Quenching reagent

The addition of trimethylsllyl chloride proved crucial to the success of the procedure described here. Use of aqueous ammonium chloride as a quenching reagent (instead of trimethylsilyl chloride) resulted in a reaction mixture that contained up to 30% of the corresponding tertiary alcohbl. 

Scheme 2.34 Polymer-supported quenching reagents for paraiiei purification.

The ALIS-based off-rate measurement method was applied to a proprietary series of Zap-70 Kinase inhibitors. First, an ACE50 experiment was conducted to demonstrate that the compounds bind the same site as the quench reagent staurospor-ine. As shown in Fig. 3.15, sigmoidal plots indicate that, with the exception of one compound, the ACE50 values were all very similar to one-another. Linear ratio plots of the same ACE50 data confirm that the compounds all bind isosteri-cally with respect to the quench reagent, a necessary prerequisite for effective competition. 

Fig. 3.16 The ALIS-MS responses from a dissociation rate experiment for a mixture of Zap-70 ligands using staurosporine as the quench reagent. See text for details. (A) The raw data and its fit curve for NGD-6367, one of the compounds in the mixture. (B) The exponential decay curves fit to normalized...

A similar process can be efficiently used for the deallylation or debenzylation of the corresponding ethers 52 and 53, just using water as the quenching reagent after the lithiation process. Some examples giving alcohols or phenols 54 are included in Scheme 17 . 

The reaction shown in Scheme 25 has been successfully used to deprotect Al-benzylic carboxamides using water as the quenching reagent, after the naphthalene-catalyzed lithiation . 

Another additional chemical complication can arise from the presence of quenching reagents which deactivate the reactive polymers. This kinetic quenching mechanism may also be included in the formalism through the addition of an additional differential equation. A more thorough treatment of these extensions and their applications to polymerization reactions is currently in progress. 

Entry Base Quenching Reagent Product Config. op (%) Yield (%) Ref... 

Chain end functionalization of reactive carbocationic monomers, like isobutyl vinyl ether, can occur using ionic nucleophilic quenching reagents, i.e., methanol, alkyl lithium, etc. (6). 

Booth RJ, Hodges JC, Polymer-supported quenching reagent for parallel purification, J. Am. Chem. Soc., 119 4882-4886, 1997. 

Nicewonger RB, Ditto L, Yarady L, Alternative base matrices for solid phase quenching reagents, Tetrahedron Lett., 41 2323-2326, 2000. 

Carbanions which are particularly electron rich cannot be titanated smoothly with quenching reagents having chloro or alkoxy groups at titanium due to reduction of Ti(IV) to Ti(III) via single electron transfer (SET). 

Entry Metal Ma Reagent6 Time A (min) Quench Reagent Time B (min) Yield (%) ... 

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