Synthetic studies in quest of Platonic hydrocarbon dodecahedrane

Abstract

In pursuit of Platonic hydrocarbon dodecahedrane1, a retrosynthetic theme indicated in scheme 1, was formulated. The precursor tetraquinanedione synthon5 was first designed through a photo-thermal olefin metathesis approach. The tetraquinanedione 5 was further elaborated toexo, exo-tetraquinane diester15 through carbonyl homologation, oxidation, esterification sequence, scheme 5. Bis-cyclopentannulation ofexo,exo-diester15 by Greene methodology delivered a functionalised C₂₀-hexaquinane44, havingexo-annulated cyclopentane rings. Cyclopentane inversion was achieved by a set of reactions involving enone generation, double bond isomerisation and hydrogenation to give spheroidal (C_2v)-C₂₀-hexaquinanedione-diester47, the penultimate precursor of dodecahedrane 1. Several interesting transformations and rearrangements of polyquinanes are also described.