Synthesis and application of novel imidazole and 1H-tetrazolic acid containing catalysts in enantioselective organocatalyzed Diels–Alder reactions

Herein we report studies on the organocatalytic Diels–Alder reaction using a variety of catalysts capable of activating α,β-unsaturated carbonyl compounds for reactions with dienes. The structurally attractive catalysts 4 and 14 were utilized in the enantioselective organocatalytic Diels–Alder reactions. Catalyst 4 provided the products in fair yields and more importantly in good enantioselectivities of up to 83% ee. Catalyst 14 was synthesized in high yield and was assessed in the enantioselective organocatalytic Diels–Alder reaction. Catalyst 14 proved to be a highly active and selective catalyst providing the products in high yield and high enantioselectivities up to 95% ee.

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(5S)-5-((1H-Tetrazole-5-yl)methyl)-2,2,3-trimethyl-imidazolidin-4-oneC8H14N6O[α]D23=-72.2 (c 1.0, MeOH)Absolute configuration: (5S)Source of chirality: l-asparagine

(5S)-5-(Acetonitrile-5-yl)-2,2,3-trimethyl-imidazolidin-4-oneC8H13N3O[α]D23=+112.1 (c 1.8, MeOH)Absolute configuration: (5S)Source of chirality: l-asparagine

Methyl-(2S)-2-amino-N1-methyl-N4-tritylsuccinamideC24H25N3O2[α]D23=-1.1 (c 1.0, MeOH)Absolute configuration: (2S)Source of chirality: l-asparagine

(5S)-5-(N-Trimethylacetamide-5-yl)-2,2,3-trimethyl-imidazolidin-4-oneC27H29N3O2[α]D23=-25.6 (c 1.0, MeOH)Absolute configuration: (5S)Source of chirality: l-asparagine

(5S)-5-(Acetamide-5-yl)-2,2,3-trimethyl-imidazolidin-4-oneC8H15N3O2[α]D23=+11.6 (c 2.85, MeOH)Absolute configuration: (5S)Source of chirality: l-asparagine