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Abstract:
The relative rates of the addition of CH3TiCl3 and CH3Ti (OCHMe2)3 to various cyclic ketones of different ring size have been determined. In contrast to CH3Li and CH3MgCl, significant rate differences were observed. For CH3TiCl3 (at 18°C) the following decreasing order in rate pertains, the numbers symbolizing the ring size: 6 > 5 > 7 > 15 > 8 > 12 > 9 > 11 > 10. For CH3Ti (OCHMe2)3 (at +22°C) it is slightly different: 6 > 5 > 7 > 8 > 15 > 9 > 12 > 13 > 11 > 10. Most of the results can be explained on the basis of Brown's hypothesis of I-strain. However, the 15-membered ring cyclopentadecanone represents the major “irregularity”.
