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M.A. Battiste, R.G. Posey / Journal of Fluorine Chemistry 102 (2000) 285±292
which on preparative glpc gave a colorless oil (12b)
(0.122 g, 64%). IR (Neat, NaCl) cm 1: 2998, 2960, 2880,
1442 (s), 1319 (s), 1255 (s), 1221, 1208, 1130 (s), 1022 (s),
980, 952, 932, 895, 860, 812, 779; MS (70 eV) m/e (rel.
intensity): 146 (1.90), 145 (0.58), 128 (1.1), 97 (54.4), 90
(100.0), 77 (37.2). Anal. Calc. for C7H8F2O: C, 57.53; H,
5.52. Found: C, 57.52; H, 5.61.
Anal. Calc. for C7H6Cl2F2O: C, 39.10; H, 2.81; Cl, 32.92.
Found: C, 39.13; H, 2.83; Cl, 32.87.
3.9. Dechlorination of 2,4-dichloro-3,3-difluoro-8-
oxatricyclo[3.2.1.02,4]octane (12c)
In a three-necked round bottom ¯ask equipped with a
magnetic stirrer, a nitrogen inlet, and a re¯ux condenser
were placed 12c (0.357 g, 1.66 mmol), 10 ml of dry THF,
and tert-butyl alcohol (2 ml). Sodium metal (0.784 g,
0.034 g at.) was added, the system ¯ushed with nitrogen,
and the mixture stirred at 508C under N2 for 32 h. Standard
workup using pentane as the extraction solvent afforded a
yellow oil which was free of starting material according to
1H MNR. Preparative glpc gave a pure sample as a colorless
oil which was identical by IR to authentic 12b.
3.6. 3,3 Difluoro-8-oxatricyclo[3.2.1.02,4]oct-6-ene (7b)
In a 10 ml round bottom ¯ask chilled in an icewater
bath were placed 3,3-di¯uoro-2,4-dibromo-8-oxatricyclo-
[3.2.1.02,4]oct-6-ene (7a) (2.42 g, 16.8 mmol), tri-n-butyltin
hydride (5.82 g, 20.0 mmol), and one drop of di-tert-butyl
peroxide. The resulting yellow-orange solution was heated
with stirring for 6 h (458C). The volatile product was
distilled bulb to bulb, and the colorless oil puri®ed by
preparative glpc to yield 0.44 g of (7b) (38.0%); IR (Neat,
NaCl) cm 1: 3060, 3005, 2985 (sh), 1415 (s), 1392, 1296,
1250 (s), 1130 (s), 1080, 1024 (s), 948 (s), 861 (s); MS
(70 eV) m/e (rel. intensity): 144 (1.6), 143 (15.2), 115
(74.4), 96 (51.8), 95 (45.0), 75 (40.6). Anal. for
C7H6F2O: C, 58.33; H, 4.20. Found: C, 58.45; H, 4.25.
3.10. 2,4-Dibromo-3,3-difluoro-8-(diphenylmethylene)-
tricyclo[3.2.1.02,4]oct-6-ene (8a)
Diphenylfulvene (4.60 g, 20.0 mmol), (1a) (5.68 g,
20.0 mmol), and ca. 40 ml of CCl4 were placed in a sealed
tube (Fischer±Porter) and heated at 1208C for 15 h. The tube
was then cooled, opened, solvent removed, and the dark
residue chromatographed on a Florex column with pentane.
Removal of pentane gave an orange oil, which, when
dissolved in a minimum amount of hot hexane, afforded
6.41 g (69%) of (8a) as an off-white solid, mp 153±1558C;
IR (KBr) cm 1: 3082 (w), 3050 (w), 3017 (w), 2990 (sh),
1597, 1490, 1442, 1392, 1379 (broad, d), 1315, 1192 (s),
1155, 1072, 974 (s), 829, 770, 748, 721, 700 (s), 660, 620;
MS (70 eV) m/e (rel. intensity): 466 (8.3), 464 (15.8), 462
(8.3), 386 (71.9), 385 (18.7), 384 (73.8), 383 (22.5), 305
(100), 304 (65.6), 285 (63.5), 284 (72.6), 191 (69.0) 165
(42.4), 126 (39.4). Anal. Calc. for C21H14Br2F2: C, 54.34, H,
3.04; Br, 34.44. Found: C, 54.40; H, 3, 3.12; Br, 34.39.
3.7. 2,4-Dichloro-3,3-difluoro-8-oxatricyclo[3.2.1.02,4]-
oct-6-ene (7c) [3]
In a sealed tube (Fischer±Porter) were placed 1,2-
dichloro-3,3-di¯uorocyclopropene (1b) (which had been
passed through NaHCO3 with CCl4; 2.20 g, 15.2 mmol),
5 ml of CCl4, and an excess (5 ml) of furan. The tube was
sealed and placed in an oil bath at 808C for 24 h. At this
time, the tube was cooled, opened, the contents concen-
trated, and then percolated through a ¯orex column with
CH2Cl2. Evaporation of the solvent left a yellowish oil,
which upon distillation at reduced pressure, gave the color-
less product 7c as a clear oil that became semisolid at 08C.
The yield was 2.03 g (63%), bp2.75 60±618C; IR (Neat,
NaCl) cm 1: 3150, 3104, 3022, 1436 (s), 1400 (s, br), 1350,
1205 (s, br), 1049 (s), 1030 (s, br), 922 (s), 837 (s), 782 (s),
3.11. 2,4-Dibromo-3,3-difluoro-8-(diphenylmethylene)-
tricyclo[3.2.1.02,4]octane (13a)
A suspension of (8a) (2.50 g, 5.40 mmol), p-toluenesul-
fonylhydrazine (5.03 g, 27.0 mmol), diglyme (150 ml), and
NEt3 (5 ml) was stirred under nitrogen while heating at
808C for 24 h. The resulting orange solution was poured into
an equal volume of pentane and further workup as described
for 7a led to an orange-yellow solid which was recrystal-
lized from hexane to yield 1.48 g (58.8%) of 13a as off
white crystals, mp 119.5±120.58C; IR (KBr) cm 1: 3080,
3050, 3020, 2999, 2970, 1590 (m), 1402 (s), 1258 (m), 1197
(s), 1124 (m), 1060 (m), 986 (m), 959 (s), 820 (m, s), 769
(sharp, m), 711 (m), 692 (s); MS (70 eV) m/e (rel. intensity);
468 (13.8), 466 (28.3), 464 (14.1), 388 (11.6), 387 (38.2),
386 (14.6), 385 (38.5), 307 (54.5), 306 (100.0), 286 (26.2),
217 (26.8), 191 (34.5). Anal. Calc. for C21H16Br2F2: C,
54.10; H, 3.46; Br, 34.29. Found: C, 54.15; H, 3.54; Br,
34.10.
741 (s), 726, 678 (s); lit (CCl4): 3020 (m), 1430, 1400, 1215,
1
1200, 1047, 1030, 920, 834, 674, cm
.
3.8. 2,4-Dichloro-3,3-difluoro-8-oxatricyclo[3.2.1.02,4]-
octane (12c)
Hydrogenation of (7c) (0.85 g, 4.0 mmol) in 30 ml of
absolute ethanol over Pd/C (10%, 0.050 g) afforded 0.66 g
(77%) of a white, crystalline solid, (12c); mp 56±57.58C; IR
(KBr) cm 1: 3006, 2999 (sh), 2962, 2920, 2880, 1468, 1430
(s, br), 1310 (s), 1290 (s), 1272, 1222 (s), 1196 (s), 1136,
1021 (s, br), 936 (s), 892 (s), 830 (s), 812 (s), 771 (s), 623 (s),
540 (s); MS (70 eV) m/e (rel. intensity): 216 (0.1), 214 (0.2),
188 (8.5), 186 (14.5), 167 (38.0), 165 (41.4), 151 (100.0),
131 (45.4), 124 (52.3), 115 (42.8), 93 (43.6), 75 (24.6).