Chiral ytterbium silylamide catalyzed enantioselective phospha-Michael addition of diethyl phosphite to chalcones

An efficient and enantioselective phospha-Michael addition of diethyl phosphite to chalcones has been established. In the presence of a catalytic amount of chiral lanthanide silylamide generated from [(Me3Si)2N]3Yb(μ-Cl)Li(THF)3 and salen, the reaction produced the target γ-oxophosphonates with high yields and enantioselectivity.

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(S)-Diethyl 3-oxo-3-phenyl-1-(thiophen-2-yl)propylphosphonateC17H21O4PS[α]D28 = −25 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)

(S)-Diethyl 3-(4-chlorophenyl)-3-oxo-1-o-tolylpropylphosphonateC20H24ClO4P[α]D29 = −64 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)

(S)-Diethyl 3-(4-methoxyphenyl)-3-oxo-1-o-tolylpropylphosphonateC21H27O5P[α]D29 = −63 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)

(S)-Diethyl 1-(2,6-dimethylphenyl)-3-oxo-3-p-tolylpropylphosphonateC22H29O4P[α]D28 = −58 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)

(S)-Diethyl 1-(2,6-dimethylphenyl)-3-(4-fluorophenyl)-3-oxopropylphosphonateC21H26FO4P[α]D29 = −46 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)

(S)-Diethyl 3-(4-chlorophenyl)-1-(2,6-dimethylphenyl)-3-oxopropylphosphonateC21H26ClO4P[α]D29 = −43 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)

(S)-Diethyl 3-(4-bromophenyl)-1-(2,6-dimethylphenyl)-3-oxopropylphosphonateC21H26BrO4P[α]D27 = −49 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)

(S)-Diethyl 1-(2,6-dimethylphenyl)-3-(4-methoxyphenyl)-3-oxopropylphosphonateC22H29O5P[α]D29 = −59 (c 1.0, CHCl3)Source of chirality: asymmetric addition of HOP(OEt)2Absolute configuration: (S)