Cryptophycin unit B analogues

• Thomas Schachtsiek,
• Jona Voss,
• Maren Hamsen,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40

• of N-alkylation on the non-chlorinated unit B derivatives. Results and Discussion For the synthesis of unit B derivatives with amino groups instead of the naturally occurring methoxy group ᴅ-phenylalanine served as the fundamental substrate (Scheme 1). Nitration [23] followed by methyl ester

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• susceptible to alkylation than the OH group. However, under more basic conditions and using the alkylating agent in excess can lead to a dialkylated product. It has already been established that N-alkylation takes place before O-alkylation because the nitrogen atom is a softer nucleophile as compared to the

• oxygen atom [50]. Preferential N-alkylation (over O-alkylation) of 1,2-benzothiazine scaffolds has also been carried out by Ahmad and co-workers in 2014 and Szczęśniak-Sięga and companions in 2018 [37][51]. Structure elucidation of all the synthesized derivatives was carried out using 1H, 13C NMR, and

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• carried out (Scheme 27). An N-alkylation of 69b was performed leading to 70 bearing two stereogenic axes, the biaryl C–C axis and the N–N axis. The removal of the Boc group led to product 71 in a 98% yield. Then, this derivative was subjected to different transformations. Firstly, the hydrogenation using

• enantioselectivities (87–99% ee) [49]. Furthermore, to demonstrate the synthetic potential of the methodology, further transformations were carried out. Firstly, the N-alkylation of 78e with ethyl bromoacetate led to the synthesis of tetrasubstituted hydrazine 79 in an excellent yield. This derivative has a newly

Direct trifluoroethylation of carbonyl sulfoxonium ylides using hypervalent iodine compounds

• Radell Echemendía,
• Carlee A. Montgomery,
• Fabio Cuzzucoli,
• Antonio C. B. Burtoloso and
• Graham K. Murphy

Beilstein J. Org. Chem. 2024, 20, 3182–3190, doi:10.3762/bjoc.20.263

• we were unable to isolate any N-alkylated products, it is possible that competing C-alkylation and N-alkylation processes were responsible for the decreased yields observed with the anilides (compared to the ester-derived precursors). Finally, the bis-sulfonyl ylide reacted to produce 3r in good

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• at β- and meso-positions, N-alkylation, arylation or protonation, interruption of the conjugated system, reduction/oxidation of the macrocycle and/or strapping of the macrocycle via covalent linkage of the meso- or β-pyrrole positions [22][53][54][55][56][57]. These alternations can significantly

• electron-withdrawing substituents at the meso- and/or β-positions and highly saddle-distorted geometry (27, 29–31) are inactive (Table 2). Mono-N-alkylation of the macrocycles resulted in a slight improvement of activity giving up to 50–62% conversion for 34 and 37, both of which are alkylated versions of

• an inactive tetraarylporphyrin 18, by increasing the porphyrin basicity and distortion. On the other hand, di-N-alkylation of 18 (providing compound 38) reduced the catalytic activity to only 5% conversion. The authors also screened cationic N-alkylated macrocycles (39–41) and found that only 39 with

Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• intramolecular photoredox reaction. Photoredox-catalyzed intramolecular N-alkylation reactions of various β-lactams. The trans/cis dr was determined by 1H NMR analysis of the crude reaction mixture. Synthesis of the model substrate 14 and its photoredox-catalyzed intramolecular N-alkylation reaction. The trans

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• or novel properties can be prepared by conventional chemical modifications of simple DPP derivatives [3][18]. The most frequently used transformations include: i) N-alkylation with adequately functionalized alkyl groups [19][20][21][22], ii) N-arylation [23][24][25], and functionalization at the 3,6

• -di(het)aryl groups via Suzuki–Miyaura [26][27][28] or Sonogashira [29][30][31] reactions. In this study, we report a straightforward method to obtain a diverse array of N-substituted DPP derivatives through a two-step process. Firstly, the N-alkylation of Pigment Red 254 (DPP 1) is achieved using

• conducted under remarkably mild conditions. Results and Discussion The initial step of our method involved the N-alkylation of DPP 1 with pentafluorobenzyl bromide (Scheme 1). Although a similar reaction had been previously reported for other DPP derivatives, the experimental conditions used (DMF, K2CO3

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• been developed for the N-alkylation of amines with alcohols, including methanol (Figure 1). Beller and co-workers introduced the first intriguing manganese-catalyzed BH for the N-alkylation of amines with alcohols in 2016 [34]. The potential Mn(I)-pincer complex Mn1 (3 mol %) catalyzed the coupling of

• condenses with hydrazine followed by reduction and condensation with another aldehyde to afford the N-substituted hydrazones (Scheme 8). Balaraman and co-workers established a phosphine-free manganese catalyst generated in situ from a manganese precursor and a ligand for the N-alkylation of anilines with

• alcohols [39]. Various ligands were screened for the N-alkylation of m-toluidine with benzyl alcohol using Mn(CO)5Br (5 mol %) and t-BuOK (1 equiv) in toluene at 140 °C (Scheme 9). Among these, L1 and L2 showed better activity for the N-alkylation reactions. Different substituted anilines and alcohols

One-pot Ugi-azide and Heck reactions for the synthesis of heterocyclic systems containing tetrazole and 1,2,3,4-tetrahydroisoquinoline

• Jiawei Niu,
• Yuhui Wang,
• Shenghu Yan,
• Yue Zhang,
• Xiaoming Ma,
• Qiang Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2024, 20, 912–920, doi:10.3762/bjoc.20.81

• the Ugi reaction products 5 could affect the yield of the Heck reaction. To address the issue, compounds 5 were N-alkylated to afford intermediates 7 which were used in the subsequent Heck reaction step. Thus, an alternative one-pot Ugi-azide/N-alkylation/Heck reaction procedure was developed (Scheme

• tetrazolyl-1,2,3,4-tetrahydroisoquinoline 8a in 74% isolated yield which is higher than the one-pot Ugi/Hecke reaction to give product 6b (58%). Under the alternative one-pot reaction conditions involving an N-alkylation step, the substrate scope was explored by the preparation of 10 derivatives 8a–j (Scheme

Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• , entry 3); thus, the phosphate base plays a crucial role in N-alkylation, while its basicity is insufficient to promote aza-Michael addition (pKa of the conjugate acid of the phosphate base is 1.72 in H2O) [12]. Furthermore, N-alkylation proceeded in a divided cell (anodic chamber); thus, the possibility

• of conjugate addition of a cathodically generated carbamate anion was ruled out, prompting us to consider that N-alkylation proceeded via a radical mechanism. On the other hand, the addition of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) led to the predominant formation of cyclized dimer 4 without N

• (Figure 2B, blue line). However, in the presence of AcOH, the N-alkylation yield was low (Table 1, entry 6) owing to the competitive Kolbe oxidation of the cathodically generated acetate anion. In fact, the oxidation potential of Bu4NOAc is lower than that of 1 (Figure 2C, orange line). A decrease in the

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• -stacking interactions, and displayed high stability against dilution (CMC < 0.1 mM). The molecular design allowed installation of various nonionic side-chains (i.e., CH3 and CH2CH2(OCH2CH2)2–Y (Y = OCH3, OH, and imidazole)) via simple N-alkylation, enabling the nonionic surface modification of nanocarbons

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• -triazolines and their derivatives via tandem 1,2-addition/cyclization reactions between trifluoromethyl acylhydrazones and cyanamide [105] (Scheme 17b). Afterwards, Hu et al. developed a method for the N-arylation and N-alkylation of trifluoromethyl acylhydrazones with diaryliodonium salts and alkyl halides

• acylhydrazines. Synthesis of trifluoromethylated cyanohydrazines and 3-trifluoromethyl-1,2,4-triazolines. N-Arylation and N-alkylation of trifluoromethyl acylhydrazones. [3 + 2]-Cycladditions of trifluoromethyl acylhydrazones.

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• cyano N-annulated ethyl propyl perylene diimide) are reported within for the first time. Starting from PDIN-H, PDIN-B and PDIN-FB can be synthesized via N-alkylation by use of a base (K2CO3) in the presence of either benzyl bromide for PDIN-B or pentafluorobenzyl bromide for PDIN-FB (Scheme 1). Starting

• from CN-PDIN-H, CN-PDIN-B and CN-PDIN-FB can be synthesized by N-alkylation by use of a base (K2CO3) in the presence of either benzyl bromide for CN-PDIN-B or pentafluorobenzyl bromide for CN-PDIN-FB (Scheme 1). The products were collected by precipitating the product out of the reaction mixtures by

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation–cyclization–iodination–alkylation sequence

• Nadia Ledermann,
• Alae-Eddine Moubsit and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2023, 19, 1379–1385, doi:10.3762/bjoc.19.99

• transition-metal catalysis [31], we disclosed an activating group-free alkynylation–cyclization sequence to (aza)indoles [32][33] that could be readily concatenated with a concluding N-alkylation of the 7-azaindole intermediate in the sense of consecutive three-component coupling–cyclization–alkylation

• N-iodosuccinimide prior to N-alkylation to give substituted 3-iodoindoles in a concise consecutive four-component fashion in modest to good yields. These target compounds are versatile building blocks for instance for a Suzuki coupling to give 1-alkyl-2,3-diarylindoles that can be of particular

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

• (Scheme 32). Yao et al. [75] reported the reaction of 1a with aryl halides 140 and 141 to afford N-aryldibenzo[b,f]azepines 142 in good to excellent yields. N-Alkylation of the 5H-dibenzo[b,f]azepine (1a) scaffold is a common point of functionalisation of 1a and the dihydro derivative, 2a. Indeed, the

• -dihydrodibenzo[b,f]heteropines via intramolecular Wurtz reaction. Phenol deprotonation and intramolecular etherification in the synthesis of bauhinoxepine J. Palladium-catalysed N-arylation of dibenzo[b,f]azepine. Cu- and Ni-catalysed N-arylation. N-Alkylation of dibenzo[b,f]azepine (1a) and dihydrodibenzo[b,f

Synthesis, α-mannosidase inhibition studies and molecular modeling of 1,4-imino-ᴅ-lyxitols and their C-5-altered N-arylalkyl derivatives

• Martin Kalník,
• Sergej Šesták,
• Juraj Kóňa,
• Maroš Bella and
• Monika Poláková

Beilstein J. Org. Chem. 2023, 19, 282–293, doi:10.3762/bjoc.19.24

• than parent DIM [15]. Also, screening of a large library of N-alkyl and N-arylalkyl DIMs revealed that they are less effective inhibitors of JBMan than DIM, indicating that N-alkylation might lead to better selectivity profiles. However, this library has not been assayed for GMII and LM, therefore the

• -benzyl group with the Cbz group, trityl ether hydrolysis, oxidation of the liberated OH group, and stereoselective addition of MeMgBr to the resulting aldehyde functionality. Hydrogenolysis of the Cbz protecting group in 13 followed by N-alkylation afforded pyrrolidines 14–16 which after acidic

• of 28 is weaker than ΔEring-E = −514.35 kcal mol−1 of 29) and the overall ΔEI-E for 28 became lower than for 29, which is in agreement with the measured inhibitory activities of these compounds. This is a surprising result because N-alkylation of 30 (structure 31 in Table 1) did not decrease

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• membrane fouling after 1 hour. An automated fill-empty gravity separator was also used for the separation of phases in a scale up of an N-alkylation reaction reported by Eli-Lilly as an alternative to the Zaiput membranes that were better used for rapid screening of conditions [57]. The use of these

A versatile way for the synthesis of monomethylamines by reduction of N-substituted carbonylimidazoles with the NaBH₄/I₂ system

• Lin Chen,
• Xuan Zhou,
• Zhiyong Chen,
• Changxu Wang,
• Shunjie Wang and
• Hanbing Teng

Beilstein J. Org. Chem. 2022, 18, 1032–1039, doi:10.3762/bjoc.18.104

• ][31] and carbon dioxide (CO2) [32][33][34][35][36][37][38][39] have been developed for the N-methylation of amines. However, these N-alkylation methods often require the employment of expensive catalysts, and the N-alkylation of primary amines generally does not stop with monomethylation as expected

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

• 180 °C at 4.5 MPa for 7.5 min. These conditions allowed to suppress the decomposition of the N-alkylation product 78 by using a 1/8“-reactor. The subsequent purification was realized by a clever catch and release protocol based on a silica column, yielding iloperidone (80, 67%). The tricyclic

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

• were coupled with a benzoic acid-based stopper using N,N′-diisopropylcarbodiimide (DIC) and tributylphosphine (26–75% yield). The isolated rotaxanes were then used for subsequent reductive N-alkylation to obtain the tert-amine-type rotaxanes (R)-29a–f in yields of 67–92%. Finally, dimethyldioxirane

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• -butyloxycarbonylation and N-alkylation (Scheme 14) [25]. The C5 cyclization regioselectivity and trans-diastereoselectivity were not influenced by the electronic nature of the indole-N-substituent. Conclusion As illustrated by these studies, SEAr-based intramolecular cyclization and annulation reactions of 3,5

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• and thioureas were screened for the enantioselective N-alkylation of isoxazolin-5-ones via a 1,6-aza-Michael addition of isoxazolin-5-ones 64 to p-quinone methides (p-QMs) 65 to give isoxazolin-5-ones 67 bearing a chiral diarylmethyl moiety attached to the N atom. The best result in terms of

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• 19a. This enaminone-based method for constructing a pyrrole ring is similar to that in our reported routes to lamellarin alkaloids, in which N-alkylation of (Z)-configured 3,4-dihydroisoquinoline-derived enaminones with ethyl bromoacetate under either conventional [49][50] or microwave [51] heating