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

• methoxy group to yield intermediate B. The electron-deficient carbon of intermediate B is then attacked by the amine in a nucleophilic reaction to produce intermediate C, which is then followed by the removal of the second OMe group to produce intermediate D. Further, the lone pair of N attacks the

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• esters 1a have recently attracted considerable attention from synthetic organic chemists. In addition to their polyfunctionality, their ring strain and electron deficiency lead to a wide variety of reactivities. Based on their electron-deficient nature, these compounds have been used as substrates in the

• example, when esters 1a are subjected to Lewis acid-induced denitration, highly electron-deficient enones (reaction b) [4] are obtained. The latter compounds are highly reactive and undergo reaction with, e.g., mercaptoacetaldehyde affording thiophenes (reaction c) [5] or with activated (hetero)aromatic

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

• stoichiometric waste. The challenges associated with the functionalization of pyridine are based on the low reactivity of the pyridine ring system for undergoing substitution reactions. This is attributed to the electron-deficient nature of the ring system due to the presence of the sp2-hybridized nitrogen atom

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

• Joydev K. Laha,
• Pankaj Gupta and
• Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

• their unique stability, defined reactivity, and versatility in organic synthesis [2]. Leveraging their electron-deficient nature, N-arylsulfonylimines are widely used in organic transformations including nucleophilic addition, cycloaddition, imino-aldol reaction, ene reactions, aza-Friedel–Crafts

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• yield the final products "A–D". This approach is not limited to reagents with appropriate donor–acceptor characteristics [13][19]. Indeed, sacrificial electron donors and electron-deficient radical precursors can be used to form photoactive EDA complexes. Specifically, these aggregates can be employed

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• 48% for Phen-Py-1 and Phen-Py-2, respectively). The phenanthridine nitrogen was protonated under weakly acidic conditions, which made the phenanthridinium moiety relatively electron deficient compared to the electron-rich pyrene moiety that favored intramolecular stacking. Molecular dynamics

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

• 17 (Scheme 4) [36]. While broadly successful, when electron-deficient arylboronic acids were used, slightly diminished yields were observed. Moreover, when 3-hexyne was used, the reaction failed to afford any product. The reaction likely begins similarly to Cheng’s 2003 report (Scheme 1) [31] where

• norbornene derivatives 15 using imides 27 and tetraarylborates 28 (Scheme 5) [37]. The method utilizes C–N bond activation to trigger the reaction. The authors demonstrated a broad reaction scope. Electron-deficient amides were shown to perform worse than their electron-rich counterparts with the p

• ) and O-benzoylhydroxylamine derivatives 54 (Scheme 9) [43]. While the scope of bicyclic alkenes was quite extensive with aza-, carbo-, and oxabicyclic alkenes being amenable to the reaction, electron-deficient substrates resulted in lowered yields. Of note, the reaction is highly regioselective with

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

• order to obtain higher yields in the intramolecular cyclization step, the authors also investigated the use of a strategy based on an SNAr reaction using an electron-deficient aryl halide. Thus, 4-fluoro-3-nitrobenzaldehyde (118) was subjected to the Still–Gennari reaction, to give the corresponding cis

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• remove the m-chlorobenzoic acid (Table 1, entry 6). When we employed the chlorinated, electron-deficient iodoarene 4ah, the yield of the product 5ah dropped significantly (Table 1, entry 7). Combining an electron-deficient heterocycle and an iodoarene with electron-withdrawing substituents results in a

• electron-deficient dibrominated salt 5as could not be obtained. This further demonstrated the crucial influence of the electronic properties on the reactivity of those substrates. Especially, electron deficiency is particularly counterproductive for the final cyclization step. To prove the influence of the

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• triene system for an intramolecular Diels–Alder reaction. Oxidation of 8 with IBX changed the electronic properties of the system implementing an electron-deficient double bond suitable for a heat-induced intramolecular Diels–Alder reaction. The higher reaction temperature compared to the original

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• reaction. This type of olefin E–Z isomerization is likely to take place after the N-acyliminium formation, possibly via a Michael/retro-Michael addition sequence between the chloride (Cl−) anion and the electron-deficient olefin of the N-acyliminium intermediate at 80 °C (Scheme 9c). In conclusion, these

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• ][78][95] less reactive and less electron-deficient N-oxyl radicals (usually isolable and storable amine-N-oxyl radicals) are used as precursors of the active oxidants, oxoammonium cations. This oxidative organocatalysis type is highly important for the chemoselective oxidation of alcohols. Two

• several cases, a good regioselectivity was achieved for complex molecules. Quinuclidine cation radicals were also involved in the generation of nucleophilic α-hydroxyalkyl radicals from alcohols for the addition to the electron-deficient C=C bond of methyl acrylate followed by lactonization [107] (Scheme

• perform the CH-functionalization of alkanes by electron-deficient alkenes. Photoredox catalysis was employed for the one-electron oxidation of the DABCO-derived organocatalyst to the dication radical. The authors noted that the introduction of a substituent X near the radical center further improves the

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• reaction of Meldrum’s acid (26) and aldehyde 27 resulting in the formation of the electron-deficient enone 30, which then participated in a Michael-type addition reaction with 1,3-dipolar 2-unsubstituted imidazole N-oxide 28 to provide the intermediate 31. In the last step, the final product 29 was

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• pattern. The reason for this behavior is probably due to the collective electron-withdrawing effect of the chlorine atoms making the glucose residues of the fully DCB-protected compound more electron deficient at the ring oxygen. This means that the Lewis acidic aluminum reagent has more difficulty

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C–Si bond functionalization

• Sebastien Curpanen,
• Per Reichert,
• Gabriele Lupidi,
• Giovanni Poli,
• Julie Oble and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2022, 18, 1256–1263, doi:10.3762/bjoc.18.131

• combination with CuI (20 mol %), cross-coupling between 4c and iodobenzene was achieved, giving 18 in reasonably good yield (70%). 4-Iodoanisole could also be coupled (giving 19 in 57% yield), but not electron-deficient 1-iodo-4-nitrobenzene. At this point, it should be mentioned that treatment of aldehyde 2c

Dienophilic reactivity of 2-phosphaindolizines: a conceptual DFT investigation

• Nosheen Beig,
• Aarti Peswani and
• Raj Kumar Bansal

Beilstein J. Org. Chem. 2022, 18, 1217–1224, doi:10.3762/bjoc.18.127

• reaction with an electron-rich diene such as DMB. However, in the case of compound 1 (R1 = R2 = CO2Me), the EWG at the 1-position functions as electron-sink between the nitrogen lone-pair and the >C=P– functionality. As a result, the latter retains its electron-deficient character and undergoes DA reaction

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• , indicated the protonation of the pyridinyl nitrogen atom (Figure S6a, Supporting Information File 1). This enhanced the electron-deficient character of the BPy acceptor core and the ground-state communication between the donor and acceptor units. As a result, the red-shifted CT absorption band in the acidic

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• radical anions formed are relatively stable, at least in the CV time scale) at close potential values (E1/2 = −1.42 V (1), −1.42 V (2) ; for comparison: E1/2 for AlaNi = −1.53 V [52] vs Ag/AgCl, KCl(sat.)). The complexes containing one (3) or two (4) electron-deficient COOMe groups in the cyclopropane

Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides

• Dharmendra Das,
• Akhil A. Bhosle,
• Amrita Chatterjee and
• Mainak Banerjee

Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100

• monobromination under the optimized reaction conditions to validate the effectiveness of our method using an indigenous electrical grinder. The results are summarized in Scheme 3. At the outset, several electron-rich and electron-deficient phenol derivatives were converted to the corresponding monobrominated

• equiv to 2 equiv (X = Br, I) (Scheme 4). Several electron-rich (products 3a and 3k, Scheme 4) and electron-deficient (product 3c–h, Scheme 4) phenols and anilines were successfully converted to the corresponding dibromo derivatives in good to excellent yields within 5–15 min when 2.1 equiv of NBS were

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• multifunctionalized carboxamide-bridged dicyclopentenes in moderate to good yields and with high diastereoselectivity. Keywords: carboxamide; cycloaddition; cyclopentene; electron-deficient alkyne; phenacylmalononitrile; Introduction Phenacylmalononitrile is one of the privileged functionalized compounds [1][2][3

• -carboxamides with unprecedented rearrangement of the alkyl group [34] (reaction 4 in Scheme 1). Inspired by these novel reactions and in continuation of our aim to develop domino reactions of electron-deficient alkynes [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], we have investigated the

• base to catalyze the C–C bond formation via a Michael addition of active methylene groups [31]. Therefore, in the presence of TBAB, the bromide assisted with the deprotonation of the phenacylmalononitrile to give a carbanion intermediate A. Secondly, the nucleophilic addition of carbanion A to electron

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• all the sulfur atoms of the DTT core and the electron-withdrawing [20] keto groups. The LUMO is presented strongly in the seven fused rings, but is poorly represented in the outer ethylhexylthiophenes, which are electron-rich and twisted out of plane. The LUMO is strongly localised at the electron

• -deficient keto groups. Interestingly, neither the HOMO, nor the LUMO, is present at the central sulfur atom of the DTT motif. Organic field-effect transistors To estimate the charge carrier mobility from the saturation regime of the current–voltage plot, bottom gate/bottom contact (BG/BC) OFETs [76][77

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• -phenylphosphonamidates 240a (R’ = OEt) and diaryl-N-phenylphosphinamides 240b–d (R’ = Ar), respectively, with methyl acrylate (241) via the rhodium-catalyzed oxidative coupling and subsequent intramolecular aza-Michael addition. Methyl acrylate (241) could be replaced by various electron-deficient olefins 244, including

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• ]. Considering the electrostatic potential surface (EPS) maps (see Figure 11b) of the pyrazine-containing polymers before and after B(C6F5)3 coordination, it is likely that B(C6F5)3 sacrificed the electron density of the polymer skeleton and turned it from an electron-rich to an electron-deficient species. This

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• temperature of the nanostructured particles (Figure 4B). The Claisen rearrangement of the electron-deficient aryl allyl ether 9 was chosen to compare the versatility and performance of inductive heating with conventional and microwave heating (Scheme 8A) [50]. The effectiveness of inductive heating is clearly

Tri(n-butyl)phosphine-promoted domino reaction for the efficient construction of spiro[cyclohexane-1,3'-indolines] and spiro[indoline-3,2'-furan-3',3''-indolines]

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 669–679, doi:10.3762/bjoc.18.68

• the construction of diverse carbocyclic systems [17][18][19][20][21][22][23][24]. In these reactions, the tertiary phosphine firstly adds to electron-deficient alkenes, alkynes, and allenes to give active ionic intermediates. Then, the in situ-generated ionic intermediates further react with various

• respect, we have also developed several domino reactions by employing tertiary phosphine addition to electron-deficient alkynes as key protocol for the construction of diverse polycyclic spirooxindoles [53][54][55][56][57][58][59]. In continuation of our aim to explore elegant domino reactions for spiro