Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

• Arnaldo G. de Oliveira Jr.,
• Martí F. Wang,
• Rafaela C. Carmona,
• Danilo M. Lustosa,
• Sergei A. Gorbatov and
• Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

• circumvent this side reaction, we envisioned that a more electron-withdrawing protecting group could reduce the tendency of the starting olefin to oxidation. Therefore, the N-tosylated 2,5-dihydro-1H-pyrrole 1b was evaluated under the same reaction conditions with the same three aryldiazonium salts used

• before. Before exploring the reactivity of the olefin towards other aryldiazonium salts, we performed a brief optimization of the process by testing several other N,N-ligands. Therefore, five other N,N-ligands were evaluated as follows: PyraBox (L2), QuinOx (L3), PyOx L4 and L5, and PyriBOx (L6) (Figure

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

• Jun Kikuchi,
• Roi Nakajima and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

• between 4ba and 4-methoxybenzenethiol furnished the N,S-substituted olefin 7 in 59% yield. The treatment of 4aa with stoichiometric CuI and ʟ-proline effected the iodine(III)-to-iodine(I) conversion to give the vinyl iodide 8 in 76% yield. Compound 8 was used for the Ullmann coupling with imidazole

• , producing the vicinal N-heterocycle-substituted olefin 9 as a mixture of stereoisomers in 65% yield. Finally, 4aa proved to be a viable nucleophilic VBX for the carboiodanation of 3-methoxybenzyne [35], furnishing the new ortho-alkenylated arylbenziodoxole 10 with exclusive C–C bond formation at the distal

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• with subsequent reduction of the olefin motif respectively. In contrast to the approach of Mykhailiuk, this route yields the exo-1,5-BCHs as the major diastereomer. 1,5-BCH (±)-64 and 1,5-BCH (±)-71 were prepared as bioisosteres of the fungicides fluxapyroxad and boscalid, respectively [45]. Comparison

Confirmation of the stereochemistry of spiroviolene

• Yao Kong,
• Yuanning Liu,
• Kaibiao Wang,
• Tao Wang,
• Chen Wang,
• Ben Ai,
• Hongli Jia,
• Guohui Pan,
• Min Yin and
• Zhengren Xu

Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77

• the 9-organoborane intermediate IM-16 probably through borane–olefin complexes. The suprafacial nature of the boron migration allowed the boron to be α-oriented in intermediate IM-16, which would give 10 with retention of the configuration after NaOH/H2O2 oxidation. The formation of a significant

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• endocyclic olefin led to a series of separable allylic chlorides 16 and 17a,b, from direct displacement or transposition of the allylic system (Scheme 3). This substrate has previously been examined in the reaction with SOCl2 by Matsumoto et al. in THF and CH2Cl2 and similar results were obtained [28]. When

Methodology for awakening the potential secondary metabolic capacity in actinomycetes

• Shun Saito and
• Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

• carbonate and terminal olefin functionalities [50]. Thus, artificial methods of genetic engineering and chemistry also play an important role in the identification of novel secondary metabolites. Culture conditions Medium composition, pH, oxygen supply, light Simply modifying the culture conditions is an

New variochelins from soil-isolated Variovorax sp. H002

• Jabal Rahmat Haedar,
• Aya Yoshimura and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2024, 20, 692–700, doi:10.3762/bjoc.20.63

• from 1. The 1H NMR spectrum showed additional olefinic proton signals at δH 5.35, as compared with that of 1. In line with this, two sp2 carbon signals at δC 130.6 and 131.0 were detected in the 13C NMR spectrum, demonstrating the presence of an olefin in 4. The comparative analysis of the MS/MS

Production of non-natural 5-methylorsellinate-derived meroterpenoids in Aspergillus oryzae

• Jia Tang,
• Yixiang Zhang and
• Yudai Matsuda

Beilstein J. Org. Chem. 2024, 20, 638–644, doi:10.3762/bjoc.20.56

• -dependent monooxygenase InsA4. In this engineered pathway, FncE first synthesizes 5-MOA, which then undergoes farnesylation by FncB, methyl ester formation by InsA1, and epoxidation of the terminal olefin in the farnesyl moiety by InsA4 (Figure 2A). Thus, we heterologously expressed the genes encoding these

(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• significantly. One of the new and budding directions in recent years is the stereoselective olefin metathesis processes based on catalysis by complexes of molybdenum, tungsten and ruthenium [3][4][5]. The first publications have recently appeared that molybdenum complexes can catalyze cross-metathesis of butene

• the formation of the corresponding olefin [12]. Another area of application of olefins 1a,b is based on C=C double bond addition reactions. As early as 1968, Atherton and Fields showed that (Z)- and (E)-butenes 1a,b reacted with diazotrifluoroethane to give 3,4,5-tris(trifluoromethyl)pyrazoline [13

• method it was possible to achieve complete dehydrobromination of (Z)-isomer 3b and isolation of (E)-isomer 3a in pure form in 35% yield (Scheme 2). Unexpectedly the (E)-isomer 3a, upon long-term storage, transforms into the (Z)-isomer 3b. Therefore, we studied the isomerization of olefin 3a in the

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• CO2. Radical 12 undergoes intermolecular addition to the olefin acceptor 13 to form radical intermediate 14. Finally, under reductive conditions radical 14 can undergo hydrogen atom transfer (HAT) or sequential electron transfer and proton transfer (ET/PT) to form the conjugate addition product 15

• example, the NHPI ester derived from pivalic acid 58 and Hantzsch ester HE form EDA complex 59 which participates in radical mediated hydroalkylation reactions [60][61] (Scheme 13A). In the presence of electron deficient olefin 60, classic Giese-type addition takes place under photocatalyst-free

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• % yields. The success of the reaction with an ester substituent to give 12k is surprising if we compare it with other electron-withdrawing groups like CN or NO2, which failed to give the corresponding cyclization products 12l–n (not shown). Instead, olefin products 13l–n arising from an elimination were

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• the mentioned reactions, the first step of the catalytic cycle is the nucleophilic attack of the phosphine on the electrophile, in many cases an electron-deficient olefin. The zwitterion formed from this conjugate addition can subsequently act as a nucleophile or as a base [3][4][5]. The efficiency of

Synthesis of 7-azabicyclo[4.3.1]decane ring systems from tricarbonyl(tropone)iron via intramolecular Heck reactions

• Aaron H. Shoemaker,
• Elizabeth A. Foker,
• Elena P. Uttaro,
• Sarah K. Beitel and
• Daniel R. Griffith

Beilstein J. Org. Chem. 2023, 19, 1615–1619, doi:10.3762/bjoc.19.118

• secondary amine according to our previously described, solvent-free protocol [12][13]. The resulting iron complex 6 was demetallated upon irradiation with UV light [14] to give the deconjugated olefin 7. We then hoped to forge the desired bicycle 8 (Table 1) via a 6-exo-trig Heck cyclization, drawing on the

• File 1 for amine syntheses). These amines were each carried through the protocols outlined in Scheme 2 to arrive at the deconjugated olefin substrates shown in Table 2. The cinnamylamine derivative 13 underwent the Heck cyclization in 50% yield, while the prenylamine derivative 15 proceeded to give

• cleanly according to TLC analysis, but the isolated yield of the intramolecular Heck product was low, perhaps due to instability of one of the intermediate palladium complexes and/or a slow olefin insertion step. Moreover, the product was obtained as an inseparable mixture of the allylic carbamate 18 and

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• necessary. MF-ROMP, also termed photo-ROMP, is a novel technique to polymerize cyclic olefins. It begins with the reductive quenching of an photoexcited photocatalyst (PC) at an enol ether initiator to produce a radical cation carrier [90]. Then, the carrier undergoes cyclic addition with a cyclic olefin

• by radical unzipping depolymerization under photon or β-irradiation (Scheme 20a). Similarly, poly(olefin sulfone) undergoes depolymerization upon irradiation of light or electron beams [193][194]. It is an alternating copolymer of 1-olefins and SO2, and therefore the decomposition products are mostly

• gaseous [195]. While the depolymerization in both systems has a thermodynamic origin [196], the mechanism of poly(olefin sulfone) depolymerization is much more complex. Bowmer et al. proposed a simultaneous radical/cationic process (Scheme 20b) [197]. Meanwhile, an anionic process is also possible in the

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

• the nitrogen atoms adjacent to the carbene center result in kinetic stabilization of the NHC suppressing its dimerization to the corresponding olefin (the Wanzlick equilibrium). On the other hand, thermodynamic stabilization results due to donation of lone pair(s) electrons of the adjacent nitrogen

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• providing ZEONEX® 480 Cyclo Olefin Polymer (COP) used in our studies. We are grateful to Dr. Louise Natrajan at the University of Manchester for providing access to FLS-1000 fluorometer. Funding This work was supported by the Royal Society and the Academy of Finland. A.S.R. acknowledges support from the

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

• previously proposed for hypervalent iodine compounds [9][117][118][119], Moriarty proposed a carbene-free mechanism for the formation of 11 [113]. In this, the nucleophilic olefin first attacked the electrophilic iodine center to form zwitterion 15, which closed to produce iodocycle 16 and then underwent

• , they believed that the reaction was likely initiated by either single electron transfer between the reagents (not shown), or by electrophilic addition of the olefin onto the ylide, forming intermediate adduct 17. This was followed by formation of iodocycle 18, from which reductive elimination of

• was also viable with a selection of other mono- and bicyclic olefin motifs, undergoing intramolecular cyclopropanations in moderate to high yields (Scheme 3). They also conducted a mechanistic investigation to better understand this metal-free pathway, again on the premise that a free carbene

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

• olefin partners were generally well-tolerated, the protocol was limited to perfluoroalkyl iodides. The reductive power of *PDI•− (*E1/2 = −1.87 V vs SCE) was well-matched to the redox potentials of perfluoroalkyl iodides, but was insufficient for perfluorobromides (e.g., Epred = −1.52 V vs SCE for CF3I

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• radical is stabilized by both the indole ring and the Δ2-olefin. Next, the resonance-stabilized radical intermediate III was trapped by the active α-aminoalkyl radical, generated by reductive decarboxylation by Ir(II) produced in the photocatalytic cycle (which undergoes oxidation to afford the Ir(III

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• the construction of a range of δ-olefin-containing aliphatic nitriles with (E)-configuration selectivity. This new method features wide substrate scope, mild conditions, and direct N–O activation. Keywords: direct N–O activation; E-selectivity; nitrile synthesis; ring-opening cross-coupling; sulfuryl

• ][26][27][28][29], a synthesis method for δ-olefin-containing aliphatic nitriles by the radical C–C bond cleavage of cycloketone oxime ester derivatives was developed by Shi’s group (Scheme 2a) [30], which emerged as an efficient strategy to construct C(sp2)–C(sp3) bonds [31][32][33]. Later, Xiao [34

• translated into experimental reality, developing a new SO2F2-mediated C–C single bond cleavage method for constructing δ-olefin-containing aliphatic nitriles. Results and Discussion We started our investigation by selecting cyclobutanone oxime (1a) and 1,1-diphenylethylene (2a) as model starting materials to

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

• formed after oxidative addition via C–H-bond cleavage followed by olefin insertion to form intermediate 218, which on subsequent reductive elimination results in the formation of monoalkylated bipyridine 219. This intermediate reenters into another cycle of hydroarylation by starting as bidentate complex

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

• moderate to good yield (35–82%). 3.5 Ring-closing metathesis Olefin metathesis is a metal-catalysed reaction wherein carbon–carbon double bonds are cleaved and formed through an intermediate cyclometallacarbene 114, thus allowing for transalkylidenation and the formation of mixed alkenes 115 (Scheme 24

• coupling in dibenzo[b,f]oxepine synthesis. Wittig reaction and Ullmann coupling as key steps in dihydrobenz[b,f]oxepine synthesis. Pd-catalysed dibenzo[b,f]azepine synthesis via norbornene azepine intermediate 109. A simple representation of olefin metathesis resulting in transalkylidenation. Ring-closing

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

• with good productivity. Alkenes without silicon in the vinyl position seemed much less reactive, such as a vinylacetal, a hindered olefin (3,3-dimethyl-1-butene), or styrene. In these cases, functionalized furfurals were not isolated. In contrast, norbornene, which has a more reactive double bond due

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

• involving these strained bicyclic alkenes are thermodynamically driven forward with the release of ring-strain energy (Figure 1) [7][8]. Intuitively, increasing the number of olefin moieties in the bicyclic system from zero, one, and two, increases the ring-strain energy. Moreover, the introduction of a

• -defined and rigid nature of these bicyclic alkenes creates two diastereotopic faces, namely the endo and exo face (Figure 2). The exo face is sterically less congested than the endo face; therefore, the exo face will typically interact with metal catalysts through side-on coordination of the olefin, and

• into the S–C bond of the thiocyanate 70 to afford intermediate 71 which can side-on coordinate to the exo face of 30b. Subsequently, the thiocyanate attacks the olefin from the endo face via 72 to give complex 73. Reductive elimination furnishes the final difunctionalized product and regenerates the

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

• -olefin 119 which was reduced using DIBAL to lead to the allylic alcohol 120. Subsequent Mitsunobu reaction between the alcohol 120 and carboxylic acid 26 gave the corresponding ester 121 in a 64% yield. However, the intramolecular cyclization step did not lead to the desired compound 122, even when

• to be inactive indicating that the olefin was necessary for cancer cell growth inhibition. For salts 184–187, the authors attributed the decrease in the activity to the lack of phosphatases necessary for the cleavage of the prodrug ester bond and needed to regenerate the drug in the isolated cancer