The relative reactivity of cyclic ketones towards methyltitanium reagents

✍ Scribed by M.T. Reetz; H. Hugel; K. Dresely

• Book ID: 104205038
• Publisher: Elsevier Science
• Year: 1987
• Tongue: French
• Weight: 356 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)89936-1

✦ Synopsis

The relative rates of the addition of CH3TiC13 and CH3Ti(OCHMe213 to various cyclic ketones of different ring size have been determined. In contrast to CH3Li and CH3MgCl, significant rate differences were observed. For CH3TiC13 (at -18OC) the following decreasing order in rate pertains, the numbers symbolizing the ring size: 6 >5 >7 >15 >8 >12 >9 >ll >lO. For CH3Ti(OCHMe2)3 (at +22'C) it is slightly different: 6 >5 >7 >8 >15 >9 >12 >13 >ll >lO. Most of the results can be explained on the basis of Browns hypothesis of I-strain. However, the 15-membered ring cyclopentadecanone represents the major "irregularity".