Enzymatic resolution of α-tetralols by CALB-catalyzed acetylation

A series of homochiral α-tetralols, as well as their respective acetates, has been obtained by esterification of racemic tetralols, using Candida antarctica lipase (CALB—Novozym® 435) as the biocatalyst. This enzyme is shown to be highly efficient for the kinetic resolution of the substrates studied, affording the (+)-tetralols and the (+)-acetates in excellent enantiomeric excess (up to >99%) and very good yields (>40%).

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(S)-1,2,3,4-Tetrahydro-5-methoxynaphthalen-1-olC11H14O2Ee >99%[α]D27=+23.3 (c 1.04, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (1S)

(R)-1,2,3,4-Tetrahydro-5-methoxynaphthalen-1-yl acetateC13H16O3Ee >99%[α]D27=+101.8 (c 1.30, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (1R)

(S)-1,2,3,4-Tetrahydro-7-methoxynaphthalen-1-olC11H14O2Ee >99%[α]D24=+41.9 (c 1.05, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (1S)

(R)-1,2,3,4-Tetrahydro-7-methoxynaphthalen-1-yl acetateC13H16O3Ee >99%[α]D24=+88.5 (c 1.14, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (1R)

(S)-1,2,3,4-Tetrahydro-5,7-dimethylnaphthalen-1-olC12H16OEe = 99%[α]D27=+38.9 (c 1.20, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (1S)

(R)-1,2,3,4-Tetrahydro-5,7-dimethylnaphthalen-1-yl acetateC14H18O2Ee = 99%[α]D22=+98.1 (c 1.22, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (1R)

(+)-1,2,3,4-Tetrahydro-6-methyl-7-methoxynaphthalen-1-olC12H16O2Ee = 98%[α]D27=+36.9 (c 0.99, CHCl3)Source of chirality: enzymatic resolution

(+)-1,2,3,4-Tetrahydro-6-methyl-7-methoxynaphthalen-1-yl acetateC14H18O3Ee >99%[α]D27=+106.6 (c 1.22, CHCl3)Source of chirality: enzymatic resolution