Alkynylcyclopropenylium Salts
J . Org. Chem., Vol. 65, No. 5, 2000 1429
NMR (CD2Cl2) δ 130.14, 129.53, 129.42, 128.70, 112.76, 83.24,
131.57, 120.44, 85.76, -1.16; IR (KBr) 2158, 1837, 1395 cm-1
;
74.67, 31.86, 22.51, 18.92, 13.95, 7.97; IR (neat) 1830 cm-1
.
UV (CH3CN) 295 sh, 304, 321 nm. Anal. Calcd for C20H19
SiSbCl6: C, 38.63; H, 3.08. Found: C, 38.35; H, 3.12.
-
1,2-Dip h en yl-3-eth yn ylcyclop r op en e (3). Cyclopropene
2a (0.46 g, 1.6 mmol) was dissolved in ether (10 mL) and
methanol (30 mL). Anhydrous K2CO3 (0.24 g, 1.7 mmol) was
added and the resulting suspension was stirred at ambient
temperature for 18 h. Ether and water were added, the layers
were separated, and the aqueous phase was extracted with
ether. The combined organics were washed with brine and
dried (MgSO4). The suspension was filtered through Celite and
concentrated to give 0.346 g (100%) of a light yellow solid. 3:
mp 93-95 °C; 1H NMR (CD2Cl2) δ 7.77 (d, J ) 7 Hz, 4H), 7.52
(t, J ) 7 Hz, 4H), 7.43 (t, J ) 7 Hz, 2H), 2.57 (d, J ) 1 Hz,
1H), 1.76 (d, J ) 1 Hz, 1H); 13C NMR δ (CD2Cl2) 130.18, 129.79,
129.47, 128.11, 111.22, 87.81, 62.29, 7.46; IR (KBr) 3281, 2102,
1837 cm-1; UV (CH3CN) 294, 307, 325 nm.
2,3-Dip h en yl-1-(t r iisop r op ylsilylet h yn yl)cyclop r op e-
n yliu m h exa ch lor oa n tim on a te (7b) was prepared in a
manner analogous to 7a from cyclopropene 2b (0.042 g, 0.11
mmol) and 6 (0.067 g, 0.12 mmol) to yield a light yellow
precipitate. Recrystallization from acetonitrile gave 0.054 g
(70%) of colorless needles. 7b: mp 161 °C (dec); 1H NMR (CD3-
CN) δ 8.42 (d, J ) 7 Hz, 4H), 8.09 (t, J ) 7 Hz, 2H), 7.89 (t, J
) 7 Hz, 4H), 1.40 (m, 3H), 1.24 (d, J ) 7 Hz, 18H); 13C NMR
(CD3CN) δ 156.76, 144.30, 140.72, 137.88, 137.40, 131.63,
120.56, 88.35, 18.91, 11.93; IR (KBr) 2158, 1838, 1391 cm-1
.
Anal. Calcd for C26H31SbCl6: C, 44.23; H, 4.43. Found: C,
44.38; H, 4.41.
2,3-Diphenyl-1-(phenylethynyl)cyclopropenylium hexachlo-
r oa n tim on a te (7c) was prepared in a manner analogous to
7a from cyclopropene 2c (0.097 g, 0.33 mmol) and 6 (0.195 g,
0.34 mmol) to give a yellow powder. Recrystallization from
acetonitrile gave 0.137 g (66%) of yellow needles. 7c: mp 167
°C (dec); 1H NMR (CD3CN) δ 8.53 (dd, J ) 7, 2 Hz, 4H), 8.14-
8.00 (m, 4H), 7.91 (t, J ) 7 Hz, 4H), 7.80 (tt, J ) 7, 2 Hz, 1H),
7.67 (t, J ) 7 Hz, 2H); 13C NMR (CD3CN) δ 155.78, 143.71,
140.43, 137.29, 135.91, 135.55, 131.56, 130.65, 126.90, 120.66,
119.31, 74.63; IR (KBr) 2197, 1835, 1401 cm-1; UV (CH3CN)
1,4-Bis(2,3-diph en ylcyclopr op-2-en yl)-1,3-bu tadiyn e (4).
Cyclopropene 3 (0.10 g, 0.46 mmol) and cupric acetate (0.25
g, 1.2 mmol) were suspended in pyridine (1 mL), water (0.7
mL), and dioxane (0.5 mL). The suspension was warmed with
stirring to 45 °C, and all solids were dissolved to give a blue
solution. A precipitate started to form after 20 min at 45-50
°C. After a total of 2 h of stirring at 45-50 °C, during which
the blue color gradually changed to green, the flask was cooled
to 0 °C and the precipitate was collected by filtration. The tan
precipitate was washed with 10% HCl solution and water and
then dried in vacuo. The precipitate was recrystallized from
benzene (∼2 mL) to give 0.065 g (65%) of white needles. 4:
mp 183 °C (discoloration), 211-213 °C (decomposed to a black
275, 300 sh, 317, 340, 364 sh nm. Anal. Calcd for C23H15
SbCl6: C, 44.14; H, 2.42. Found: C, 43.92; H, 2.41.
-
13C-La beled Cyclop r op en yliu m 7c was prepared in a
manner analogous to 7a from 13C-labeled 2c (0.112 g, 0.38
mmol) and 6 (0.215 g, 0.372 mmol) to give a yellow powder.
Recrystallization from acetonitrile gave 0.185 g (79%) of yellow
needles. 7c-13C: mp 168 °C (dec); 1H NMR (CD3CN) δ 8.53
(m, 4H), 8.12-8.01 (m, 4H), 7.90 (t, J ) 7 Hz, 4H), 7.80 (t, J
) 7 Hz, 1H), 7.67 (t, J ) 7 Hz, 2H); 13C (CD3CN) δ 126.9 (13C-
1
tar); H NMR (CDCl3) δ 7.74 (d, J ) 7 Hz, 8H), 7.69 (t, J ) 7
Hz, 8H), 7.37 (t, J ) 7 Hz, 4H), 2.59 (s, 2H); 13C NMR (CDCl3)
δ 129.73, 129.15, 128.84, 127.45, 110.41, 79.64, 59.79, 7.83;
IR (KBr) 2127, 1828 cm-1. Anal. Calcd for C34H22: C, 94.85;
H, 5.15. Found: C, 95.15; H, 4.95.
labeled carbon); IR (KBr) 2158, 1832, 1402 cm-1
.
Bis(2,3-d ip h en ylcyclop r op -2-en yl)eth yn e (5). A 0.5 M
solution of ethynyldimagnesium dibromide in THF was pre-
pared according to the literature procedure.25 A portion of the
solution (1.4 mL, 0.70 mmol) was diluted with THF (50 mL)
and cooled to -78 °C under N2. Diphenylcyclopropenyl per-
chlorate (0.209 g, 0.718 mmol) was added to the cold Grignard
solution and the reaction was stirred for 2 h. The reaction was
warmed to ambient temperature and stirred for an additional
12 h. Ether and saturated NH4Cl solution were added. The
phases were separated, and the organic phase was washed
with saturated NaHCO3 solution, water, and brine. The
organic phase was dried (MgSO4), filtered through Celite, and
concentrated. The residual material was chromatographed
(preparative radial thin-layer chromatography, 2 mm rotor,
10% ethyl acetate/petroleum ether) to yield 0.084 g of a yellow
solid that contained at least three different compounds judging
from analytical TLC analysis. Recrystallization of this material
in boiling hexane (∼5 mL) yielded 0.024 g (9%) of white
2,3-Diph en yl-1-(1-h exyn yl)cyclopr open yliu m h exach lo-
r oa n tim on a te (7d ) was prepared in a manner analogous to
7a from 2d (0.091 g, 0.33 mmol) and 6 (0.193 g, 0.33 mmol) to
give a yellow powder. Recrystallization from acetonitrile gave
0.144 g (71%) of yellow crystals. 7d : mp 151 °C (dec); 1H NMR
(CD3CN) δ 8.43 (d, J ) 7 Hz, 4H), 8.06 (t, J ) 7 Hz, 2H), 7.88
(t, J ) 7 Hz, 4H), 2.99 (t, J ) 7 Hz, 2H), 1.82, (pentet, J ) 7
Hz, 2H), 1.59 (sextet, J ) 7 Hz, 2H), 1.02 (t, J ) 7 Hz, 3H);
13C NMR (CD3CN) δ 156.71, 146.05, 140.68, 137.47, 134.77,
137.90, 120.88, 66.47, 30.44, 23.22, 22.35, 14.27; IR (KBr) 1409
cm-1; UV (CH3CN) 294 sh, 303, 321 nm. Anal. Calcd for C21H19
SbCl6: C, 41.63; H, 3.16. Found: C, 41.59; H, 3.15.
-
1-[(2,3-Dip h en ylcyclop r op -2-en yl)eth yn yl]-2,3-d ip h en -
ylcyclop r op en yliu m Hexa ch lor oa n tim on a te (10). Cyclo-
propene 5 (0.010 g, 0.024 mmol) was dissolved in CH2Cl2 (5
mL) at ambient temperature and 6 (0.016 g, 0.028 mmol) was
added to the solution. The reaction was allowed to stir for 15
min. The volume of the solution was concentrated to ∼1 mL
by rotary evaporation and ether was added to precipitate 10.
The orange precipitate was collected by filtration and washed
with ether. Recrystallization from acetonitrile gave 0.014 g
(77%) of pale orange crystals. 10: 1H NMR (CD3CN) δ 8.36
(dd, J ) 7, 1 Hz, 4H), 8.01 (tt, J ) 7, 1 Hz, 2H), 7.90 (d, J )
7 Hz, 4H), 7.82 (t, J ) 7 Hz, 4H), 7.62, (t, J ) 7 Hz, 4H), 7.55
(t, J ) 7 Hz, 2H), 3.29 (s, 1H); 13C NMR (CD3CN) δ 154.70,
145.13, 140.61, 139.96, 136.83, 131.51, 131.45, 131.07, 130.44,
126.91, 120.65, 109.45, 62.19, 11.83; IR (KBr) 2177, 1859, 1834,
1
needles. 5: mp 167 °C (dec); H NMR (CD2Cl2) δ 7.73 (d, J )
7 Hz, 8H), 7.48 (t, J ) 7 Hz, 8H), 7.39 (t, J ) 7 Hz, 4H), 2.55
(s, 2H); 13C NMR (CD2Cl2) δ 130.12, 129.46, 129.35, 128.68,
112.66, 77.05, 8.13; IR (KBr) 1833 cm-1
.
2,3-Dip h e n yl-1-(t r im e t h ylsilyle t h yn yl)cyclop r op e -
n yliu m Hexach lor oan tim on ate (7a). Cyclopropene 2a (0.053
g, 0.18 mmol) was dissolved in CH2Cl2 (10 mL) at ambient
temperature. Triphenylmethyl hexachloroantimonate (6) (0.105
g, 0.18 mmol) was added as a solid to the CH2Cl2 solution.
The triphenylmethyl salt dissolved to give an orange solution
which gradually (after 5 min) developed a greenish tint. After
10 min the volume of the solution was concentrated to ∼2 mL
and ether was added to precipitate the cyclopropenylium salt
as light yellow powder. The precipitate was collected by
filtration and washed with ether. Recrystallization of the solid
from acetonitrile yielded 0.083 g (74%) of light yellow needles.
1394 cm-1
.
Attem p ted Syn th esis of Dica tion 11. Cyclopropene 5
(0.014 0 g, 0.0344 mmol) was dissolved in CH2Cl2 (5 mL) at
ambient temperature and 6 (0.0407 g, 0.0704 mmol) was
added. The solution was stirred for 20 min at ambient
temperature. The volume was concentrated to ∼1 mL by rotary
evaporation and ether was added. The resulting precipitate
was collected by filtration, washed with ether (5 mL), and then
dried in vacuo. A 1H NMR (CD3CN) spectrum of the material
appeared to be identical to the corresponding spectrum of 10.
The spectrum also showed signals arising from 6.
1
7a : mp 165 °C (dec); H NMR (CD3CN) δ 8.44 (d, J ) 7 Hz,
4H), 8.09 (t, J ) 7 Hz, 2H), 7.89 (t, J ) 7 Hz, 4H), 0.46 (s, 9H);
13C NMR (CD3CN) δ 156.90, 144.10, 140.71, 139.80, 137.41,
1,6-Bis(2,3-d ip h en ylcyclop r op -2-en yl)-1,5-h exa d iyn e
(15). Ethylmagnesium bromide was prepared from Mg (0.050
(25) Brandsma, L. Preparative Acetylenic Chemistry; Elsevier: Am-
sterdam, 1988; pp 28-29.