[19693-75-5]  · C4H8O3  · 2-Methoxy-1,3-dioxolane  · (MW 104.12)

(mild acetalization agent;1 protected formyl group synthon5)

Physical Data: bp 129 °C; d 1.092 g cm-3.

Solubility: sol alcohol, acetone, THF, CH2Cl2.

Form Supplied in: colorless liquid; widely available.

Analysis of Reagent Purity: GC, NMR spectroscopy.

Handling, Storage, and Precautions: moisture sensitive, flammable liquid. Incompatible with oxidizing agents and strong acids.

Mild Acetalization Agent.

A principal advantage of 2-methoxy-1,3-dioxolane for carbonyl protection is the mild reaction conditions (25 °C to reflux, 2-24 h, usually in CH2Cl2, or neat, with catalytic p-Toluenesulfonic Acid) used. Efficient trans-acetalization occurs with aldehydes or ketones, especially with acid-labile substrates or when other methods fail (eqs 1-4).1-4

Protected Formyl Group Synthetic Equivalent.

The reagent can be used for the introduction of a base-stable protected formyl substituent on carbonyl compounds. With silyl enol ethers (eq 5),5 morpholino enamines,6 or titanium enolates (eq 6),7 2-methoxy-1,3-dioxolane gives regiospecifically protected dicarbonyl compounds.

This reagent can also be used as a protected formyl synthetic equivalent when reacted with aryl Grignard reagents (eq 7)8 and allylsilanes (eq 8)9 to afford acetals.

Related Reagents.

2-Butanone Ethylene Acetal; Ethylene Glycol.

1. Friedrich, D.; Bohlmann, F. T 1988, 44, 1369.
2. Glatz, B.; Helmchen, G.; Muxfeldt, H.; Porcher, H.; Prewo, R.; Senn, J.; Stezowski, J. J.; Stojda, R. J.; White, D. R. JACS 1979, 101, 2171.
3. Holladay, M. W.; Salituro, F. G.; Rich, D. H. JMC 1987, 30, 374.
4. Schmidlin, T.; Gamboni, R.; Strazewski, P.; Tamm, C. HCA 1983, 66, 1796.
5. (a) Akgun, E.; Pindur, U. M 1984, 115, 587. (b) Schmidt, R. R.; Hirsenkorn, R. TL 1984, 25, 4357. (c) Akgun, E.; Tunali, M.; Pindur, U. M 1987, 118, 363. (d) Hirsenkorn, R.; Schmidt, R. R. LA 1990, 883.
6. Akgun, E.; Tunali, M.; Pindur, U. CZ 1987, 110, 335.
7. (a) Evans, D. A.; Urpi, F.; Somers, T. C.; Clark, J. S.; Bilodeau, M. T. JACS 1990, 112, 8215. (b) Xiang, Y.; Olivier, E.; Ouimet, N. TL 1992, 33, 457.
8. Tanimoto, S.; Shimojo, S.; Oda, R. Yuki Gosiei Kagaku Kyokai Shi 1968, 26, 435 (CA 1968, 69, 77 137g).
9. Cambanis, A.; Bauml, E.; Mayr, H. S 1989, 128.

Peter P. Giannousis

Ciba-Geigy Corporation, Summit, NJ, USA

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