[621-62-5] · C6H13ClO2 · 2-Chloro-1,1-diethoxyethane · (MW 152.62)
Alternate Names: 1-chloro-2,2-diethoxyethane; chloroacetaldehyde diethyl acetal.
Physical Data: colorless liquid, bp 151 °C; d 1.018 g cm-3.
Solubility: sol most organic solvents.
Form Supplied in: neat liquid of high purity; readily available.
Handling, Storage, and Precautions: flammable, moisture sensitive. Use in a fume hood.
Sodium ethoxyacetylide is formed on treatment with Sodium Amide/liq. NH3, from which ethoxyacetylene, 1-ethoxyalkynes, or 1-ethoxyalkynols can be obtained by quenching the acetylide anion with the appropriate electrophile (eq 1).
The alkoxyalkynols formed can easily be converted to a,b-unsaturated esters on acid treatment.3
Biologically important 4-hydroxycyclopentenones are readily available in a high yielding route by reaction of 2-chloro-1,1-diethoxyethane with a dithiane (eq 2). It is noteworthy that yields are much lower with the corresponding bromoacetal.
With 1-ethoxy-3-trimethylsilyl-1-propyne, the reagent under Titanium(IV) Chloride catalysis affords 2-carbonylethoxyallyltrimethylsilane regio- and stereoselectively (eq 3).
An electrophilic species equivalent to a vinyl cation can be generated by treating the reagent with Sodium Dicarbonylcyclopentadienylferrate (eq 4).
Isocytosine can be vinylated with 2-chloro-1,1-diethoxyethane to give the corresponding imidazolo[1,2-a]pyrimidine-5(1H)-one and -7(8H)-one (eq 5).7 The process is reversable upon treatment with Lead(IV) Acetate and mild basic hydrolysis. Annulations to give six-membered ring systems containing a bridgehead nitrogen are also common.8
Miscellaneous applications include the synthesis of vinyl ethers9 under acid catalysis and ketene acetals10 under base catalysis; synthesis of sulfonic esters or sulfonyl ethers in reactions with a sulfinic acid in the presence of Boron Trifluoride Etherate;11 as a precursor to glycol aldehyde;12 and use in the synthesis of N-nitrosamino aldehydes.13 Among the heterocycles synthesized are imidazopyrazines,14 imidazopyrazoles,15 phenoxypyrimidinones,16 3-substituted 1,5-dihydrobenzodithiepines,17 P-functionalized phospholene oxides,18 etc.
A. V. Rama Rao
Indian Institute of Chemical Technology, Hyderabad, India
Van A. Martin
The Upjohn Company, Kalamazoo, MI, USA