チオアセタールのチタン-カルベン錯体への変換を利用する新しい有機合成

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Recently we found that various titanium-carbene complexes were produced by the desulfurization of thioacetals with the low-valent titanium species Cp2Ti [P (OEO)3] 2. This article deals with their application to organic synthesis including some guiding conceptions of the study. Desulfurization of thioacetals prepared from α, β-unsaturated aldehydes or 1, 3-bis (phenylthio) propene derivatives in the presence of 1-olefins afforded alkenylcyclopropanes. The intermediates of this reaction, vinylcarbene complexes, reacted with carbonyl compounds to afford the Wittig-like olefination products in good yields. The similar carbonyl olefination using various types of thioacetals and orththioformates with carbonyl compounds including carboxylic acid derivatives also produced a variety of olefins. Furthermore the alkylidenetitanocenes formed from saturated thioacetals reacted with organic molecules having a carbon-carbon multiple bond. When they were treated with alkynes, conjugated dienes were produced with high stereoselectivity. The reaction with allyltrialkylsilanes afforded (Z) -γ-substituted allylsilanes via the formation of titanacyclobutane intermediates. We also found the first [2+1] carbenoid insertion reaction of titanium-carbene complexes with trialkylsilanes and related group 14 organometallics.
社団法人有機合成化学協会の論文
1998-12-01