Ogata A, Nemoto M, Kobayashi K, Tsubouchi A, Takeda T. Titanocene(II)-Promoted Multicomponent Reactions Utilizing Alkynyl Sulfones, Alkenyl Sulfones, and Carbonyl Compounds: A Novel Method for the Synthesis of Vinylallenes.
Chemistry 2007;
13:1320-5. [PMID:
17072934 DOI:
10.1002/chem.200601326]
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Abstract
Titanocene(II)-promoted cross coupling of alkynyl- and (Z)-alkenyl sulfones affords alpha-(phenylsulfonyl)alkenyltitanium species. Further treatment of these species with the titanocene(II) reagent generates titanium vinylvinylidene complexes, which react with carbonyl compounds in one pot to produce substituted vinylallenes with complete stereoselectivity. By using alpha,beta-unsaturated ketones, 1,3,4,6-tetraenes are also obtained stereoselectively.
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