Oximes lithium salts

Lithium salts of ketone derivatives such as imines, oximes and hydrazones have also been used for directed aldol reactions (Scheme 103).374 375 A recent example involves triple coordination of lithium in a very rigid transition state, to lead to regiospecificity in the product (Scheme 104).376... 

In the reaction of the lithium salt of 62 with acetone after a short lithiation time of 30 min, a 10% or 25% E Z mixture of 63 was obtained together with the addition product 64 in 65% yield (equation 42)65. The formation of only one addition product, and the quick disappearance of the -isomer, are due to a fast deprotonation process the -isomer compared with the Z-isomer, and the high rate of equilibration between the lithium compounds that greatly favors the syn anion, which reacts with acetone to give 64. These results point out that the formation of the syn lithium compounds is favored in oxime ethers for kinetic as well as for thermodynamic reasons. The kinetic preference, according to Ensley and Lohr65, is due to coordination between the lithium amide and the oxime oxygen. 

While most reducing agents lead to the expected bornylamines as products of the reduction of camphor oxime (see above), diisobutylaluminum hydride is a notable exception, as a ring-enlarged amine, (1/ ,47 )-1.8,8-trimethyl-2-azabicyclo[3.2.1]octane (67) is obtained in high yield when starting with the oxime of (+ )-camphor16, It has been used as the lithium salt in enantioselective deprotonation and elimination reactions (Section C.). 

Isoxazolines have been prepared by the condensation of aldehydes and ketones with the di-lithium salts of oximes it was unnecessary to isolate the intermediate -hydroxyoximesX (Scheme 127). 

The lithium and thallium (I) salts of i satin-3-oxime (isatin oximates) were employed in the development of ion-selective electrodes for these cations. Transition metal complexes of isatin derivatives can also be employed as catalysts for the oxidative self-coupling of alkylphenol s639,640. 

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