Disila-Phantolide and Derivatives: Synthesis and Olfactory Characterization of Silicon-Containing Derivatives of the Musk Odorant Phantolide

Abstract

1-(1,1,2,3,3,6-Hexamethyl-1,3-disilaindan-5-yl)ethanone (disila-phantolide, 4), a disila-analogue of the musk odorant phantolide (3), and its silicon-containing derivatives 5−13 were prepared in multistep syntheses and studied for their olfactory properties. In addition, 7 and 11 were structurally characterized by single-crystal X-ray diffraction, and compounds 4−13 were studied computationally (calculations of minimum-energy conformers and the electrostatic potentials). Compounds 4−13 differ in their Si−X−Si moiety (X = CHMe, C═CH2, CH2, O, cyclopropane-1,1-diyl) and in an optional C-6 methyl substituent on the 1,3-disilaindane skeleton. Disila-phantolide (4, X = CHMe), the methylene derivatives 6 and 7 (X = C═CH2), and the cyclopropane-1,1-diyl derivatives 12 and 13 (X = cyclopropane-1,1-diyl) are new musk odorants, with 6 and 7 being the most interesting and powerful ones. In contrast, compounds 8 and 9 (X = CH2) as well as 10 and 11 (X = O) were found to be very weak to odorless and devoid of any musk character.