[19693-75-5] · C4H8O3 · 2-Methoxy-1,3-dioxolane · (MW 104.12)
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.
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
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.
2-Butanone Ethylene Acetal;
Peter P. Giannousis
Ciba-Geigy Corporation, Summit, NJ, USA