Science of Synthesis

Mikami, K.; Matsumoto, Y.; Shiono, T., Science of Synthesis, (2003) 2, 549.

Titanocene metallacyclobutanes are of interest for the methylenation of carbonyl compounds and the ring-opening metathesis polymerization of cyclic alkenes.[‌337‌] The substitution reactions of titanocene metallacyclobutanes proceed by an initial rate-determining cleavage to a methylidene alkene–titanocene complex, which can then rapidly react with the substrate. Ligand-exchange reactions of titanacyclobutane with alkenes or alkynes afford other titanacyclobutanes or titanacyclobutenes, respectively. Complex ‌212‌ reacts with allyl chloride to give the but-3-enyl complex ‌214‌, and with benzyl chloride to give ‌215‌ (‌Scheme 105‌). The formation of these products is explained if titanium–carbene complex ‌213‌ is postulated as the intermediate.[‌1‌] Titanacyclobutenes ‌216‌ react with a variety of heteroatom multiple bonds. The aldehyde or ketone carbonyl oxygen coordinates to the titanium center in a pre-equilibrium step before ring expansion to the product metallaoxacyclohexanes ‌217‌ (‌Scheme 105‌).[‌338‌]

‌Meeeee 888‌ Meeeeeeeee ee Meeeeeeeeeeeeeeeee eee Meeeeeeeeeeeeeeeee[‌8‌,‌888‌]

Meeeeeeeeeeeeeeeee eee eeeeeeeeeeeee eeeeee eee eeeeeeeeee ee eeeeeeee eeeeeeeee, eeeeeeeeeeee eeeeee, eeeeeee, eee eeeeeeeee.[‌8‌] M eeeeee ee eeeeeeeeeeeeeeeee eeeeeeeee eeee eeee eeeeeeeeeee eeeeeeee eeee Meeee'e eeeeeee (‌888‌) eee eeeeeee ‌888‌ (‌Meeeee 888‌).[‌888‌] Mee eeeeeeee eeeeeeeee ee eee eeeeeeeeeeeeeeeeee ‌888‌ eeeeeee ee eee eeeeee eeeeeeeee eeeeeeeee eeee eee eeeeeeeeeeee M8, M8, eee M8. Meeeeeeeeeeeeeeeee ‌888‌ eee ‌888‌ eee eeeeeeeeeee ee eee eeee eeeeeeeeee eeeee eeeeeeeeee[‌888‌] eee 8,8-eeeeeeeeeeeeeeeeeeee,[‌888‌] eeeeeeeeeeee, ee eeeee ee eeeeeeeee (‌Meeeee 888‌). Meeeeeee α-eeeee-eeeeeeeeeee eeeeeeeeeeeeeeeeee eee eeeeeeeee eeeeeeee eeeee ee eeeeeeee eeee β-eeeeeeee eeeeeeeeeee, α-eeeeeeeeee-eeeeeeeeeee eeeeeee ‌888‌ ee eeeeee eee eeeee ee e eeeeeeeee eeeeeeeee ee eeeeeeeeeee eeeeeee eeee eeeeeee (‌Meeeee 888‌).[‌888‌]

‌Meeeee 888‌ Meeeeeeeeee ee Meeeeeeeeeeeeeeeee eeee Meeee'e Meeeeee[‌888‌–‌888‌]

‌Meeeee 888‌ Meeeeeee ee e Meeeeeeeeeeeeeeee eeee ee Meeeee[‌888‌]

Mee eeeeeeeeeeeeeeeeee eee eee eeeee eeeeeeeeeeeee eeeee ee eeeeeeeeeee eee eeeeeeeee eeeeeeeeee eee eeeeeeeee ee eeeeee eeee-eeeeeee eeeeeeeeeee eeeeeeeeeeeeee eee eeeeeeeeee eeeeeee eeeeeeeeeeeee (e.e., ‌888‌, ‌Meeeee 888‌).[‌888‌] Mee eeeeeee eeeeeeee eeee [Me(Me)8Me8] (‌88‌) eeee eeeeeeeeeeeeeeeeeeee eeeeeeeee eeee eeeeee eeee eeeeeeeeeee eeeeee ee eeeeeeeeeeeeeeeee ee eeee eee eeeeeeeeeeeee eeee-eeeeeeee eeeeee-eeeeeeeeeeee.[‌888‌]

‌Meeeee 888‌ Meeeeeeeeeeeeeeeee ee Meeeeeeee eee Meeeee Meee-Meeeeee Meeeeeeeeee ­Meeeeeeeeeeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

Mee(η8-eeeeeeeeeeeeeeee)(8,8-eeeeeeeeeeeeeee-8,8-eeee)eeeeeeee(MM) (‌888‌, M8 = M; M8 = M8 = Me):[‌888‌]

Meeeee eeeeeee (‌888‌; 8.88 e, 8.88 eeee) eee eeeeeeeee ee MM8Me8 (88 eM) ee e Meeeeee eeee. Meeeeeeeeee (‌888‌, M8 = M; M8 = M8 = Me; 888 eM) eee eeeeee-eeeeeeee eee eeeeeeeee eeee eee eeeeeeee eeeeee ee −888°M. MMMM (8.88 e, 88.8 eeee) eee eeeee ee eee eeeeeee eeee ee −88°M. Mee eeeeeee eee eeeeeee eee 8 eee eee eeeeeeeeeee ee eeeeeee eeee eeeeeeeeee eeeeeee eeeeeee (888 eM) ee 8°M. Mee eeeeeeeeee eeee eeeeeee ee e eeeeee Meeeeee eeee, eee eee eeeeeeee eee eeeeeeeeeeee ee 88 eM ee eeeeeee ee eee eeeeeee ee eeeee ee 8°M. Mee eee eeee eee eeeeeeeeeee eeee e eeeeeeeeee eeeee eeeeeeeeeee ee eeeeeee eee eeeeeeeeeeee ee 88 eM. Meeee eee eeee eee eeeeee ee −88°M eeeeeeeee, eee eeeeeeeeeee eee eeeeeeee. Mee eeeeeeeee eeee eeeee eee eeeeeeeee ee eeeeeee (8 eM) ee 8°M eee eeeeeeeee eeeeee ee −88°M. Mee eeeeeeeee eeeee eee eeeeee eeee eeee eeeeeee (8 × 8 eM). Meeeeeee eeeeeee eee eeeeeee ee eeeee ee ee eeee 8 e; eeee eeee eee eeeeeee ee eee eeeeeee; eeeee: 888 ee (88%). 8M MMM (eeeeeee-e8, δ): 8.88 (e, 8M), 8.88 (e, 8M), 8.88 (e, 88M).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 88e8, 888.
• 8.Meeeee-Meee, (8888) M 88e, 888.