A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• -metathesis (ROCM) have found high utility in the creation of C=C bonds and in the synthesis of a number of organic molecules, functionalized scaffolds or various building blocks. The efficient catalytic activity and remarkable functional group tolerance of commercially available versatile Ru-based olefin

• across ROM or ROCM into a variety of alkenylated, functionalized scaffolds [22][23][24][25][26][27][28][29][30][31][32][33][34]. Although metathesis is a reversible process, it is often shifted towards a certain direction. For example, the equilibrium of the reaction of ethylene with a strained ring

• outcome of metathesis, various publications were dedicated to studies describing selective CM or ROCM transformations. The accurate prediction of selectivity regarding CM reactions is still considered to be a challenging issue among synthetic organic chemists. Of numerous factors contributing to the

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• by NMR, ESIMS, and X-ray crystallography. The utility of this chemistry is further demonstrated by the tests of the novel catalysts (up to 10−2 mol %) in different metathesis reactions such as cross metathesis (CM), ring-closing metathesis (RCM) and ring-opening cross metathesis (ROCM). Keywords: CM

• ; cross metathesis; Hoveyda–Grubbs catalyst; olefin metathesis; RCM; ring-closing metathesis; ring-opening cross metathesis; ROCM; ruthenium metathesis catalyst; styrene; 2-vinylbenzylamine; Introduction Ruthenium-catalysed olefin metathesis reactions have been playing an important role in various fields

• (14) for CM reactions, ii) diethyl diallylmalonate (17) and diallyltosylamide (19) for RCM reactions, iii) norbornene (21) and styrene/hex-1-ene for ROCM metathesis reactions. This selection of model subtests for metathesis is also explained by the possibility to control the course of metathesis and

A tutorial review of stereoretentive olefin metathesis based on ruthenium dithiolate catalysts

• Daniel S. Müller,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2018, 14, 2999–3010, doi:10.3762/bjoc.14.279

• ), ring-opening/cross metathesis (ROCM), cross metathesis (CM), self-metathesis and ring-closing metathesis (RCM) reactions. Scheme 2 and Scheme 3 display selected examples for each of these reactions [1]. ROMP is one of the most facile metathesis reactions, thus allowing for very low catalyst loadings

• norbornadiene was also investigated by Hoveyda [16]. A highly syndiotactic polymer was obtained by fine tuning of the steric and electronic characteristics of the catalyst (not depicted in this review) [16]. ROCM reactions of norbornene (1) with styrene (5) could be carried out with only one mole percent of

Stereochemistry of ring-opening/cross metathesis reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitriles with allyl alcohol and allyl acetate

• Piotr Wałejko,
• Michał Dąbrowski,
• Lech Szczepaniak,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 1893–1901, doi:10.3762/bjoc.11.204

• Piotr Walejko Michal Dabrowski Lech Szczepaniak Jacek W. Morzycki Stanislaw Witkowski Institute of Chemistry, University of Białystok, ul. Ciołkowskiego 1K, 15-245 Białystok, Poland 10.3762/bjoc.11.204 Abstract The ROCM reactions of exo- and endo-2-cyano-7-oxanorbornenes with allyl alcohol or

• allyl acetate promoted by different ruthenium alkylidene catalysts were studied. The stereochemical outcome of the reactions was established. The issues concerning chemo- (ROCM vs ROMP), regio- (1-2- vs 1-3-product formation), and stereo- (E/Z isomerism) selectivity of reactions under various conditions

• are discussed. Surprisingly good yields of the ROCM products were obtained under neat conditions. Keywords: Grubbs’ catalysts; metathesis; ROCM; ROMP; Z-selectivity; Introduction Substituted tetrahydrofurans are a common motif found in many biologically active natural products [1][2], e.g

The allylic chalcogen effect in olefin metathesis

• Yuya A. Lin and
• Benjamin G. Davis

Beilstein J. Org. Chem. 2010, 6, 1219–1228, doi:10.3762/bjoc.6.140

• stereoselective ring-opening cross-metathesis (ROCM) (Scheme 5) [24]. The activating effect from the allylic hydroxy group in metathesis is prominent in this example. The ROCM of cyclopropene 13 with enantiomerically enriched allylic alcohol 14a is complete in 5 minutes (>98% conversion) with a high

• ]. a) Acceleration of ring-closing enyne metathesis by the allylic hydroxy group [23]. b) Proposed mode of action by the allylic hydroxy group in this reaction. a) Effect of the hydroxy group on the rate and steroselectivity of ROCM [24]. b) Proposed H-bonded ruthenium complex for stereoselective ROCM

Desymmetrization of 7-azabicycloalkenes by tandem olefin metathesis for the preparation of natural product scaffolds

• Wolfgang Maison,
• Marina Büchert and
• Nina Deppermann

Beilstein J. Org. Chem. 2007, 3, No. 48, doi:10.1186/1860-5397-3-48

• and 12. A sequence of ring opening and cross metathesis is extremely efficient for desymmetrization of 7 and 12 as depicted in Scheme 4 for the synthesis of isoindole 19 and the disubstituted pyrrolidine 20. In these cases, catalyst loadings can be low and yields are excellent. Unfortunately the ROCM

• intramolecular RORCM or intermolecular ROCM sequences to give a range of common natural product scaffolds such as pyrrolidines, indolizidines and isoindoles. The protocols use readily available starting materials, are simple and give densely functionalized metathesis products ready for further manipulations

• styrene, CH2Cl2, rt, 12 h; B: 10 mol % 1, C2H4, CH2Cl2, rt, 12 h. ROCM of 7-azabicycloalkenes 7 and 12 to isoindole and pyrrolidine scaffolds 19 and 20. Catalytic enantioselective desymmetrization of 7-azabicycloalkene 10 to scaffold 23. Supporting Information Supporting Information File 120