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One-pot synthesis of α-methylene-γ-butyrolactones from benzaldehydes and bromomethylacrylates. Bis-(cyclopentadienyl)-titanium dichloride alkylaluminum complexls acts as catalysts for the polymerization of ethylene. Polyethylene prepared with these catalysts. Complexes of aluminum chloride and methylaluminum dichloride with bis-(cyclopentadienyl)-titanium dichloride as catalysts for the polymerization of ethylene.
Wendell P. Long,; David S. Breslow. Polymerization of Ethylene with Bis-(cyclopentadienyl)-titanium Dichloride and Diethylaluminum Chloride. J. Am. Chem. Soc. 1960, 82 (8), 1953-1957.
Wendell P. Long. Complexes of Aluminum Chloride and Methylaluminum Dichloride with Bis-(cyclopentadienyl)-titanium Dichloride as Catalysts for the Polymerization of Ethylene . J. Am. Chem. Soc. 1959, 81 (20),5312-5316.
In combination with trimethyaluminum, generates an ylide (Tebbe reagent): J. Am. Chem. Soc., 100, 3611 (1978), which transfers a methylene group not only to aldehydes and ketones (cf Wittig reaction) but also to the carbonyl groups of esters and lactones: J. Am. Chem. Soc., 102, 3270 (1980):
A similar reagent can be prepared by reaction with the Simmons-Smith adduct (see Diiodomethane, A15457) and used for the methylenation of ketones in excellent yields: Tetrahedron Lett., 24, 2043 (1983).
Reacts with Grignard reagents with a ß-hydrogen atom (e.g. isobutyl or isopropyl) to form, in a catalytic cycle, a titanium hydride species, which reduces aldehydes, ketones and esters to alcohols: Tetrahedron Lett., 21, 2171, 2175 (1980). The same combination effects regioselective cis-hydromagnesation of alkynes to give alkenyl Grignard reagents: Tetrahedron Lett., 22, 85 (1981); J. Chem. Soc., Chem. Commun., 718 (1981). For application in a highly stereospecific synthesis of vinylsilanes in excellent yields, see: Tetrahedron Lett., 24, 1041 (1983):
For further examples of the hydroxymagnesation of alkynes, see: Org. Synth. Coll., 8, 507 (1993). Similarly π-allyl complexes with 1,3-dienes can be generated, which react regio-and stereo-selectively with aldehydes to give homoallylic alcohols: J. Chem. Soc., Chem. Commun., 621 (1984):
For use, in combination with Mg metal, in formation of titanocycle intermediates, see: J. Org. Chem., 63, 9285 (1998); for reaction scheme, see Triphosgene, A14932.
Dichiarazioni di rischio (UE): H302-H332-H315-H319-H341-H335
Harmful if swallowed. Harmful if inhaled. Causes skin irritation. Causes serious eye irritation. Suspected of causing genetic defects. May cause respiratory irritation.
Dichiarazioni precauzionali: P201-P261-P280-P305+P351+P338-P405-P501a
Obtain special instructions before use. Avoid breathing dust/fume/gas/mist/vapours/spray. Wear protective gloves/protective clothing/eye protection/face protection. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.