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.
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.