31499-72-6Relevant articles and documents
First enantioselective synthesis of marine diterpene ambliol-A
Serra, Stefano,Lissoni, Veronica
, p. 2226 - 2234 (2015)
The first enantioselective synthesis of furanditerpene ambliol-A, which is a major metabolite of marine sponge Dysidea amblia, has been accomplished by starting from racemic α-ionone. The key steps of the synthesis include lipase-mediated resolution of 4-hydroxy-γ-ionone, its stereoselective transformation into trans-α-epoxy-dihydroionone, C2 homologation to trans-α-epoxy-monocyclofarnesyl acetate and Li2CuCl4-catalysed sp3-sp3 cross-coupling reaction of the latter ester with (furan-3-ylmethyl)magnesium chloride. This work confirms the chemical structure previously assigned to ambliol-A and proves that the natural levorotatory isomer does not possess (1S,2S) absolute configuration, as previously indicated, but is the opposite enantiomer, (1R,2R)-2-[(E)-6-(furan-3-yl)-3-methylhex-3-enyl]-1,3,3-trimethylcyclohexanol.
I2-PPh3 mediated spiroannulation of unsaturated β-dicarbonyl compounds. the first synthesis of (±)-negundoin A
Tapia, Ruben,Cano, M. Jose,Bouanou, Hanane,Alvarez, Esteban,Alvarez-Manzaneda, Ramon,Chahboun, Rachid,Alvarez-Manzaneda, Enrique
, p. 10257 - 10259 (2013)
An efficient and stereoselective spiroannulation of unsaturated enols is reported. Unsaturated β-dicarbonyl compounds undergo cyclization by reaction with catalytic I2-PPh3, affording the corresponding spiro enol ether derivatives, with complete regio- and stereoselectivity, under mild conditions. Utilizing this new methodology, the first total synthesis of the anti-inflammatory diterpene negundoin A and a naturally occurring trypanocidal aldehyde is reported.
Highly Selective Hydrogenation of C═C Bonds Catalyzed by a Rhodium Hydride
Gu, Yiting,Lisnyak, Vladislav G.,Norton, Jack R.,Salahi, Farbod,Snyder, Scott A.,Zhou, Zhiyao
supporting information, p. 9657 - 9663 (2021/07/19)
Under mild conditions (room temperature, 80 psi of H2) Cp*Rh(2-(2-pyridyl)phenyl)H catalyzes the selective hydrogenation of the C═C bond in α,β-unsaturated carbonyl compounds, including natural product precursors with bulky substituents in the β position and substrates possessing an array of additional functional groups. It also catalyzes the hydrogenation of many isolated double bonds. Mechanistic studies reveal that no radical intermediates are involved, and the catalyst appears to be homogeneous, thereby affording important complementarity to existing protocols for similar hydrogenation processes.
Asymmetric Cation-Olefin Monocyclization by Engineered Squalene–Hopene Cyclases
Aeberli, Natalie,Berweger, Raphael,Bornscheuer, Uwe T.,Buller, Rebecca,Dossenbach, Sandro,Eichenberger, Michael,Eichhorn, Eric,Flachsmann, Felix,Hüppi, Sean,Hortencio, Lucas,Patsch, David,Voirol, Francis,Vollenweider, Sabine
supporting information, p. 26080 - 26086 (2021/09/20)
Squalene–hopene cyclases (SHCs) have great potential for the industrial synthesis of enantiopure cyclic terpenoids. A limitation of SHC catalysis has been the enzymes’ strict (S)-enantioselectivity at the stereocenter formed after the first cyclization step. To gain enantio-complementary access to valuable monocyclic terpenoids, an SHC-wild-type library including 18 novel homologs was set up. A previously not described SHC (AciSHC) was found to synthesize small amounts of monocyclic (R)-γ-dihydroionone from (E/Z)-geranylacetone. Using enzyme and process optimization, the conversion to the desired product was increased to 79 %. Notably, analyzed AciSHC variants could finely differentiate between the geometric geranylacetone isomers: While the (Z)-isomer yielded the desired monocyclic (R)-γ-dihydroionone (>99 % ee), the (E)-isomer was converted to the (S,S)-bicyclic ether (>95 % ee). Applying the knowledge gained from the observed stereodivergent and enantioselective transformations to an additional SHC-substrate pair, access to the complementary (S)-γ-dihydroionone (>99.9 % ee) could be obtained.
Capturing the Monomeric (L)CuH in NHC-Capped Cyclodextrin: Cavity-Controlled Chemoselective Hydrosilylation of α,β-Unsaturated Ketones
Bistri-Aslanoff, Olivia,Derat, Etienne,Leloux, Sébastien,Leyssens, Tom,Ménand, Micka?l,Meijide Suárez, Jorge,Riant, Olivier,Roland, Sylvain,Sollogoub, Matthieu,Xu, Guangcan,Zhang, Pinglu,Zhang, Yongmin
supporting information, p. 7591 - 7597 (2020/03/23)
The encapsulation of copper inside a cyclodextrin capped with an N-heterocyclic carbene (ICyD) allowed both to catch the elusive monomeric (L)CuH and a cavity-controlled chemoselective copper-catalyzed hydrosilylation of α,β-unsaturated ketones. Remarkably, (α-ICyD)CuCl promoted the 1,2-addition exclusively, while (β-ICyD)CuCl produced the fully reduced product. The chemoselectivity is controlled by the size of the cavity and weak interactions between the substrate and internal C?H bonds of the cyclodextrin.
Hydroformylation of recalcitrating biorenewable compounds containing trisubstituted double bonds
Faria, Amanda de Camargo,de Oliveira, Mileny P.,Monteiro, Amanda C.,Mota, Rayssa L.V.,Oliveira, Kelley C.B.,Santos, Eduardo N. dos,Gusevskaya, Elena V.
, (2020/01/09)
Hydroformylation is a useful tool in industrial organic syntheses and it is easily applied to substrates containing terminal C[sbnd]C double bonds. Applying this reaction to substrates containing other functionalities or trisubstituted C[sbnd]C double bonds is not straightforward. Herein, the hydroformylation of several biorenewable alkenes with these features, namely: α-terpineol, terpinen-4-ol, limonene (double hydroformylation), and α-ionone, is presented. Only by the judicious choice of the catalytic system and reaction conditions, was it possible to obtain good yields and selectivity for these substrates.
Synthesis of the BCDE molecular fragment of azadiradione mediated by titanocene(III)
Fernandez-Mateos,Madrazo, S. Encinas,Teijon, P. Herrero,Clemente, R. Rabanedo,Gonzalez, R. Rubio,Gonzalez, F. Sanz
, p. 9571 - 9578 (2013/10/22)
A practical, short, and diastereoselective synthesis of the azadiradione BCDE fragment from a readily available starting material is described. The key step was the titanocene(III)-promoted tandem cyclization of unsaturated epoxy nitrile.
(BDP)CuH: A "hot" Stryker's reagent for use in achiral conjugate reductions
Baker, Benjamin A.,Boskovic, Zarko V.,Lipshutz, Bruce H.
, p. 289 - 292 (2008/09/19)
(Chemical Equation Presented) A ligand-modified, economical version of Stryker's reagent (SR) has been developed based on a bidentate, achiral bis-phosphine. Generated in situ, "(BDP)CuH" smoothly effects conjugate reductions of a variety of unsaturated substrates, including those that are normally unreactive toward SR. Substrate-to-ligand ratios typically on the order of 1000-10000:1 can be used leading to products in high yields.
Lewis base-catalyzed conjugate reduction and reductive aldol reaction of α,β-unsaturated ketones using trichlorosilane
Sugiura, Masaharu,Sato, Norimasa,Kotani, Shunsuke,Nakajima, Makoto
supporting information; experimental part, p. 4309 - 4311 (2009/03/12)
Lewis bases such as Ph3P=O and HMPA catalyze the 1,4-reduction of α,β-unsaturated ketones with trichlorosilane, and because the 1,2-reduction of aldehydes scarcely proceeded under the conditions, one-pot reductive aldol reactions with aldehydes were successfully achieved; preliminary studies using a chiral Lewis base revealed a high potential for enantioselective catalysis. The Royal Society of Chemistry.
Conjugate reduction of α,β-unsaturated carbonyl compounds promoted by nickel nanoparticles
Alonso, Francisco,Osante, I?aki,Yus, Miguel
, p. 3017 - 3020 (2008/02/12)
The system composed of nickel(II) chloride, lithium metal, a catalytic polymer-supported arene, and ethanol, has been efficiently applied to the conjugate reduction of a variety of α,β-unsaturated carbonyl compounds (ketones and carboxylic acid derivatives) under very mild reaction conditions. Georg Thieme Verlag Stuttgart.
