A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• diselenides (Scheme 23b) [32]. 1.2 Organo-mediators-enabled anodic oxidation The Baran group has made significant contributions to the field of organic electrochemistry. One of their developments is the electrochemical allylic oxidation, a highly useful C–H functionalization method applicable to several

• generated tert-butyl peroxide to form an allylic peroxide, which ultimately transforms into an enone upon elimination of t-BuOH (Scheme 24). One year later, they developed an electrochemical transformation closely related to their electrochemical allylic oxidation, i.e. the oxidation of unactivated C(sp3)–H

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• secondary alcohol of 21, the utilization of another variant, MoBsc9 L110A, Y112R, generated through the directed evolution of MoBsc9, facilitated the optimal conversion in the corresponding oxidative allylic rearrangement to afford brassicicene I (9) in 64% yield. Further palladium-catalyzed allylic

• oxidation with the incorporation of a ketone at the C13 position yielded brassicicene A (23). After conversion of 23 into the corresponding silyl enol ether, Rubottom oxidation allowed completion of the total synthesis of brassicicene R (24). As an effort to explore the biomimetic rearrangement, analogous

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• arylselenium compounds [26][27][28]. Noteworthy examples are the use of SeO2 as selenium source in aromatic electrophilic substitution reactions [27][28][29]. Selenium dioxide is a well-known oxidizing agent for the allylic oxidation and oxidation of α-CH bonds located adjacent to electron-withdrawing groups

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

• hydroxy group, or a keto group) for further derivatization. Spiroviolene was not transformed when subjected to conditions for allylic oxidation (SeO2) even at elevated temperature [27], and the starting material was fully recovered. We have also tried hydroboration/oxidation conditions for transforming

Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• then transformed into aldehyde 31 through several protecting group adjustments and the corresponding alcohol and Ley oxidation. After the preparation of 33 using Evans syn-aldol condensation as a critical step, 34 was produced by thioester formation, desilylation, and allylic oxidation. Incubating 34

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• . And the derivative 16 was also synthesized by allylic oxidation of compound 15 using selenium dioxide. As helical chiral NGs, helicene 14 and its derivatives 15 and 16 showed highly distorted helical conformation and also exhibited a relatively high isomerization barrier (over 28.9 kcal/mol determined

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• and industrial applications [1]. Among them, allylic oxidation and olefin epoxidation constitute fundamental tools for the synthesis of homoallylic alcohols or α,β-unsaturated carbonyl compounds, and epoxides, respectively. In particular, epoxides are pivotal building blocks for the synthetic chemists

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

• the desired alcohol 133 in 75% yield as a single diastereomer. Allylic oxidation of freshly prepared 133 with SeO2 followed by silylation with TBSOTf/Et3N afforded enyne 134. Enyne 134 was subjected to rhodium-catalyzed intramolecular [3 + 2] cycloaddition with a catalytic amount of [Rh(cod)OH]2 to

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

• Tatsuya Kumon,
• Miroku Shimada,
• Jianyan Wu,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 2193–2200, doi:10.3762/bjoc.16.184

• ][32]. Therefore, we also accomplished the synthesis of 2-fluoroalkylated indenone and indanone by simple reactions (Scheme 3). An allylic oxidation was carried out with 10 equiv of manganese dioxide in dichloromethane as the solvent at 0 °C for 30 minutes, leading to the corresponding 2

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• metathesis using Grubbs’ 2nd generation catalyst (G-II, Scheme 3) [13]. Replacing the N-Boc protecting group with an N-tosyl group and allylic oxidation gave 30. The introduction of the allyl group at C-11 made use of the Kishi protocol [22] of the allyl-Grignard addition, followed by an ionic reduction. The

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• catalyst (3 mol %) to give the corresponding 1,3-diene intermediate in 85% yield (Scheme 16). The subsequent hydroboration and oxidation to homoallylic alcohol, followed by a palladium-catalyzed Heck cross-coupling, an allylic oxidation with SeO2, mesylation, and deprotection, afforded (−)-galanthamine (13

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• and reacted with 3,3-dimethylallyl bromide, followed by changing the protecting group from MOM ether to methyl ether to provide olefin 86. Allylic oxidation of 86 followed by nucleophilic bromination of the resulting allylic alcohol gave bromide 87. Dianion displacement of the bromide of 87 gave ester

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

• Christiane Schultze and
• Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

• defined order. One class of products, pyrano[2,3-f]chromene-2,8-diones, were inaccessible through direct RCM of an acrylate, but became available from the analogous allyl ether via an assisted tandem catalytic RCM/allylic oxidation sequence. Keywords: coumarins; heterocycles; isomerization; olefin

• an assisted tandem catalytic [68] RCM/allylic oxidation sequence. Such tandem sequences are characterized by the combination of two mechanistically distinct catalytic reactions in a defined order, which proceed with a single precatalyst that undergoes a transformation in situ upon addition of a

• suitable reagent, a “chemical trigger” [69]. In the case of the RCM/allylic oxidation sequence tert-butyl hydroperoxide is added after completion of the metathesis reaction, which most likely induces a conversion of the metathesis active Ru–carbene species to a Ru(IV)–oxo species. The latter are known to

Cobalt-catalyzed nucleophilic addition of the allylic C(sp³)–H bond of simple alkenes to ketones

• Tsuyoshi Mita,
• Masashi Uchiyama,
• Kenichi Michigami and
• Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

• remained underdeveloped even though C–O bond formation of allylic C(sp3)–H bonds was firmly established by using SeO2 [14] or CrO3/3,5-dimethylpyrazole [15] (ene-type allylic oxidation). Although the most prominent work on catalytic allylic functionalization studied thus far is considered to be a palladium

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• is followed by allylic oxidation at the 9a-position in 78 and cyclisation [13]. This reaction was exploited in the chemoenzymatic total synthesis of (+)-aureothin (79) [67][68]. The molecule also contains a pyran-4-one. Reminiscent of type II and type III-PKS, this results from elimination

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• iron(II) triflate as previously reported to generate the complexes [Fe(TPA)(CH3CN)2](OTf)2 (FeTPA, 4) [52], [Fe(BPMEN)(OTf)2] (FeBPMEN, 5) [48] and [Fe(R,R′-PDP)(OTf)2] (Fe(R,R′)-PDP, 6) [51]. Allylic amination reactions As an extension of our previously reported iron-catalysed allylic oxidation of

• loading of FeTPA from 10 to 5 mol % led to a small increase in the yield of allylic hydroxylamine 9 with a significant decrease in the appearance of allylic oxidation products 10 and 11. The amount of FeTPA (4) could be further lowered to 2 and 1 mol %, bringing further small increases in the yield of 9

• . However increasing loading of FeTPA (4) to 20 mol % halts the amination reaction, returning only allylic oxidation products 10 and 11. In contrast, changing the catalyst loading of FeBPMEN (5) up or down from 10 mol % lowers yields of 9; at 1 mol % or 20 mol % loading of catalyst 5, increased levels of 10

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• affords different products depending on the reaction conditions. Keywords: allylic oxidation; cholesterol; electrochemical halogenation; electrochemical oxidation; Introduction Cholesterol is the most common steroid in the mammalian body. It is necessary to ensure a proper membrane permeability and

Selective allylic hydroxylation of acyclic terpenoids by CYP154E1 from Thermobifida fusca YX

• Anna M. Bogazkaya,
• Clemens J. von Bühler,
• Sebastian Kriening,
• Alexandrine Busch,
• Alexander Seifert,
• Jürgen Pleiss,
• Sabine Laschat and
• Vlada B. Urlacher

Beilstein J. Org. Chem. 2014, 10, 1347–1353, doi:10.3762/bjoc.10.137

• Supporting Information File 1). There is no literature procedure for the synthesis of alcohol derivatives of geraniol (1) or nerol (2) by direct allylic oxidation. However, various conditions have been reported for geranyl acetate [32][33][34]. Following a modified procedure by Li [33], geranyl acetate ((E

• into neryl acetate ((Z)-19) in 87%, followed by allylic oxidation [38], to provide enal (Z)-20 and allylic alcohol (Z)-21 in 14% and 41% yield, respectively. Saponification of 8-hydroxyneryl acetate ((Z)-21) under the above mentioned conditions gave 8-hydroxynerol (4) in 73% yield (Scheme 2). Following

• ], modified Sharpless conditions [36] for the allylic oxidation of geranylacetone (9) were used. Purification of the crude product by chromatography yielded the enal (E)-22 (9%) and a 11:89 mixture of the alcohols 7-hydroxygeranylacetone (11) and 11-hydroxygeranylacetone (13) in 34% yield and 11% of starting

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• unconventional biosynthesis mechanisms [5][6]. The carbonitrile for example is probably formed by allylic oxidation of the 12-methyl group in 12-desnitrile-12-methylborrelidin to the corresponding aldehyde and transamination to the amine followed by oxidation [6]. In the course of our studies on borrelidin

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

• Verena Weidmann,
• Mathias Schaffrath,
• Holger Zorn,
• Julia Rehbein and
• Wolfgang Maison

Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262

• developed. The oxidations follow a radical mechanism and the regioselectivity of the reaction is mainly determined by bond-dissociation energies of the available allylic CH-bonds and steric accessibility of the oxidation site. Keywords: allylic oxidation; CH-activation; chiral separation; enones; flavors

• addition, metal-free and biocatalytic methods have been reported [5]. Several of these biocatalytic protocols have been applied to the synthesis of fine chemicals [20][21][22], drugs [23], and food ingredients [24][25][26]. A particularly interesting biocatalytic system for allylic oxidation is the edible

• responsible for the allylic oxidation of valencene to nootkatone, and the same enzyme oxidizes unsaturated fatty acids [29][31]. It is thus likely that this dioxygenase is the major oxidant in other allylic oxidations with PSA-lyophilisate, too. However, since the lyophilisate is a mixture of enzymes

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• diastereoselective allylic oxidation to provide (±)-nominine (225). In 2008, the same group reported the first total synthesis of (+)-nominine by introducing the desired stereochemical information to the nitrile 235 [179]. Conclusion The outlined syntheses of natural products containing the uncommon isoindole

Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

• Lynnie Trzoss,
• Jing Xu,
• Michelle H. Lacoske and
• Emmanuel A. Theodorakis

Beilstein J. Org. Chem. 2013, 9, 1135–1140, doi:10.3762/bjoc.9.126

• the way for a diversity-oriented synthesis. For example, a Mn(III) promoted C-2 allylic oxidation [24][101][102] would provide a C-2 oxygenated functionality. Similarly, C-10 α-substitution would provide a large diversity of neurotrophic analogues based on our recent findings [26]. Conclusion We

Synthesis and characterization of Sant-75 derivatives as Hedgehog-pathway inhibitors

• Chao Che,
• Song Li,
• Bo Yang,
• Shengchang Xin,
• Zhixiong Yu,
• Taofeng Shao,
• Chuanye Tao,
• Shuo Lin and
• Zhen Yang

Beilstein J. Org. Chem. 2012, 8, 841–849, doi:10.3762/bjoc.8.94

• the presence of catalytic NaOMe, followed by treatment with NH4Cl. Then, condensation of 13 with acetylacetaldehyde dimethyl acetal in 1,4-dioxane afforded 6-methyl-2-(4-pyridinyl)pyrimidine 14 in 62% yield [47]. Consequent allylic oxidation of 14 with selenium dioxide gave 11e in moderate yield