The preparation and some reactions of tricyclo[4.4.4.0]tetradecane-2,7-dione ([4.4.4]propellane-2,7-dione): X-ray crystal structure of 2,7-bis(trimethylsilyloxy)tetracyclo-[4.4.4.0.0]tetradecane

Abstract

Tricyclo[4.4.4.0]tetradecane-2,7-dione (1) has been made by reductive alkylation of bicyclo[4.4.0]-dec-1-ene-2,7-dione, using Na–NH₃ and Br(CH₂)₄Br. Reduction of (1) with sodium–potassium alloy in benzene in the presence of chlorotrimethylsilane yields 2,7-bis(trimethylsilyloxy)tetracyclo[4.4.4.0.0]tetradecane (13), whose crystal structure is reported. Reduction of (1) with LiAlH₄ and with Na–NH₃–Bu^tOH–THF gave mixtures of the three possible diastereoisomeric diols (15)–(17), which could not be separated, but whose isomeric composition could be estimated by ¹³C n.m.r. spectroscopy. Conformational equilibria in dione (1) and in diol (15) are discussed with the aid of force field calculations.