Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• occurs, giving radical 146 and radical cation 147, respectively. Finally, radical 146 undergoes decarboxylation to afford an aryl radical and then combines with radical cation 147, yielding product 144 (Scheme 50). It should be noted that only when NHPI is firstly activated can it turn into an electron

• electron-donor catalyst to form an EDA complex with electron acceptor 158, and then a molecule of carbon dioxide was removed under 455 nm light irradiation, giving decarboxylation product 159 (Scheme 55). It was found that many ester groups can be activated by the structural motif of tetrachlorophthalimide

• initiated by an EDA complex. Synthesis of boration product 151 initiated by an EDA complex. Synthesis of boronic acid ester derivative 154 initiated by an EDA complex. Synthesis of β-azide product 157 initiated by an EDA complex. Decarboxylation reaction initiated by an EDA complex. Synthesis of amidated

Breakdown of 3-(allylsulfonio)propanoates in bacteria from the Roseobacter group yields garlic oil constituents

• Anuj Kumar Chhalodia and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 569–580, doi:10.3762/bjoc.17.51

• collapses to methanethiol (MeSH) and malonyl-CoA semialdehyde (21). This compound further degrades to acetaldehyde (22) through the thioester hydrolysis and decarboxylation [27]. Feeding of (methyl-2H6)DMSP to Phaeobacter inhibens DSM 17395 and Ruegeria pomeroyi DSM 15171 resulted in the efficient uptake of

1,2,3-Triazoles as leaving groups: S_NAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles

• Dace Cīrule,
• Irina Novosjolova,
• Ērika Bizdēna and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37

• yield of compound 5d was obtained due to the ethyl ester hydrolysis and subsequent decarboxylation. Such side reactions were also observed for similar compounds in literature [79][80]. As a limitation of the method we have found that 2,6-bistriazolylpurine 2c was inert to SNAr reactions with

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• Baeyer–Villiger-type ring expansion, hydrolysis and decarboxylation, cyclization and dehydration, and finally hydroxylation at C(7a). Just one month later, Bode reported the identification of an unknown gene cluster in the symbiotic bacterium Xenorhabdus stockiae [23]. Cloning and expression of this

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• this method was able to add at moderate temperatures to unreactive alkenes such as butyl acrylate (26) (Scheme 12). Fluoride ions can initiate a chain process, whereby TFDA undergoes desilylation which is followed by a subsequent decarboxylation, and loss of SO2 to form difluorocarbene :CF2 and F−; NaF

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• obtained (Table 1, entries 24–27). At a lower temperature or at a shorter reaction time, the consumption of the starting materials and the decarboxylation process were incomplete. Having established the ideal reaction conditions, we first proceeded to examine the reaction of the different β-keto esters 1a

• place in β-keto esters, which is followed by CO2 displacement under heating [61][62][63][64]. We assume that in our case, when only 2 equiv of base are used, the keto–enol tautomer intermediates undergo a hydrolysis–decarboxylation process preferentially to a retro-Claisen reaction. This process forms

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

• subsequent decarboxylative trifluoromethylthiolation were performed in a one-pot fashion. Keywords: decarboxylation; fluorinated compounds; pyridine compounds; trifluoromethylthiolation; Introduction The pyridine ring is found in numerous biologically active compounds. Therefore, efficient methods for

• recently attracted much attention [12][13][14][15]. Previously, our research group achieved decarboxylative functionalization of tertiary β-ketocarboxylic acids by exploiting their special ability to readily undergo decarboxylation [16][17][18][19][20][21]. During the course of this study, we found that

• mechanism for this reaction, as outlined in Scheme 5. An electrophilic sulfur atom of 6 approaches the nitrogen atom on the pyridine ring to promote decarboxylation via the formation of N-trifluoromethylthio-2-alkylidene-1,2-dihydropyridine intermediate I, which immediately isomerizes to afford 2 (Scheme 5

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• -methyl-[1,1’-biphenyl]-3,3’,4-triol (1, Scheme 1) has been first mentioned 1974 as a reduction and decarboxylation product of dehydroaltenusin [1]. As the compound has later been isolated from Ulocladium sp. [2], Nigrospora sphaerica, Phialophora sp. [3], Penicillium pinophilum SD-272 [4], Alternaria sp

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• % yield (Scheme 6B). This adduct 92a underwent decarboxylation to afford 92b in 72% yield [42]. Exposure of freshly prepared 92b to triazabicyclodecene [45] led to a ring-expansion/aromatization/aldol cascade producing 93, which was reduced with Et3SiH/TFA smoothly to give indane 94 in 68% yield over two

• adduct 105 in 93% yield with 99% ee. The freshly prepared enantioenriched adduct 105 was subjected to ozonolysis [47] followed by decarboxylation to give bisoxindole 106 in 68% yield over two steps. Conversion of 106 to the corresponding acetal and subsequent allylation afforded 108 in 86% yield over two

• on 160 to the enone and produces 161. The newly formed 161 was subjected to 5-exo radical addition to the allyl sulfane and subsequent loss of a thiyl radical produces 162. A successive hydrolysis/decarboxylation upon heating and cleavage of acetal on 162 afforded aldehyde 163 in 90% yield. Coupling

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• -substituted thienopyrrole 26, saponification to carbonic acid 27, and subsequent Cu-mediated decarboxylation in quinoline resulted in thienopyrrole 28 in more than 80% yield over three steps. Lithiation of 28 with n-BuLi and reaction with TIPS chloride selectively occurred at the thiophene α-position to give

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• quenching cycle, generating [Ir]•−, which reduces the phthalimide ester 117 to give α-amino radicals 117• after decarboxylation. The CPA then activates the azaarene 118 through protonation and brings the two reactive species together in a hydrogen bonded complex 119, which facilitates radical addition

• a CPA provided good enantioselectivity (Scheme 20) [69]. The putative mechanism proceeds via a reductive quenching cycle to give α-amino radical 145• after decarboxylation, which is then oxidised further to the imine 146 in the presence of oxygen. Imine 146 is in equilibrium with the enamine

• decarboxylation. The excited photocatalyst is reductively quenched by 242• to give the imine intermediate 243. Indoles 241 and 243 are then brought together by the chiral phosphate catalyst 244 and the lithium counterion in a hydrogen-bonded complex 245 to give the desired enantioenriched products 246 in

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• (3) was treated with Meldrum’s acid (2,2-dimethyl-1,3-dioxane-4,6-dione) followed by decarboxylation in methanol to give methyl 3-oxotetradecanoate (4) in 77% yield. The enantioselective hydrogenation of the β-carbonyl group using (R)-Ru(OAc)2(BINAP) at 65 °C and under 1.5 MPa H2 afforded methyl (R

On the hydrolysis of diethyl 2-(perfluorophenyl)malonate

• Ilya V. Taydakov and
• Mikhail A. Kiskin

Beilstein J. Org. Chem. 2020, 16, 1863–1868, doi:10.3762/bjoc.16.153

• . Keywords: decarboxylation; fluorinated aromatic compounds; hydrolysis of esters; 2-(perfluorophenyl)acetic acid; 2-(perfluorophenyl)malonic acid; Introduction 2-Phenylmalonic acid (1) and its esters are useful and versatile intermediates in the synthesis of many practically important compounds, e.g

• starting ester remained intact, while under drastic conditions (high concentration of alkali, homogeneous solutions, elevated temperatures), decomposition and/or decarboxylation occurred. However, it is possible that decarboxylation took place during the isolation of the free acid. In all cases, no desired

• be formed by thermal decarboxylation of the desired 2-(perfluorophenyl)malonic acid. To prove this hypothesis, 2-(perfluorophenyl)malonate (3) was heated under reflux conditions with an excess of 48% aqueous HBr solution according to the method described in [36], but only traces of 2-(perfluorophenyl

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• activation step to produce a palladacyclic intermediate. In parallel, the oxidative decarboxylation of the α-ketoacid induced by the photocatalyst in its excited state generates the corresponding acyl radical. The latter is intercepted by the palladacycle, leading to a Pd(III) species. Remarkably, the

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• are used as the photoredox catalyst to prepare the corresponding primary and secondary alcohols from terminal and internal olefins. The substrate scope is broad, with excellent regioselectivities and yields up to 96% (Scheme 17). Decarboxylation reactions Carboxylic acid often serves as an inexpensive

• and abundant source of biomass-derived molecules. Decarboxylative transformations of carboxylic acids into value-added chemical products (such as biofuels) are a key objective in organic synthesis [25]. In 2014, Wallentin and co-workers reported a type of decarboxylation reaction of α-amino acids, α

• hydrodecarboxylation product 55. Nicewicz and co-workers also reported the decarboxylation of carboxylic acids and malonic acid derivatives catalyzed by an acridinium photoredox catalyst (Mes–Acr–Ph) and PhSSPh in 2015 (Scheme 20) [27]. This direct method of the organocatalytic decarboxylation of carboxylic acids to

[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin

• Margareta Sohora,
• Leo Mandić and
• Nikola Basarić

Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110

• inclusion complexes 2@β-CD and 3@β-CD was investigated, and we found out that β-CD does not affect the decarboxylation efficiency, while it affects the subsequent photochemical H-abstraction, resulting in different product distribution upon irradiation in the presence of β-CD. The formation of ternary

• decarboxylation and [3 + 2] cycloaddition take place in the ternary complex, whereas such a reactivity from bulky adamantane 3 is less likely. This proof of principle that decarboxylation and cycloaddition can be performed in the β-CD cavity has a significant importance for the design of new supramolecular

• most probably undergoes decarboxylation delivering 1AMY from the S1 state [49]. In CH3CN, 1AMY decays with a rate constant of 2.9 × 106 M−1 s−1, and reacts with methyl acrylate in [3 + 2] cycloaddition with the rate constant 2.7 × 107 M−1 s−1 [49]. Protic solvents such as CH3OH or H2O quench

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• solutions Xu et al. used energy-rich carbon precursors for the spherical carbon preparation via ultrasonic spray pyrolysis. Lithium, sodium or potassium propiolates are one class of such energy rich materials and exhibit leaving groups such as CO, CO2 or C2H2 eliminated by decarbonylation or decarboxylation

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• ), such as carboxylates or RAEs (Redox Active Esters), oxidative fragmentations, and reductive fragmentations of various redox-active groups (X) as well as hydrogen atom abstractions (Scheme 2). Decarboxylation Carboxylic acids are naturally abundant functionalities that provide an easy access to C(sp3

• ) radicals. Since the dawn of organic chemistry, several radical decarboxylations have been developed, including the Kolbe electrolysis [33][34], the Hunsdiecker reaction [35], and the Barton decarboxylation [36][37][38]. More recently, photoredox catalysis has appeared as a mild alternative to these

• difficult to be directly activated by the excited state photocatalyst. For these reasons, the photocatalyzed decarboxylation often proceeds on the corresponding carboxylates, which are easier to be oxidized. This photoinduced SET, followed by the loss of CO2 as the sole byproduct, gives access to the

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• diesters 20a–c. Partial hydrolysis followed by decarboxylation gave the N-benzyloxycarbonyl ᴅʟ-amino acid esters 22a–c, which upon enzymatic hydrolysis of the ester group using the subtilisin-type Carlsberg enzyme led to ᴅ-amino acid esters 23a–c and the corresponding Cbz-protected p, m-fluoro-, or

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• ) [36]. The authors hypothesized that the C–O bond cleavage could be achieved via cobalt-mediated alcohol carbonylation followed by radical decarboxylation of the alkoxycarbonyl intermediate. In a proof-of-concept study, they proceeded with the carbonylation of 1-phenylethanol using Co(II) tetrakis(4

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

• highlighting organocatalytically-mediated reactions [7][8][9][10] with potential in the field of photoorganocatalysis. The power of metal-based photocatalysts is indisputable and can be pinpointed through the ease that they can catalyze difficult photocatalytic reactions, such as the decarboxylation of

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• explored on redox-active alkyl esters derived from N-hydroxyphthalimide (NHPI, 37), in which case the reactions proceeded through a similar radical pathway due to, in part, the alkyl radical surrogate nature of the NHPI esters. The radical generated via decarboxylation of these esters is easily trapped by

Visible-light-induced addition of carboxymethanide to styrene from monochloroacetic acid

• Kaj M. van Vliet,
• Nicole S. van Leeuwen,
• Albert M. Brouwer and
• Bas de Bruin

Beilstein J. Org. Chem. 2020, 16, 398–408, doi:10.3762/bjoc.16.38

• (ppy)3]+ (+0.77 V vs SCE) is insufficient to oxidatively decarboxylate an acetate intermediate (≈ +1.2 V vs SCE). Unexpected electron transfer pathways can be considered, such as the self-decarboxylation that was previously observed for a [Cl3CCO2H][O2CCl3] mixture [57]. Inspired by the result above on