Asymmetric synthesis of 1-benzyl-2-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)-1H-pyrrole using chiral imines

A new synthesis of chiral alkyl pyrroles and pyrrolines has been achieved in an easy straightforward way, using the addition of organometallics to chiral imines.

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Tetrahydropyranyl derivative of (R)-4-(benzylamino)-4-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)but-2-yn-1-olC21H29NO4Ee, de: >95% (NMR)[α]D20=+16.3 (c 0.90, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 4R,4′S

Tetrahydropyranyl derivative of (S)-4-(benzylamino)-4-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)but-2-yn-1-olC21H29NO4Ee, de: >95% (NMR)[α]D20=-59.0 (c 1.25, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 4S,4′S

Tetrahydropyranyl derivative of (R,Z)-4-(benzylamino)-4-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)but-2-en-1-olC21H31NO4Ee, de: >95% (NMR)[α]D20=+6.4 (c 1.38, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 4R,4′S

Tetrahydropyranyl derivative of (S,Z)-4-(benzylamino)-4-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)but-2-en-1-olC21H31NO4Ee, de: >95% (NMR)[α]D20=-13.9 (c 1.02, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 4S,4′S

(R,Z)-4-(Benzylamino)-4-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)but-2-en-1-olC16H23NO3Ee, de: >95% (NMR)[α]D20=-99.2 (c 1.27, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 4R,4′S

(S,Z)-4-(Benzylamino)-4-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)but-2-en-1-olC16H23NO3Ee, de: >95% (NMR)[α]D20=-0.7 (c 0.67, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 4S,4′S

(S)-1-Benzyl-2,5-dihydro-2-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)-1H-pyrroleC16H21NO2Ee, de: >95% (NMR)[α]D20=+138.4 (c 0.41, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 2S,4′S

(R)-1-Benzyl-2,5-dihydro-2-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)-1H-pyrroleC16H21NO2Ee, de: >95% (NMR)[α]D20=-73.0 (c 0.63, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 2R,4′S

1-Benzyl-2-((S)-2′,2′-dimethyl-1′,3′-dioxolan-4′-yl)-1H-pyrroleC16H19NO2Ee, de: >95% (NMR)[α]D20=-20.7 (c 0.83, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: 4′S