Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials

• Jessica Villegas,
• Bryce C. Ball,
• Katelyn M. Shouse,
• Caleb W. VanArragon,
• Ashley N. Wasserman,
• Hannah E. Bhakta,
• Allen G. Oliver,
• Danielle A. Orozco-Nunnelly and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108

• previously been shown in the literature that the first two steps of this Smiles-rearrangement approach can be effectively performed in one pot [49]. Therefore, after allowing the O-alkylation to proceed at room temperature in dimethylethyleneurea (DMEU), we proceeded directly to the hydroxyamides 7 and 8

• through the use of additional NaOH and refluxing the crude alkylation mixture. After heating for 3 h, the desired intermediates were recovered in acceptable yields over this two-step one-pot sequence. The amide hydrolysis of 7 and 8 to the desired free naphthylamines 9 and 10 proved challenging, but was

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• changed alkylation pattern. Results and Discussion Function of the proline-rich N-terminal domain of 2MIBS S. coelicolor 2MIBS was selected to investigate the function of the proline-rich N-terminal domain (hereafter termed A domain, the C-terminal domain is named as domain B). Based on a sequence

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

• complex 57 was obtained through reduction of the phenoxyimine-imidazolium bromide 55a (R = t-Bu) with NaBH4 followed by successive alkylation with iPrBr and reaction with Cu2O (Scheme 19) [32]. The use of the synthesized complexes 56a and 57 as precatalysts for the 1,4-conjugate addition to enones and the

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

• synthesis of 1,2,5-trisubstituted 7-azaindoles [34]. Inspired by the coupling–cyclization–alkylation sequence and the stepwise Sonogashira coupling–cyclization–iodination protocol to give valuable 3-iodoindoles by Amjad and Knight [35], we reasoned that the interception by an electrophilic iodination step

• prior to terminal alkylation could provide a straightforward entry to trisubstituted 3-iodoindoles, which are valuable building blocks for accessing highly decorated (aza)indoles (Scheme 1). Here, we report the concise consecutive four-component synthesis of trisubstituted 3-iodoindoles. Results and

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

• hydrogenolysis to produce 1-O-octadecyl-sn-glycerol (4.10). It must be noted that the authors, after the deprotection of the two alcohol functions of 4.7, attempted the direct alkylation of the primary alcohol with octadecyltosylate. However, a mixture of mono and dialkylation was formed and were separated by

• with the alkylation of the racemic thioglycerol with bromooctadecane in the presence of potassium hydroxide. Then, the protection of the primary alcohol was achieved either with trityl chloride or with dimethyl-tert-butylchlorosilane. The authors also attempted to use chlorotrimethylsilane but the

• was selectively alkylated on the primary alcohol to produce 20.2 via the use of dibutyltin oxide as selective reagent for the alkylation of diols [109]. For this reaction, CsF was added to increase the reactivity of the alkyl bromide, likely by a combined effect that includes the interaction of the

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• interest in developing novel methodologies in this field of organic chemistry. Keywords: alkylation; cross-dehydrogenation coupling; ether; non-noble metals; Introduction Since the 1970s, organic chemists have developed many selective cross-coupling methods for the construction of C–C bonds, such as the

• oxidative alkylation of cyclic benzyl ethers with malonates or ketones. Oxygen is used as a terminal oxidant at atmospheric pressure. The key intermediate of this oxidative coupling reaction is benzyl alcohol intermediate C (Scheme 4) [52]. The generation of N–O radicals from NHPI in the presence of oxygen

• method allows the efficient alkylation of aromatic rings, can directly afford pharmaceutically significant heterocycles, and the raw materials and iron catalysts are safe and readily available. In 2017, Xu, Loh, and co-workers, demonstrated an iron-catalyzed hydroalkylation reaction of α,β-unsaturated

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

• Olfa Mhasni,
• Jalloul Bouajila and
• Farhat Rezgui

Beilstein J. Org. Chem. 2023, 19, 1251–1258, doi:10.3762/bjoc.19.93

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• the use of 3-substituted furans. For example, the intramolecular Friedel–Crafts alkylation reaction (Scheme 1a) of alcohols [9][10][11], alkenes [12] or acetylenes [13] affords the desired tetrahydrofuro[3,2-c]pyridines. A related method is based on a Au(I)-catalyzed domino sequence dearomatization

• /ipso-cyclization/Michael-type Friedel–Crafts alkylation (Scheme 1b) [14][15][16]. Unfortunately, approaches including the intramolecular alkylation of 3-substituted furans are underinvestigated as these substrates are usually hard to reach and the resulting benzyl carbocation is often prone to undergo

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

• -ketimino esters 62 as potential electrophiles. The chiral phosphoric acid P21 catalyzed this process facilitating the formation of a quaternary stereocenter containing α-amino esters. Switching the solvent from non-polar to polar showed a regioselectivity shift to a C7 alkylation of the indole ring. The

• solvent-controlled regioselectivity switch of this aza-Friedel–Crafts reaction can be explained by the involvement of the polar solvent (acetonitrile) in the H-bonding with the catalyst thus creating a more hindered environment for a C3 alkylation, rather favoring the reaction through the less congested

• rigidity in the corresponding transition state (Scheme 23) [53]. In 2023, a chiral phosphoric acid ent-P17-mediated aza-Friedel–Crafts alkylation was reported between 5-aminopyrazole 92 as the π-nucleophile and 3H-indol-3-ones 69 as electrophilic reagents. The presence of an amino group in pyrazole 92 is

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

• , diversely functionalized pyridines have been synthesized via C–H activation under transition-metal and rare earth metal catalysis, including C–H alkylation, alkenylation, arylation, heteroarylation, borylation, etc. Recently, metal-free approaches have also been developed for the C–H functionalization of N

• . Review C–H Alkylation of pyridine The C–H bond is the backbone of an organic molecule and the conversion of a C–H bond to a C–X bond (X = carbon or heteroatom) forms the basis in organic synthesis. The functionalization of C–H bonds is challenging due to a large kinetic barrier for C–H bond cleavage and

• also achieving selectivity is difficult due to its ubiquitous nature [40]. The metal-catalyzed C–H bond functionalization is a good strategy for synthesizing highly functionalized organic frameworks. In this context, the C–H alkylation is one of the most important C–C bond-formation reactions [41][42

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• a 6π-electrocyclization of the hexatriene system and ESIPT-induced contraction of the pyranone ring. At the same time, the blocking of the ESIPT-promoted process via alkylation of the hydroxy group allows one to realize the regiospecific cyclization of the triene system. Based on these previous

• results, we started the photochemistry study of the considered pyrimidines from the corresponding methylated derivatives of 9. The products 10 were obtained by alkylation of compounds 9 with methyl iodide in DMF in the presence of K2CO3 (Scheme 4). At first, the photochemical behavior was investigated for

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

• (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

• first reported synthesis of imipramine (3) by Schindler and Häfliger [76] proceeded by alkylation of 2a by alkyl halides. Selected N-alkylations of 1a and 2a are included in Scheme 33. N-Allylation of 1a or 2a with allyl bromide (143) can be achieved by a base-promoted substitution reaction (Scheme 33A

Synthesis of medium and large phostams, phostones, and phostines

• Jiaxi Xu

Beilstein J. Org. Chem. 2023, 19, 687–699, doi:10.3762/bjoc.19.50

• . Allyl benzyl ((4-allyl-2-(4-methylphenyl)benzo[b]thiophen-3-yl)methyl)phosphonate (30) was prepared in 75% yield from benzyl hydrogen ((4-allyl-2-(4-methylphenyl)benzo[b]thiophen-3-yl)methyl)phosphonate (29) and allyl bromide in the presence of Cs2CO3 in acetonitrile at 80 °C for 2.5–3 h via alkylation

• -methylphenyl)benzo[b]thiophen-3-yl)methyl)phosphonate (34) was prepared in 70% yield from benzyl hydrogen ((4-allyl-2-(4-methylphenyl)benzo[b]thiophen-3-yl)methyl)phosphonate (29) and but-3-enyl bromide in the presence of Cs2CO3 in acetonitrile at 80 °C for 2.5–3 h via alkylation. It was cyclized via a RCM

• derivatives were synthesized. Benzyl ((4-chloro-6-(4-methylphenyl)thieno[2,3-d]pyrimidin-5-yl)methyl) allylphosphonate (44) was prepared in 87% yield from 4-chloro-3-(chloromethyl)-2-(4-methylphenyl)benzo[b]thiophene (42) and benzyl hydrogen allylphosphonate (43) via alkylation in the presence of Cs2CO3 in

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• functionalization is still challenging for chemists to combine a C(sp3) carbon of incoming functionalities and C(sp2) carbon of the IP core. The direct C-3 alkylation of imidazopyridines using active malonates and related moieties has been achieved by different routes [17][18][19][20]. However, these reactions rely

• either on harsh reaction conditions or require the preactivation of substrates, which limits their synthetic efficiency. A photocatalytic quaternary C-3 alkylation has also been reported recently (Scheme 1A) [21][22]. During the course of our study, the Wu group reported a solvent-controlled

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

• developed a copper/Rev-Josiphos-catalyzed asymmetric conjugate addition of Grignard reagents to 2-methylcyclopentenone (78), which provided 2,3-disubstituted cyclopentanones in high yields and enantiomeric purities [53]. The one-pot alkylation reaction of the in situ formed magnesium enolate with alkylating

• synthesis of (+)-artemisinin (Scheme 55) [102]. Using the commercially available and cheap cyclohexenone 1 as starting material, they have demonstrated an economic synthesis plan in only five steps. In the first step, the Cu-catalyzed conjugate addition of Me2Zn is followed by alkylation with 1-bromobut-2

• addition to cyclohexenone 1, followed by the trapping of the Mg enolate with ethyl cyanoacetate (221). Consequent α-alkylation resulted in the multifunctionalized product 223 in 61% yield (Scheme 58). Natural products with complex multicyclic structures lacking functional groups (lack of oxygenation) are

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

• develop a continuous flow process specifically for the C3-alkylation of furfural (Murai reaction). The transposition of a batch process to a continuous flow process is often costly in terms of time and reagents. Therefore, we chose to proceed in two steps: the reaction conditions were first optimized

• 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

• -situ imine formation is currently impossible with catalytic or stoichiometric amounts of amine due to decarbonylation of furfural under the reaction conditions [21]. We thus present here an adaptation of our Ru(0)-catalyzed C3-alkylation strategy of furfural derivatives to a continuous flow system

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

• ). Mechanistic investigations are reported. These studies provide convincing evidences for the photochemical formation of reactive open-shell species. Keywords: alkylation; EDA complex; halogens; indoles; photochemistry; Findings Direct replacement of carbon–hydrogen (C–H) bonds with new carbon–carbon (C–C

• photochemical alkylation, leading to the products 3e–i (up to 96% yield). It is worth noting that derivatives 3e–g were isolated in moderate yields as single regioisomer since the alkylation step took place exclusively in position 2 of the starting indoles. As limitation, we observed that indole-3

• -carboxaldehyde (1g) was not a suitable substrate for this transformation. Conclusion In conclusion, we reported a novel photochemical method for the direct C–H alkylation of indoles with α-iodosulfones. This approach exploits the photochemical activity of halogen-bonded EDA complexes, formed between α

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• -Cl [21], 3,4-di-Cl [21][22], 2/3/4-F [23]) were inserted in the N-benzyl moiety as well as in the aromatic rings of the benzophenone fragment [24][25][26] (selected examples are given in Scheme 1). Insertion of halogen atoms increased enantioselectivity, e.g., in alkylation reactions [27][28

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

• final ring-opened adduct 37. Copper-catalyzed reactions In 2009, Pineschi and co-workers explored the Cu-catalyzed rearrangement/allylic alkylation of 2,3-diazabicyclo[2.2.1]heptenes 47 with Grignard reagents 48 (Scheme 8) [41]. The reaction is thought to proceed via the Lewis acid-catalyzed [3,4

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

• hydroxybenzaldehyde 80 into the corresponding acetal followed by Ullmann-type coupling with 52, led to the formation of diaryl ether 83. Subsequent Corey–Fuchs reaction [49] and in situ alkylation led to formation of the propargylic alcohol 85. Deprotection of the aldehyde followed by chain elongation through the

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

• iminosugars can be achieved by an alkylation of the endocyclic nitrogen. This reduces their high hydrophilicity which in turn may have a positive impact on the interactions with the hydrophobic pocket of the GMII active site. For example, N-benzylation of DIM afforded a slightly more potent GMII inhibitor

• 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

• -1 further enhanced the potency and led to highly selective nanomolar GMII inhibitors [14] (Figure 1). Our first investigations were focused on the development of selective GMII inhibitors derived from 1,4-imino-1,4-dideoxy-ʟ-lyxitol. Initially, we modified this core by an alkylation of the

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• steps from accessible methylcyclopentenone 16 (Scheme 2). The sequence included a Mukaiyama–Michael reaction with silyl enol 15 followed by a Tsuji alkylation. With diene 17 in hands, the RCM reaction was performed by addition of G-II catalyst and furnished the expected C5-C8 bicyclic framework 18 in 95

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• derivatives (see Scheme 1). First, the arylimidazole is obtained through a ring closing reaction using an aniline derivative, glyoxal, formaldehyde and ammonium chloride. The following alkylation with hexyl bromide yields the bromido ionic liquid. TAAILs 1–6 are then formed by an anion exchange reaction using