39721-65-8Relevant articles and documents
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
, 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.
Enantioselective synthesis of α-ionone derivatives using an anti SN2′ substitution of functionalized zinc organometallics
Soorukram, Darunee,Knochel, Paul
, p. 2409 - 2411 (2007/10/03)
(Equation Presented) The allylic substitution of sterically hindered (2-iodocycloalkyl)phosphates proceeds with complete anti SN2′ stereoselectivity with mixed diorganozincs of the type RZnCH 2SiMe3 in the presence of CuCN·2LiCI. Only the group R of the copper-zinc reagent is transferred in the allylic substitution. This method was used to prepare odoriferous substances such as (R)-α-ionone in 97% ee and (R)-dihydro-α-ionone in 98% ee.