C. S. Kniep et al. / Tetrahedron 56 (2000) 4279±4288
4287
cyclobutanone 4b, 32% glutaric diester 9b and 32%
isomeric 5b (GC/MS). Although relative amounts of 5b
could be increased to 72% (see above), isolation was not
trated and extracted with ether (6£5 mL). The ether layers
were washed with a saturated aqueous solution of sodium
bicarbonate, dried over MgSO4 and the solvent was
removed under reduced pressure. Kugelrohr distillation
(0.1 mmHg) of the residue afforded 0.5 g (43%) of an
1
possible. H NMR (CDCl3) d 3.4 (br s, disappears after
treatment with D2O). IR (neat) 3461, 1728 cm21
.
1
isomeric mixture of 13a. H NMR (CDCl3) d 4.58±4.47/
1-Cyano-2-ethoxycyclobutene (10a). Over a dropping
funnel, solution of cyclobutane ketal 3a (8.1 g,
4.03±3.90 (1 H, m, 2 isomers), 4.12 (1 H, br s, disappears
after treatment with D2O), 2.41±1.23 (4 H, m), 1.47/1.44 (3
H, s, 2 isomers). 13C NMR (CDCl3) d 124.0/122.5, 72.3/
69.3, 42.7/36.1, 28.4/27.7/24.8/24.7, 22.4/16.2. IR (neat)
3430, 2235 cm21. MS (EI) m/z (rel intensity) 112 (MH1,
1), 83 (M1228, 8). HRMS (EI) Calcd for C6H9NO (M1):
111.0684. Found: 111.0695.
a
0.048 mol) in THF (20 mL) was added to a 1 M solution
of sodium bis(trimethylsilyl)amide in THF (50 mL,
0.050 mol) at 788C. The reaction mixture was stirred for
1 h at 788C, for an additional hour at room temperature
and quenched with water. The layers were separated, the
aqueous slurry saturated with sodium chloride and extracted
with ether (3£20 mL). The combined organic extracts were
washed with brine, dried over MgSO4 and the ether stripped
off in vacuo. Subsequent Kugelrohr distillation (0.1 mmHg)
afforded 2.5 g (43%) of 10a. 1H NMR (CDCl3) d 4.29 (2 H,
q, J7.1 Hz), 2.60 (2 H, t, J3.3 Hz), 2.36 (2 H, t,
J3.3 Hz), 1.39 (3 H, t, J7.1 Hz). 13C NMR (CDCl3) d
164.2, 115.0, 77.5, 66.4, 30.8, 21.2, 14.3. IR (neat) 2202,
1641 cm21. MS (EI) m/z (rel intensity) 123 (M1, 25), 95
(M1228, 25). HRMS (EI) Calcd for C7H9NO (M1):
123.0689. Found: 123.0684.
Acknowledgements
This work was supported by the National Science Founda-
tion, Division of Materials Research, and the Petroleum
Research Foundation. The authors are indebted to the
Wacker Corporation in Adrian MI, and in particular Dr
Dan Schefferle, for generous donations of ketene diethyl
acetal.
1-Cyano-1-methyl-2,2-diethoxycyclobutane (11a). Over a
period of 20 min, a 1 M solution of sodium bis(trimethyl-
silyl)amide in THF (50 mL, 0.05 mol) was added dropwise
to a 2788C cold mixture of 3a (8.3 g, 0.049 mol) and iodo-
methane (3.2 mL, 0.052 mol) in THF (20 mL). After stirring
for 1 h at 2788C, the suspension was allowed to warm up to
room temperature and stirred for an additional hour. Water
was added, and the layers were separated. The aqueous
slurry was saturated with sodium chloride and extracted
with ether (3£20 mL). The combined organic extracts
were washed with brine and dried over MgSO4. Removal
of the ether in vacuo followed by Kugelrohr distillation
(0.1 mmHg) gave 6.5 g (78%) of 11a as a colorless liquid.
1H NMR (CDCl3) d 3.52±3.34 (4 H, m), 2.32±1.55 (4 H,
m), 1.48 (3 H, s), 1.27 (3 H, t, J6.9 Hz), 1.20 (3 H, t,
J6.9 Hz). 13C NMR (CDCl3) d 122.3, 100.8, 57.5, 57.4,
41.5, 28.9, 26.0, 19.7, 14.9, 14.7. IR (neat) 2236 cm21. MS
(EI) m/z (rel intensity) 155 (M1228, 4). HRMS (FAB)
Calcd for C10H18NO2 (MH1): 184.1338. Found: 184.1346.
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1
give 2.3 g (71%) of 12a. H NMR (CDCl3) d 3.46±3.37
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