3-(Phenylsulfonyl)propanal Ethylene Acetal

[56161-51-4]  · C11H14O4S  · 3-(Phenylsulfonyl)propanal Ethylene Acetal  · (MW 242.32)

(synthetic reagent for 2-alkenals, 4-oxoalkanals, and 5-hydroxyalkanals)

Physical Data: mp 62-63 °C or 67-68 °C.1,2

Form Supplied in: colorless crystals.

Preparative Methods: by oxidation of 3-(phenylthio)propanal ethylene glycol1 or by reaction of Sodium Benzenesulfinate with 3-bromopropanal ethylene acetal.2

Synthesis of Alkanals.

Monoalkylation of 3-(phenylsulfonyl)propanal ethylene acetal (1) takes place at the position a to the phenylsulfonyl group on successive treatment with n-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).1

A second alkylation is also possible by treatment with alkyl iodide and n-BuLi. Acidic deprotection of the dialkylated product gives the corresponding 2-alkenal (eq 2).1

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).3,4

Synthesis of 5-Hydroxyalkanals.

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

Multiple Bond Formation.

Lithiated (1) adds to aldehydes. After acetylation, treatment of the adduct with Potassium t-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).6,7

Related Reagents.

4-Phenylsulfonyl-2-butanone Ethylene Acetal.

1. Kondo, K.; Tunemoto, D. TL 1975, 1007.
2. Gaoni, Y.; Tomazic, A.; Potgieter, E. JOC 1985, 50, 2943.
3. Kondo, K.; Tunemoto, D. TL 1975, 1397.
4. Menicagli, R.; Wis, M. L.; Lardicci, L.; Botteghi, C.; Caccia, G. JCS(P1) 1979, 847.
5. Kondo, K.; Saito, E.; Tunemoto, D. TL 1975, 2275.
6. Mandai, T.; Yanagi, T.; Araki, K.; Morisaki, Y.; Kawada, M.; Otera, J. JACS 1984, 106, 3670.
7. Mandai, T.; Moriyama, T.; Tsujimoto, K.; Kawada, M.; Otera, J. TL 1986, 27, 603.

Katsuyuki Ogura

Chiba University, Japan

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