Enolate zincate

The infrared experiments revealed to ns the formation of a new species, which was apparently an amide zincate enolate, the first observation of its kind. The strnctnre of this enolate was not clear from the data, however. The absorbances at 1536 cm and 1559 cm appeared too low to assign to either an oxygen-metallated enolate carbon-carbon donble bond strnctnre as in 9, or to a carbon-metallated enolate with a free amide carbon-oxygen donble-bond stretch as in 10 (Figure... 

The in situ IR observations shown in Figure 20.5 provided the key result that led us to propose that an activator was needed to drive the homologation of zincate enolate 11a, and that the activator in this case was a second equivalent of 7. Our observations appeared similar to those described by Harada and Oku. They had observed certain a-halo diorganozinc compounds could be driven to undergo 1,2-migration if an excess of alkoxide was added (Scheme 20.6). Because higher conver-... 

Naturally, we followed the reaction by in situ IR (Figure 20.6). We learned from our inverse addition experiments that quenching 7 as the zincate enolate 11a had the benefit of minimizing... 

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