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Sterically Crowded Heterocycles. XII. Atropisomerism of (1-Aryl-3,5-diphenyl-1H-pyrrol-2-yl)(phenyl)methanones

2000; Wiley-VCH; Volume: 65; Issue: 5 Linguagem: Inglês

10.1135/cccc20000651

1212-6950

Robert Klvaňa, Radek Pohl, Jan Pawlas, Jan Čejka, Hana Dvořáková, Richard Hrabal, Stanislav Böhm, Bohumil Kratochvíl, Josef Kuthan,

Crystallography and molecular interactions

Some 1-(2-substituted phenyl)- and 1-(1-naphthyl)-2,4,6-triphenylpyridinium perchlorates were treated with potassium hexacyano ferrate(III)-potassium hydroxide reagent to give the title pyrroles. Restricted rotation around the C-N bond in the products is demonstrated by NMR experiments with homochiral shift reagents, by semiempirical PM3 calculations as well as using their atropodiastereoselective and enantioselective transformations. Racemisation barriers for the ( R )-2-( N -methyl- N -phenylcarbamoyl) derivative were estimated from NMR and polarimetric measurements.