There have been great strides in expanding the scope, application, and versatility of known reaction types (i.e., Mukaiyama aldol). It is interesting to speculate that limitations in the number of such known basic reaction types constitute the greatest barrier in the development of practical processes. The catalytic generation of transition-metal metalloenolates and alkynilides under conditions compatible with electrophilic reaction partners provides fresh avenues for the development of new efficient asymmetric processes leading to C-C bond formation.

No abstract

An IR study of terminal acetylenes and Zn(OTf)2 in the presence of amine bases provides evidence that is consistent with the generation of Zn-acetylides.

35] The MS and MS-MS experiments were carried out on a PE Sciex Qstar Pulsar quadrupole/time-of-flight tandem mass spectrometer (Applied Biosystems, Foster City, California) operated with a room temperature turbo-ionspray source and using Analyst QS data acquisition software. The samples were dissolved in a 1:10 mixture of pyridine and acetonitrile, and infused via a syringe pump at 5 mL min À1 . The instrument was run in the negative ion mode with the capillary voltage at À4500 V and the dissociation potential (source CID) at À20 V. The TOF Pulser frequency was set for 5 kHz with a 1 s accumulation time per spectrum. Data were aquired over the mass range of 10±600 m/z for MS acquisition. In the MS-MS mode, the quadrupole mass analyzer was set to pass the parent ion at unit mass resolution. N 2 or Ar was used as the collision gas. The gas settings were as follows: source nebulizer gas ¼ 30, desolvation gas ¼ 0, curtain gas ¼ 25, collision gas ¼ 5.

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