Enantioselective Diels–Alder reaction of o-quinodimethanes by utilizing tartaric acid ester as a chiral auxiliary

The asymmetric Diels–Alder reaction of o-quinodimethanes, generated from benzocyclobutenols in situ, with fumaric acid esters was achieved by utilizing diisopropyl (R,R)-tartrate as a chiral auxiliary to afford the corresponding optically active 1,2-cis-substituted 1-hydroxy tetrahydronaphthalene derivatives with enantioselectivities up to 83% ee.

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Diethyl (1S,2S,3R)-1-hydroxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC16H20O5Ee = 83%[α]D25=-121(c0.27,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Dimethyl (1S,2S,3R)-1-hydroxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC14H16O5Ee = 75%[α]D25=-89(c0.82,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Diisopropyl (1S,2S,3R)-1-hydroxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC18H24O5Ee = 72%[α]D25=-82(c0.75,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Diethyl (1S,2S,3R)-1-hydroxy-8-methoxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC17H22O6Ee = 65%[α]D25=-55(c0.50,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Diethyl (1S,2S,3R)-1-hydroxy-7-methoxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC17H22O6Ee = 80%[α]D25=-94(c0.77,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Diethyl (1S,2S,3R)-1-hydroxy-6-methoxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC17H22O6Ee = 79%[α]D25=-52(c0.28,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Diethyl (1S,2S,3R)-8-chrolo-1-hydroxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC16H19O5ClEe = 54%[α]D25=-56(c0.54,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Diethyl (1S,2S,3R)-7-chloro-1-hydroxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC16H19O5ClEe = 68%[α]D25=-57(c0.78,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)

Diethyl (1S,2S,3R)-6-chloro-1-hydroxy-1,2,3,4-tetrahydronaphtalene-2,3-dicarboxylateC16H19O5ClEe = 66%[α]D25=-75(c0.51,EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,3R)