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

• V. Electrocyclization of V followed by loss of proton from the intermediate VI afforded the corresponding cyclopenta[e]indol-6-ones 35a,b. While involved in the synthesis of 9H-fluorenes and 9,10-dihydrophenanthrenes through intramolecular arylative ring-opening of indole-tethered donor–acceptor

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• -(trifluoromethyl)-9H-fluorenes, compounds containing a 9-(trifluoromethyl)-9H-fluoren-9‑ol partial structure can be found in the patent literature [33][34][35], where they have been claimed for their pyruvate dehydrogenase kinase (PDHK) inhibitory activity. The remarkable dienophilic reactivity of 1-CF3

• reaction mechanism. Thus, the reaction of 1a with α-methylstyrene or 1,1-diphenylethene proceeded at a faster rate than with styrene and yielded 3-methyl- and 3-phenyl-2-vinylindenes 12b and 12c (structure confirmed by an XRD analysis, see Figure 2) in high yields. Benzo[a]fluorenes were found to a minor

• NOESY NMR experiments and confirmed by an X-ray structure determination (see Figure 3). A mechanistic scheme for the formation of indenes 12 and benzo[a]fluorenes 13 is proposed in Scheme 5. The electrophilic propyn-1-iminium ion 1a adds chemoselectively (by conjugate addition) and regioselectively

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• emission behavior. Keywords: bromoarylaldehydes; click-chemistry; fluorenes; fluorescence; phosphorescence; Introduction Small organic luminophores exhibiting room-temperature phosphorescence (RTP) have attracted great attention due to promising applications in optoelectronic devices [1][2][3][4][5][6][7

• Scheme 3). Derivatization of fluorenyl methanol 19 To gain deeper insights into the emission behavior of fluorenes bearing different functional groups in the side chains, fluorenylmethanol 19 was subjected to derivatization reactions (see Scheme 4). Deprotonation and subsequent methylation afforded

• CuAAC. Initial photophysical investigations of azide-functionalized bromocarbaldehydes and fluorenes revealed that the azide moiety and the triazole heterocycle efficiently quench phosphorescent transitions. Efforts of installing other functional groups suitable for covalent connections or modifications

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• temperature (Scheme 4) [94]. In their study, they observed that electron-donating groups provided better yields as compared to electron-withdrawing groups. The earlier reported methods for the synthesis of fluorenones, viz, Friedel–Craft acylations [95][96], oxidations of fluorenes [97][98], and Diels–Alder

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

• Clara Orofino-Pena,
• Diego Cortizo-Lacalle,
• Joseph Cameron,
• Muhammad T. Sajjad,
• Pavlos P. Manousiadis,
• Neil J. Findlay,
• Alexander L. Kanibolotsky,
• Dimali Amarasinghe,
• Peter J. Skabara,
• Tell Tuttle,
• Graham A. Turnbull and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2704–2714, doi:10.3762/bjoc.10.285

• computational efficiency of the optimisations, the hexyl chains on the fluorene units were shortened to methyl groups. The twist between the β-fluorenes and BODIPY in T-B1 (56.6°) is greater than that obtained for the fluorenes in α-positions in Y-B1 (42.9°), probably due to steric restrictions imposed by the

• greater degree of conjugation of the fluorenes with the core in Y-B1 compared with T-B1 is also evident from the examination of their frontier orbitals. The HOMO of Y-B1 shows increased electron-density over the fluorene units (Figure 5) with respect to the analogous units in T-B1 (Figure 6). Also, the

• LUMO of Y-B1 shows some delocalisation over the fluorenes, but the LUMO of T-B1 is localised on the BODIPY unit, which supports the idea that the increase in the fluorene twist reduces conjugation in T-B1, hence its absorption spectrum is hypsochromically shifted with respect to Y-B1. The calculated

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• [1,2-b]fluorenes and related indeno[1,2-b]fluorene-6,12-diones. UV–vis spectrum (left) and cyclic voltammogram (right) of dione 8c. Kohn–Sham HOMO (left) and LUMO (right) plots of 8a. Views perpendicular to the average plane of the π stack. 1st row left to right – 8a, 8b, 8c; 2nd row – 8d, 8d, 8e; 3rd

Incorporation of perfluorohexyl-functionalised thiophenes into oligofluorene-truxenes: synthesis and physical properties

• Neil Thomson,
• Alexander L. Kanibolotsky,
• Joseph Cameron,
• Tell Tuttle,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2013, 9, 1243–1251, doi:10.3762/bjoc.9.141

• ′,2′-c]fluorene, also known as truxene (Figure 1), is a heptacyclic polyarene with C3 symmetry that can be envisaged as three fluorenes that are superimposed through a common central benzene ring [2][3]. Truxene has been used as a starting compound, or a core unit, for larger star-shaped polyarenes

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• + 3] [106][107][108] cycloaddition reactions have been developed in last 3 years. Treatment of 1-aryl-1-allen-6-enes 220 with [PPh3AuCl]/AgSbF6 (5 mol %) in CH2Cl2 at 25 °C led to intramolecular [3 + 2] cycloadditions to afford cis-fused dihydrobenzo[a]fluorenes 221 efficiently and selectively [99

Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

• Yu-Hsuan Wang,
• Joshua F. Bailey,
• Jeffrey L. Petersen and
• Kung K. Wang

Beilstein J. Org. Chem. 2011, 7, 496–502, doi:10.3762/bjoc.7.58

• synthesized by treatment of the corresponding benzannulated enediynes with potassium tert-butoxide in refluxing toluene to give benzannulated enyne–allenes for the subsequent Schmittel cascade cyclization reactions. The structures of these two 5-(1-naphthyl)-11H-benzo[b]fluorenes could be regarded as 2,2

• '-disubstituted 1,1'-binaphthyls with the newly constructed benzofluorenyl group serving as a naphthyl moiety. Keywords: benzannulated enediynyl alcohols; benzannulated enyne–allenes; 2,2'-disubstituted 1,1'-binaphthyls; 5-(1-naphthyl)-11H-benzo[b]fluorenes; Schmittel cascade cyclizations; Introduction

• Benzannulated enyne–allenes bearing an aryl substituent at the alkynyl terminus are excellent precursors of 5-aryl-11H-benzo[b]fluorenes [1][2][3][4][5]. Several synthetic pathways to the benzannulated enyne–allene systems have been reported, including generation in situ from the corresponding benzannulated

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• . Furthermore, an efficient intramolecular variant of this procedure starting from biaryl benzyl alcohol 23 led to substituted fluorenes 24 which have shown to be valuable scaffolds for blue light emitting polymers (Scheme 11A) [46]. A similar route to fluorenes and other annulated cycloalkanes 26 was