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Please login to access the full content or check if you have access via Method 5: (η1-Allyl)bis(isopropoxy)titanium(IV) Complexes by Reaction of Low-Valent Titanium Complexes with Allylic Halides, Acetates, Carbonates, Phosphates, Sulfonates, or Aryl Ethers

DOI: 10.1055/sos-SD-002-00576

Mikami, K.; Matsumoto, Y.; Shiono, T.Science of Synthesis, (20032525.

Sato and co-workers report the reaction of divalent titanium complex 142, prepared from [Ti(OiPr)4] or [TiCl(OiPr)3] and 2 equivalents of isopropylmagnesium bromide, with allyl alcohol derivatives that have a leaving group at the allylic position, such as allylic halides, acetates, carbonates, phosphates, sulfonates, or aryl ethers (Scheme 71). A ligand exchange reaction followed by β-elimination gives [Ti(η1-allyl)(OiPr)2X] complexes 143 in excellent yields. The synthesis can be carried out starting with readily available allylic alcohol derivatives and an inexpensive titanium alkoxide.[‌276‌‌278‌] The method allows the preparation of σ-allyltitaniums that have functional groups such as esters and halides. The reaction with seven-, eight-, and nine-membered cyclic allylic halides or carbonates affords the corresponding cyclic allyltitaniums.[‌277‌] Allyltitanium complex 144, prepared from 1-vinylcyclopropyl carbonate and a titanium(II)alkene complex, reacts highly selectively with electrophiles at the less substituted carbon to give alkylidenecyclopropane derivatives.

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