Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• construction of the 8-membered ring from an appropriate cyclopentane precursor. The proposed strategies include metathesis, Nozaki–Hiyama–Kishi (NHK) cyclization, Pd-mediated cyclization, radical cyclization, Pauson–Khand reaction, Lewis acid-promoted cyclization, rearrangement, cycloaddition and biocatalysis

• precursor. The proposed strategies include metathesis, Nozaki–Hiyama–Kishi (NHK) cyclization, Pd-mediated cyclization, radical cyclization (including SmI2), Pauson–Khand reaction, Lewis acid-promoted cyclization, rearrangement, cycloaddition, and biocatalysis. In particular, the purpose will focus on the

• refluxed in the presence of a small amount of dilauroyl peroxide (DLP) as radical initiator. The eight-membered ring 176 was obtained in 60% yield as a single diastereomer [79]. 5 Pauson–Khand reaction Discovered in the seventies [80], the Pauson–Khand reaction has been widely used for the formation of

Synthetic study toward the diterpenoid aberrarone

• Liang Shi,
• Zhiyu Gao,
• Yiqing Li,
• Yuanhao Dai,
• Yu Liu,
• Lili Shi and
• Hong-Dong Hao

Beilstein J. Org. Chem. 2022, 18, 1625–1628, doi:10.3762/bjoc.18.173

• the 6-5-5 tricyclic skeleton includes the mediation of Nagata reagent for constructing the C1 all-carbon quaternary centers and gold-catalyzed cyclopentenone synthesis through C–H insertion. Keywords: aberrarone; C–H insertion; gold; Pauson–Khand; total synthesis; Introduction Marine natural

• functional transformation from 10, which itself would be prepared through methylation and conjugate addition from Pauson–Khand adduct 11. This cyclopentenone could be readily accessed from 1,7-enyne 12 which could be obtained through the reported procedure [35] from the commercially available 5-hexenoic acid

• stereoselectivity is possible through the conformation of 14 where the OTBS group is in pseudoequatorial position (Scheme 2). Therefore, the Pauson–Khand reaction proceeded to afford 11 containing an α-H at C6. From this intermediate, to our delight, the stereoselective attachment of the requisite methyl group

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

• corresponding methyl ester, to give compounds 101. Subsequent, reductive ammination with 3-phenyl-2-propynal led to reaction intermediates 102, which under typical Pauson–Khand reaction conditions gave cyclopenta[c]proline derivatives 103 in moderate yields, with high diastereoselectivities (Scheme 30

Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

• Viola Kolaříková,
• Markéta Rybáčková,
• Martin Svoboda and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

• for other catalytic reactions, e.g., for the Pauson–Khand reaction [14]. In the enantioselective RCM, prochiral trienes have been most often employed, leading to chiral cycloalkenes. The Schrock molybdenum precatalysts [15][16][17] proved to be more effective than the Grubbs or Collins ruthenium

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• , Facultad de Química, Universidad de Oviedo, Av. Julián Clavería 8, Campus Universitario de El Cristo, 33006 Oviedo, Spain 10.3762/bjoc.16.138 Abstract The Pauson–Khand reaction (PKR) is one of the key methods for the construction of cyclopentenone derivatives, which can in turn undergo diverse chemical

• transformations to yield more complex biologically active molecules. Despite the increasing availability of fluorinated building blocks and methodologies to incorporate fluorine in compounds with biological interest, there have been few significant advances focused on the fluoro-Pauson–Khand reaction, both in the

• inter- and intramolecular versions. Furthermore, the use of vinyl fluorides as olefinic counterparts had been completely overlooked. In this review, we collect the advances both on the stoichiometric and catalytic intermolecular and intramolecular fluoro-Pauson–Khand reaction, with special attention to

Diversity-oriented synthesis of 17-spirosteroids

• Benjamin Laroche,
• Thomas Bouvarel,
• Martin Louis-Sylvestre and
• Bastien Nay

Beilstein J. Org. Chem. 2020, 16, 880–887, doi:10.3762/bjoc.16.79

• structures due to the poor diastereoselectivity of the Diels–Alder reaction in this case. Finally, we expect to apply this strategy to complementary reactions like the Pauson–Khand reaction that may be useful to cyclize enyne substrates like 5–7 and expand the spirosteroid diversity. All compounds will be

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• , Viale Morgagni 85, 50134 Florence, Italy 10.3762/bjoc.16.23 Abstract The Cu-catalyzed multicomponent ketone–amine–alkyne (KA2) reaction was combined with a Pauson–Khand cycloaddition to give access of unprecedented constrained spirocyclic pyrrolocyclopentenone derivatives following a DOS couple-pair

• cyclopentenone ring [37], as this heterocycle is a powerful synthon for the synthesis of a variety of bioactive target molecules, due to the broad diversity of chemical modifications available for the enone structural motif [38]. The most common approach to access such chemotype is the Pauson–Khand (PK) reaction

• . Following our interest to DOS as a synthetic strategy for the generation of molecular scaffolds according to a couple/pair approach [45][46][47], we reasoned to combine the copper-catalyzed ketone–amine–alkyne (KA2) multicomponent coupling reaction [48] with the Pauson–Khand cycloaddition as the pairing

Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation

• Gisela V. Saborit,
• Carlos Cativiela,
• Ana I. Jiménez,
• Josep Bonjoch and
• Ben Bradshaw

Beilstein J. Org. Chem. 2018, 14, 2597–2601, doi:10.3762/bjoc.14.237

• reactions [27] to achieve cis-hydrindan-2,4-diones, their application to rapidly assemble the five-membered ring of the targeted 6,5-bicylic system has not been reported until now. Two examples using cycloaddition processes in this field should be mentioned: Diels–Alder [28] and Pauson–Khand [29] reactions

Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

• Matthias Wünsch,
• David Schröder,
• Tanja Fröhr,
• Lisa Teichmann,
• Sebastian Hedwig,
• Nils Janson,
• Clara Belu,
• Jasmin Simon,
• Shari Heidemeyer,
• Philipp Holtkamp,
• Jens Rudlof,
• Lennard Klemme,
• Alessa Hinzmann,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2017, 13, 2428–2441, doi:10.3762/bjoc.13.240

• acid function of amino acids can be easily converted into amides or esters (Figure 1), propargylamines have been converted into acids, alcohols [12] or olefins in order to obtain natural products like angustureine and cuspareine [13]. Intramolecular Pauson–Khand reaction [14], Diels–Alder reaction [15

• ], it provides a versatile protective group for the amine during the conversion of the alkyne. Additionally, it’s chirality indicates epimerization and, for example in the Pauson–Khand reaction [14], allows the determination of the stereoselectivity of asymmetric conversions by simple 1H NMR experiments

• ) Intramolecular Pauson–Khand reaction, R = (S)-tert-butylsulfinyl, R’ = CH2CH2OTBDPS [14]. b) Diels–Alder reaction, R = pTs, R’ = H, R’’ = Me [15]. c) Gold-catalyzed intramolecular reaction to azetidin-3-ones, R = tert-butylsulfonyl, R’ = aromatics, aliphatics [16]. d) Sonogashira cross-coupling, R = tert

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• plumisclerin A by Pauson–Khand annulation and SmI2-mediated radical cyclization [59]. The xenicane-related diterpenoid (isolated from the same marine organism as xenicin 116) possesses a complex ring system that is proposed to be biosynthetically derived from the xenicin diterpenoid 116 by an intramolecular [2

• three steps enabled preparation of the annulation precursor 121. The following Pauson–Khand reaction [61] for the construction of the fused bicyclic structure 122 was performed by treatment of 121 with dicobaltoctacarbonyl in the presence of cyclohexylamine. Hydrolysis of the acetonide, chemoselective

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• the fabulous Pauson–Khand reaction [10][11] to introduce simultaneously the two adjacent five-membered rings. Outlined in Scheme 2 is a very short total synthesis of (±)-13-deoxyserratine (11) [12][13]. The first two of the four rings in 11 are again created through the powerful Pauson–Khand reaction

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

• Andrew Tigchelaar and
• William Tam

Beilstein J. Org. Chem. 2012, 8, 1765–1770, doi:10.3762/bjoc.8.201

• alkynes, [2 + 2 + 2] cyclotrimerizations of alkynes [14][15], and Pauson–Khand-type [2 + 2 + 1] cycloadditions of enynes [17][18][19] and allenynes [20]; however, Ir-catalyzed [4 + 2] cycloadditions are rare in the literature [26][27]. Transition-metal-catalyzed (TMC) [4 + 2] cycloadditions are an

Synthesis and in silico screening of a library of β-carboline-containing compounds

• Kay M. Brummond,
• John R. Goodell,
• Matthew G. LaPorte,
• Lirong Wang and
• Xiang-Qun Xie

Beilstein J. Org. Chem. 2012, 8, 1048–1058, doi:10.3762/bjoc.8.117

• subset of α-methylenecyclopentenone-containing tetrahydro-β-carbolines was synthesized. These compounds contain a general substructure that has recently been shown to inhibit DNA damage checkpoints [8]. Allene-ynes 9{1,3}–9{1,4} undergo Pauson–Khand cyclocarbonylation reactions when treated with

Rh(I)-catalyzed intramolecular [2 + 2 + 1] cycloaddition of allenenes: Construction of bicyclo[4.3.0]nonenones with an angular methyl group and tricyclo[6.4.0.0^1,5]dodecenone

• Fuyuhiko Inagaki,
• Naoya Itoh,
• Yujiro Hayashi,
• Yumi Matsui and
• Chisato Mukai

Beilstein J. Org. Chem. 2011, 7, 404–409, doi:10.3762/bjoc.7.52

• carbonylative [2 + 2 + 1] cycloaddition of allenenes was developed to prepare bicyclo[4.3.0]nonenones possessing a methyl group at the ring junction, which is difficult to achieve by the Pauson–Khand reaction of the corresponding enynes. This method also provided a new procedure for the construction of the

• tricyclo[6.4.0.01,5]dodecenone framework in a satisfactory yield. Keywords: allene; bicyclo[4.3.0] derivatives; carbonylative [2 + 2 + 1] cycloaddition; quaternary center construction; rhodium; Introduction The Co2(CO)8-mediated Pauson–Khand reaction (PKR) [1][2] is well recognized as a formal [2 + 2 + 1

• %) under a CO atmosphere) provided the ring-closing product 8a in 75% yield (Table 1, entry 3). It has already been shown that the Rh(I)-catalyzed Pauson–Khand type reaction (PKTR) of enynes under a low CO pressure [26][27] leads to better results. Thus, the ring-closing reaction of 7a was performed under

The use of silicon- based tethers for the Pauson- Khand reaction

• Adrian P. Dobbs,
• Ian J. Miller and
• Saša Martinović

Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21

• range of silicon-based tethers and promoters have been investigated for use in the development of a silyl-tethered Pauson-Khand reaction. Background Since its discovery in 1973, the Pauson-Khand (P-K) reaction has become one of the principal methods for the construction of cyclopentenones.[1][2

• from the molecule by the reaction conditions and leaves no functionality for further synthetic modifications. There are only two examples of silicon tethers being successfully applied to a Pauson-Khand type reaction. Brummond researched a large variety of potential systems but found that silicon

• tethers did not seem to be compatible with the Pauson-Khand reaction. Fortunately her research discovered that by combining the silicon tether with the allenic Pauson-Khand reaction mediated by molybdenum hexacarbonyl the corresponding bicyclic cyclopentenone could be formed although with poor yields