Polarized multiple bonds

On the other hand these are compounds with marked 1,4-dipolar character, having electron lone pairs at the terminal heteroatom and an electrophilic center at C-4 Consequently, they can react with polarized multiple bond systems, even when these are extremely electron-poor [225]... 

Addition of organomagnesium compounds to polarized multiple bonds O OMgX OH... 

The conversion of a nitrile R —CN into a ketone R —CO—R demonstrates that polarized multiple bonds other than C=0 also react with Grignard reagents, and that such reactions are synthetically useful. Esters 22 and acid chlorides can react subsequently with two equivalents of RMgX the initially formed tetravalent product from the first addition reaction can decompose to a ketone that is still reactive, and reacts with a second RMgX. The final product 23 then contains two substituents R, coming from the Grignard reagent ... 

In the second group of ring-chain tautomeric interconversions, an open-chain system is transformed into a cyclic system through the intramolecular reversible addition of a functional group to a polar multiple bond lA IB 2A 2B 3A 3B and 4A 4B. The book (I) and this article deal with... 

The most important synthetic use of Grignard reagents and organolithium reagents is to form new carbon-carbon bonds by addition to polar multiple bonds, particularly carbonyl bonds. An example is the addition of methyl-magnesium iodide to methanal ... 

In general [for a review, see (92KGS851)], this type of equilibrium actually proceeds via the scheme ring-chain-ring, but with a very small concentration of the intermediate open-chain tautomer at equilibrium, which prevents its detection by the methods used for the investigation of these equilibria. The two cyclic tautomers may be formed either by the competitive intramolecular addition of two different nucleophilic groups XH to one multiple bond, or by the same process, but of one nucleophilic group to the two different polar multiple bonds. 

Protic reagents such as water, or alcohols, or amines, in which hydrogen is bonded to an electronegative group, will add, often reversibly, to a variety of polar multiple bonded compounds, such as aldehydes, isocyanates, or carbon dioxide, for example ... 

Answer The functional groups are a ketone and an ester. Both CH2S are adjacent to the 6+ end of a polarized multiple bond and are acidic. The pATgS of each set of hydrogens are given below. 

Acidic Hs are found on heteroatoms and adjacent to polarized multiple bonds. 

Although the Sn of leaving groups bound to a sp center is a mechanism that has been searched for, with one or two rare exceptions there is little evidence in the literature that it has ever been found. The correct mechanism is path AdN, addition to a polarized multiple bond, followed by path Ep, beta elimination from an anion. 

POLARIZED MULTIPLE BONDS WITHOUT LEAVING GROUPS... 

Section 6.4 Polarized Multiple Bonds Without Leaving Groups... 

The heterocumulene derivatives, C=C=Y or Z=C=Y, are a minor variation of the polarized multiple-bond sink and undergo an identical nucleophilic attack at the C=Y bond. The only difference is that the intermediate is a resonance hybrid that protonates to form the most stable product. The product with the stronger bonds predominates. 

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