Organic Syntheses, CV 8, 124
Submitted by Thomas Liese, Frank Jaekel, and Armin de Meijere
1.
Checked by John R. Berry, James S. Piecara, and Bruce E. Smart.
1. Procedure
A
1-L Hastelloy C-276 shaker tube (Note
1) fitted with a
temperature sensor, a
rupture-disk safety device, and a
gas inlet valve attached to an ethylene cylinder is charged with
120.0 g (0.675 mol) of freshly distilled tetrachlorocyclopropene (Note
2),
350 mL of dry tetrachloroethylene (Note
3), and
10 g of anhydrous sodium carbonate (Note
4). The tube is pressurized to 20 atm with
ethylene and shaken for 3 hr. The ethylene cylinder is disconnected, and the pressure vessel is gradually heated to 170°C over a 30-min period and is shaken at this temperature for 19.5 hr. The vessel is allowed to cool to room temperature, and the excess
ethylene is slowly released and bubbled through a
wash bottle containing methylene chloride (Note
5). The light-brown liquid in the shaker tube is decanted and the remaining solid washed twice with
50 mL of methylene chloride. The organic phases are combined and the
methylene chloride is removed by distillation. The residual liquid is distilled at water-aspirator vacuum through a
40-cm Vigreux column. The solvent
tetrachloroethylene, bp
35°C (27 mm), is collected (Note
6), followed by
104.1–105.6 g (
75–76%) of
1-chloro-1-(trichloroethenyl)cyclopropane as a colorless liquid, bp
81–83°C (27 mm) (Note
7).
2. Notes
1. The submitters used a
1-L autoclave lined with Hastelloy C-4. Hastelloy C materials are high nickel alloys. A highly resistant alloy is employed to avoid possible side reactions.
4. Anhydrous
sodium carbonate was obtained from the J. T. Baker Chemical Company and dried under vacuum at 130°C.
5. The wash bottle serves to
trap any product carried with the
ethylene vapors, to monitor and control the release of
ethylene pressure and to indicate when no excess pressure remains, and to diminish the release of toxic materials.
7. The submitters obtained
111–116 g of product, bp
72–75°C (14–18 mm). The spectral properties of
1-chloro-1-(trichloroethenyl)cyclopropane are as follows; IR (neat) cm
−1: 3100 (CH), 3020 (CH), 1585 (C=C), 1415, 1170, 1040, 1015, 940, 910, 875, 800, 750, 645;
1H NMR (CDCl
3) δ: 1.42 (m, 2 H), 1.52 (m, 2 H).
3. Discussion
Tetrachlorocyclopropene has been known for some time to be a reasonably reactive dienophile.
4 Its thermal ring opening to
perchlorovinyl carbene is in accord with the behavior of other cyclopropenes under thermolytic conditions,
5 but the efficiency with which this vinyl carbene intermolecularly adds to a wide variety of olefins
6,7 is unprecedented. The resulting
1-chloro-1-(trichloroethenyl)cyclopropanes
6,7 can be reductively dechlorinated to vinylcyclopropanes,
6 transformed into variously substituted cyclopropylacetylenes
7,8 or cyclopropylidenacetates.
9 The simple cyclopropyl derivatives, accessible from the reported
1-chloro-1-(trichloroethenyl)cyclopropane, like
methyl 2-chloro-2-cyclopropylidenacetate (see accompanying procedure) and
1-trimethylsilyl-1-(trimethylsilylethynyl)cyclopropane (prepared by reductive silylation with
magnesium/chlorotrimethylsilane in
tetrahydrofuran10), are especially useful building blocks for the construction of complex organic molecules.
11,12,13
This preparation is referenced from:
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