(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• esterification of alcohol (±)-5 gave redox active ester (±)-6, which was itself shown to be a suitable substrate for nickel-catalysed decarboxylative cross coupling reactions to aryl-substituted BCPs (±)-7. Oxidation of alcohol (±)-8 gave acid (±)-9 which yielded amine (±)-10 after a Curtius rearrangement

• oxidation of alcohol 175 with Dess–Martin periodinane. Synthesis of cubane 166 was then achieved by [2 + 2] cycloaddition of enone 176 using acetone as the photosensitiser (to 177), the first Favorskii ring contraction (to 178), deketalisation, the second Favorskii ring contraction and esterification (to

Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• diaryliodonium salts in a cascade cyclization, the cyclization features a copper-catalyzed activation strategy involving the cleavage of the C–I bond and esterification. The resulting cascade of selective arylation/intramolecular cyclization facilitated the synthesis of 3,4-benzocoumarin derivatives. The

Substrate specificity of a ketosynthase domain involved in bacillaene biosynthesis

• Zhiyong Yin and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2024, 20, 734–740, doi:10.3762/bjoc.20.67

• ) allowed for test incubations with unlabelled glutamic acid in the presence of the cofactor pyridoxal phosphate (PLP), showing the complete conversion of glutamic acid (3) into γ-aminobutyric acid (4) (Scheme 2). The crude product was used without purification for a Schotten–Baumann esterification with

• ester 5 was coupled with the carboxylic acid (S)-8, derived from ʟ-leucine ((S)-6) via hydroxyacid (S)-7, to yield the amide (S)-9. Deprotection through catalytic hydrogenation to (S)-10, saponification of the acetate ester and Steglich esterification with N-acetylcysteamine gave access to the desired

Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• pikromycin and the aglycones in this family, 10-deoxymethynolide (24) and norbonolide (25), using asymmetric aldol reaction, Yamaguchi esterification, and ring-closing metathesis as key steps [65][66]. Nevertheless, the inherent complexity of these natural products demands high step counts, leading to low

Copper-catalyzed multicomponent reaction of β-trifluoromethyl β-diazo esters enabling the synthesis of β-trifluoromethyl N,N-diacyl-β-amino esters

• Youlong Du,
• Haibo Mei,
• Ata Makarem,
• Ramin Javahershenas,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2024, 20, 212–219, doi:10.3762/bjoc.20.21

• IKERBASQUE, Basque Foundation for Science, Alameda Urquijo 36-5, Plaza Bizkaia, 48011 Bilbao, Spain 10.3762/bjoc.20.21 Abstract An efficient multicomponent reaction of newly designed β-trifluoromethyl β-diazo esters, acetonitrile, and carboxylic acids via an interrupted esterification process under copper

• . Conclusion In summary, a series of new β-trifluoromethyl β-diazo esters have been designed, which are applied for the first time in a cascade reaction through an interrupted esterification with nitrile ylides as the key intermediates under copper-catalysis conditions. Varieties of unsymmetric trifluoromethyl

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• 5.78 (d, J = 7.8 Hz, 1H, H-1′); δC 94.0 (C-1′)] implied that compound 4 was a β-glycosyl ester. The HMBC correlation of H-1′ with a carbonyl carbon [δC 174.7 (C-3)] revealed that esterification occurred at C-3 with a glucopyranose moiety at the anomeric position (Figure 4). A β-1,3-glucosyl linkage

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

• -enyl) lipid chain (Figure 9) [88]. The synthesis starts from serine 9.1 and produce (R)-solketal (9.2) following a three-step protocol [89] that was recently revisited [90] (diazotation, esterification, acetalization). Then, the incorporation of the oleyl chain (C18H35) was achieved by the

• Markowska et al. in 1993 [134]. As detailed in Figure 28, the synthesis starts with a Mitsunobu esterification of 28.1 with thioacetic acid to produce the thioester 28.2. Then, the reduction with lithium aluminium hydride produced the thiol 28.3. Finally, the phosphocholine moiety was introduced by using

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• was shown to be a key player in lanostane triterpenoid cytotoxicity; increased activity was demonstrated either by its esterification with glucose or by its reduction into a hydroxymethylene group unlike its presence as a free carboxylic acid moiety [23]. Thus, our findings provide further insights

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• reactions (e.g., hydrolysis, esterification, oxidation) might be due to the isolation conditions or they could be attributed to unspecific enzymatic biotransformations. For compound 1, no spontaneous conversion to the ester 2 was observed, even after storage in methanol for two months. In contrast, the

Synthesis of medium and large phostams, phostones, and phostines

• Jiaxi Xu

Beilstein J. Org. Chem. 2023, 19, 687–699, doi:10.3762/bjoc.19.50

• intramolecular esterification gave the cyclized products 74 and 75 in 82% yield with a 5:1 ratio of anti/cis diastereomers accompanied by a dimeric byproduct 76 in 2.5% yield. The anti-diastereomer with cis-PhO and Me groups as major product 74 is attributed to the stereoelectronic effect between the n-orbital

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• , the authors employed an Ullmann-type condensation [28] between ester 14 and 4-iodobenzaldehyde (15) to give the corresponding diaryl ether 16 in 78% yield. The subsequent demethylation reaction using boron triiodide also promoted the hydrolysis of the ester, and thus a re-esterification step was

• esterification reactions gave the ester 33 which was submitted to a Sonogashira coupling reaction with propargyl alcohol to give the advanced intermediate 34 [34]. Partial hydrogenation of the triple bond in 34 using Lindlar’s catalyst led to the cis-allylic alcohol 35 and subsequent ester hydrolysis led to the

• protection with BnBr and oxidation led to the carboxylic acid 107. Esterification of the carboxylic acid followed by the cleavage of the silyl ether using TBAF and hydrolysis led to the seco-acid 108. Macrolactonization using the Mitsunobu conditions gave combretastatin D-4 (4) after cleavage of the benzyl

Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• H10Bpin with the borinic ester intermediate 44 showed no scrambling of the 10B label, suggesting a σ-bond metathesis mechanism for this transborylation reaction (Scheme 10). Thomas et al. reported the H-B-9-BBN-catalysed esterification of alkyl fluorides, using carboxylic acids and HBpin (Scheme 11) [75

• -catalysed asymmetric reduction of propargylic ketones and the proposed mechanism. H-B-9-BBN-catalysed C–F esterification of alkyl fluorides and the proposed mechanism. H-B-9-BBN-catalysed 1,4-hydroboration of enones and the proposed mechanism. Boric acid-promoted reduction of esters, lactones, and

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• compound. The diastereoselectivity was modest with a dr of 3:2. Esterification of the secondary alcohol followed by silyl removal gave access to the key scaffold 122 (Scheme 22). 2.2 Synthesis of aquatolide (4): Late-stage NHK medium-ring formation Aquatolide (4) is a sesquiterpene lactone isolated from

Nostochopcerol, a new antibacterial monoacylglycerol from the edible cyanobacterium Nostochopsis lobatus

• Naoya Oku,
• Saki Hayashi,
• Yuji Yamaguchi,
• Hiroyuki Takenaka and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2023, 19, 133–138, doi:10.3762/bjoc.19.13

• esterification. The resulting ester 2a or 2b was purified by reversed-phase HPLC and deprotected by a short treatment with 80% aqueous acetic acid at 58–59 °C to give 1-linoleoyl-sn-glycerol (3a) or 3-linoleoyl-sn-glycerol (3b), respectively (Scheme 1). Similarly, to our experience during the isolation of

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• cyclodextrin/polysaccharide. The 1200 cm−1 band is also more intense when changing that ratio. This difference is also correlated to the C=O band found at 1700 cm−1. In the case of the chitosan matrices, for a high concentration of chitosan, the crosslinking reactions include esterification links, amide

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• basic deprotection of the acetyl and benzoyl groups, followed by intramolecular cyclization and angelate esterification. Also, the differently redox-active DBCOD bearing an angelate functional group enabled the synthesis of kadsuphilin N (234). The synthetic sequence utilizes Fu’s protocol for palladium

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• hydrolysis, esterification, and Jones oxidation, affording intermediate 14 with a good 79% yield over 4 steps. Next, the methyl ketone was converted to an enol triflate, and then coupled with Li2CuCN(CH2SPh)2. A reduction of the ester with DIBAL, followed by Dess–Martin oxidation and Wittig reaction lead to

Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• cross-coupling [34] in excellent yield. Esterification of 6 with monomethyl H-phosphonate tert-butylamine salt [35] resulted in the mixed H-phosphonate ester 7 in excellent yield. Cyclization using our homolytic aromatic substitution methodology [36] gave P-heterocycle 8 in modest yield. Other methods

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• biosynthetic gene clusters of valanimycin and KA57-A, respectively. The in vitro characterization of Ady1 suggested the late-stage biosynthetic pathway of azodyrecin: the azoxy bond formation is followed by the Ady1-mediated methyl esterification to form saturated azodyrecins, and then the subsequent

• installation of a cis-olefin on the 1,2-positions of the alkyl side chain would afford azodyrecins A–C (1–3), in a reaction likely to be mediated by Ady9, a putative fatty acid desaturase. Nevertheless, the possibility that the desaturation occurs prior to the methyl esterification could not be excluded. The

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• used as organocatalyst in two classical umpolung reactions of cinnamaldehyde: its cyclodimerization and its oxidative esterification. Keywords: Breslow intermediate; cathodic reduction; flow electrochemistry; N-heterocyclic carbene; oxidative esterification; Introduction Ionic liquids (ILs) are well

• atom is reversed (umpolung) from electrophilic to nucleophilic (Scheme 3). This approach can be exploited in many organic reactions, such as: the benzoin condensation [16][17], esterification and amidation of benzaldehydes and cinnamaldehydes [18][19], synthesis of γ-butyrolactones [20], synthesis of

• electrochemistry, NHC instability (and anodic electroactivity) prevented its cathodic generation and subsequent use as catalyst or reagent. Instead, the NHC was generated by chemical deprotonation using a strong base (DBU) and then applied in anodic esterification [30][31][32], and amidation of aromatic aldehydes

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• . Starting materials. Methyl 2-formylbenzoate (1a) and methyl 2-benzoylbenzoate (1h) were purchased from Tokyo Chemical Industry Corporation. Methyl 2-acetylbenzoate (1g) [17] was prepared from commercially available 2-acetylbenzoic acids (Tokyo Chemical Industry Corporation) by usual esterification using

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• esters with mainly fruity odor profiles are obtained in moderate to excellent yields. Some selected esters (14–16) and their odor profiles are shown in Scheme 4 [32]. Related methods for the esterification of natural occurring alcohols, such as geraniol, utilizing immobilized enzyme-catalysis in packed

• ) to (+)-nootkatone (8) under catalyst and solvent-free conditions in a segmented flow. Enzyme-catalyzed acetylation of isoamyl alcohol (9) in a biphasic n-heptane/water mixture utilizing a CorningTM Low Flow reactor. Esterification of alcohols by transesterification, catalyzed by immobilized

An isoxazole strategy for the synthesis of 4-oxo-1,4-dihydropyridine-3-carboxylates

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2022, 18, 738–745, doi:10.3762/bjoc.18.74

• cyanation of the resulted isoxazoles 8a–f to cyanides 9a–f using Me2C(OH)CN/(Me2N)2C=NH [29], their acid hydrolysis, followed by esterification of the resulting acids 9a–f with diazomethane. 4-Iodoisoxazoles 12a–f, necessary for the preparation of 3,4-disubstituted isoxazoles, were obtained by iodination of

Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• heating. This observation explains the formation of side-product 8 in the original Flematti’s synthesis [21] (Scheme 1). With thiopyranthiones 6b, 15b, 16b in hand, we carried out the esterification step with 2-chloropropionyl chloride, followed by intramolecular cyclization which provided the desired

• prepare the desmethyl analogue 26 through esterification of 6b with chloroacetyl chloride followed by intramolecular cyclization stayed unrewarded due to the lack of reactivity in the cyclization step. In order to overcome this problem a new strategy was developed. We combined the synthetic protocol of

• multistep procedure [33]. The synthesis of target compound 26 was accomplished in two steps by double esterification and elimination of 23. Dicarbonate 24 partially eliminated over C7–C7a to give 25 upon aqueous workup. In order to maximize the yield, the organic fraction containing a mixture of 24 and 25

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• polyacetylene, with a special focus on the different possible co-conformations of the rotaxane (see Figure 7) [54]. The synthesis of the acetylene monomers 31, containing a chiral rotaxane side-chain, was achieved by tributylphosphane-catalyzed esterification. Two different macrocycles having either one BINOL