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

• fragmentation to afford alkene 72 in 61% yield. Marcfortine B (8) was synthesized from alkene 72 in seven steps. The enantioselective synthesis of marcfortine C (9) commenced with a catalytic asymmetric cyano-substituted TMM cycloaddition of oxindole 73 and TMM donor 75 with Pd(dba)2/74 as catalyst to give a

• enantioselective synthesis of marcfortine C (9, Scheme 4B). Another brilliant example is the development of a chiral-phosphine-catalyzed [3 + 2] annulation reported by Lu in 2019, in which the chiral phosphine catalyst confers high stereocontrol on the formation of a spiro adduct bearing two vicinal all-carbon

• carboxylatve TMM [3 + 2] cycloaddition [38][39]. (B) Enantioselective synthesis of marcfortine C (9) features a palladium-catalyzed asymmetric cyano-substituted TMM [3 + 2] cycloaddition [39]. (A) Phosphine-catalyzed [3 + 2] cycloaddition [17]. (B) The proposed mechanism. Lu’s [3 + 2] cycloaddition in natural

3-Acetoxy-fatty acid isoprenyl esters from androconia of the ithomiine butterfly Ithomia salapia

• Florian Mann,
• Daiane Szczerbowski,
• Lisa de Silva,
• Melanie McClure,
• Marianne Elias and
• Stefan Schulz

Beilstein J. Org. Chem. 2020, 16, 2776–2787, doi:10.3762/bjoc.16.228

• catalysis [33]. Final acetylation of the hydroxy esters delivered the target compound isoprenyl 3-acetoxyoctadecanoate (11). Comparison of mass spectra and retention index confirmed the identity of the naturally occurring compound and 11. An enantioselective synthesis of isoprenyl (Z)-3-acetoxyoctadec-13

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• transformative synthetic strategy, including in enantioselective synthesis. From the pioneering work by MacMillan [1] and Bach [2], enantioselective photocatalysis has grown into a well-established field of its own. A large proportion of photocatalysis focuses on photoredox catalysis, which involves single

• to allenes 80 to give complex bicyclic products 81 in moderate yields and good enantioselectivities (20 examples, up to 92:8 er) (Scheme 9b) [47]. The Bach group recently developed an enantioselective synthesis of cyclobutane 82 from enal 83 and diene 84 (Scheme 11a) [48]. Most of the examples

• dual catalytic mode. Ooi et al. reported an enantioselective synthesis of 1,2 diamines 247 from tertiary amines 248 and aldimines 249 (Scheme 39) [100]. The proposed mechanism involves a reductive quenching pathway with 248 to produce radical cations 248•+, which following deprotonation and a [1,2

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• can not only be useful for enantioselective synthesis of π-bowls but also to produce novel building blocks for molecular switches, chemical machines, molecular motor, ferroelectric memories, molecular devices, and sensory materials etc. Interestingly, electronic switching, thermal transport and

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• alkaloid-promoted electrophilic fluorination producing enantioenriched post-Ugi adducts fluorinated at the peptidyl position. Keywords: cinchona alkaloids; electrophilic fluorination; enantioselective synthesis; 2-oxo-aldehydes; Ugi reaction; Introduction Multicomponent reactions (MCRs) [1][2][3][4][5][6

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• the 4′-OH group. This work is currently underway in our lab. Chemical structures of hexa-acylated Escherichia coli lipid A, monophosphorylated lipid X (the reducing monosaccharide lipid A precursor), and disaccharide lipid A precursor (“disaccharide lipid X”). Enantioselective synthesis of Nap

NHC-catalyzed enantioselective synthesis of β-trifluoromethyl-β-hydroxyamides

• Alyn T. Davies,
• Mark D. Greenhalgh,
• Alexandra M. Z. Slawin and
• Andrew D. Smith

Beilstein J. Org. Chem. 2020, 16, 1572–1578, doi:10.3762/bjoc.16.129

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• disulfide-catalyzed enantioselective synthesis of ophirin B. Disulfide-catalyzed isomerization in the total synthesis of (+)-hitachimycin. Disulfide-catalyzed isomerization in the synthesis of (−)-gloeosporone. Acknowledgements I thank Prof. Xiao Wang (Nanjing University) for helpful discussions. Funding I

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• in recent years, many strategies have been reported for their highly enantioselective synthesis. However, while catalytic asymmetric C–C bond formations by ACAs of organometallics is a routine procedure for additions to common Michael acceptors, such as enones and enoates, examples of catalytic

• ). Meldrum’s acid and its derivatives are versatile reagents in organic synthesis that can be transformed into a wide range of compounds. In 2006, the group of Fillion described the highly enantioselective synthesis of all-carbon benzylic quaternary stereocentres via a conjugate addition of dialkylzinc

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

• ) as the final product. Kempene diterpenes The first enantioselective synthesis of kempene diterpenes 14a–c, natural compounds exhibiting a significant antibiotic activity against B. subtilis, relying on the domino enyne metathesis of the adequate dienyne precursors as a key step, was disclosed by Metz

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• attributed this to a stabilization of the NH proton by hydrogen bonds to the triazole nitrogen and methoxy oxygen atoms. The initial step in the synthesis of 120 is the enantioselective synthesis of the propargylamine 118 through the reaction of propargyl acetate 117 with the corresponding amine. This

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• enantioselective synthesis of valnoctamide, a commercialized mild tranquilizer. Finally, this methodology was extended to the sequential Michael/halogenation reaction using NFSI or NCS as electrophiles, with similar efficiency. Similarly, a cocatalyzed enantioselective β-functionalization of enals was developed by

• Grignard reagents to α,β-unsaturated thioesters and their application in the asymmetric total synthesis of (–)-lardolure. Improved Cu ECA of Grignard reagents to α,β-unsaturated thioesters, and their application in the asymmetric total synthesis of (−)-mintlactone. Catalytic enantioselective synthesis of

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• method for the enantioselective synthesis of 4,5,5-trisubstituted γ-butyrolactones 193 using an electroreductive coupling of diaryl ketones 191 with α,β-unsaturated carbonyl compounds 190 bearing chiral auxiliaries derived from imidazolidin-2-one and oxazolidine-2-ones (Scheme 60). Compound 191 underwent

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• binaphthyl system and the Lewis acidic metal center facilitated the enantioselective synthesis of cyclic carbonates from epoxides. Various catalyst was screened by changing the linker length (n = 4 to 8) and nucleophilic counter anion (X = I, Cl, Br), and 16c was found to be the best catalyst for the

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• separated by column chromatography. Photooxygenation of 3,4-diphenylbutanal (1) with chiral organocatalysts The highly enantioselective synthesis of 3,4-diphenylbutanal (1), according to the procedure developed by Melchiorre, requires the use of noncommercially available sterically bulky silyl ethers [16

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

• 12 steps with 15% yield. Interestingly, in this synthesis only four intermediates needed to be purified. In 1999, Yang and co-workers reported an elegant chiral auxiliary-assisted, lanthanide triflate-catalyzed oxidative radical polycyclization of olefin-cation-based enantioselective synthesis of

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• (2S,1'S)-6 correspond to (S)- or ʟ-serinal (Figure 3) [13]. Furthermore, since the aziridine ring openings can be accomplished with other nucleophiles and the reductive cleavage is also known [14][15] the aziridines 5–8 offer a plethora of opportunities for enantioselective synthesis of structurally

An efficient synthesis of the guaiane sesquiterpene (−)-isoguaiene by domino metathesis

• Yuzhou Wang,
• Ahmed F. Darweesh,
• Patrick Zimdars and
• Peter Metz

Beilstein J. Org. Chem. 2019, 15, 858–862, doi:10.3762/bjoc.15.83

• roots of Parthenium hysterophorus [5]. A recent enantioselective synthesis of (−)-isoguaiene (1) from (+)-dihydrocarvone [6] enabled an unambiguous assignment of its absolute configuration as depicted in Figure 1. Due to the structural similarity of 1 and the trisnorsesquiterpene clavukerin A (2), we

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• when the same sequence of diastereoselective carbometalation/oxidation was performed on cyclopropenyl ester 1, the in situ-formed donor–acceptor cyclopropanol undergoes a selective ring-opening to provide the acyclic product possessing a quaternary carbon stereocenter [57]. As the enantioselective

• synthesis of the cyclopropenylmethyl ether 3 was easily achieved in high enantiomeric ratio (er 93:7, Scheme 5 [78][81][82]), the subsequent combined diastereoselective carbometalation reaction and oxidation gave the enantiomerically enriched cyclopropanols 5 as unique diastereoisomer with the same

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• and inexpensive synthesis of HPA-12 was felt. Our own interest in developing anticancer agents also prompted us to develop a new and practical enantioselective synthesis of 2 [26][27][28][29]. To realize our objective, we paid particular attention to obtain 2 using reactions that are high-yielding and

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• ][6]. Notably, organofluorine compounds bearing a tetrafluoroethylene (–CF2CF2–) unit have attracted significant interest as a promising framework for various functional molecules. In the medicinal field, for example, Linclau and co-workers reported the first enantioselective synthesis and the

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• precatalyst in iodine(III)-catalyzed enantioselective synthesis of spiroketals with high selectivities. In this report, substrates 128 were reacted with 10 mol % of chiral iodoarene 129a and 129b in the presence of mCPBA oxidant in chloroform at 0 °C. The desired ortho-spirocyclic ketals 130 were obtained in

• chiral auxiliaries 129a or 129b under similar reaction conditions mentioned in Scheme 48. Furthermore, the synthesized spiroketal 159 (R2 = iPr; R4 = SiMe3) was used as synthetic intermediate for enantioselective synthesis of natural product (−)-biscarvacrol [8] (Scheme 59). Additionally, Parra and

Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 1421–1427, doi:10.3762/bjoc.14.119

• the organic phase. Due to the sterical hindrance from the benzyl group, the alkylation by 1,5-dibromopentane takes place at the opposite side of the benzyl group of C7 to afford 3a. Conclusion In summary, an enantioselective synthesis of (R)-(+)-1-(5-bromopentyl)-1-methyl-7-methoxy-2-tetralone (3a), a

Enantioselective dioxytosylation of styrenes using lactate-based chiral hypervalent iodine(III)

• Morifumi Fujita,
• Koki Miura and
• Takashi Sugimura

Beilstein J. Org. Chem. 2018, 14, 659–663, doi:10.3762/bjoc.14.53

• )-isomer. Keywords: 1,2-difunctionalization of alkenes; enantioselective synthesis; hypervalent iodine; oxidation; Findings Hypervalent aryl-λ3-iodanes have been widely used for metal-free oxidation with high selectivity in organic synthesis [1][2][3]. The reactivity of an aryl-λ3-iodane is controlled by

Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)

• Tao Wang,
• Kathrin I. Mohr,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 135–147, doi:10.3762/bjoc.14.9

• natural product is 6-nonyl-2H-pyran-2-one. The antimicrobial and cytotoxic effects of the synthetic volatiles are also reported. Keywords: enantioselective synthesis; gas chromatography; mass spectrometry; natural products; volatiles; Introduction A large variety of volatile organic compounds from

• 11 were separable by GC on a homochiral stationary phase, one of which matched the natural product in terms of same retention times and mass spectra (Figure 3). To clarify the relative and absolute configuration of the natural stereoisomer of 11 an enantioselective synthesis was performed (Scheme 5

• unfortunately not of 11c. However, as described above, enantiomerically pure (4R,5S,6S)-11c was obtained by enantioselective synthesis, and the peaks for the enantiomers of 11c in the GC analysis on a homochiral stationary phase could be readily assigned by comparison to synthetic (4R,5S,6S)-11c. Finally, a