A titanium (IV) mediated one-pot double condensation synthesis of 5,6-dihydro-4H-pyran-4-ones
作者:Joel Morris、Donn G. Wishka、George P. Luke、Thomas M. Judge、Ronald B. Gammill
DOI:10.1016/s0040-4020(97)00378-5
日期:1997.8
is described. This preparation makes use of the condensation of titanium enolates derived from β-hydroxy ketones with phosgene iminium chloride or trimethylorthoformate, respectively. The in situ formation of the necessary titanium complex from an aldol condensation using simple ketone and aldehyde precursors makes for a one-pot double condensation synthesis of the desired dihydropyrones.
Zr(OtBu)4 was found to catalyze the Tishchenko reduction of β-hydroxy ketones giving rise to differentiated 1,3-anti-diol monoesters in high yields and excellent stereoselectivity.