The synthesis of new diastereomers of (4S,8aS)- and (4R,8aS)-4-phenyl-perhydropyrrole[1,2-a]pyrazine-1,3-dione

The synthesis of new (4S,8aS)- and (4R,8aS)-4-phenyl-perhydropyrrole[1,2-a]pyrazine-1,3-diones in the cyclocondensation reaction of the respective derivatives of l-prolineamide is described. The effect of the amount of NaOEt, temperature, and reaction time on the proportions of diastereomers formed in the cyclocondensation reaction was examined. The structures of the diastereomers were confirmed by GC/MS, HRMS, HPLC, XRD, and 1H and 13C NMR investigations.

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(R)-(−)-2-(4-Toluenesulfonyloxy)-phenylacetic acid methyl esterC16H16O5S[α]D = −63.3 (c 2, CHCl3)Source of chirality: (−)-methyl-(R)-α-hydroxyphenyl acetateAbsolute configuration: (αR)

(2S,αS)-α-(2-Carbamoylpyrrolidinyl)-α-phenylacetic acid methyl esterC14H18N2O3[α]D = +29.7 (c 2, MeOH)Source of chirality: (R)-(−)-2-(4-toluenesulfonyloxy)-phenylacetic acid methyl ester (S)-prolineamideAbsolute configuration: (2S,αS)

(2S,αR)-α-(2-Carbamoylpyrrolidinyl)-α-phenylacetic acid methyl esterC14H18N2O3[α]D = −116.4 (c 2, MeOH)Source of chirality: (S)-(+)-2-(4-toluenesulfonyloxy)-phenylacetic acid methyl ester (S)-prolineamideAbsolute configuration: (2S,αR)

(4S,8aS)-4-Phenyl-perhydropyrrole[1,2-a]pyrazine-1,3-dioneC13H14N2O2[α]D = −138.15 (c 2, CHCl3)Source of chirality: (2S,αS)-α-(2-carbamoylpyrrolidinyl)-α-phenylacetic acid methyl esterAbsolute configuration: (4S,8aS)

(4R,8aS)-4-Phenyl-perhydropyrrole[1,2-a]pyrazine-1,3-dioneC13H14N2O2[α]D = −138.5 (c 2, CHCl3)Source of chirality: (2S,αR)-α-(2-carbamoylpyrrolidinyl)-α-phenylacetic acid methyl esterAbsolute configuration: (4R,8aS)