A novel bis-triazole scaffold accessed via two tandem [3 + 2] cycloaddition events including an uncatalyzed, room temperature azide–alkyne click reaction

• Ksenia Malkova,
• Andrey Bubyrev,
• Vasilisa Krivovicheva,
• Dmitry Dar’in,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1636–1641, doi:10.3762/bjoc.18.175

• valuable part of the drug discovery chemistry toolbox. For the same reason, development of new methods [3] to either build 1,2,3-triazoles de novo and/or incorporate them into polycyclic scaffolds is a worthy undertaking which can help discover biological activity associated with hitherto unattainable

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• for the construction of such polycyclic scaffolds, and the last decade has witnessed a remarkable improvement in the palladium-catalyzed C–H/C–H oxidative coupling as one of the potential synthetic strategies [1]. This method is straightforward and highly step-economical, enabling us to produce

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• fulvenes and complex polycyclic scaffolds. Keywords: cycloaddition; fulvene; polycyclic scaffolds; Introduction Fulvenes are an interesting organic class of cross-conjugated, cyclic molecules first discovered by Thiele in 1900, with the preparation of pentafulvenes by condensation of aldehydes and

• interest as a result of their unique reactivity resulting from their exocyclic double bond [9][29][30][31][32], and more recently, as intermediates in the synthesis of more complex polycyclic scaffolds via cycloaddition reactions. While this highlight article will focus primarily on the cycloaddition

• and unique range of fused ring and polycyclic scaffolds. In the subsequent sections, the cycloaddition chemistry of fulvenes will be discussed in terms of their dimerization, and intra- and intermolecular reactions. Whereas the high reactivity and poor stability of triafulvenes have limited studies

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

• Shuai Qiu,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2016, 12, 2293–2297, doi:10.3762/bjoc.12.222

• three kinds of biologically important chiral 1,4-sulfur-bridged piperidinones and their related derivatives [10]. In order to develop novel chiral S-containing polycyclic scaffolds, the development of [4 + 2] annulations of 5H-thiazol-4-ones with unusual activated alkenes still remains highly desirable

Stereoselective synthesis of fused tetrahydroquinazolines through one-pot double [3 + 2] dipolar cycloadditions followed by [5 + 1] annulation

• Xiaofeng Zhang,
• Kenny Pham,
• Shuai Liu,
• Marc Legris,
• Alex Muthengi,
• Jerry P. Jasinski and
• Wei Zhang

Beilstein J. Org. Chem. 2016, 12, 2204–2210, doi:10.3762/bjoc.12.211

• using one-pot intermolecular or intramolecular [3 + 2] azomethine ylide cycloadditions [22][23][24][25][26][27] as the initial step followed by cyclization or cycloaddition reactions to form polycyclic scaffolds with skeleton, substitution, and stereochemistry diversities. Introduced in this paper is a

• product 7 under the optimized reaction conditions, see Table 1, entry 5. nd = not detected. X-ray structure of 7h. [5 + 1] Annulation for tetrahydroquinazolines 1. Polycyclic scaffolds derived from [3 + 2] adducts 2. Proposed mechanism for the 2nd [3 + 2] cycloaddition and denitrogenation. One-pot double

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• reactions for constructing structurally novel and complex polycyclic scaffolds (Scheme 53). A pioneering work has been done on the 3-indolylmethanol-involved cycloaddtion reactions by the Shi group. In 2014, Shi et al. developed a CPA-catalyzed asymmetric [3 + 3] cycloaddition of 3-indolylmethanols with

• entry to polycyclic scaffolds for further biological screening. Similarly, Shi et al. established CPA-catalyzed highly enantioselective aza-ene reactions of cyclic enaminones with 3-indolyl-3-hydroxyoxindoles, incorporating enaminones and 3-indolyl-3-hydroxyoxindoles into C3-functionlized chiral indoles

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• temperature (Scheme 11) [48]. This method was used to prepare polycyclic scaffolds that can be encountered in diverse alkaloid natural products such as coralyne and berberine (Scheme 12) [49]. Similarly, enyne ring-closing metathesis reactions were performed to access a variety of vinyl-3,4

• -induced decomposition of GII in RCM conditions. Deactivation of methylidene 2 in the presence of pyridine. Reaction of G-HII with various amines. Formation of olefin 22 from styrene. Hypothetic deactivation pathway of G-HII. RCM of dienic pyridinium salts. Synthesis of polycyclic scaffolds using RCM

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• utilized the RRM and the enyne RRM to generate various polycyclic scaffolds. In this context, enones, such as 121a and 121b were assembled easily from dicyclopentadiene derivative 119. Later, these componds were subjected to a RRM to generate the tricyclic enones 122a and 122b, respectively. To this end

Synthesis of a novel chemotype via sequential metal-catalyzed cycloisomerizations

• Bo Leng,
• Stephanie Chichetti,
• Shun Su,
• Aaron B. Beeler and
• John A. Porco Jr.

Beilstein J. Org. Chem. 2012, 8, 1338–1343, doi:10.3762/bjoc.8.153

• processes and chemotypes [5]. For example, we have conducted multidimensional reaction screens using alkynyl o-benzaldehyde scaffolds, which revealed a number of reactions affording novel polycyclic scaffolds, including Au(III)-catalyzed addition of diethyl malonate to 1 to afford isochromene 2 (Scheme 1