Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• cyclization to release an active alkyl radical intermediate C. Once formed, C added to the aldehyde group via a [4 + 2] annulation, releasing the alkoxy radical intermediate D. The latter then underwent a subsequent 1,2-H atom shift to generate the alkyl radical intermediate E which was further oxidized by

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• oscillator model of aromaticity) indexes [43] of the rings: while the trimethoxy-substituted, hydrazide-derived one presents values of 0.995 (hdz-CH3) and 0.990 (hdz-NO2), indicating high aromaticity, the aldehyde-derived ring shows HOMA indexes of 0.964 (hdz-CH3) and 0.961 (hdz-NO2), suggesting that, for

• corresponded to the aldehyde-derived ring, containing the –CH3 (or –NO2) substituents, an effect which is more explicit in hdz-NO2, probably due to the intrinsic disorder observed in its structure. The comparison between theoretical and experimental selected geometric parameters can be seen in Tables S1 and S2

• -substituent in the aldehyde-derived portion of hdz-NO2 caused a strong deshielding of the hydroxy group (assigned at 12.84 ppm) due to the removal of electron density on the carbon adjacent to –OH. On the other hand, in hdz-CH3, the presence of the methyl substituent moderately shields this proton (11.89 ppm

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• condensation between phenylene-1,2-diamines and carboxylic acids YCO2H [28], oxidative condensation between YCHO and phenylene-1,2-diamines [29], or reductive condensation between YCHO and 2-nitroanilines [24]. In this work we condensed the appropriate YCHO aldehyde (II) and 1,2-diaminobenzene (I) derivatives

• condenses with the aldehyde but where the subsequent second condensation and oxidation does not take place, i.e., structures of type IV (Scheme 1), which are known to be converted to benzimidazoles by various oxidants and/or catalysts [30][31][32]. The benzimidazoles were then doubly methylated with

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• hydroxy group showed DPPH radical scavenging activity. Compound 3d with a catechol-like structure exhibited the best antioxidant activity. Experimental General procedure for the Knoevenagel condensation DES (0.8 g) was introduced in a 10 mL round-bottomed flask. Then, the aldehyde (0.5 mmol) and rhodanine

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• , generated from the tetranuclear complex, as the catalytically active species. 2.4 A3 reactions In recent years, the three component reaction of an aldehyde, a secondary amine and a terminal alkyne, known as A3 reaction to afford chiral propargylamines 140 has received much attention. The latter compounds

• multifunctional catalytic system 142 incorporating ruthenium nanoparticles (RuNPS) and an NHC–Cu–Cl complex supported on silica (Scheme 56). The catalyst, Ru@SiO2–[Cu(NHC)] was successfully applied to a one-pot tandem A3 reaction of an aldehyde, alkyne, and secondary amine followed by hydrogenation of the

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

• intermediate 6.3 (ᴅ- or ʟ-threitol) that was then alkylated with mesityl lipid alcohol to produce 6.4 [80][81]. The acetal protecting group was removed in acidic conditions and then the intermediate 6.5 was subjected to oxidative cleavage to yield an aldehyde that was reduced with NaBH4 to produce 6.6a,b

• the secondary alcohol under catalytic hydrogenolysis conditions produced 25.6. Then, the deprotonation of 25.6 followed by the alkylation of the alcoholate with iodomethane produced 25.7. The oxidative cleavage of the gem-diol with lead acetate produced an aldehyde that was reduced with sodium

• polyunsaturated analogues, the reaction started with the metalation of tert-butyl methyl ether according to the conditions reported by Corey and Eckrich [140], followed by the nucleophilic addition on unsaturated or polyunsaturated aldehyde to produce, as an example, 31.5. Then, the alkylation of the secondary

Acetaldehyde in the Enders triple cascade reaction via acetaldehyde dimethyl acetal

• Alessandro Brusa,
• Debora Iapadre,
• Maria Edith Casacchia,
• Alessio Carioscia,
• Giuliana Giorgianni,
• Giandomenico Magagnano,
• Fabio Pesciaioli and
• Armando Carlone

Beilstein J. Org. Chem. 2023, 19, 1243–1250, doi:10.3762/bjoc.19.92

• process. The ingenious crafting of the reaction lies in the selection of the reactivity of the different nucleophiles and electrophiles present in the mixture, both as reagents and as intermediates. First, the chiral aminocatalyst 1 activates the saturated aldehyde 2 via enamine intermediate A, which

• intercepts the nitroalkene 3 in a Michael-type addition forming intermediate B. Hydrolysis regenerates catalyst 1 that can then selectively condense with the α,β-unsaturated aldehyde 4 to form chiral iminium ion intermediate C. Iminium ion C reacts with intermediate B in a further Michael-type reaction. The

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• ; 0.157 mmol) and trichloroacetic acid (0.026 mmol) were added and the reaction mixture was stirred at reflux temperature for 30 minutes. Then, the aromatic aldehyde (0.157 mmol) and dimedone (0.157 mmol) were added and the reaction mixture was refluxed for additional two and a half hours. The progress of

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• oxidation noted that the corresponding dimethyl amine – p-benzaldehyde oxidized at 0.79 V vs Fc/Fc+ and underwent a slow re-reduction [73]. Similar compounds, ketone derivatives rather than aldehyde, were developed with more negative potentials as anolytes for aqueous and non-aqueous RFBs by Sanford and co

• -workers [65][66]. The redox potential of the aldehyde is too positive for reductive quenching but low enough to regenerate photooxidized Ru(bpy)3. The aldehyde has been added to the figure because it is an interesting compound to consider when designing recyclable sacrificial donors, even though an

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

• Vladislav Yu. Shuvalov,
• Ekaterina Yu. Vlasova,
• Tatyana Yu. Zheleznova and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2023, 19, 1155–1160, doi:10.3762/bjoc.19.83

• aldehyde with thioglycolic acid and aminopyrazole, followed by the extrusion of sulfur from the resulting thiazepine [20] (method C). The three-stage synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones, involving the preparation of 3-aryl-N-(1H-pyrazol-5-yl)propiolamides (method D), also leads to the

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• activities for all the new derivatives. Furthermore, we recall the skeletons in our current study and our previously reported ones [16][22][23][24][25][26], which revealed the SAR. Moreover, eudesmane-type sesquiterpenes constructed with aldehyde groups are more active even in the form of dimers. In the

• present study, it was described that skeletons with 1°-alcohols and/or acid groups suppress activity, which was consistent with the A. sinensis literatures that 1°-alcohols and/or acid groups suppress activity [25][27], and concluded that eudesmane-type sesquiterpenes constructed with aldehyde groups are

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• force the π-nucleophile to approach from the less sterically congested para-position. As ortho-substituents in the phenol derivatives, mainly sterically bulky alkyl, silyl, and iodo groups were incorporated to ensure the complete regioselectivity. On the other hand, various aromatic aldehyde-based

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• shown in Scheme 20b. In this mechanism, calcium nitrate first activates the decomposition process of 2,5-DMTHF (2) from A to B. Further, a nucleophilic attack of amines 42 on B generates imine intermediate C. Finally, intramolecular nucleophilic attack by enamine D on the aldehyde group, dehydration and

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

• accordance with eight degrees of unsaturation. The NMR data for 4 is closely related with that of compound 3. The carbon atom at 184.9 ppm (C-15) possesses an HSQC correlation to a proton resonance at δH 9.98 (H-15), which is characteristic of an aldehyde function. This is in full accordance with the loss of

• seven degrees of unsaturation. The NMR data of compound 5 are very similar to those of compounds 3 and 4. However, instead of the aldehyde function seen in compound 4, a proton signal at δH 4.63 (H-15) can be observed. Together with its distinct carbon signal at 60.3 ppm (C-15), HMBC correlations to the

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• proximal C–H functionalizations in pyridine substrates under different catalytic systems. However, the intermolecular undirected distal C–H functionalization in pyridine remained unstudied. In these circumstances, the distal C–H alkylation by addition of the pyridine C–H bond to an aldehyde 50 under

• addition of 1 gives the silyl-iridium complex 52. The insertion of aldehyde 50 into the Ir–Si bond of 52 provides the pyridyl alkyl iridium species 53 that finally by C–C formation via reductive elimination furnishes the desired products 51 along with the formation of an iridium hydride species (Scheme 11b

Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke–Blackburn–Bienaymé and Ugi reactions

• Oleksandr V. Kolomiiets,
• Alexander V. Tsygankov,
• Maryna N. Kornet,
• Aleksander A. Brazhko,
• Vladimir I. Musatov and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2023, 19, 727–735, doi:10.3762/bjoc.19.53

• proved to be inefficient. In addition, we also tested the one-pot method for the synthesis of similar structures [32]. Aminopyridine, aldehyde and Sc(OTf)3 as catalyst were stirred in MeOH/DCM for 45 min at room temperature, then the isocyanide was added and the mixture was stirred for another 8 h

• . Without isolation, the corresponding aldehyde, amine and isocyanide were added to the resulting iminopyridine product and the mixture was then stirred at room temperature for 12 h. But again, the expected compounds could not be obtained. Following this trend and based on published data, we synthesized

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• palladium-catalyzed three-component reactions between arylboronic or carboxylic acids, amides or sulfonamides and different aldehyde components as attractive and broadly applicable alternative to the classical Petasis borono-Mannich reaction (Scheme 1b) [17][18][19][20][21]. Recently, we were able to extend

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• precursor 102 and the complementary aldehyde 103. 3.4 Catellani-type reaction The Catellani reaction involves palladium-norbornene cooperative catalysis to functionalise the ortho- and ipso-positions of aryl halides by alkylation, arylation, amination, acylation, thiolation, etc. [63]. Della Ca' et al. [64

• synthesising the tethers and RCM products are reported, the method does not currently allow for the synthesis of unsymmetrical compounds. 3.6 Alkyne–aldehyde metathesis Bera et al. [69] reported on the synthesis of a series of 10-acyldibenzo[b,f]oxepines 125 by alkyne–aldehyde metathesis catalysed by iron(III

• metathesis as key step in the synthesis of dibenzo[b,f]heteropines. Alkyne–aldehyde metathesis in the synthesis of dibenzo[b,f]heteropines. Hydroarylation of 9-(2-alkynylphenyl)-9H-carbazole derivatives. Oxidative coupling of bisphonium ylide intermediate to give pacharin (13). Preparation of 10,11

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• isolated with equally good yields and excellent stereoselectivities (98–99% ee) (Scheme 41B). Surprisingly, when the aldehyde was exchanged with imine 163, the Mannich product 164 was gained only in 23% yield, however, with excellent enantioselectivity of 94%. In the following year, Aponick et al

• activation of aryl pyrazoles, followed by the asymmetric conjugate addition to the Michael acceptor. Then, the formed cobalt enolate participates in the intermolecular aldol reaction with an aldehyde 207. The stereochemistry of this tandem procedure is controlled by the chiral Co(III) complex C4 bearing

• addition of organozirconium reagent 227 to enone 1. In the presence of the (R)-BINAP ligand, the Michael adduct 228 could be isolated in 97% ee. Finally, the Zr enolate was trapped by aldehyde 229 prepared from ᴅ-ribose. The aldol adduct 230 was isolated in 80% yield and excellent diastereoselectivity (>20

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• changing the redox state of the aldehyde function, we have developed a number of directed Ru(0)-catalyzed C3-functionalizations of furfurylimines, such as alkylation [21], arylation [22], alkenylation [23] and acylation [24], as well as an Ir-catalyzed directed C3-silylation (Scheme 1a) [25]. These batch

• starting material had proved to be the most reactive imine in batch, leading, in the presence of 5 mol % of [Ru3(CO)12] and 3 equivalents of triethoxyvinylsilane in toluene at 150 °C after 5 h, to the alkylated aldehyde 2a with 62% yield, after purification on silica gel (Scheme 2) [21][39]. The flow

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• allylic alcohol isomerization in 137 resulting in the aldehyde 138. This aldehyde, in close proximity to the tertiary alcohol, leads to the production of the hemiacetal 139 which can finally undergo an oxidation producing the final bicyclo[2.2.2]lactone product 136. In 2011, the Radhakrishnan laboratory

• salicylaldehydes with EWGs failed to react. The authors hypothesized the reaction mechanism begins with the association of the Rh(III) catalyst with the hydroxy group of salicylaldehyde (151a) resulting in a selective cleavage of the aldehyde C–H bond producing the rhodocycle 153 which side-on coordinates with the

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• broad range of functional groups such as halogens, ester, aldehyde, cyano, and nitro (36c–g, 36–74% yield). It is noteworthy that a disubstituted compound 35j and a thiophene derivative 35k were also efficiently difluoromethylthiolated (36j and 36k, 72% and 65%, respectively). α-Substituted

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• (13,14)-bond of 1 and 2, respectively. Conversely, we envisaged an alternative disconnection to form the (16,17)- or the (14,15)-bond of 1 and 2, through an aldol reaction of aldehyde 8 readily available from ʟ-cysteine, leading to aldol adduct 7 (Figure 2, route B). The methyl ketone partner 9 could be

• formed by the oxidation of an allyl moiety introduced by the asymmetric allylation of an aldehyde derived from (+)-β-citronellene. At this stage, we can speculate that the stereocontrol of this reaction could either follow a polar Felkin–Anh model [14][15][16] based on chiral aldehyde partner 8 [17], or

• 11 in 78% yield (Scheme 1). Due to easier purification, this alcohol was preferred to the aldehyde in our synthetic route, allowing a key stereoselective Krische allylation [21][22] to be envisaged. Applying reported conditions for this allylation – in presence of allyl acetate (10 equiv), [Ir(COD)Cl

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

• necessary to give compound 17 in 85% yield after the two steps. Subsequent reaction of the aldehyde 17 following a modified Still–Gennari protocol [29] employing the phosphonate 18 gave the alkene 19 in 90% yield and high selectivity (cis/trans = 25:1). Removal of the silane group with TBAF furnished the

• coupling reaction. Thus, the olefination reaction of aldehyde 15 with phosphonate 23, followed by the reduction of the obtained ester 24 using DIBAL led to the alcohol 25. The latter was submitted to the reaction with carboxylic acid 26 under Mitsunobu conditions [30], giving the corresponding ester 27 in

• ] between halide 37 and phenol 38 leading to the formation of diaryl ether 39, which was subjected to a regioselective iodination reaction to give compound 40. Conversion of the nitrile in compound 40 into the corresponding aldehyde 41 followed by Z-selective Still–Gennari olefination gave the cis α,β

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

• . Alongside this, H-B-9-BBN underwent reduction of the ester or lactone 57, to give a hemiacetal intermediate 58, which underwent B‒O/B‒H transborylation with HBpin to give an O-Bpin hemiacetal 59. Borane-mediated collapse of the O-Bpin hemiacetal gave an aldehyde 60 which reacted with the O-Bpin enolate 52