New efficient synthesis of polysubstituted 3,4-dihydroquinazolines and 4H-3,1-benzothiazines through a Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution sequence

• Long Zhao,
• Mao-Lin Yang,
• Min Liu and
• Ming-Wu Ding

Beilstein J. Org. Chem. 2022, 18, 286–292, doi:10.3762/bjoc.18.32

• /nucleophilic substitution reactions. Compared with the synthetic method to 4H-3,1-benzothiazines in Scheme 1f, we provide another new sequential synthetic route to 4H-3,1-benzothiazines, especially for N,N-disubstituted 2-amino-4H-3,1-benzothiazines. Results and Discussion We initially selected 2

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

• Yelong Lei and
• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

• -oxoalkanoates are used in the reaction, showing specific chemoselectivities controlled by the electronic effect (Scheme 4). Conclusion A new and efficient synthetic method for the synthesis of oxazolines has been developed with alkyl 2-diazo-3-oxoalkanoates and 2-arylaziridines as starting materials. Alkyl 2

First total synthesis of hoshinoamide A

• Haipin Zhou,
• Zihan Rui,
• Yiming Yang,
• Shengtao Xu,
• Yutian Shao and
• Long Liu

Beilstein J. Org. Chem. 2021, 17, 2924–2931, doi:10.3762/bjoc.17.201

• have a relatively simple structure and therefore make an attractive target for further medicinal chemistry studies. To enable these new SAR studies, we need to develop an efficient synthetic method to provide sufficient materials firstly. Hoshinoamide A shows a better antimalarial activity and less

A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones

• Yuki Yamamoto,
• Akihiro Tabuchi,
• Kazumi Hosono,
• Takanori Ochi,
• Kento Yamazaki,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 2906–2914, doi:10.3762/bjoc.17.198

• synthetic method that relies on a two-phase reaction system. Specifically, lactones are ring-opened and converted into dibromocarboxylic acids when treated with Br2 and a substoichiometric amount of PBr3. Subsequent treatment of these carboxylic acids with a base leads to the corresponding α-bromolactones

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• , this synthetic method (nucleophilic aromatic substitution reaction) is crucial for the development of alternative C–N bond-forming reactions to conventional metal-involved cross-couplings, providing axially chiral N-arylcarbazoles 60 in good yields with remarkable enantiocontrol through a

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

• was found to adopt “(S)” configuration which was unambiguously established by single crystal X-ray diffraction analysis (Figure 1) [45]. To prove the scalability of this synthetic method, we examined the synthesis of 3c and ent-3d in a 1 mmol scale (Scheme 5). The products 3c and ent-3d were isolated

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• of ammonia, formaldehyde, and acetaldehyde; and iii) preparation from furfural and ammonia. In addition, Hantzsch pyridine synthesis from ethyl acetoacetate, formaldehyde, and ammonia is a commonly used laboratory synthetic method. Recently, extensive and efficient methods for the construction of

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• [141] independently demonstrated photoredox/nickel-catalyzed approaches to olefin difunctionalizations involving C(sp3)–H activation. Thus, Kong devised a synthetic method combining nickel catalysis with tetrabutylammonium decatungstate (TBADT) as photocatalyst for the three component reaction of

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

• phosphoramidate and the guanidinobutyl phosphoramidate were synthesized [112]. A facile post-synthetic method was successfully employed to convert amine functionalities attached to ONs into guanidinium tethers. Both, the aminobutyl (76) and guanidinobutyl (77) modifications were introduced into α-ONs which

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

• Ákos Bajtel,
• Mounir Raji,
• Matti Haukka,
• Ferenc Fülöp and
• Zsolt Szakonyi

Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80

• (Figure 2). To synthesize the regioisomeric spiro-oxazolidinone derivative 12, (1R)-(−)-myrtenol (10) was chosen as starting material (Scheme 2). The synthetic method was similar to that mentioned above for (−)-isopinocarveol. In the first step, carbamate 11 was prepared [37], then the aminohydroxylation

Highly regio- and stereoselective phosphinylphosphination of terminal alkynes with tetraphenyldiphosphine monoxide under radical conditions

• Dat Phuc Tran,
• Yuki Sato,
• Yuki Yamamoto,
• Shin-ichi Kawaguchi,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 866–872, doi:10.3762/bjoc.17.72

• synthetic method for the highly selective synthesis of the (E)- or (Z)-isomers is strongly desired [27][28][29][30]. Furthermore, since it was reported that the introduction of a substituent into the ethylene moiety has a great effect on the catalytic activity [31], it is considered important to synthesize

Synthesis, structural characterization, and optical properties of benzo[f]naphtho[2,3-b]phosphoindoles

• Mio Matsumura,
• Takahiro Teramoto,
• Masato Kawakubo,
• Masatoshi Kawahata,
• Yuki Murata,
• Kentaro Yamaguchi,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2021, 17, 671–677, doi:10.3762/bjoc.17.56

• approaches for phosphine oxide B [12][13][14], alkylated products C [15], and transition metal complexes D [16][17] have also been developed. However, for isomers E [18][19] and G [20], only the synthetic method for pentavalent phosphine oxides has been reported. To the best of our knowledge, the synthesis

Synthesis and properties of oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing adenine, guanine, or 5-methylcytosine nucleobases

• Naohiro Horie,
• Takao Yamaguchi,
• Shinji Kumagai and
• Satoshi Obika

Beilstein J. Org. Chem. 2021, 17, 622–629, doi:10.3762/bjoc.17.54

• the middle position of 12-mer oligonucleotides (Table 1). The oligonucleotide synthesis was performed using an automated DNA synthesizer following the established synthetic method for GuNA[Me]-T-modified oligonucleotides [20]. 5-(Ethylthio)-1H-tetrazole (ETT) was used as an activator for the coupling

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

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

• esters 109 and hydroxy esters 110 by using (1H-benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) or (1H-benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (PyBOP) as activating agents as well (Scheme 18) [33]. The synthetic method was further investigated and

• directly. The multicomponent condensation reaction was applied as a direct synthetic method for phosphonodepsipeptides via the formation of 1-aminoalkylphosphonic acids and simultaneous construction of the phosphonate bond. A series of phosphonodepsipeptides 158 was prepared in good yields in a one-pot

Decarboxylative trifluoromethylthiolation of pyridylacetates

• Ryouta Kawanishi,
• Kosuke Nakada and
• Kazutaka Shibatomi

Beilstein J. Org. Chem. 2021, 17, 229–233, doi:10.3762/bjoc.17.23

• ]. Introducing a trifluoromethylthio group (CF3S–), which has high lipophilicity and strong electron-withdrawing properties, into medicinal compounds can improve their pharmacokinetic properties [7][8][9][10][11]. Hence, the development of a synthetic method for the preparation of trifluoromethyl thioethers has

A sustainable strategy for the straightforward preparation of 2H-azirines and highly functionalized NH-aziridines from vinyl azides using a single solvent flow-batch approach

• Michael Andresini,
• Leonardo Degannaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2021, 17, 203–209, doi:10.3762/bjoc.17.20

• the elements that affect the sustainability of a synthetic method, the choice of the solvent is crucial [5]. In fact, chemical solvents represent most of the total amount of chemical species used in manufacturing processes, and therefore, strongly affect waste disposal requirements and process related

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• developing the first successful synthetic method, groundbreaking news came from Sakurai’s laboratory around a decade after Mehta’s first unsuccessful attempt for the synthesis of sumanene (2, Scheme 2) [13]. Their exciting non-pyrolytic synthetic pathway for its construction commenced with an easily

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• 39. The latter was further converted into the thietane-containing spironucleoside 40 [40] (Scheme 8). The same research group synthesized the optically active 2-methylthietane-containing spironucleoside 43 by following a similar synthetic method [40] (Scheme 9). In 2009, Da Silva and co-worker

Synthesis of pyrrolidinedione-fused hexahydropyrrolo[2,1-a]isoquinolines via three-component [3 + 2] cycloaddition followed by one-pot N-allylation and intramolecular Heck reactions

• Xiaoming Ma,
• Suzhi Meng,
• Xiaofeng Zhang,
• Qiang Zhang,
• Shenghu Yan,
• Yue Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2020, 16, 1225–1233, doi:10.3762/bjoc.16.106

• ]isoquinolines. The multicomponent reaction was combined with one-pot reactions to make a synthetic method with good pot, atom and step economy. MeCN was used as a preferable green solvent for the reactions. Keywords: [3 + 2] cycloaddition; Heck reaction; hexahydropyrrolo[2,1-a]isoquinoline; one-pot reactions

• reactions to make it a green synthetic method with pot, atom and step economy (PASE) [55][56]. Results and Discussion Following the reported procedures for amino ester- and amino acid-based [3 + 2] cycloaddition reactions, pyrrolidine adducts 5 and 6 were synthesized by a three-component reaction of 1 or 2

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• three-component method was used for the quinazoline formation by refluxing 2-aminobenzophenone, difluorobenzaldehyde, ammonium acetate, and CuCl2 in ethanol. The synthetic method using a cheap catalyst, easy workup, and the high yield (78%) of quinazoline Q1 makes the compound a promising candidate as

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• synthetic chemists. However, only a few examples are reported for the synthesis of N-substituted thiazolidinones although the synthetic method of thiazolidinone was described in 1993 [16]. Frost and co-workers explored an efficient ruthenium-catalyzed O-to-S-alkyl migration of N-alkyloxazolidine-2-thiones

Synthesis of six-membered silacycles by borane-catalyzed double sila-Friedel–Crafts reaction

• Yafang Dong,
• Masahiko Sakai,
• Kazuto Fuji,
• Kohei Sekine and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2020, 16, 409–414, doi:10.3762/bjoc.16.39

• , Fukuoka 816-8580, Japan 10.3762/bjoc.16.39 Abstract We have developed a catalytic synthetic method to prepare phenoxasilins. A borane-catalyzed double sila-Friedel–Crafts reaction between amino group-containing diaryl ethers and dihydrosilanes can be used to prepare a variety of phenoxasilin derivatives

• phenoxasilin 5 in 87% yield [43]. Conclusion In summary, we have developed a new catalytic synthetic method to prepare six-membered silacyclic compounds, such as phenoxasilin and phenothiasilin derivatives, using a double sila-Friedel–Crafts reaction. The reaction system is applicable to diaryl ethers with

Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid

• Fei You,
• Xing He,
• Song Gao,
• Hong-Ru Li and
• Liang-Nian He

Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34

• -quality oligomeric ricinoleic acid, the synthetic method has kept on developing. Traditionally, p-toluenesulfonic or sulfuric acid are used as catalysts for the preparation of oligomeric ricinoleic acid. However, the equipment corrosion and the tedious workup process are inevitable, which reduce the

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• -catalyzed allylic substitution. Keywords: aldehyde; copper; copper catalysis; cross-coupling; palladium; synthetic method; Introduction α-Alkoxy-substituted carbanions (α-alkoxyalkyl anions) are useful C(sp3) nucleophiles for the construction of alcohol units found in a majority of pharmaceuticals