131702-30-2Relevant articles and documents
One-pot two-step chemoenzymatic deracemization of allylic alcohols using laccases and alcohol dehydrogenases
Albarrán-Velo, Jesús,Gotor-Fernández, Vicente,Lavandera, Iván
, (2020)
A series of enantioenriched (hetero)aromatic secondary allylic alcohols has been synthesized through deracemization of the corresponding racemic mixtures combining a non-selective chemoenzymatic oxidation (laccase from Trametes versicolor and oxy-radical TEMPO) and a stereoselective biocatalyzed reduction (lyophilized cells of E. coli overexpressing an alcohol dehydrogenase, ADH). Both steps were performed in aqueous medium under very mild reaction conditions. After optimization, a sequential one-pot two-step protocol was set up, obtaining the corresponding chiral alcohols in moderate to high conversions (48–95%) and enantiomeric excess (65->99% ee). Depending on the ADH stereopreference, both antipodes from these valuable chiral synthons could be prepared, even at preparative scale (119?178 mg), in a straightforward manner.
Sequential Two-Step Stereoselective Amination of Allylic Alcohols through the Combination of Laccases and Amine Transaminases
Albarrán-Velo, Jesús,Lavandera, Iván,Gotor-Fernández, Vicente
, p. 200 - 211 (2019/12/03)
A sequential two-step chemoenzymatic methodology for the stereoselective synthesis of (3E)-4-(het)arylbut-3-en-2-amines in a highly selective manner and under mild reaction conditions is described. The approach consists of oxidation of the corresponding racemic alcohol precursors by the use of a catalytic system made up of the laccase from Trametes versicolor and the oxy-radical TEMPO, followed by the asymmetric reductive bio-transamination of the corresponding ketone intermediates. Optimisation of the oxidation reaction, exhaustive amine transaminase screening for the bio-transaminations and the compatibility of the two enzymatic reactions were studied in depth in search of a design of a compatible sequential cascade. This synthetic strategy was successful and the combinations of enzymes displayed a broad substrate scope, with 16 chiral amines being obtained in moderate to good isolated yields (29–75 %) and with excellent enantiomeric excess values (94 to >99 %). Interestingly, both amine enantiomers can be achieved, depending on the selectivity of the amine transaminase employed in the system.
Chemo-, regio-, and stereoselective Heck-Matsuda arylation of allylic alcohols under mild conditions
Chaudhari, Tohasib Yusub,Hossian, Asik,Manna, Manash Kumar,Jana, Ranjan
supporting information, p. 4841 - 4845 (2015/05/05)
Heck arylation with allylic alcohol is extremely challenging due to chemo-, regio-, and stereoselective scrambling. Here we report a mild protocol for the alcohol selective β- and α-arylation of allylic and cinnamyl alcohols respectively with aryldiazonium salts. The steric and electronic parameters of the alkene play a prominent role in the regioselectivity.
Sequential hydrocarbon functionalization: Allylic C-H oxidation/vinylic C-H arylation
Delcamp, Jared H.,White, M. Christina
, p. 15076 - 15077 (2007/10/03)
A Pd(II)/sulfoxide-catalyzed sequential allylic C-H oxidation/vinylic C-H arylation of α-olefins to furnish E-arylated allylic esters in high regio- and E:Z selectivities (>20:1) is reported. The broad scope of this method with respect to the α-olefin, ca
Synthesis of 1,3-Diol Synthons from Epoxy Aromatic Precursors: An Approach to the Construction of Polyacetate-Derived Natural Products
Evans, David A.,Gauchet-Prunet, Joelle A.,Carreira, Erick M.,Charette, Andre B.
, p. 741 - 750 (2007/10/02)
The identification of stereoregular polyol subunits within polyacetate-derived natural products such as bryostatin 1 and amphotericin B has led to the convergent synthesis of six- and seven-carbon 1,3-diol fragments in high yields and stereoselectivities.This plan relies upon the enantioselective asymmetric epoxidation/kinetic resolution of cinnamyl alcohols and the use of meta-substituted anisyl rings as masked β-keto ester synthons.Birch reduction of 9 (R = SiiPr3) followed by ozonolysis afforded the hydroxyl keto ester 11 in 66percent overall yield.Anti-selective β-selective β-hydroxy ketone reduction employing Me4NBH(OAc)3 afforded 12 in 93percent yield and 13:1 diastereoselectivity while syn-selective reduction with Et2BOMe/NaBH4 gave 13 in 82percent yield and 15:1 diastereoselectivity.An analogous sequence of reactions provided 25 and 26 from epoxy alcohol 18.Epoxy aromatic alcohol 17 (R = H) was easily converted to 18 (93percent yield, > 99:1) by Mitsunobu inversion followed by methanolysis.This reaction sequence provides access to all stereoisomers of 3,5,6-trihydroxyhexanoic acid heptanoic acids which should be useful chiral subunits of polyacetate-derived natural products such as amphotericin and bryostatin.
