Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• atmosphere afforded the quinoxaline azobenzene derivative 11 [68]. Subsequent methylation using methyl iodide [69] mainly resulted in the formation of the N-methylated non-photochromic product 12b but in low yields also the desired photochromic methoxy-substituted quinoxaline azobenzene derivative 12a

Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

• Clémence Moitessier,
• Ahmad Rifai,
• Pierre-Edouard Danjou,
• Isabelle Mallard and
• Francine Cazier-Dennin

Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67

• reported synthesis [28]. 5-Methoxy-4,5-dihydroisobenzofuran (4b): Compound 3 (3.3 g, 24.3 mmol) was added to a solution of NaH (1.46 g, 36.4 mmol) in anhydrous dioxane (20 mL). After 15 minutes, methyl iodide (1.8 mL, 29.1 mmol) was slowly added and the resulting solution was stirred overnight at room

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• , whereas the use of exactly stoichiometric amounts resulted in incomplete N-methylation. Treating the Boc-protected methyl ester of iodotyrosine 21 with a larger excess of base and methyl iodide (10 equiv each) led to the formation of the α-quaternary amino acid 23 (Scheme 4). An alternative route to the N

Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• phthalimides 16 and 23 [29]. These intermediary compounds 16 and 23 also allowed an N-methylation of the azaindole moiety with sodium hydride (NaH) and methyl iodide (MeI) to yield 17 and 24. By ethanolic hydrazinolysis and microwave irradiation the phthalimides (16, 17, 23, and 24) were deprotected yielding

Ammonium-tagged ruthenium-based catalysts for olefin metathesis in aqueous media under ultrasound and microwave irradiation

• Łukasz Gułajski,
• Andrzej Tracz,
• Katarzyna Urbaniak,
• Stefan J. Czarnocki,
• Michał Bieniek and
• Tomasz K. Olszewski

Beilstein J. Org. Chem. 2019, 15, 160–166, doi:10.3762/bjoc.15.16

• Discussion The structures of the catalysts 1–5 used in this work are depicted in Figure 1. Catalyst 1b was prepared by alkylation of the non-ionic tertiary amine-containing analogue with methyl iodide [71]. Complexes 1c,d were prepared from their commercially available corresponding chloride salt 1a [72] by

A simple and effective preparation of quercetin pentamethyl ether from quercetin

• Jin Tatsuzaki,
• Tomohiko Ohwada,
• Yuko Otani,
• Reiko Inagi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2018, 14, 3112–3121, doi:10.3762/bjoc.14.291

• for about 2 hours, affording quercetin pentamethyl ether (QPE) quantitatively as a single product. When methyl iodide was used in place of dimethyl sulfate, the C-methylation product 6-methylquercetin pentamethyl ether was also formed. A computational study provided a rationale for the experimental

• is also presented. Results and Discussion Reported per-O-methylation reactions and our re-examination Conventional methylation of phenolic compounds is generally performed with methyl iodide (MeI) or dimethyl sulfate (Me2SO4) in an aprotic polar solvent in the presence of a base. Although acetone and

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum

• Jan Rinkel,
• Alexander Babczyk,
• Tao Wang,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277

• ]+), suggesting the structure of a trimethylanisole for 24. Six constitutional isomers of this compound exist (Table 2). For four of these compounds the corresponding trimethylphenols were commercially available that were O-methylated with methyl iodide and K2CO3 to yield compounds 24a, 24b, 24c and 24e. The

• (CH3), 12.1 (CH3). Synthesis of trimethylanisoles 24 and 24a–e To a solution of the respective phenol derivative (23f–k, 15.0 mg, 0.11 mmol, 1 equiv) in dry DMF (2.2 mL), K2CO3 (15.2 mg, 0.11 mmol, 1 equiv) was added and the mixture was stirred at room temperature for 30 min. Methyl iodide (31 mg, 0.22

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• -amino esters, we tried their preparation via a C-methylation of α-nitroester 6a in DMF using sodium hydride and methyl iodide. Upon purification, this gave 46% of the nitro compound 9 with 94% purity (as assessed by 1H NMR). Despite this modest yield, the ensuing reduction using zinc and hydrochloric

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• ) species readily react with various methyl halides such as methyl iodide to form a methyl–cobalt complex. Moreover, methanol could also serve as a methyl donor after the activation of the OH group by a Lewis acid such as Zn2+ [70][71]. Thiols could also mediate the methylation of 1 with methyl iodide or

Studies towards the synthesis of hyperireflexolide A

• G. Hari Mangeswara Rao

Beilstein J. Org. Chem. 2018, 14, 2106–2111, doi:10.3762/bjoc.14.185

• subjected to methylation using 1.1 equiv of K2CO3 in the presence of methyl iodide (MeI). The α-methylated β-ketoester 8 was obtained in good yield. In the 1H NMR, 8 showed a signal at 3.70 ppm as doublet for C-10 (ring junction) proton confirming the selective methylation at C-8. Further, installation of

• . Experimental procedures and analytical data Methyl 1,1,5-trimethyl-3,4-dioxohexahydro-1H-cyclopenta[c]furan-5-carboxylate (8): To a solution of the γ-lactone-fused cyclopentanone 6 (16 mg, 0.07 mmol) in dry acetone (0.4 mL) under argon was added anhydrous K2CO3 (9.7 mg, 0.07 mmol) and methyl iodide (12 mg

• . Methyl 1,1,3a,5-tetramethyl-3,4-dioxohexahydro-1H-cyclopenta[c]furan-5-carboxylate (9): To a solution of the γ-lactone-fused cyclopentanone 8 (15 mg, 0.07 mmol) in dry acetone (0.4 mL) under argon was added anhydrous K2CO3 (9.7 mg, 0.07 mmol) and methyl iodide (12 mg, 0.08 mmol) at 0 °C. The reaction was

Oligonucleotide analogues with cationic backbone linkages

• Melissa Meng and
• Christian Ducho

Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111

• -deprotection cycle afforded thiourea-linked oligonucleotide analogue 41. Subsequent reaction of the thiourea internucleotide linkages with methyl iodide furnished the protected S-methylthiourea-linked oligomer 42 and finally, after cleavage from the solid support and acidic deprotection, the envisioned DNmt

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• derivate 57 were N,N-dimethylformamide, methyl iodide, 4,5-benzotropone (11), and NaClO4 [65]. As polycyclic conjugated π systems can endow new properties to the original π system, conjugated systems are important in terms of both theoretical and experimental aspects. Nitta’s group extensively studied the

Volatiles from the xylarialean fungus Hypoxylon invadens

• Jeroen S. Dickschat,
• Tao Wang and
• Marc Stadler

Beilstein J. Org. Chem. 2018, 14, 734–746, doi:10.3762/bjoc.14.62

• hydroxy-methylbenzaldehydes were converted into the corresponding methoxy derivatives by methylation with potassium carbonate and methyl iodide. The GC–MS analysis of all the obtained methylation products unequivocally established the identity of 17 and 2-methoxy-4-methylbenzaldehyde by the same retention

• the mixture was stirred at room temperature for 30 minutes. Then, methyl iodide (30 μL, 68 mg, 0.5 mmol) was added and the reaction was stirred at room temperature overnight. The reaction was quenched by the addition of distilled water, and the aqueous phase was extracted three times with ethyl

Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

• Rebecca Pittkowski and
• Thomas Strassner

Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54

• synthesized from 3-methyl-1-phenylimidazolium iodide (1) according to a modified literature procedure (Scheme 1) [41][42]. The starting imidazolium salt 1 was prepared from phenylimidazole by addition of methyl iodide as previously described [43]. Complexes 2 and 3 were obtained as yellow solids in isolated

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• , reduction, nitro-aldol reaction, and dehydration (Scheme 1). Methylation of the ester 2 in the alpha position proceeded easily with LDA as a base and methyl iodide as an alkylating agent. The ester functionality was then reduced with DIBAL in dichloromethane to afford aldehyde 4 in 90% yield. A base

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• monofluoro-substituted dye TO-1F. Reagents, conditions and yields: (i) sodium methanethiolate (NaSCH3), 7 h, reflux; (ii) methyl iodide, overnight, overall yield for (i) and (ii) 9%; (iii) 5-fluoro-2,3-dimethylbenzothiazolium iodide and triethylamine, rt, overnight, yield 24%. Synthesis of new halogen

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• alkyl halides. Shutt and Trippett were able to alkylate vinylphosphines with methyl iodide or benzyl iodide, although attempts to use other alkyl halides, including benzyl bromide, ethyl bromoacetate and ethyl iodoacetate, in the presence of aprotic solvents provided only β-phosphonioylides 2 or

• addition reaction only in reactions with methyl iodide and benzyl iodide [9]. A similar alkylation of isopropenyldiphenylphosphine with methyl iodide in ether solution under a nitrogen atmosphere leading to isopropenylmethyldiphenylphosphonium iodide (3) in a yield of 97% was described by Schweizer and

• phosphorus ylides from vinylphosphonium salts. Intramolecular Wittig reaction with the use of vinylphosphonium salts. Alkylation of diphenylvinylphosphine with methyl or benzyl iodide. Methylation of isopropenyldiphenylphosphine with methyl iodide. Alkylation of phosphines with allyl halide derivatives and

Synthesis of 2-aminosuberic acid derivatives as components of some histone deacetylase inhibiting cyclic tetrapeptides

• Shital Kumar Chattopadhyay,
• Suman Sil and
• Jyoti Prasad Mukherjee

Beilstein J. Org. Chem. 2017, 13, 2153–2156, doi:10.3762/bjoc.13.214

• an overall yield of 42% over five steps. One-pot deprotection–oxidation [14] of the oxazolidine moiety in 9 proceeded uneventfully to provide N-Boc-2-amino-6-heptenoic acid (10) in good yield. The latter was smothly protected as its methyl ester using methyl iodide in the presence of cesium carbonate

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

• Valentin A. Rassadin,
• Mirko Scholz,
• Anastasiia A. Klochkova,
• Armin de Meijere and
• Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

• methyl iodide (Scheme 2). Unfortunately, this apparently simple transformation yielded a mixture of C-, N- and C,N-methylation products due to similar reactivities of the C- and N-nucleophilic centers in 3a. At best, the tertiary sulfonamide 5 was isolated in 32% yield. In contrast to the behavior of 3a

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• DreM did not appear to be promising. Finally, the alkaloids 6-O-demethylmenisporphine (4) and dauriporphinoline (5) were converted into their corresponding 6-methoxy derivatives, the oxoisoaporphine alkaloids menisporphine (2) and dauriporphine (3). Using Kunitomo’s [7][17] protocol (methyl iodide in

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• to give pure compound 10. General procedure 3. Synthesis of methyl esters 10'. The Castagnoli–Cushman product 10 was dissolved in dry acetone (10 mL per 1 mmol). Methyl iodide (2.5 equiv) and K2CO3 (2.5 equiv) were added to the solution and the resulting suspension was stirred for 24 h at room

Total syntheses of the archazolids: an emerging class of novel anticancer drugs

• Stephan Scheeff and
• Dirk Menche

Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108

• borohydride delivered the desired alcohol in a 10:1 diastereoselectivity. The alcohol was methylated by a protocol involving methyl iodide and LiHMDS, that had been previously used by the group [45]. The stannane was finally converted to the iodide 55 by iododestannylation [95] to complete the fragment

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• -octyl bromide by the corresponding tosylated compound, the yield of 5a decreased from 78% to 67% (Table 3, entries 1 and 2). A comparable reactivity was found for the reactions with methyl iodide and n-butyl bromide, affording 5b and 5c in 77% and 79% yields, respectively (Table 3, entries 3 and 4