Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• ) [66]. Variations of this reaction include alkyne metathesis [67] and carbonyl metathesis [68]. Ring-closing metathesis (RCM) gave access to a series of dibenzo[b,f]heteropines, as reported by Matsuda and Sato [31] (Scheme 25). The authors synthesised a series of Si-, Sn-, Ge- and B-tethered dienes 118

Earth-abundant 3d transition metals on the rise in catalysis

• Nikolaos Kaplaneris and
• Lutz Ackermann

Beilstein J. Org. Chem. 2022, 18, 86–88, doi:10.3762/bjoc.18.8

• syntheses, crop protection or medicinal chemistry. Particularly, cross-coupling reactions [1], as well as alkene and alkyne metathesis [2][3], have considerably changed the art of molecular synthesis, with a major impact on neighboring disciplines, such as molecular biology or materials sciences. Despite of

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

• of known, in vivo effective substances but also for designing chemically modified analogs as valid alternatives for further therapeutic agents. Keywords: bioactive compounds; enyne metathesis; ring-closing metathesis; ruthenium catalysts; tandem reactions; Introduction Alkene and alkyne metathesis

• total synthesis of amphidinolides [73][74][75], Fürstner et al. applied both ring-closing alkyne metathesis and intramolecular enyne metathesis with ethylene in a sequential mode for the synthesis of amphidinolide V (7) [75]. As a special merit of this original protocol, the macrocyclization of the

• stereoisomeric diyne precursors was performed first by a ring-closing alkyne metathesis in the presence of Schrock’s molybdenum catalyst. Next, the diene units were installed by intermolecular enyne metathesis of the preformed cyclic alkyne with ethylene using Grubbs second-generation ruthenium catalyst (Scheme

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• from the corresponding terminal diacetylenic ferrocenes [fc{CO2(CH2)nC≡CH}2] (1a: n = 2; 1b: n = 3) through ring-closing alkyne metathesis (RCAM) utilizing the highly effective molybdenum catalyst [MesC≡Mo{OC(CF3)2CH3}3] (MoF6; Mes = 2,4,6-trimethylphenyl). The metathesis reaction occurs in short time

• isolated from THF solution. Keywords: alkyne metathesis; ferrocene; homogeneous catalysis; molybdenum; terminal alkynes; Introduction Alkyne metathesis, the reversible making and breaking of carbon–carbon triple bonds, is clearly gaining more attention. Not only could a great number of active catalysts

• for alkyne metathesis be developed over the past decades, but also their field of applications is steadily growing [1][2][3][4][5][6][7]. Numerous symmetric complexes of the Schrock type [RC≡MX3] [8][9] bearing a great variety of ancillary ligands X were successfully explored for several types of

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• ; W2F3, M = W, R = OC(CF3)Me2) were synthesized as bimetallic congeners of the highly active alkyne metathesis catalysts [MesC≡M{OC(CF3)nMe3−n}] (MoF6, M = Mo, n = 2; WF3, M = W, n = 1; Mes = 2,4,6-trimethylphenyl). The corresponding benzylidyne complex [PhC≡W{OC(CF3)Me2}] (WPhF3) was prepared by

• cleaving the W≡W bond in W2F3 with 1-phenyl-1-propyne. The catalytic alkyne metathesis activity of these metal complexes was determined in the self-metathesis, ring-closing alkyne metathesis and cross-metathesis of internal and terminal alkynes, revealing an almost equally high metathesis activity for the

• bimetallic tungsten complex W2F3 and the alkylidyne complex WPhF3. In contrast, Mo2F6 displayed no significant activity in alkyne metathesis. Keywords: alkylidyne complexes; alkyne metathesis; catalysis; terminal alkynes; tungsten; Introduction While the field of olefin metathesis has seen significant

An eco-compatible strategy for the diversity-oriented synthesis of macrocycles exploiting carbohydrate-derived building blocks

• Sushil K. Maurya and
• Rohit Rana

Beilstein J. Org. Chem. 2017, 13, 1106–1118, doi:10.3762/bjoc.13.110

• transition-metal-catalyzed coupling reactions [19]. Recently, ring-closing alkyne metathesis (RCAM) [20][21] and ring closing metathesis (RCM) [22][23][24][25][26][27][28][29][30][31] have emerged as very powerful tools for macrocyclization including for the preparation of peptidomimetic [17][18][32

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• saturated alkyl chain (22), whereas the unsaturated turrianes 23, 24 containing a (Z)-alkene moiety have been prepared by alkyne metathesis followed by reduction using Lindlar’s catalyst (Figure 5). Muscopyridine and its analogues Musk is a widly used component in Chinese pharmaceuticals and it has also

• 139 by using the Wurtz coupling as a key step (Scheme 20). Metathesis Alkyne metathesis reaction: In 2010, Murphy and Jarikote [139] have developed a useful protocol for assembling non-natural macrocyclic compounds containing carbohydrates. Compound 140 was prepared in several steps and was further

• subjected to the RCM with G-I (12) as a catalyst in CH2Cl2. Later, catalytic hydrogenation followed by deacetylation gave compound 141 (48%). Similarly, alkyne metathesis of compound 142 was carried out in the presence of Mo(CO)6 and 2-fluorophenol in chlorobenzene and heated under reflux to yield the

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• Xian Wu Matthias Tamm Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.7.12 Abstract The number of well-defined molybdenum and tungsten alkylidyne complexes that are able to catalyze alkyne metathesis

• natural product synthesis and advanced material science [1]. Alkyne metathesis, which deals with the breaking and making of C–C triple bonds, has only relatively recently become part of the tool box of organic and polymer chemists for the preparation of their target molecules [2][3][4][5][6][7][8][9][10

• ][11]. Catalyzed by organotransition metal complexes, this reaction type creates new C–C triple bonds very simply via the Katz mechanism (Scheme 1) [12], based on which a series of different reaction types such as alkyne cross metathesis (ACM), ring-closing alkyne metathesis (RCAM), ring-opening alkyne

Progress in metathesis chemistry

• Karol Grela

Beilstein J. Org. Chem. 2010, 6, 1089–1090, doi:10.3762/bjoc.6.124

• more sensitive towards air and moisture, molybdenum catalysts provide excellent results in stereoselective metathesis and are sometimes more active. Therefore these catalyst families can be used in a complementary fashion. Currently, olefin metathesis (and its sister reaction, alkyne metathesis) [3] is

• many of the leading practitioners in the area, which cover a wide range of topics related to alkene and alkyne metathesis, are presented. It is therefore a pleasure to serve as Guest Editor for this Thematic Series in the Beilstein Journal of Organic Chemistry, on “Progress in metathesis chemistry”. I