[621-62-5]  · C6H13ClO2  · 2-Chloro-1,1-diethoxyethane  · (MW 152.62)

(versatile two-carbon synthon; forms carbocycles,4 heterocycles;14-18 used in the synthesis of alkynes1,2 and alkenes3,5,6)

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.

Alkoxyalkynes1 and Alkynols.2

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.

Functionalized Allylsilanes.5

With 1-ethoxy-3-trimethylsilyl-1-propyne, the reagent under Titanium(IV) Chloride catalysis affords 2-carbonylethoxyallyltrimethylsilane regio- and stereoselectively (eq 3).

Vinylation of Enolates.6

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.

Related Reagents.

Chloroacetaldehyde; Ethoxyacetylene.

1. Stalick, W. M.; Hazlett, R. N.; Morris, R. E. S 1988, 287.
2. Stalick, W. M. OPP 1988, 20, 275.
3. Olah, G. A.; Wu, A. H.; Farrog, O.; Surya Prakash, G. K. S 1988, 537.
4. Woessner, W. D.; Ellison, R. A. TL 1972, 3735.
5. Pornet, J.; Rayadh, A.; Miginiac, L. TL 1986, 27, 5479.
6. Chang, T. C. T.; Rosenblum, M.; Simms, N. OS 1988, 66, 95.
7. Sako, M.; Totani, R.; Hirota, K.; Maki, Y. CPB 1992, 40, 235.
8. Dhaka, K. S.; Mohan, J.; Chadha, V. K.; Pujari, H. K. IJC 1974, 12, 287.
9. Taskinen, E.; Sainio, E. T 1976, 32, 593.
10. Taskinen, E.; Pentikainen, M.-L. T 1978, 34, 2365.
11. Schank, K.; Schmitt, H.-G. CB 1977, 110, 3235.
12. Nielsen, A. T.; Lawrence, G. W. JOC 1977, 42, 2900.
13. Suzuki, E.; Okada, M. CPB 1979, 27, 541.
14. Depompei, M.; Paudler, W. W. JHC 1975, 12, 861.
15. Eleguero, J.; Jacquier, R.; Mignonac-Mondon, S. JHC 1973, 10, 411.
16. Lipinski, C. A.; Stam, J. G.; Pereira, J. N.; Ackerman, N. R.; Hess, H. J. JMC 1980, 23, 1026.
17. Gross, H.; Keitol, I.; Costicella, B. JPR 1978 320, 255.
18. Mathey, F.; Lampin, J.-P.; Thavard, D. CJC 1976, 54, 2402.

A. V. Rama Rao

Indian Institute of Chemical Technology, Hyderabad, India

Van A. Martin

The Upjohn Company, Kalamazoo, MI, USA

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