Phenylsulfonyl propanal Ethylene Acetal

4-Oxoalkanal Synthesis. The lithio derivative of (1) can be acylated with a methyl ester to afford an acylated product which easily undergoes reductive desulfurization with aluminum amalgam or sodium amalgam to produce a 4-oxoalkanal ethylene acetal, an important synthetic precursor (eq 3).  

Synthesis of S-Hydro alkanals. The lithio derivative of (1) reacts with terminal epoxides to give ring-opened products. Reductive desulfurization followed hy acidic deprotection forms 5-hydroxyalkanal, which cyclizes to give a 5-lactol (eq 4).  

Multiple Bond Formation. Lithiated (1) adds to aldehydes. 

After acetylation, treatment of the adduct with potassium tert-butoxide causes elimination of benzenesulfinic acid and acetic acid to form an acetal having a triple bond or a conjugated double bond, depending on circumstances (eqs 5 and 6).  

Solubility insol H2O sol pyridine, CH2CI2 reacts slowly with H2O and protic solvents. 

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Related Reagents. 1,3-Dibutoxy-l-lithio-l-propene 1-Methoxyallenyllithium 3-(Phenylsulfonyl)propanal Ethylene Acetal. 

Synthesis of Alkanals. Monoalkylation of 3-(phenylsulfo-nyl)propanal ethylene acetal (1) takes place at the position a to the phenylsulfonyl group on successive treatment with butyllithium and then with an alkyl halide. Deprotection of the acetal group and subsequent elimination of benzenesulfinic acid with a base produces the corresponding 2-alkenal (eq 1). ... 

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