Stereochemistry of 4‐amino‐( D 3 )‐trishomocubanes. NMR study of 3‐phenyl‐4‐amino‐( D 3 )‐trishomocubane

Amino compounds of the highly symmetrical ( D 3 )‐trishomocubane were recently shown to possess promising biological activities, i.e. antiviral and antiparkinson. This series was synthesized via a modified Ritter reaction. The unique hydrocarbon skeleton of these compounds has a D 3 point group symmetry with a propeller shape. Several geometrical isomers are possible for the derivatives of ( D 3 )‐trishomocubane. This paper reports the complete 1 H and 13 C NMR assignments and the configuration at C‐4 of one of the most promising compounds of the present series, i.e. 3‐phenyl‐4‐amino‐( D 3 )‐trishomocubane. The 13 C NMR spectrum of this amine indicates the presence of only one geometrical isomer for the compound. NOE experiments on the fully assigned 1 H NMR spectrum show that this isomer has the 3S4 S /3 R 4 R configuration, and not the 3 S 4 R /3 R 4 S configuration. These results indicate that the Ritter rearrangement proceeds stereospecifically and that it provides a facile method for the synthesis of ( D 3 )‐trishomocuban‐4‐amines from tertiary alcohols of pentacyclo[5.4.0.0 2,6 .0 3,10 .0 5,9 ] undecan‐8‐ol.