Methanol benzaldehyde reaction with excess

To demonstrate the feasibility of organic synthesis using this support, the authors immobilized a N-Boc protected glycin (22) on the support (Scheme 7.5). After deprotection imine formation readily occurs with an excess of benzaldehyde. The product was then subjected to a Staudinger reaction with phenoxyacetylchlor-ide to yield the polymer supported / -lactam (26) which could be released to give the yS-lactam (27) with TEA in methanol. 

The tantalum-benzyne complex (130) is much less reactive than other early transition-metal aryne complexes. It shows no reaction with acetone, benzophenone, benzaldehyde, acetonitrile, 3-hexyne, or methanol. The lack of reactivity of 130 was attributed to nonlability of the PMe3 ligand. Indeed, no phosphine exchange was observed when 130 was mixed with an excess of PMe3-d9. Refluxing 129 in a mixture of methanol and toluene (3 10 v/v) leads to clean formation of 131. This presumably results from reaction of a 16-electron benzyne complex with the alcohol. 

Alternatively, compound 54 was converted to the corresponding benzylidene acetal, upon reaction with benzaldehyde dimethylacetal, whose dithioacetal was hydrolyzed to give 58, which was reacted with nitromethane to afford 59 in 83% yield and >99 1 diastereose-lectivity. Treatment of 59 with ethanethiol and stannous chloride effected removal of the benzylidene acetal, without dehydration of the 3-hydroxynitro functionality, to afford the corresponding triol in 82% yield. Protection of the triol with excess TBSOTf afforded a 91% yield of the corresponding TBS ether. Selective removal of the phenolic TBS group was effected by treatment with CSA in methanol to afford 56 in 88% yield, which upon similar sequence of reactions as shown above afforded 60 as the sole cyclization product in 90% yield. 

Problem 14.20. Write equations to show the reactions of benzaldehyde and butanone with excess methanol. Show both the hemiacetal (hemiketal) and acetal (ketal) compounds. 

Write an equation for the reaction of benzaldehyde with excess methanol and an acid catalyst. 

Unsymmetrical ethers may be produced from the acid-promoted reactions of aldehydes and organosilicon hydrides when alcohols are introduced into the reaction medium (Eq. 173).327,328 An orthoester can be used in place of the alcohol in this transformation.327 335 A cyclic version of this conversion is reported.336 Treatment of a mixture of benzaldehyde and a 10 mol% excess of triethylsilane with methanol and sulfuric, trifluoroacetic, or trichloroacetic acid produces benzyl methyl ether in 85-87% yields.328 Changing the alcohol to ethanol, 1-propanol, 2-propanol, or 1-heptanol gives the corresponding unsymmetrical benzyl alkyl ethers in 45-87% yield with little or no side products.328 A notable exception is the tertiary alcohol 2-methyl-2-propanol, which requires 24 hours.328 1-Heptanal gives an 87% yield of //-lie ply I methyl ether with added methanol and a 49% yield of benzyl n-heptyl ether with added benzyl alcohol under similar conditions.328... 

A mixture of benzaldehyde (2 mmol), malononitrile (2 mmol), a-naphthol (2 mmol), and MgO (50 mg) in water (15 mL) was refluxed for 1 h. After completion of the reaction, as indicated by TLC, the mixture was extracted with ethyl acetate (3x5 mL). The organic phase was dried, filtered, and excess ethyl acetate was distilled off (filtration ofboth organic and aqueous phases led to recovery of solid magnesium oxide). The residue was recrystallized from methanol to afford the pure product in 86% yield. 

H. Synthesis of m-Styrylbemamidine p-Toluenesvlfonate 31) and m-Phenylethylbenzamidine p-Toluenesulfonate 82). By a procedure similar to that for compound 52, equal molar amounts of m-cyanobenzyl-triphenylphosphonium bromide 50) and benzaldehyde 54) are allowed to react with a slight excess of sodium methoxide in methanol. The resulting 2-(3-cyanophenyl) styrene is used directly in the Pinner reaction to yield compound 31. 

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