Intramolecular Cannizzaro reaction

Suitable dialdehydes can also undergo intramolecular hydride transfer, as in the Cannizzaro reaction of ethan- 1,2-dial (55, glyoxal ) — hydroxyethanoate ( glycollate, 56) anion,... 

The slow, rate-limiting step is almost certainly the migration of phenyl that occurs in the initial eOH adduct (135). This is essentially the analogue for 1,2-diketones of the intramolecular Cannizzaro reaction on the 1,2-dialdehyde glyoxal, OHCCHO (p. 217). In the latter... 

A different behavior is exhibited by naphthalene-1,8-dicarbocal-dehyde (73). No m-naphthane derivatives are obtained on reaction with nitromethane, nitroethane or other methylene components. The basic medium, required for aldol type additions, causes the dialdehyde to undergo Cannizzaro reaction to the naphthopyranon (74) via an intramolecular 1,5-hydride shift, which is sterically favoured by the peri-position of the two aldehyde functions 28). 

Nucleophilic addition to C=0 (contd.) ammonia derivs., 219 base catalysis, 204, 207, 212, 216, 226 benzoin condensation, 231 bisulphite anion, 207, 213 Cannizzaro reaction, 216 carbanions, 221-234 Claisen ester condensation, 229 Claisen-Schmidt reaction, 226 conjugate, 200, 213 cyanide ion, 212 Dieckmann reaction, 230 electronic effects in, 205, 208, 226 electrons, 217 Grignard reagents, 221, 235 halide ion, 214 hydration, 207 hydride ion, 214 hydrogen bonding in, 204, 209 in carboxylic derivs., 236-244 intermediates in, 50, 219 intramolecular, 217, 232 irreversible, 215, 222 Knoevenagel reaction, 228 Lewis acids in, 204, 222 Meerwein-Ponndorf reaction, 215 MejSiCN, 213 nitroalkanes, 226 Perkin reaction, 227 pH and, 204, 208, 219 protection, 211... 

The lactone 223 was isolated from 2-benzoyl-3-hydroxymethylquin-oxaline 1-oxide 221 on treatment with alkali and subsequent acidification, probably by intramolecular Cannizzaro reaction of 2-benzoyl-3-quinoxaline carboxyaldehyde (222), which in turn is obtained from 221 by a series of tautomeric shifts and 1,4-elimination.221... 

Pretazettine (242) has a trans B-D ring juncture and seems a fairly strained molecule whereas tazettine (240) bears a cis B-D fusion allowing more flexibility, and the driving force for the B-ring opening is attributed to the relief of this internal strain. The reaction would be completed by an intramolecular crossed Cannizzaro reaction followed by hemiketal formation yielding the cis B-D fusion present in 242. 

An effective concentration for the second aldehyde group of 13 has been quoted, obtained by taking the value of (kobs/[NaOH]) at low [NaOH] and comparing it with the third-order rate coefficient for the intermolecular Cannizzaro reaction of benazaldehyde under the same conditions. This does not compare inter- and intramolecular hydride transfer steps. 

Intramolecular Cannizzaro reaction (a 3-Buten-2-one + (CH3CH2CH2)2CuLi... 

J. Rebek et al. synthesized novel dibenzoheptalene bislactones via a double intramolecular Cannizzaro reaction for condensation polymerization and remote catalysis studies. These bislactones are chiral, atropisomeric molecules. 

Russell, A. E., Miller, S. P., Morken, J. P. Efficient Lewis acid catalyzed intramolecular Cannizzaro reaction. J. Org. Chem. 2000, 65, 8381-8383. 

Bowden, K., Butt, A. M., Streater, M. Intramolecular catalysis. Part 8. The intramolecular Cannizzaro reaction of naphthalene-1,8-dicarbaldehyde and [a,a -2H ]naphthalene-1,8-dicarbaldehyde. J. Chem. Soc., Perkin Trans, 21992, 567-571. 

The prototype reaction is the conversion of glyoxal into glycolic acid (equation 2), and here the benzilic acid rearrangement mechanism coincides with that for an intramolecular Cannizzaro reaction. The reaction is observed with other purely aliphatic a-diketones such as f-butyl 2,3-dioxobutyrate and cyclohexane-1,2-dione (equations 3 and 4), but the scope is limited in the aliphatic series by competing (c.g. aldol) reactions. Suitably constructed heterocyclic systems also rearrange, and the conversion of alloxan (3) into alloxanic acid (4) was among the first of the benzilic acid rearrangements to be discovered (equation 5). ... 

An interesting reactivity is displayed by peri-dialdehyde 110. On boiling in water solution it undergoes an intramolecular Cannizzaro reaction to form the naphtho[l,8-c,d]pyranone derivative 198. It is noteworthy that the reaction does not require an addition of alkali, probably because the necessary basicity of the medium is provided by the substrate itself188. 

In the Cannizzaro reaction, the hydride ion that is being used to effect this reduction may come from an aldehyde that lacks an a-hydrogen atom, e.g. methanal or benzaldehyde. The receiving molecule may be a second molecule of the same aldehyde or a different one. The reaction requires a strong base, and the rate law is found to depend on the square of the concentration of the aldehyde and either the concentration or the square of the concentration of the base used. Overall a carboxylate anion and an alcohol are formed from two molecules of the aldehyde(s). The reaction may occur intramolecularly, i.e. a-ketoaldehydes give the a-hydroxycarboxylic acids on treatment with hydroxide ions. A variation of this process is called the Tollens reaction. In this case, a ketone or aldehyde that contains an a-hydrogen is treated with formaldehyde in the presence of Ca(OH)2. 

Successive elimination of an alkoxy group adjacent to an active hydrogen atom and intramolecular Cannizzaro reactions in alkaline solution, such as are found in saccharinate formation, are demonstrated by the conversion of 2-hydroxy-3-methoxy-3-phenylpropiophenone (X) to a salt of 2,3-diphenyllactic acid (XI). 

A proposed mechanism, involving an intramolecular Cannizzaro reaction, is outlined below. The mechanism is not conclusive especially as the vicinal diols 87-90 have been reported to give the expected a-diketones under Swem conditions.50-53... 

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