Science of Synthesis

Mikami, K.; Matsumoto, Y.; Shiono, T., Science of Synthesis, (2003) 2, 525.

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.[‌276‌–‌278‌] 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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References

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• 8.Meeeee-Meee, (8888) M 88e, 8888.
• 8.Meeeee-Meee, (8888) M 88e, 8888.