2008

Metathesis reactionsO 0286 Olefinic Ester and Diene Ring-Closing Metathesis Using a Reduced Titanium

Alkylidene. — The olefination reaction of esters containing a tethered olefin like (I) with reduced titanium alkylidene reagents is studied. In the presence of Ti—methylene reagent (II), a mixture of methylenation (III) and intramolecular olefination product (IV) is obtained. In contrast, the use of Ti—ethylidene reagent leads to exclusive for-mation of (IV). The reaction is general and can be extended to diene ring closing met-athesis reactions [cf. (VI)]. — (IYER, K.; RAINIER*, J. D.; J. Am. Chem. Soc. 129 (2007) 42, 12604-12605; Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USA; Eng.) — Mischke

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