isolated in trace quantities from the mixture with isomers 5–11 (Scheme 2). A selective protection of the 4-OH position of 4 has been reported, and as such this tritylation was carried out, delivering 12 in 74% yield [12]. The

Synthesis of oligonucleotides on a soluble support

• Harri Lönnberg

Beilstein J. Org. Chem. 2017, 13, 1368–1387, doi:10.3762/bjoc.13.134

• -detritylation and the second after the coupling/oxidation step (Scheme 5). The detritylation was carried out with HCl in a 1:1 (v/v) mixture of MeOH and DCM under carefully controlled conditions. The acid was neutralized with slight excess of pyridine. To prevent re-tritylation of the exposed 5´-OH by trityl

An improved preparation of phorbol from croton oil

• Alberto Pagani,
• Simone Gaeta,
• Andrei I. Savchenko,
• Craig M. Williams and
• Giovanni Appendino

Beilstein J. Org. Chem. 2017, 13, 1361–1367, doi:10.3762/bjoc.13.133

• , problematic for the multigram isolation of phorbol due to the extensive handling of the toxic croton oil and the ultra-toxic mixture of phorbol diesters obtained in the acidic transesterification step. Furthermore, the tritylation of the crude mixture of phorbol diesters suffered from interference from

• hydrolyzed without epimerization to 4α-phorbol (2) and extensive degradation, and accounted for ca 30% of the amount of phorbol obtained from the transesterification. The recovery of phorbol from the monoesters 1d and 1e was, however, possible after tritylation of the primary 20-hydroxy group (vide infra

• the other hand, tritylation of the primary 20-hydroxy group had a surprising stabilizing effect toward basic degradation, making it possible to remove the remaining ester group. 20-Tritylphorbol (1c) [18] obtained in this way could be directly used for the synthesis of specific esters, or

Facile synthesis of a 3-deazaadenosine phosphoramidite for RNA solid-phase synthesis

• Elisabeth Mairhofer,
• Elisabeth Fuchs and
• Ronald Micura

Beilstein J. Org. Chem. 2016, 12, 2556–2562, doi:10.3762/bjoc.12.250

• amidine protection of the exocyclic C6-NH2 group. At the same time, the applied excess of the reagent allowed to transiently form the corresponding nucleoside 2’,3’-O-acetal [32], leaving the primary 5’-OH group available for selective tritylation with 4,4’-dimethoxytrityl chloride to give compound 6

Qualitative evaluation of regioselectivity in the formation of di- and tri-6-O-tritylates of α-cyclodextrin

• Keisuke Yoshikiyo,
• Yoshihisa Matsui and
• Tatsuyuki Yamamoto

Beilstein J. Org. Chem. 2015, 11, 1530–1540, doi:10.3762/bjoc.11.168

• -isomer mainly retard the additional tritylation of the C(6)-OH of the adjacent glucopyranoses in a counter-clockwise direction (Glu-F and -C, respectively). 1H NMR spectra of the AD-isomer showed that the O(6)-H and C(6)-H signals of Glu-C and -F are shifted upfield due to the ring current of the trityl

• groups. Thus, it is concluded that the bulky trityl groups on Glu-A and Glu-D are oriented to Glu-F and Glu-C, respectively, and sterically retard additional tritylation on Glu-F and Glu-C. Similar steric hindrance was also observed in the additional tritylations of mono-6-O-trityl-α-CD, 6A,6B-di- and 6A

• ,6C-di-O-trityl-α-CD’s. Keywords: 1H and 13C NMR spectroscopy; quantitative analysis; regioselectivity; tritylation; ultra-fast liquid chromatography (UFLC); Introduction Regioselective modification and deprotection on the primary hydroxy side of cyclodextrins (CDs) are of great importance in

Synthesis and biological evaluation of a novel MUC1 glycopeptide conjugate vaccine candidate comprising a 4’-deoxy-4’-fluoro-Thomsen–Friedenreich epitope

• Manuel Johannes,
• Maximilian Reindl,
• Bastian Gerlitzki,
• Edgar Schmitt and
• Anja Hoffmann-Röder

Beilstein J. Org. Chem. 2015, 11, 155–161, doi:10.3762/bjoc.11.15

• [48] in excellent 85% yield over three steps. Acid-catalyzed 4,6-benzylidene deprotection and 6-O-tritylation then afforded alcohol 5 (83% over two steps), which was further converted into an intermediate triflate for subsequent nucleophilic fluorination with TBAF to provide the 4-fluorothioglycoside

Synthesis of phosphoramidites of isoGNA, an isomer of glycerol nucleic acid

• Keunsoo Kim,
• Venkateshwarlu Punna,
• Phaneendrasai Karri and
• Ramanarayanan Krishnamurthy

Beilstein J. Org. Chem. 2014, 10, 2131–2138, doi:10.3762/bjoc.10.220

• protecting group approach. We silylated 1 to afford 8 whose ketal was deprotected followed by tritylation to give the derivative 10, which is expected to be suited for the introduction of nucleobases by an SN2 reaction (Scheme 2). Once again, the Mitsunobu reaction with thymine proceeded smoothly. However

• di-Boc-adenine. An attempt to remove both Boc and silyl groups simultaneously. The synthesis of 26 via tritylation and benzoylation. Result of Boc deprotection of 29 with TFA. Supporting Information Supporting Information File 409: Experimental procedures. Supporting Information File 410: 1H, 13C

Structure/affinity studies in the bicyclo-DNA series: Synthesis and properties of oligonucleotides containing bc^en-T and iso-tricyclo-T nucleosides

• Branislav Dugovic,
• Michael Wagner and
• Christian J. Leumann

Beilstein J. Org. Chem. 2014, 10, 1840–1847, doi:10.3762/bjoc.10.194

• treatment with Bu4NOH in a mixed organic/aqueous solvent gave nucleosides 8α,β in good yield. It was at this step where the two anomers could be readily separated by flash chromatography. Continuing with 8β the synthesis of 10 was concluded by standard tritylation (→ 9) and phosphitylation. To extend on the

• ,β in a ratio of β:α = 1.2:1. After standard tritylation of 11α,β the anomeric mixture 12α,β became separable by flash chromatography and the corresponding β-nucleoside 12β could be smoothly converted into the phosphoramidite 13 by standard methods. Structural properties of nucleosides To get an