Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• acetaldehyde (36) was also capable of initiating the photografting of methacrylic acid (MAA, 42) onto HDPE, highlighting that acetaldehyde (36) is a better initiator that outperformed formaldehyde (35) and acetone (4) [46]. In more detail, in 2011, Wang and co-workers studied the efficiency of acetaldehyde (36

• ) as the photoinitiator for the photografting of MAA (42) onto high-density polyethylene (39) in an aqueous solution [46]. The light source was a high-pressure mercury UV lamp (2 kW), and a cooling fan was used in order to maintain ambient temperature. Acetaldehyde (36) proved to be more efficient than

• polymerization of monomeric MMA (26) using the quinoxalines 32 and benzaldehyde (8). Acetone (4) and formaldehyde (35) as photografting initiators. Photografting by employing acetaldehyde (36) as the photoinitiator. Proposed photolysis mechanism for aliphatic ketones 44 and formaldehyde (35). Initiator 50

Synthesis of novel sulfide-based cyclic peptidomimetic analogues to solonamides

• José Brango-Vanegas,
• Luan A. Martinho,
• Lucinda J. Bessa,
• Andreanne G. Vasconcelos,
• Alexandra Plácido,
• Alex L. Pereira,
• José R. S. A. Leite and
• Angelo H. L. Machado

Beilstein J. Org. Chem. 2019, 15, 2544–2551, doi:10.3762/bjoc.15.247

• , some observations can be made: (1) 9e is the only one among all the analogues derived from the acetaldehyde adduct that, regardless of the configuration of the stereogenic centres, has the same amino acid residue sequence found in solonamides; (2) despite the close similarity on the amino acid residue

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

• Irina G. Tkachenko,
• Sergey A. Komykhov,
• Vladimir I. Musatov,
• Svitlana V. Shishkina,
• Viktoriya V. Dyakonenko,
• Vladimir N. Shvets,
• Mikhail V. Diachkov,
• Valentyn A. Chebanov and
• Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

• , Ukraine Bar-Ilan University Ramat Gan, 5290002, Israel 10.3762/bjoc.15.231 Abstract The three-component reaction of 5-aminotetrazole with aliphatic aldehydes (formaldehyde, acetaldehyde) and acetoacetic ester derivatives in water under microwave irradiation leads to the selective formation of 4,7

• Da. Therefore, the minimization of molecular masses for the targeted tetrazolo[1,5-a]pyrimidines can be achieved by exclusion of large aryl substituents from their structures. Thus, we selected aliphatic aldehydes, i.e., formaldehyde and acetaldehyde, as the starting material and chose a

• in this case. The three-component reactions of 5-aminotetrazole (1) with aldehydes 7a,b (paraformaldehyde, acetaldehyde) and a set of acetoacetic ester derivatives 8a–d in water under microwave irradiation at 100 °C led to the formation of the corresponding 5,6,7-trisubstituted 4,7-dihydrotetrazolo

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Host–guest interactions between p-sulfonatocalix[4]arene and p-sulfonatothiacalix[4]arene and group IA, IIA and f-block metal cations: a DFT/SMD study

• Valya K. Nikolova,
• Cristina V. Kirkova,
• Silvia E. Angelova and
• Todor M. Dudev

Beilstein J. Org. Chem. 2019, 15, 1321–1330, doi:10.3762/bjoc.15.131

• ., acetaldehyde – ethanal, CH3CHO) are required in condensation reactions with resorcinol and pyrogallol [1]. Thiacalixarenes are macrocycles (or cyclic oligomers) based on a condensation of the same phenol derivatives and sulfur [2]. They are characterized by a larger cavity size than the conventional

Tuning the stability of alkoxyisopropyl protection groups

• Zehong Liang,
• Henna Koivikko,
• Mikko Oivanen and
• Petri Heinonen

Beilstein J. Org. Chem. 2019, 15, 746–751, doi:10.3762/bjoc.15.70

• simplest of the formaldehyde-type acetals, methoxymethyl (MOM) [2], is rather stable to acidic hydrolysis. The acetaldehyde acetals, 1-ethoxyethyl (EE) [2][3] and tetrahydropyranyl (THP) [2] are widely used as protecting groups, but they have a disadvantage of generating an additional asymmetric center

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

• Mannich reaction of N-Boc-isatin imines 3 with aldehydes, such as acetaldehyde (15a) [39]. When these reactions were catalyzed by simple chiral primary amine 16 in aqueous THF at 0 °C, they led to the corresponding chiral Mannich products 17 in good yields (74–81%) and uniformly excellent

• acetylacetone catalyzed by a cinchona alkaloid-derived squaramide. Mannich reaction of isatin-derived benzhydrylketimines with trimethylsiloxyfuran catalyzed by a phosphoric acid. Mannich reaction of N-Boc-isatin imines with acetaldehyde catalyzed by a primary amine. Mannich reaction of N-Cbz-isatin imines with

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• . The selectivity of these reactions depends on the geometry of the intermediate enolates. Here, we have reacted octyl pentafluoro-λ6-sulfanylacetate with substituted benzaldehydes and acetaldehyde under the conditions of the silicon-mediated Mukaiyama aldol reaction. The transformations proceeded with

• . Among the saturated and unsaturated aliphatic aldehydes, only acetaldehyde gave the expected aldolates (58% yield, ratio 87:13, Table 2, entry 17), while cyclohexane carbaldehyde, acrolein, and crotonaldehyde did not give any aldol products (Table 2, entries 18–20). During the aldol addition, two

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• shape of compound 93 makes it chiral in nature. It was proposed that there is in situ oxidation of ethanol to ethanal by conc. HNO3 which turned the reaction into a multi-component domino assembly of reactants hydrazine 14, β-ketonitriles 15 and acetaldehyde. Rahmati [75] carried out a reaction of 5

Conformational preferences of α-fluoroketones may influence their reactivity

• Graham Pattison

Beilstein J. Org. Chem. 2017, 13, 2915–2921, doi:10.3762/bjoc.13.284

• decreases on solvation [22]. Work on related halo-acetaldehyde systems suggested that steric repulsions were the key contributing factor in determining these preferred conformations [23]. Finally, the conformational profiles of fluoroacetone and fluoroacetophenone were compared by overlaying on the same

Is the tungsten(IV) complex (NEt₄)₂[WO(mnt)₂] a functional analogue of acetylene hydratase?

• Matthias Schreyer and
• Lukas Hintermann

Beilstein J. Org. Chem. 2017, 13, 2332–2339, doi:10.3762/bjoc.13.230

• [W(O)(mnt)2] (1; mnt = maleonitriledithiolate) was proposed (Sarkar et al., J. Am. Chem. Soc. 1997, 119, 4315) to be a functional analogue of the active center of the enzyme acetylene hydratase from Pelobacter acetylenicus, which hydrates acetylene (ethyne; 2) to acetaldehyde (ethanal; 3). In the

• (classification: hydro-lyases, EC 4.2.1) was isolated from the bacterium Pelobacter acetylenicus [1], which feeds anaerobically on acetylene as sole carbon source [2]. The enzyme is a tungsten iron–sulfur protein requiring a strongly reducing environment for converting acetylene (ethyne; 2) to acetaldehyde

• -sensitive but water-stable tungsten(IV) complex (Et4N)2[W(O)(mnt)2] (1) (mnt = maleonitriledithiolate) is a catalyst for hydration of acetylene to acetaldehyde, with 9 turnovers over 4 h at ambient temperature (Scheme 1c) [13]. Tungsten(IV) complex 1 with its two dithiolate ligands that resemble the natural

Diosgenyl 2-amino-2-deoxy-β-D-galactopyranoside: synthesis, derivatives and antimicrobial activity

• Henryk Myszka,
• Patrycja Sokołowska,
• Agnieszka Cieślińska,
• Andrzej Nowacki,
• Maciej Jaśkiewicz,
• Wojciech Kamysz and
• Beata Liberek

Beilstein J. Org. Chem. 2017, 13, 2310–2315, doi:10.3762/bjoc.13.227

• presented reductive alkylation consists of a reaction of amine 4 with the appropriate aldehyde, which results in the respective imine subsequently reduced with sodium cyanoborohydride to the alkylated amine. Thus, the reaction of 4 with 1.5 molar excess of acetaldehyde followed by the in situ reduction with

Synthesis and enzymatic ketonization of the 5-(halo)-2-hydroxymuconates and 5-(halo)-2-hydroxy-2,4-pentadienoates

• Tyler M. M. Stack,
• William H. Johnson Jr. and
• Christian P. Whitman

Beilstein J. Org. Chem. 2017, 13, 1022–1031, doi:10.3762/bjoc.13.101

• ]. VPH catalyzes the addition of water to the C-4 position of 5a to produce (S)-2-keto-4-hydroxypentanoate (6a) [9][10][11]. A retro-aldol cleavage of 6a by pyruvate aldolase yields pyruvate and acetaldehyde (7a). Pyruvate aldolase is tightly coupled with an acetaldehyde dehydrogenase, which uses NAD

• the actions of pyruvate aldolase and acetaldehyde dehydrogenase would produce 2-chloroacetaldehyde (7b) and 2-chloroacetyl CoA (8b), which are potential alkylating agents of these enzymes as well as other cellular proteins and DNA. This observation and the potential effects of the halogen on other

NMR reaction monitoring in flow synthesis

• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

• , (iii) reaction conditions can be examined very easily by real-time monitoring and (iv) integration of small amounts of products and intermediates would be possible [45]. Harbou et al. [46] performed a kinetic study on the multicomponent reaction of acetaldehyde and water to produce poly

• and Sons. Flowsheet of the experimental setup used to study the reaction kinetics of the oligomer formation in mixtures of acetaldehyde (AA) and water (A) (Flow rates VAA 254 μL min−1 and VW 748 μL min−1). Reproduced with permission from reference [46]. Copyright 2014 The American Chemical Society

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• ]. Carbonyl oxides (Criegee intermediates) are one of the most important compounds in tropospheric chemistry [309]. Direct investigations of formaldehyde oxide (CH2OO) or acetaldehyde oxide (CH3CHOO) reactions with water vapor, SO2, NO2 were carried out [310][311][312]. 1.3 Hock rearrangement The Hock

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• -catalyzed addition of zinc acetylide to acetaldehyde for the synthesis of a chiral 1,6-enyne substrate. Curtin–Hammitt scenario of redox bicycloisomerization in acetone. Initial result for the asymmetric redox bicycloisomerization of 1,7-enyne 13 with chiral CpRu-sulfoxide complex 1 and the effect of added

Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

• Daniel Wiegmann,
• Stefan Koppermann,
• Marius Wirth,
• Giuliana Niro,
• Kristin Leyerer and
• Christian Ducho

Beilstein J. Org. Chem. 2016, 12, 769–795, doi:10.3762/bjoc.12.77

• glycine (100). Hence, LipK was revealed to be a transaldolase mediating a retro-aldol reaction of L-threonine (119) towards the enol(ate) and acetaldehyde (120), followed by a stereoselective aldol addition of the former to uridine-5'-aldehyde 99 (Scheme 12). Using synthetic reference compounds, it could

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• with acetaldehyde. The reaction showed an interesting divergence in reactivity controlled by the catalysts, viz., the thiazolium salt 19 and triazolium salt 20. The thiazolium-derived carbene preferentially mediated the formation of the Breslow intermediate from the aromatic aldehyde followed by

• coupling with acetaldehyde. In contrast, the triazolium-derived carbene prefered to activate acetaldehyde to generate the corresponding acyl anion equivalent followed by coupling with aromatic aldehydes (Scheme 9) [22]. It may be mentioned that Connon, Zeitler and co-workers have also reported the use of

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• acetaldehyde, thus shifting the state of equilibrium in product direction. Therefore, in next experiments three different vinyl esters were used: vinyl acetate, vinyl butanoate, and vinyl decanoate. The influence of the acyl donor nature on the course of the alcohol acylation reaction was examined using 3

(2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues

• Armin de Meijere,
• Sergei I. Kozhushkov,
• Dmitrii S. Yufit,
• Christian Grosse,
• Marcel Kaiser and
• Vitaly A. Raev

Beilstein J. Org. Chem. 2014, 10, 2844–2857, doi:10.3762/bjoc.10.302

• equivalent with aldehydes the situation is more complicated. The reaction of (S)-10 with acetaldehyde under strongly basic conditions led to the (R)-threonine complex 29 (inverse configuration relative to that of the proline moiety of (S)-10 due to epimerization on C-2), but when a weaker base such as

• by experimental tests [36]. The initially formed main product (R,R,R)-28 in the aldol reaction of acetaldehyde with 10 had the same configuration at C-2 as the proline unit in 10. The absolute configuration of this nickel(II) complex was determined by a single crystal X-ray structure analysis (see

• product 28 can coordinate the Ni atom liberating the carboxylate moiety and thus making the proton at C-2 accessible to base attack (Scheme 4). In order to obtain (R)-allo-threonine (4), it is necessary to carry out the aldol reaction of (R)-10 with an excess of acetaldehyde under strongly basic

Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

• Amjid Iqbal,
• El-Habib Sahraoui and
• Finian J. Leeper

Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270

• acetaldehyde completes the catalytic cycle. The 4’-aminopyrimidine ring of ThDP can interconvert among three ionization/tautomeric states, the protonated form and two neutral forms, the amino tautomer and the imino tautomer (Scheme 1) and it is believed to be the imine nitrogen atom of the latter that is the

• column. The His6-tag does not appear to affect the enzymic activity. The normal coupled enzyme assay for PDC was used, in which PDC catalyses the decarboxylation of pyruvate to acetaldehyde and alcohol dehydrogenase (ADH) converts the acetaldehyde to ethanol using NADH (Scheme 5). The oxidation of NADH

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• acid compared to aldehydes, and especially compared to aliphatic aldehydes, like acetaldehyde, which give very poor yields [84]. Since carbonyl compounds have the tendency to accept an electron more easily than CO2, the reaction mixture contains a lot of carbonyl radical anions, which can form vicinal

A new approach for the synthesis of bisindoles through AgOTf as catalyst

• Jorge Beltrá,
• M. Concepción Gimeno and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2014, 10, 2206–2214, doi:10.3762/bjoc.10.228

• acetaldehyde by evaporation (bp 20 °C) and the consequent poorer yield of the final product, instead of 1 equivalent of aldehyde (0.5 mmol) 2 equivalents (1 mmol) were used. The result was 90% of yield compared with 67% for 1 equivalent of acetaldehyde, confirming our concern. It is worth mentioning that this

• clean crude product was obtained since acetaldehyde is also evaporated, and the final product was purified by a simple column chromatography. Moreover, we were able to obtain single crystals for compounds 6ad and 6al for the first time in the literature (Figure 2) [50]. Although the mechanism is not

Proton transfers in the Strecker reaction revealed by DFT calculations

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 1765–1774, doi:10.3762/bjoc.10.184

• Shinichi Yamabe Guixiang Zeng Wei Guan Shigeyoshi Sakaki Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-Nishihiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103, JAPAN. Phone: +81-075-711-7907 10.3762/bjoc.10.184 Abstract The Strecker reaction of acetaldehyde, NH3, and HCN to afford

• Strecker reported a reaction that affords alanine from acetaldehyde, ammonia and hydrogen cyanide [1]. The original form of Strecker amino acid synthesis is shown in Scheme 1(a). In this reaction, the aldehyde reacts with hydrogen cyanide to form an aminonitrile, which undergoes hydrolysis to afford

• complex 1. The reaction begins with the addition of NH3 to the carbonyl carbon of acetaldehyde to form a Mulliken charge-transfer complex 2. This complex was firstly proposed here. In 2, the C–O bond is elongated to1.345 Å, which has an alkoxide character and the complex is not stable in the gas phase