New pyrrolidine-triazole-based C2 symmetric organocatalysts and their utility in the asymmetric Michael reaction of β-nitrostyrenes and the synthesis of nitrochromenes

The synthesis of new C2 symmetric bis(pyrrolidine-triazole)-based organocatalysts and their utility in the asymmetric Michael reaction of β-nitrostyrenes with very high diastereo- and enantioselectivity in water without any additives is reported. The asymmetric synthesis of nitrochromenes is also illustrated.

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(2S,2′S)-tert-Butyl 2,2′-(4,4′-(pyridine-2,6-diyl)bis(1H-1,2,3-triazole-4,1-diyl))bis(methylene)dipyrrolidine-1-carboxylateC29H41N9O4[α]D34=+32.3 (c 1.0, CHCl3)Source of chirality: l-prolineAbsolute configuration: (2S,2′S)

(2S,2′S)-tert-Butyl 2,2′-(4,4′-(1,3-phenylene)bis(1H-1,2,3-triazole-4,1-diyl))bis(methylene)dipyrrolidine-1-carboxylateC30H42N8O4[α]D29=-41.9 (c 0.7, CHCl3)Source of chirality: l-prolineAbsolute configuration: (2S,2′S)

2,6-bis(1-((S)-Pyrrolidin-2-ylmethyl)-1H-1,2,3-triazol-4-yl)pyridineC19H25N9[α]D34=-18.3 (c 1.08, CHCl3)Source of chirality: l-prolineAbsolute configuration: (2S,2′S)

1,3-bis(1-((S)-Pyrrolidin-2-ylmethyl)-1H-1,2,3-triazol-4-yl)benzeneC20H26N8[α]D34=+16.6 (c 1.0, CHCl3)Source of chirality: l-prolineAbsolute configuration: (2S,2′S)

(S)-2-(1-(Pyrrolidin-2-ylmethyl)-1H-1,2,3-triazol-4-yl)pyridineC12H15N5[α]D34=+13.2 (c 1.0, CHCl3)Source of chirality: l-prolineAbsolute configuration: (S)