Organometallic compounds deprotonation

Alkenes are deprotonated by the organometallic compounds of the heavier alkali metals to give allylmetal derivatives. As these are normally highly... 

More reactive carbon nucleophiles than enolates can also be prepared on insoluble supports (see Chapter 4) and are used to convert aldehydes or ketones into alcohols. Organolithium compounds have been generated on cross-linked polystyrene by deprotonation of formamidines and by metallation of aryl iodides (Table 7.5). Similarly, support-bound organomagnesium compounds can be prepared by metallation of aryl and vinyl iodides with Grignard reagents. The resulting organometallic compounds react with aldehydes or ketones to yield the expected alcohols (Table 7.5). 

The addition of a-deprotonated alkyl halides to alkenes or carbonyl compounds can, because of the good leaving-group properties of halides, also lead to formation of cyclopropanes [292] or epoxides [187, 304, 306, 310], respectively. Because of the inherent instability of a-halo organometallic compounds, these intermediates should be handled carefully and on a small scale only. The ketone produced by the last reaction in Scheme 5.34 is probably formed by Oppenauer oxidation of the intermediate alcohol by the excess benzaldehyde [310],... 

Heiss, C. Marzi, E. Schlosser, M. Buttressing effects rerouting the deprotonation and functionalization of 1,3-dichloro- and 1,3-dibromo-benzene. Eur J. Org. Chem. 2003, 4625 -629. Murahashi, S.-I. Naota, T. Tanigawa, Y. Palla-dium-phosphine-complex-catalyzed reaction of organometallic compounds and alkenyl halides (Z)-/j-[2-( N,. -di rn ethyl ami no) pheriyl]-styrene. Org. Synth. 1990, Coll. Vol. VII, 172— 176. 

THE DEPROTONATION OF WEAK ACIDS WITH POTASSIUM HYDROXIDE APPLICATIONS TO THE SYNTHESIS OF ORGANOMETALLIC COMPOUNDS... 

Despite very efficient stirring during the addition of R OD to 2, not all molecules of 2 will be deuterated at the same time. Deprotonation of 3 by 2 leads to the formation of some di-deuterated compound 5. More polar conditions (K+ as a counter ion HMPT as a co-solvent) are likely to favour such processes. These can be minimized by inverse addition a solution of the organometallic compound is added to an excess of R OD in the organic solvent (for an example see Chap. V, Exp. 44). 

Technically, XMgC=CCH3 is a Grignard reagent because it is an organometallic compound of magnesium. However, it is not made in the usual fashion it is made by deprotonating the terminal alkyne as shown. 

If the normal addition procedure is applied, the initial product may be deprotonated by the original organometallic compound and the newly generated intermediate will react with the disulfide ... 

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