Studies on the asymmetric, phosphine-promoted [3+2] annulations of allenic esters with 2-aryl-1,1-dicyanoalkenes

The first enantioselective variant of the phosphine-promoted [3+2] cycloaddition reaction between allenoates and 2-aryl-1,1-dicyanoethylenes has been developed. The use of (S)-t-butyl-Binepine as the chiral organocatalyst allows the synthesis of functionalized cyclopentenes with both aryl and heteroaryl substituents on the stereogenic carbon, in high yields and ees of up to 95%.

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Ethyl 4,4-dicyano-5-phenylcyclopent-1-ene-1-carboxylateC16H14N2O2Ee = 73%[α]D25=+153 (c 0.95, CHCl3)Source of Chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(4-methoxyphenyl)cyclopent-1-ene-1-carboxylateC17H16N2O3Ee = 65%[α]D24=+148 (c 0.9, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 5-(4-chlorophenyl)-4,4-dicyanocyclopent-1-ene-1-carboxylateC16H13ClN2O2Ee = 74%[α]D25=+151 (c 1.1, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(4-nitrophenyl)cyclopent-1-ene-1-carboxylateC16H13N3O4Ee = 74%[α]D25=+151 (c 1.3, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(naphthalen-1-yl)cyclopent-1-ene-1-carboxylateC20H16N2O2Ee = 74%[α]D25=+58 (c 1.1, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(naphthalen-2-yl)cyclopent-1-ene-1-carboxylateC20H16N2O2Ee = 70%[α]D24=+183 (c 1.05, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(furan-2-yl)cyclopent-1-ene-1-carboxylateC14H12N2O3Ee = 83%[α]D25=+177 (c 0.6, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(thiophen-2-yl)cyclopent-1-ene-1-carboxylateC14H12N2O2SEe = 81%[α]D25=+204 (c 0.9, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(pyridin-2-yl)cyclopent-1-ene-1-carboxylateC15H13N3O2Ee = 82%[α]D25=+147 (c 0.4, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(quinolin-2-yl)cyclopent-1-ene-1-carboxylateC19H15N3O2Ee = 28%[α]D25=+44 (c 1.05, CHCl3)Source of chirality: asymmetric synthesis

Ethyl 4,4-dicyano-5-(1-methyl-1H-indol-2-yl)cyclopent-1-ene-1-carboxylateC19H17N3O2Ee = 99%[α]D25=+272 (c 0.9, CHCl3)Source of chirality: asymmetric synthesis

Cyclohexyl 4,4-dicyano-5-(thiophen-2-yl)cyclopent-1-ene-1-carboxylateC18H18N2O2SEe = 88%[α]D25=+155 (c 1.1, CHCl3)Source of chirality: asymmetric synthesis