Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• structures of new compounds were elucidated via a joint use of spectroscopic analyses and single-crystal X-ray diffractions. Compounds 1 and 2 belong to a rare class of tricyclic 6/5/6 diarylcyclopentenones, and compounds 3–6 possess a C-18 tricyclic aromatic skeleton. The biosynthetic gene cluster of

• skeleton exhibit a large number of structural diversity due to the differences of the center ring and the connection among rings. Structurally, most natural terphenyls are p-terphenyl derivatives consisting of a C-18 tricyclic or polycyclic C-18 aromatic skeleton. Diarylcyclopentenones, which possess a

• rare class of a tricyclic 6/5/6 system, could also belong to p-terphenyl derivatives from a biosynthetic perspective. To date, more than 230 natural products containing p-terphenyl have been unearthed in nature, among them many p-terphenyls were isolated from fungi, only a few were discovered from

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

• Nisha Devi and
• Virender Singh

Beilstein J. Org. Chem. 2022, 18, 926–934, doi:10.3762/bjoc.18.92

• and substituents was also studied during investigation of fluorescence properties of these derivatives. Keywords: β-carboline; DABCO; fluorescence; MBH reaction; Michael addition; structure–fluorescence activity relationship; Introduction Among the polycyclic alkaloids based on indole, the tricyclic

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• attacking to the carbene B followed by an intramolecular displacement. The yield was not reported (Scheme 13) [33]. Synthesis via P–C bond formation In 1979, Coppola at Sandoz, Inc. reported an alternative strategy for the synthesis of tricyclic γ-phosphonolactams 74, 78, and 81 from N-(3-chloropropyl)-2

• presence of sodium hydride in dioxane, affording tricyclic γ-phosphonolactams 74, 78, and 81 in low to moderate yields (Scheme 14) [34]. In 2005, Aladzheva and co-workers prepared γ-phosphonolactams 85 from the substitution of ethyl 2-(3-chloropropyl)aminoalkanoates 82 derived from glycine and ᴅʟ-alanine

• -methoxy-1,3-dihydrobenzo[d][1,2]azaphosphole 2-oxide 71 from dimethyl 2-(methylamino)benzoylphosphonate (70) and trimethyl phosphite. Synthesis of tricyclic γ-phosphonolactams via formation of the P–C bond. Synthesis of γ-phosphonolactams 85 from ethyl 2-(3-chloropropyl)aminoalkanoates with diethyl

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• and diselenopheno[3,2-b:6,7-b′]fluorene through the cyclization of terminal acetylene as well as six types of biselenophene-based fused tricyclic derivatives [25][26]. In 2017, we reported the first member of diselenoselenophenes (DSSs), 2,5-di(trimethylsilanyl)diseleno[2,3-b:3′,2′-d]selenophene ((TMS

Complementarity of solution and solid state mechanochemical reaction conditions demonstrated by 1,2-debromination of tricyclic imides

• Petar Štrbac and
• Davor Margetić

Beilstein J. Org. Chem. 2022, 18, 746–753, doi:10.3762/bjoc.18.75

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

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

• construct a 3,4-fused tricyclic indole in a late stage of their total synthesis. Specifically, Michael-type addition of compound 4 took place regio- and diastereoselectively at the indole C3 position, furnishing tricyclic compound 5 (77%) which was then elaborated into the target natural product 6 in two

• cyclopenta[e]indol-6-one 29k and cyclohepta[e]indol-6-one 29l from compounds 28k and 28l, respectively (Scheme 10C) [21]. In 2009, the Hansen group disclosed that treatment of 2-diazo-4-(4-indolyl)-3-oxobutanoate 30 with a catalytic amount of Rh2(OAc)4 resulted in the formation of the 4,5-fused tricyclic

• catalysis diazo compound 30 delivered 3,4-fused tricyclic indole derivative 32 which underwent spontaneous rearrangement to thermodynamically more stable naphthalene derivative 33 upon standing for a few hours. To the best of our knowledge, this is the only report of catalyst-controlled C3 versus C5

Chemical and chemoenzymatic routes to bridged homoarabinofuranosylpyrimidines: Bicyclic AZT analogues

• Sandeep Kumar,
• Jyotirmoy Maity,
• Banty Kumar,
• Sumit Kumar and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2022, 18, 95–101, doi:10.3762/bjoc.18.10

• . [23] synthesized the tricyclic azido-isonucleoside analogue 5 and Imanishi et al. [24] synthesized the azido-nucleoside 6 with a conformationally restricted sugar moiety. Recently, we have developed a greener and efficient chemoenzymatic synthetic methodology for the synthesis of conformationally

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• quinoid type to study their photophysical properties in solution and in the solid-state, Ooyama and co-workers [106] studied a synthetic route for the preparation of compounds with the tricyclic benzo[c]carbazol-6-one skeleton. The strategy used was through the reaction to β-NQS 18 with a bifunctional

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• different coupling partners, both bi- [142] and tricyclic [143] fused heterocyclic frameworks have been synthesized through iminyl radical cascade cyclization and annulation reactions. Carbooxygenation In 2017, the Bao group reported the first decarboxylative alkyl etherification of alkenes 108 with

The PIFA-initiated oxidative cyclization of 2-(3-butenyl)quinazolin-4(3H)-ones – an efficient approach to 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-ones

• Alla I. Vaskevych,
• Nataliia O. Savinchuk,
• Ruslan I. Vaskevych,
• Eduard B. Rusanov,
• Oleksandr O. Grygorenko and
• Mykhailo V. Vovk

Beilstein J. Org. Chem. 2021, 17, 2787–2794, doi:10.3762/bjoc.17.189

• nitrogen atom to nitrenium intermediates occurred initially; further stabilization of these species resulted in the formation of hydroxylated lactams [44][45][46][47][48], azaspirocycles [49][50][51][52][53], or tricyclic nitrogen-containing heterocycles [44][53]. Our study commenced with the synthesis of

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• cyclic lactones [69]. The intramolecular cyclization of the acyl radical A gives the tricyclic radical species C, which then forms fluorenone (3) after abstraction of a hydrogen radical by an additional equivalent of the tert-butoxy radical. Conclusion In summary, we have demonstrated that the metal-free

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

• ]. The pyrrolizidine motif has up to now eluded us other than when it forms part of the tricyclic 2,3-dihydro-1H-pyrrolo[1,2-a]indole system [15], as in our route to aziridinomitosenes [16][17]. In the course of our attempts at the syntheses of aryl-bearing indolizidine alkaloids via N-phenacyl

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• with high selectivity using this strategy. In these transformations, two Hg-carbene intermediates were proposed to be involved (Scheme 52). Mercury-catalyzed reactions were also well known for the formation of various complex scaffolds like tricyclic pyrazinones from the corresponding starting

• materials. For example, Zhang et al. showed that refluxing anilide 177 in presence of a catalytic amount of Hg(OAc)2 and 90% formic acid gave the tricyclic heterocyclic scaffold 178 [113]. It involved a two-step process with the rearrangement of the primary cyclization products (Scheme 53). In 2013, Lin et

• -metalation followed by a regioselective mercuri-cyclization reaction (Scheme 60). During the total syntheses of (±)-fastigilin C and (–)-fastigilin C (201), 2 equiv of Hg(TFA)2 were used to synthesize key intermediate tricyclic furan compounds 199, 200, and 203. Hg(TFA)2 helped in the desired ring-formation

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• , enabling the synthesis of a 32mer [272]. The construction of α(1–6)-mannans (up to 10mer) bearing α(1–2)-Man branches was also accomplished using phosphate, N-phenyltrifluoroacetimidate or n-pentenylorthoester donors [273][274]. An approach using a (cationic) ROP method using tricyclic orthoester Man BBs

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• White’s oxidation method as the final step in the first total synthesis of gracilioether F (75) [157], a natural polyketide with an unusual tricyclic core and five contiguous stereocenters, part of the family of gracilioethers 71–74 (Scheme 26A) extracted from the marine sponge Plakinastrella mamillaris

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• binding is G-clamp (Figure 8), the phenoxazine-derived tricyclic analogue of cytosine [124]. The improvements in affinity provided by the G-clamp are likely a combined effect of superior π-stacking of the rigid and planar aromatic system, electrostatic attraction of the positively charged amine, and

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• converted to fused sultams (Scheme 30) [56]. Anand et al. reported a Cu-catalyzed one-pot method for the preparation of 1,2,3-triazole-fused tricyclic heterocycles 106 via an intramolecular [3 + 2]-annulation. This strategy includes the 1,6-conjugate addition of Me3SiN3 to o-alkynylated p-quinone methides

• functionalized tricyclic triazoles 152–154. It was proved that o‐azidophenols 148 react well with alkynes 149 using CuI in DMF at 120 °C and then, the resulting intermediates react with isocyanides using Pd(OAc)2 and an O2 atmosphere at 120 °C to produce the desired products (Scheme 42). o‐Azidophenols 148 were

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• reaction time (up to 6 d) was required to complete these experiments, and the yield of the isolated products dropped significantly (to 41 and 64%, respectively). In analogy to the tricyclic pyrazole derivative 9a, the expected products 9b–h formed after spontaneous aromatization of the initial [3 + 2

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• veratrole or furan led to the formation of the respective tricyclic 4-aryl-1,2,3,4-tetrahydrophenanthren-2-ols 14ha and 14hb in 73% and 43% yields, respectively. In order to further explore the generality of this cascade Prins/Friedel–Crafts cyclization, the established methodology was also applied to the

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• in 41% yield (Scheme 6c). Furthermore, the tricyclic indoline 14, a structural motif in diverse natural products [4], could be obtained in 60% yield through a reductive cyclization reaction (Scheme 6d). To investigate the mechanism of the cyanomethylarylation of alkenes, a series of control

Synthesis of functionalized imidazo[4,5-e]thiazolo[3,2-b]triazines by condensation of imidazo[4,5-e]triazinethiones with DMAD or DEAD and rearrangement to imidazo[4,5-e]thiazolo[2,3-c]triazines

• Alexei N. Izmest’ev,
• Dmitry B. Vinogradov,
• Natalya G. Kolotyrkina,
• Angelina N. Kravchenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2021, 17, 1141–1148, doi:10.3762/bjoc.17.87

• 40% KOH aqueous solution resulted in a skeletal rearrangement of the tricyclic system, which, however, was accompanied by reesterification with methanol and partial hydrolysis of the ester group. As a result, the methyl ester 5a was obtained in 66% yield (Scheme 3). Rearrangement of 1,3-dimethyl- and

• an individual form were found. The methodology proved to be effective for the synthesis of a wide range of target compounds with various substituents in the tricyclic fragment. Investigations of the antiproliferative activity of the synthesized products 4 and 5, as well as possible ways of their

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82