Titanocene-promoted stereoselective eliminations on epoxy alcohols derived from R-(−)-carvone

• Published in: Tetrahedron Vol. 69; no. 5; pp. 1611 - 1616
• Main Authors: Fernandez-Mateos, A., Herrero Teijon, P., Rubio Gonzalez, R.
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 04.02.2013; Elsevier
• Subjects: Alcohols; Benzoates; Chemistry; Chemistry, Organic; Cleavage; Dehydrogenation; Derivatives; Elimination; Esters; Oxirane; Physical Sciences; Radical reactions; Radicals; Science & Technology; Tetrahedrons; Titanium; ZSTUCFBRGXAUAX-MMWGEVLESA-N; PRDKOMOYONODRV-BZUAXINKSA-N; ZSTUCFBRGXAUAX-ZRUFSTJUSA-N; Elimination; XGWUOCNZFKMMJP-HWMZRRJGSA-N; XGWUOCNZFKMMJP-MPTYRVRUSA-N; Esters; XGWUOCNZFKMMJP-QSJFSLAZSA-N; PRDKOMOYONODRV-OWCLPIDISA-N; SYFXHNVIJQBCRV-GRYCIOLGSA-N; Alcohols; NHJVCWGYXCFQJJ-OWUUHHOZSA-N; ANZAWKTYWQYILZ-QCNOEVLYSA-N; Radical reactions; ANZAWKTYWQYILZ-WHOHXGKFSA-N; Titanium; NHJVCWGYXCFQJJ-NXEZZACHSA-N; ZSTUCFBRGXAUAX-ZDCRXTMVSA-N; SYFXHNVIJQBCRV-IJLUTSLNSA-N; HYSBIPRPOGLHMK-OUAUKWLOSA-N; SYFXHNVIJQBCRV-UTUOFQBUSA-N; HYSBIPRPOGLHMK-GMTAPVOTSA-N; MONOTERPENOIDS; EPOXIDES; ENANTIOMERICALLY PURE; ALLYLIC ALCOHOLS; DEOXYGENATION; CHLORIDE
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2012.11.093

The reaction of several stereoisomeric epoxy alcohols, obtained from R-(−)-carvone, and their corresponding formates, acetates, and benzoates, promoted by Cp2TiCl has been studied. The different outcomes of the reaction of epoxy derivatives are rationalized in terms of mechanistically biased processes. The radicals emerging from oxirane cleavage provide two types of reaction: dehydroxylation (deoxycarbonylation) and dehydrogenation. The results offer considerable support for the radical elimination theory of hydroxyl, formyloxyl, and acetoxyl groups. The inability of tertiary radicals to be reduced by the Ti(III) complex is demonstrated unequivocally. [Display omitted]