M. Peter, R. Gleiter, F. Rominger, T. Oeser
FULL PAPER
solution was concentrated and filtered. The residue was then stirred
EI): m/z ϭ 296 [M]ϩ, 177 [M Ϫ C8H7O]ϩ, 119 [C8H7O]ϩ, 91
1
with dichloromethane (120 mL) for 8 h. The yellow residue was [C7H7]ϩ. Enediol: H NMR (300 MHz, CDCl3): δ ϭ 2.44 (s, 6 H,
3
collected and recrystallized from methanol to afford the bis(for-
CH3), 7.30 (d, 3J ϭ 8.2 Hz, 4 H, Ar-H), 8.16 (d, J ϭ 8.2 Hz, 4 H,
moin) 29 (67 mg, 1.11 mmol, 1%). Colorless crystals, m.p. 226Ϫ231 Ar-H), 12.34 (s, 2 H, OH) ppm. 13C NMR (75 MHz, CDCl3): δ ϭ
°C (red liquid). HRMS (positive EI): calcd. for C36H44O8 [M]ϩ 22.2 (CH3), 129.4 (CHar), 130.9 (CHar), 133.7 (C), 144.3 (C), 145.2
604.3036; found 604.3026 (Ϫ1.0 mmu). MS (positive EI): m/z ϭ
604 [M]ϩ, 586 [M Ϫ H2O]ϩ, 576 [M Ϫ CO]ϩ, 199, 187, 145
[C11H13]ϩ, 131 [C10H11]ϩ, 104 [C8H8]ϩ. IR (KBr): ν˜ ϭ 3421, 2978,
(C), 196.2 (CϭO) ppm.
Pivaloylformoin (20): Reaction mixture: tert-butylglyoxal[20] (1.56 g,
14.1 mmol), KCN (100 mg, 1.5 mmol), ethanol (10 mL), water (1
mL). Purification was performed by dissolution of the crude for-
moin in ethanol and precipitation of 20 by addition of water. Col-
orless crystals, yield 45% (724 mg, 3.2 mmol), m.p. 165Ϫ168 °C.
1H NMR (500 MHz, [D6]DMSO): δ ϭ 0.91 (s, 9 H, CH3), 1.25 (s,
9 H, CH3), 7.14 (s, 1 H, OH), 7.98 (s, 1 H, OH) ppm. 13C NMR
(125 MHz, [D6]DMSO): δ ϭ 26.7 [C(CH3)3], 26.9 [C(CH3)3], 34.3
[C(CH3)3], 37.1 [C(CH3)3], 103.0 (OϪCϪOH), 131.5 (CϭCϪOH),
177.5 (ϭCϪOϪ), 197.3 (CϭO) ppm. HRMS (positive EI): calcd.
for C12H20O4 [M]ϩ 228.1362; found 228.1342 (Ϫ2.0 mmu). MS
(positive EI): m/z ϭ 228 [M]ϩ, 143 [M Ϫ C5H9O]ϩ, 57 [C4H9]ϩ.
C12H20O4 (228.28): calcd. C 63.14, H 8.83; found C 63.26, H 8.72.
1693, 1602, 1236 cmϪ1
.
4,4,5Ј,5Ј-Tetrahydroxy-2,2,2Ј,2Ј,7,7,7Ј,7Ј-octamethyl[8.8]paracyclo-
phane-3,3Ј,4Ј,5,6,6Ј-hexaone (31): Concd. nitric acid (3 mL) was ad-
ded dropwise to a stirred and ice-cooled suspension of the crude
bis(formoin) 29 in dichloromethane and water (3.5 mL). After a
few minutes, the mixture turned red and became homogeneous. The
layers were separated, and the organic layer was dried with MgSO4.
After removal of the solvents, the reddish residue was dissolved in
a minimal amount of acetone and 2Ϫ4 drops of water were added.
Crystals of the yellow bis(hydrate) 31 were formed at Ϫ25 °C over
a period of months. M.p. 146Ϫ148 °C (red liquid, dehydration).
HRMS (positive FAB): calcd. for C36H44O10Na [M ϩ Na]ϩ
659.2832; found 659.2826 (Ϫ0.6 mmu).
2,5-Bis(furan-2-yl)-2,4-dihydroxyfuran-3(2H)-one (21): Reaction
mixture: furan-2-ylglyoxal[16] (6.30 g, 50.7 mmol), KCN (245 mg,
3.76 mol), ethanol (40 mL), water (1 mL). Orange solid, yield 66%
(4.16 g, 16.8 mmol), decomposition Ͼ 180 °C. 1H NMR (500 MHz,
[D6]DMSO): δ ϭ 6.47 (m, 1 H, Ar-H), 6.54 (m, 1 H, Ar-H),
6.80Ϫ6.81 (m, 1 H, Ar-H), 7.28 (m, 1 H, Ar-H), 7.65 (m, 1 H,
ArϪH), 8.04 (m, 1 H, Ar-H), 8.58 (s, 1 H, OH), 9.57 (s, 1 H, OH)
ppm. 13C NMR (75 MHz, [D6]DMSO): δ ϭ 97.5 (OϪCϪOH),
109.1 (CHar), 110.5 (CHar), 113.1 (CHar), 116.5 (CHar), 130.0 (C),
143.3 (C), 143.7 (CHar), 146.7 (CHar), 149.7 (C), 156.2 (C), 191.0
(CϭO) ppm. HRMS (positive EI): calcd. for C12H8O6 [M]ϩ
248.0321; found 248.0292 (Ϫ2.9 mmu). MS (positive EI): m/z ϭ
248 [M]ϩ, 220 [M Ϫ CO]ϩ, 153 [C7H5O4]ϩ, 95 [C5H3O2]ϩ. IR
(KBr): ν˜ ϭ 3437, 3123, 1452, 1306, 1086, 780 cmϪ1. UV/Vis
(CH2Cl2): λmax. (log ε) ϭ 242 (3.92), 318 (3.88), 418 (4.14) nm.
C12H8O6 (248.19): calcd. C 58.07, H 3.25; found C 58.01, H 3.39.
2,2,2Ј,2Ј,7,7,7Ј,7Ј-Octamethyl[8.8]paracyclophan-3,3Ј,4,4Ј,5,5Ј,6,6Ј-
octaone (9): The bis(tetraketone) 9 was obtained quantitatively by
heating of the bis(hydrate) 31 in vacuo, during which the yellow
crystals melted to form a red oil. 1H NMR (500 MHz, CDCl3):
δ ϭ 1.30 (s, 24 H, CH3), 2.98 (s, 8 H, CH2), 6.88 (s, 8 H, Ar-H)
ppm. 13C NMR (125 MHz, CDCl3): δ ϭ 24.6 (CH3), 44.8 (CH2),
47.5 [C(CH3)2], 130.1 (CHar), 135.4 (Car), 188.1 (CϭO), 203.1 (Cϭ
O) ppm. HRMS (positive FAB): calcd. for C36H41O8 [M ϩ H]ϩ
601.2802; found 601.2812 (ϩ1.0 mmu). MS (positive FAB): m/z ϭ
659 [M ϩ 2 H2O ϩ Na]ϩ, 623 [M ϩ Na]ϩ, 601 [M ϩ H]ϩ, 583 [M
ϩ H Ϫ H2O]ϩ, 573 [M ϩ H Ϫ CO]ϩ. IR (CDCl3): ν˜ ϭ 2970, 2926,
1728, 1692, 1514, 1365, 824 cmϪ1. UV/Vis (CH2Cl2): λmax. (log ε) ϭ
252 (3.32), 290 (3.10), 366 (2.70), 528 (2.19) nm. C36H40O8 (600.70):
calcd. C 71.98, H 6.71; found C 71.65, H 7.08.
General Procedure for the Synthesis of the Formoins 18؊23: A solu-
tion of KCN in 50% aqueous ethanol was added to an ice-cold and
stirred solution of the freshly distilled glyoxal derivative in ethanol.
The formed precipitate was collected by filtration. If not otherwise
noted, recrystallization from ethanol gave the pure formoin.
2,4-Dihydroxy-2,5-bis(thiophen-2-yl)furan-3(2H)-one (22): Reaction
mixture: thiophen-2-ylglyoxal[17] (16.0 g, 114 mmol), KCN
(800 mg, 12 mmol), ethanol (65 mL), water (5 mL). Orange solid,
yield 46% (7.42 g, 26.5 mmol), m.p. 193Ϫ196 °C. 1H NMR
(300 MHz, [D6]DMSO): δ ϭ 7.02Ϫ7.03 (m, 1 H, Ar-H), 7.11 (m,
1 H, Ar-H), 7.33 (m, 1 H, Ar-H), 7.54Ϫ7.55 (m, 1 H, Ar-H),
7.85Ϫ7.86 (m, 1 H, Ar-H), 8.00Ϫ8.02 (m, 1 H, Ar-H), 8.62 (s, 1
H, OH), 9.74 (s, 1 H, OH) ppm. 13C NMR (75 MHz, [D6]DMSO):
δ ϭ 100.1 (OϪCϪOH), 125.4 (CHar), 127.0 (CHar), 127.0 (CHar),
128.7 (CHar), 129.3 (C), 129.7 (CHar), 130.2 (C), 132.4 (CHar),
140.4 (C), 160.0 (C), 191.5 (CϭO) ppm. HRMS (positive EI):
calcd. for C12H8O4S2 [M]ϩ 279.9864; found 279.9866 (0.2 mmu).
Benzoylformoin (18):[18] Reaction mixture: phenylglyoxal hydrate
(4.80 g, 31.5 mmol), KCN (247 mg, 3.8 mmol), ethanol (17 mL),
water (5 mL). Yellow solid, yield 27% (2.29 g, 8.5 mmol), m.p.
182Ϫ185 °C. 1H NMR (300 MHz, [D6]DMSO): δ ϭ 7.36Ϫ7.43 (m,
3 H, Ar-H), 7.46Ϫ7.51 (m, 2 H, Ar-H), 7.56Ϫ7.61 (m, 3 H, Ar-H),
8.12Ϫ8.18 (m, 2 H, Ar-H), 8.32 (s, 1 H, OH), 9.58 (s, 1 H, OH)
ppm. 13C NMR (75 MHz, [D6]DMSO): δ ϭ 100.2 (OϪCϪOH),
125.4 (CHar), 126.5 (CHar), 128.3 (CHar), 128.8 (CHar), 128.9
(CHar), 129.0 (C), 131.3 (CHar), 132.0 (C), 137.2 (C), 162.6 (Cϭ
CϪPh), 195.2 (CϭO) ppm.
MS (positive EI): m/z
ϭ
280 [M]ϩ, 169 [C7H5O3S]ϩ, 111
[C5H3OS]ϩ. IR (KBr): ν˜ ϭ 3427, 3104, 1408, 1270, 1061, 731 cmϪ1
.
UV/Vis (CH2Cl2): λmax. (log ε) ϭ 240 (3.61), 260 (3.53), 328 (3.69),
422 (4.00) nm. C12H8O4S2 (280.31): calcd. C 51.42, H 2.88, S 22.87;
found C 51.47, H 3.03, S 22.92.
p-Toluoylformoin (19): Reaction mixture: p-tolylglyoxal[19] (2.76 g,
18.6 mmol), KCN (175 mg, 2.7 mmol), ethanol (20 mL), water (5
mL). Yield 71% (1.96 g, 6.61 mmol). Cyclic hemiacetal: brown-red
2,4-Dihydroxy-2,5-bis(selenophen-2-yl)furan-3(2H)-one (23): Reac-
solid, m.p. 144Ϫ148 °C. 1H NMR (300 MHz, [D6]DMSO): δ ϭ tion mixture: selenophen-2-ylglyoxal (1.92 g, 10.3 mmol), KCN
3
2.28 (s, 3 H, CH3), 2.39 (s, 3 H, CH3), 7.18 (d, J ϭ 8.2 Hz, 2 H,
(80 mg, 1.2 mol), ethanol (10 mL), water (1 mL). Brown-red solid,
3
3
Ar-H), 7.35 (d, J ϭ 8.2 Hz, 2 H, Ar-H), 7.39 (d, J ϭ 8.2 Hz, 2 yield 39% (755 mg, 2.02 mmol), m.p. 192Ϫ194 °C. 1H NMR
H, Ar-H), 8.04 (d, 3J ϭ 8.2 Hz, 2 H, Ar-H), 8.21 (s, 1 H, OH), (500 MHz, [D6]DMSO): δ ϭ 7.24 (m, 1 H, Ar-H), 7.28 (m, 1 H,
9.44 (s, 1 H, OH) ppm. 13C NMR (75 MHz, [D6]DMSO): δ ϭ 20.8 Ar-H), 7.54 (m, 1 H, Ar-H), 8.00 (m, 1 H, Ar-H), 8.17 (m, 1 H,
(CH3), 21.3 (CH3), 100.4 (OϪCϪOH), 125.4 (CHar), 126.4 (C), Ar-H), 8.56 (s, 1 H, OH), 8.66Ϫ8.67 (m, 1 H, Ar-H), 9.88 (s, 1 H,
126.6 (CHar), 128.9 (CHar), 129.6 (CHar), 131.5 (C), 134.5 (C),
138.3 (C), 141.6 (C), 163.0 (CϭC), 195.0 (CϭO) ppm. MS (positive (OϪCϪOH), 127.1 (CHar), 129.2 (CHar), 129.3 (C), 130.5 (CHar),
OH) ppm. 13C NMR (125 MHz, [D6]DMSO):
δ ϭ 101.2
3218
2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2004, 3212Ϫ3220