COMMUNICATIONS
²
8.3 Hz, olefin. H), 6.28 ± 6.32 (m, 1H, olefin. H) , 6.50 ± 6.56 (m, 2H, olefin.
spiroozonides from 1 and colchicines provides an elegant
H); b) 8 to 128C; c) 26 min (188C), 23 min (218C), 16 min
access to the class of allocolchicines.[19]
(258C).
22[22] 1:
a) 1-(1,2,4-Trioxaspiro[4.6]undeca-6,8,10-trien-6-yl)piperidine
Experimental Section
(23): 1H NMR (500 MHz, 308C): d 5.17 (s, 1H, OCH2OO), 5.40 (s,
1H, OCH2OO), 5.56 (d, 1H, J 10.0 Hz, olefin. H), 5.91 (d, 1H, J 8.1 Hz,
Procedure for trapping formaldehyde-O-oxide 1 with tropones:
²
olefin. H) , 6.36-6.48 (m, 2H, olefin. H), 6.57 ± 6.62 (m, 1H, olefin. H);
Ketene diethylacetal (1.20 mmol) in ether (5 mL) was treated with ozone at
1168C until the solution started to turn blue. After removal of the ozone
in a stream of nitrogen, a cold solution of the tropone (0.30 mmol) in ether/
dichloromethane (2:1, 5 mL) was added. The solvent was removed at room
temperature in a rotatory evaporator at 300 mbar. The less volatile benzene
derivatives 17, 25, 45, and 49 could be isolated after purification by
chromatography. The physical data of the benzene derivatives are in
agreement with authentic samples. The yields of the volatile benzene
derivatives 5, 9, 13, and 21 were determined by 1H NMR spectroscopy
relative to an inert standard.
b) 30 to 248C; c) 50 min ( 308C), 32 min ( 248C).
26[22] 1: a) 6-Fluoro-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (27): 1H
NMR (400 MHz, 108C): d 5.24 (s, 1H, OCH2OO), 5.37 (s, 1H,
²
OCH2OO), 5.87 (dd, 1H, J 11.4, 6.8 Hz, olefin. H) , 6.31 ± 6.49 (m, 3H,
²
²
olefin. H) , 6.62 (dd, 1H, J 11.7, 7.3 Hz, olefin. H) ; b) 2 to 48C
(methanol), 4 to 108C (diethyl ether/dichloromethane), 7 to 128C
(toluene); c) 49 min (58C), 25 min (108C), 17 min (158C).
30[21] 1: a) 6-Chloro-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (31): 1H
NMR (400 MHz,
58C): d 5.19 (s, 1H, OCH2OO), 5.40 (s, 1H,
²
OCH2OO), 5.86 (pseudo-d, 1H, olefin. H) , 6.45 ± 6.53 (m, 1H, olefin.
1
Procedure for the low-temperature H NMR measurements:[1]
²
²
²
H) , 6.59 ± 6.65 (m, 2H, olefin. H) , 6.86 (d, 1H, J 7.8 Hz, olefin. H) ; b)
5
Ketene diethylacetal (0.20 mmol) was dissolved in [D10]diethyl ether
(0.40 mL) and thoroughly ozonized in an NMR tube at 1168C by using a
capillary. After ozonization a precooled stream of nitrogen was passed
through the NMR tube until a moistened KI starch paper remained
colorless. Then a precooled solution of the tropone (0.050 mmol) in
[D10]diethyl ether/CD2Cl2 (2:1; 0.40 mL) was added. The tube was
immediately introduced into the precooled 1H NMR measuring cell. The
reaction temperature was determined by using the Dd-value of metha-
nol.[20]
to 08C; c) 34 min ( 58C).
34[21] 1: a) 6-Bromo-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (35): 1H
NMR (400 MHz,
158C): d 5.17 (s, 1H, OCH2OO), 5.41 (s, 1H,
²
OCH2OO), 5.85 (d, 1H, J 10.7 Hz, olefin. H) , 6.41 ± 6.47 (m, 1H, olefin.
²
²
H) , 6.58 ± 6.70 (m, 2H, olefin. H) , 7.11 (d, 1H, J 7.8 Hz, olefin. H);
b) 15 to 108C; c) 33 min ( 158C).
38[21] 1: a) 6-Iodo-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (39): 1H
NMR (400 MHz,
158C): d 5.17 (s, 1H, OCH2OO), 5.41 (s, 1H,
²
OCH2OO), 5.77 (d, 1H, J 11.0 Hz, olefin. H) , 6.31 ± 6.37 (m, 1H, olefin.
1
Results: a) H NMR data of the spiroozonides; signals whose decrease is
²
H) , 6.56 ± 6.72 (m, 2H, olefin. H), 7.40 (d, 1H, J 7.6 Hz, olefin. H); b) 20
²
monitored are marked with the symbol . The spiroozonides 7, 15, 23, and 43
to 158C; c) 72 min ( 258C), 57 min ( 208C), 22 min ( 158C).
exhibit 1H NMR signals for the substitutents that are almost identical with
those of the products 9, 17, 25, and 45; b) value of the temperature range for
the qualititative detection of CO2; c) half-lives t1/2 for different temper-
atures.
42[23] 1: a) 6,11-Diphenyl-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (43):
1H NMR (500 MHz, 108C): d 5.00 (s, 2H, OCH2OO), 6.59 ± 6.66 (m,
²
²
2H, olefin. H) , 6.73 ± 6.78 (m, 2H, olefin. H) ; b) 8 to 128C; c) 50 min
(108C), 35 min (148C).
2 1: a) 1,2,4-Trioxaspiro[4.6]undeca-6,8,10-triene (3): 1H NMR
46[24] 1: 2,7-Di-tert-butyltropone (46) (60 mg, 0.28 mmol) in pentane
(5 mL) was added to the primary ozonide generated from ketene
diethylacetal (160 mg, 1.38 mmol) dissolved in pentane (5 mL) at
1108C. The reaction mixture was allowed to warm up to 08C, the
solution was decanted from the polymeric peroxides and then concen-
trated. Compound 47 was obtained as colorless crystals (55 mg, 76%).
a) 6,11-Di-tert-butyl-1,2,4-trioxa-spiro[4.6]undeca-6,8,10-triene 47: m.p.
(pentane) 78 ± 798C (decomp), 1H NMR (250 MHz, 208C, CDCl3): d
1.37 (s, 18H, C(CH3)3), 5.26 (s, 2H, OCH2OO), 6.45 ± 6.63 (m, 4H, olefin.
H); 13C NMR (100.6 MHz, CDCl3): d 32.36, 37.66, 93.95, 110.22, 123.20,
128.42, 144.71; IR (KBr): nÄ 743, 987, 1053, 1117, 1250, 1357, 1370, 1463,
1481, 2903, 2956 cm 1; UV/Vis (ether): lmax (lg e) 271.6 nm (3.85); HRMS
calcd. for C16H24O3: 264.1725, found 264.1695; C,H analysis for C16H24O3:
calcd. C 72.69, H 9.15; found C 72.24, H 8.67, b) not measured, c) in
CD3OD: 35 min (258C), 15 min (328C), 7.6 min (368C), 5.8 min
(408C); in CDCl3: 57 min (358C), 34 min (408C), 21 min (458C); in
[D12]cyclohexane: 38 min (728C), 25 min (768C), 8.9 min (808C).
(500 MHz, 228C): d 5.20 (s, 2H, OCH2OO), 5.83 (d, 2H, J 10.5 Hz,
²
olefin. H), 6.50 ± 6.59 (m, 4H, olefin. H) ; b) 22 to
158C; c) 33 min
(
228C), 16 min ( 168C), 8.3 min ( 118C).
6[21] 1: a) 6-n-Butyl-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (7): 1H
NMR (500 MHz, 348C): d 2.35 ± 2.52 (m, 2H, CH2CH2CH2CH3), 5.09
(s, 1H, OCH2OO), 5.50 (s, 1H, OCH2OO), 5.74 (d, 1H, J 10.7 Hz, olefin.
²
²
H), 6.41 (d, 1H, J 6.8, olefin. H) , 6.43 ± 6.49 (m, 1H, olefin. H) , 6.51 ±
²
6.61 (m, 2H, olefin. H) ; b) 21 to 158C; c) 51 min ( 348C), 27 min
(
288C), 11 min ( 248C).
10: 2-tert-Butyltropone (10) was prepared analogously to the literature
procedure[21] by using tert-butyllithium (16.0 mmol, 10 mL of a 1.6m
solution in pentane) and tropolone (7.0 mmol, 0.86 g in ether). The by-
products were separated from 10 by chromatography on silica gel with
pentane/ether (40:1). Compound 10 was eluted with ether. After micro-
distillation (708 C; p 0.5 mbar) 10 was obtained as a colorless oil. Yield:
96 mg (12%). 1H NMR (250 MHz, CDCl3): d 1.31 (s, 9H, C(CH3)3),
6.71 ± 6.92 (m, 4H, olefin. H), 7.19 (d, 1H, J 9.1 Hz, olefin. H); 13C NMR
(100 MHz, CDCl3): d 29.87, 37.98, 130.89, 131.83, 132.92, 132.93, 138.33,
160.46, 188.80; IR (KBr): nÄ 1458, 1588, 1632, 2956, 3002 cm 1; UV/Vis (n-
hexane): lmax (lge) 205.0 (4.01), 230.0 (4.21), 297.0 nm (3.71); HRMS
calcd. for C11H14O: 162.1045; found 162.1057.
Warming of 47 in methylcyclohexane: Compound 47 (446 mg, 1.69 mmol)
was warmed to 1008C in methylcyclohexane (3 mL) for 1 h. From the crude
product 1,2-di-tert-butylbenzene (49) (19 mg, 6%) and 2-hydroxy-3-tert-
butylpivalophenone (50)[25] (240 mg, 60%) were separated by chromatog-
raphy with pentane as eluant. If the eluting solvent was changed to pentane/
ether (5:1), 2,7-di-tert-butyltropone (46) (48 mg, 13%) was isolated.
10 1: a) 6-tert-Butyl-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (11): 1H
NMR (500 MHz,
568C): d 1.30 (s, 9H, C(CH3)3), 4.95 (s, 1H,
OCH2OO), 5.47 (s, 1H, OCH2OO), 5.71 (d, 1H, J 10.4 Hz, olefin. H),
²
²
Received: September 8, 1997 [Z10899IE]
German version: Angew. Chem. 1998, 110, 1954 ± 1957
6.36 ± 6.41 (m, 1H, olefin. H) , 6.51 (d, 1H, J 7.1 Hz, olefin. H) , 6.57 ± 6.67
²
(m, 2H, olefin. H) ; b) 42 to
328C, c) 9.2 min ( 568C), 7.3 min
(
528C), 3.7 min ( 468C).
14[21] 1: a) 6-Phenyl-1,2,4-trioxaspiro[4.6]undeca-6,8,10-triene (15): 1H
Keywords: aromaticity ´ ozonolysis ´ spiro compounds ´
substitution effects ´ transition states
NMR (500 MHz,
168C): d 4.95 (s, 1H, OCH2OO), 5.17 (s, 1H,
²
OCH2OO), 5.96 (d, 1H, J 10.9 Hz, olefin. H) , 6.56 ± 6.62 (m, 2H, olefin.
H), 6.64 ± 6.70 (m, 1H, olefin. H); b) 16 to 128C; c) 18 min ( 258C),
13 min ( 208C), 6 min ( 158C).
18[22] 1: a) 6-Methoxy-1,2,4-trioxa-spiro[4.6]undeca-6,8,10-triene (19): 1H
NMR (500 MHz, 258C): d 3.69 (s, 3H, OCH3), 5.14 (s, 1H, OCH2OO),
5.26 (s, 1H, OCH2OO), 5.71 (d, 1H, J 10.9 Hz, olefin. H), 5.80 (d, 1H, J
[1] C. Berger, C. Bresler, U. Dilger, D. Geuenich, R. Herges, H. Röttele,
G. Schröder, Angew. Chem. 1998, 110, 1951 ± 1954; Angew. Chem. Int.
Ed. 1998, 37, 1850 ± 1853.
1856
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
1433-7851/98/3713-1856 $ 17.50+.50/0
Angew. Chem. Int. Ed. 1998, 37, No. 13/14