Facile Synthesis of [3]Cumulenes via 1,4-Elimination of Hydroxytrimethylsilane from 4-(Trimethylsilyl)-2-butyn-l-ols

摘要

The DNA-cleaving activity of neocarzinostatin (NCS) and the mechanism of the cleavage action have received much attention in recent years. It is proposed that the non protein chromophore of neocarzinostatin (NCS-Chrom) undergoes an initial transformation to a cyclic enyne cumulene followed by the formation of a carbon hiradical species. The resulting biradical is believed to be responsible for hydrogen atom abstraction from the sugar phosphate backbone of the DNA, causing the subsequent oxidative cleavage and producing the potent cytotoxicity of neocarzinostatin. The participation of a cumulene moiety in the biradical formation step of the NCS-Chrom together with the interesting chemical reactivities of cumulenes have stimulated interest in developing synthetic routes to cumulenes. A recent report by Chow et al. concerning a facile synthesis of - cumulenes via tetrabutylammonium fluoride (TBAF)-induced 1,4-eliminations of l-acetoxy-4-(trimethylsilyl)-2-butynes prompted us to disclose a full account of our independent findings in this area.