Scope and limitations of the intermolecular furan-yne cyclization

Article abstract of DOI:10.1002/adsc.201500081

Different types of alkynes were reacted with 2,5-disubstituted furans in order to evaluate the scope of the intermolecular furan-yne reaction. With ethynyl aryl ethers as starting materials, 2-phenoxy phenols were accessible in moderate to good yields. A different reaction mode was observed for alkynes bearing electron-withdrawing substituents. For these starting materials a cis-selective hydroarylation took place in an anti-Markovnikov fashion in excellent yields. 1,2-Diynes turned out to be suitable starting materials as well. Due to the second alkynyl moiety, after an initial phenol synthesis, a subsequent hydro-alkoxylation by the newly formed phenolic oxygen gives access to benzofurans in a tandem process.

Full text of DOI:10.1002/adsc.201500081

Supporting Information

Table of contents
1 General methods and remarks
2 General experimental procedures
3 Synthesis of starting materials
4 Catalyzed reactions
5 1H NMR and 13C NMR spectra
6 References

1. General methods and remarks
All reagents and solvents were obtained from ABCR, Acros, Alfa Aesar or Sigma-Aldrich and were
used without further purification. Deuterated solvents were supplied from Euriso-Top. Absolute
solvents were dried using a MB SPS-800 solvent purification system. Preparation of air- and moisture-
sensitive materials was carried out in flame-dried flasks under an atmosphere of nitrogen using
Schlenk-techniques. All reactions were performed in technical grade solvents. Thin layer
chromatography (TLC) was carried out on Polygram® precoated plastic sheets SIL G/UV254 (SiO2,
0.20 mm thickness) from Macherey-Nagel. Column chromatography was performed using silica gel
(0.040 – 0.063 mm / 230 – 400 mesh ASTM) from Macherey-Nagel. NMR spectra were recorded on
Bruker Avance DRX (300 MHz) or Bruker Avance 500 (500 MHz) spectrometers. Spectra were
calibrated in relation to the used deuterated solvents CDCl3 ( = 7.26) and CD2Cl2 ( = 5.32).[1]
Chemical shifts  are given in ppm and coupling constants J in Hz. Signal multiplicity was determined
as s (singlet), d (doublet), t (triplet), q (quartet) or m (multiplet). The designation of the 13C signals was
based on DEPT90, DEPT135 or HSQC-me spectra. MS spectra were recorded on a Vakuum
Generators ZAB-2F, Finnigan MAT TSQ 700 or JEOL JMS-700 spectrometer. GC spectra were
recorded on a HP Agilent 5890 Series II Plus with FID analyser. GC-MS spectra were recorded on an
Agilent 5890 Series II Plus with a HP 5972 mass analysator. IR spectra (in cm-1) were recorded on a
Bruker Vector 22 FT-IR. Crystal structure analysis was accomplished on Bruker Smart CCD or Bruker
APEX diffractometers.
2. General experimental procedures
General procedure for the methylation of ethinyl aryl ethers with MeI (GP1)
A flame dried Schlenk flask under inert gas atmosphere was charged with a solution of the ethynyl aryl
ether derivative (1.0 eq) in dry THF (0.4 M) and cooled to -78°C. At this temperature n-Buli (1.2 eq,
1.6 M in hexane) was added. The resulting solution was allowed to warm to room temperature over
2 hours and then cooled to -78°C. Methyl iodide (2.0 eq) was added dropwise and the reaction mixture
was allowed to warm to room temperature in the cause of 1 h. After being stirred overnight, the
reaction was quenched by addition of a saturated ammonium chloride solution (2 mL). Water (10 ml)
was added, and the aqueous layer was extracted with diethyl ether (2 x 10 ml). The combined organic
layers were then dried over anhydrous magnesium sulfate, filtered and concentrated under reduced
pressure. The crude product was adsorbed on Celite® and then purified by flash column
chromatography.[2]
General procedure for the iodination of terminal alkynes (GP2)
A mixture of iodine (1.1 eq) and morpholine (3.0 eq) in abs. toluene was stirred for 30 min at room
temperature. The terminal alkyne (1.0 eq) diluted in toluene was then added and the suspension was
stirred at 45 °C for 24 h. After filtration and washing with ethyl acetate (2 x 20 ml), the combined

organic layers were washed with saturated aqueous solutions of ammonium chloride (20 ml), sodium
hydrogen carbonate (20 ml) and water (20 ml). After drying over magnesium sulfate and filtration, the
solvent was removed under reduced pressure. The crude product was subjected to flash
chromatography.[3]
General procedure for the Sonogashira reaction with TMS-acetylene (GP3)
A flame dried Schlenk flask under an inert gas atmosphere was charged with a solution of TMS-
acetylene (1.2 eq) and the iodine derivative (1.0 eq) in degassed triethylamine. To this solution bis-
(triphenylphosphine)palladium(II) chloride (2.0 mol%) was added and the resulting mixture was stirred
at room temperature for 10 min before copper iodide (2.0 mol%) was added. The reaction mixture was
stirred over night at room temperature before being worked up. The colourless precipitate was
dissolved in dichloromethane and the solvent was removed under reduced pressure. The procedure
was repeated twice before the residue was adsorbed on Celite®. Purification was done by flash
column chromatography over silica-gel.
General procedure for the gold catalyzed furan-yne reaction (GP4)
In a flame dried Schlenk flask under an atmosphere of nitrogen IPrAu*Cl (3 mol%) and
NaBArF (3 mol%) were dissolved in abs. DCM (2.0 ml) and stirred for 10 min. To this solution the
alkyne derivative (1 eq), 2,5-dimethylfuran (2.0 eq) and abs. DCM (2.0 ml) were added and stirred
under reflux until TLC showed full conversion of the substrates. The solvent was evaporated under
reduced pressure and the crude product was adsorbed on Celite® and purified by column
chromatography.
General procedure for the gold catalyzed tandem cyclization of diynes to benzofurans GP5)
In a Schlenk flask IPrAu*Cl (5 mol%) and NaBArF (5 mol%) were dissolved in DCM (2.0 ml, saturated
with water) and stirred for 10 min. To this solution the alkyne derivative (1 eq), 2,5-dimethylfuran
(2.0 eq) and DCM (2.0 ml, saturated with water) were added and stirred under reflux until TLC showed
full conversion of the substrates. The solvent was evaporated under reduced pressure and the crude
product was adsorbed on Celite® and purified by column chromatography.
3 Synthesis of the starting materials
3.1 Synthesis of ethinyl aryl/alkyl ethers
The compounds 7a – 7k were synthesized according to the literature procedure.[4]

3.2 Synthesis of methyl substituted ethinyl aryl ethers
(Prop-1-yn-1-yloxy)benzene 9a
According to GP1 (ethynyloxy)benzene 7a (525 mg, 4.44 mmol) was dissolved in 10.0 ml abs. THF
and reacted with n-BuLi (3.33 ml, 5.33 mmol, 1.6 M solution in hexane). After 2 h MeI (553 l, 8.88
mmol) was added. Flash column chromatography was performed over silica gel with petrol ether /
ethyl acetate (40:1). The product obtained was a yellow oil (310 mg, 2.35 mmol, 53%).
1
Rf(PE: EA 10:1) = 0.68; H NMR (300 MHz, CDCl3): δ = 1.88 (s, 3H), 7.11 (t, J= 7.0 Hz, 1H), 7.23 –
7.26 (m, 2H), 7.31 – 7.36 (m, 2H) ppm; 13C NMR (125 MHz, CDCl3): δ = 1.9 (q), 40.1 (s), 82.3 (s),
115.0 (d, 2C), 124.0 (d), 129.7 (d, 2C), 156.5 (s) ppm; IR (ATR): = 3530, 3058, 3044, 2959, 2922,
2859, 2746, 2513, 2435, 2406, 2291, 1988, 1935, 1851, 1713, 1677, 1638, 1593, 1492, 1458, 1384,
1330, 1307, 1290, 1270, 1246, 1202, 1175, 1148, 1104, 1071, 1023, 1006, 984, 949, 893, 845, 783,
756, 686 cm-1; HR-MS (EI+): found: m/z = 132.0566, calc. for C9H8O [M]+:
132.0575.
1-(Ethynyloxy)-4-methoxybenzene 9b
According to GP1 1-(ethynyloxy)-4-methoxybenzene 7b (584 mg, 3.94 mmol)
was dissolved in 10.0 ml abs. THF and reacted with n-BuLi (2.95 ml, 4.73
mmol, 1.6 M solution in hexane). After 2 h MeI (491 l, 7.88 mmol) was added.
Flash column chromatography was performed over silica gel with petrol ether / ethyl acetate (40:1).
The product obtained was a yellow oil (384 mg, 2.37 mmol, 60%).
Rf(PE: EA 10:1) = 0.57; 1H NMR (300 MHz, CDCl3): δ = 1.87 (s, 3H), 3.79 (s, 3H), 6.86 (d, J = 9.1 Hz,
2 H), ), 7.17 (d, J = 9.1 Hz, 2 H) ppm; 13C NMR (125 MHz, CDCl3): δ = 1.9 (q), 39.1 (s), 55.8 (q), 83.0
(s), 114.6 (d, 2C), 115.7 (d, 2C), 150.4 (s), 156.1 (s) ppm; IR (ATR): = 3528, 3060, 2957, 2919, 2856,
2508, 2436, 2402, 2290, 1986, 1941, 1782, 1672, 1608, 1585, 1504, 1445, 1366, 1291, 1249, 1214,
1197, 1158, 1105, 1043, 1031, 974, 940, 852, 826, 756, 732, 686 cm-1; HR-MS (EI+): found: m/z =
162.0660, calc. for C10H10O2 [M]+: 162.0681.
3.3 Synthesis of alkynes with electron withdrawing substituents
4-Nitrophenyl propiolate 10d
A flame dried Schlenk tube under inert gas atmosphere was charged with a solution of para-
nitrophenol (1.39 g, 10.0 mmol) in freshly distilled ethyl acetate (10.0 mL) and cooled to 0°C. At this
temperature propiolic acid (700 mg, 10.0 mmol) and 1,3-Dicyclohexylcarbo-diimide (2.06 g, 10.0

mmol) were added and immediately a white precipitate was formed. The ice bath was
removed after 10 min and the reaction mixture was stirred at ambient temperature for a
further 18 h, before it was filtered and the filter cake was washed with ethyl acetate (6 x
5.0 mL). The combined organic layers were combined and concentrated under reduced
pressure. The residue was subjected to flash chromatography over silica gel with
dichloromethane / n-pentane (3:1). The product obtained was a colourless solid (1.41 g,
7.38 mmol, 74%).
1
Rf(DCM: Pn 3:1) = 0.66; H NMR (500 MHz, CD2Cl2): δ = 3.27 (s, 1H), 7.37 (d, J = 9.2 Hz, 2H), 8.29
(d, J = 9.2 Hz, 2H) ppm; 13C NMR (125 MHz, CD2Cl2): δ = 73.7 (s), 78.3 (d), 122.7 (d, 2C), 125.7 (d,
2C), 146.3 (s), 150.1 (s), 154.6 (s) ppm.
All spectroscopic data are in accordance with previous reports.[5]
3.4 Synthesis of diynes
3-Phenylpropiolaldehyde
A flame dried Schlenk tube under inert gas atmosphere was charged with a
solution of phenylacetylene (1.10 ml, 10.0 mmol) in abs. THF (30.0 ml) and
cooled to -60°C. At this temperature n-BuLi (4.0 ml, 12.0 mmol, 2.5 M in hexane)
was added. Then N,N-dimethylformamide (1.54 ml, 20.0 mmol) was added
dropwise to this solution. The cooling bath was removed and the solution allowed to warm to room
temperature. After 20 min of further stirring, the solution was added to a mixture of tert-butyl methyl
ether (25.0 ml) and a 10% aqueous solution of KH2PO4 (55.0 ml) which had been previously cooled to
0°C. The entire solution was stirred at 0°C for 30 min and then allowed to warm to room temperature.
The aqueous and organic layers were separated. The organic layer was dried over sodium sulfate and
the solvent was removed under vacuum to give a clear oil (1.16 g, 8.92 mmol, 89%).
1H NMR (300 MHz, CD2Cl2): δ = 7.40 – 7.46 (m, 2H), 7.49 – 7.55 (m, 1H), 7.61 – 7.65 (m, 2H), 9.42 (s,
1H) ppm; 13C NMR (125 MHz, CD2Cl2): δ = 88.6 (s), 94.9 (s), 119.8 (s), 129.1 (d, 2C), 131.7 (d),
133.6 (d, 2C), 177.1 (d) ppm; IR (Reflection): = 3427, 3060, 2957, 2932, 2870, 2361, 2189, 1775,
1728, 1663, 1599, 1579, 1506, 1497, 1443, 1389, 1304, 1252, 1175, 1135, 1111, 1027, 978, 835, 757,
690 cm-1; HR-MS (EI+): found: m/z = 130.0430, calc. for C9H6O [M]+: 130.0419.
Buta-1,3-diyn-1-ylbenzene 12
A flame dried Schlenk tube under inert gas atmosphere was charged with a
solution of 3-phenylpropiolaldehyde (500 mg, 3.84 mmol) and cesium carbonate
(3.76 g, 11.5 mmol) in abs. MeOH (20.0 ml). Then dimethyl (1-diazo-2-oxopropyl)-
phosphonate/Bestmann-Ohira reagent (1.11 g, 5.76 mmol) was added and the
reaction mixture was stirred for a further 90 min. After tis period diethyl ether (30.0 ml) and an aqueous
solution of sodium hydrogen carbonate were added. The aqueous and organic layer were separated,

the organic layer was dried over magnesium sulfate und the solvent was removed under reduced
pressure. The residue was subjected to flash chromatography over silica gel with n-pentane /
dichloromethane / (3:1). The product obtained was a colourless liquid which turned brown (299 mg,
2.37 mmol, 62%).
1
Rf(Pn: DCM 3:1) = 0.60; H NMR (500 MHz, CD2Cl2): δ = 2.57 (s, 1H), 7.34 – 7.38 (m, 2H), 7.40 –
7.44 (m, 1H), 7.52 – 7.55 (m, 2H) ppm; 13C NMR (125 MHz, CD2Cl2): δ = 68.2 (s), 71.7 (d), 73.5 (s),
75.6 (s), 121.2 (s), 128.9 (d, 2C), 130.1 (d), 133.1 (d, 2C) ppm; IR(reflection): = 3283, 3058, 2957,
2925, 2854, 2364, 2349, 2199, 1950, 1723, 1668 ,1597, 1489, 1442, 1377, 1069, 1026, 755, 689,
664 cm-1; HR-MS (EI+): found: m/z = 126.0442, calc. for C10H6 [M]+: 126.0470.
(Iodoethynyl)benzene
According to GP2 iodine (2.80 g, 11.0 mmol) and morpholine (2.62 ml, 30.0 mmol)
were dissolved in 12.0 ml abs. toluene. After 30 min a solution of phenylacetylene
(1.10 ml, 10.0 mmol) in toluene (18.0 ml) was added dropwise. Flash column
chromatography was performed over silica gel with ethyl acetate. The product
obtained was a yellow oil (2.05 g, 9.00 mmol, 90%).
Rf(EA) = 0.72; 1H NMR (300 MHz, CDCl3): δ = 7.29 – 7.33 (m, 3H), 7.43 – 7.46 (m, 2H) ppm; 13C NMR
(75 MHz, CDCl3): δ = 6.29 (s), 94.3 (s), 123.5 (s), 128.4 (d, 2C), 128.9 (d), 132.4 (d, 2C) ppm.
All spectroscopic data are in accordance with previous reports.[6]
(Phenylbuta-1,3-diyn-1-yl)trimethylsilane 14a
According to GP3 (iodoethynyl)benzene (1.91 g, 8.38 mmol), trimethylsilyl-
acetylene (1.40 ml, 10.1 mmol) and Pd(PPh3)Cl2 (118 mg, 168 mol) were
dissolved in 20.0 ml degassed triethylamine. After 10 min copper iodide
(16.6 mg, 168 mol) was added. Flash column chromatography was
performed over silica gel with petroleum ether. The product obtained was a yellow oil (728 mg, 3.67
mmol, 44%).
Rf(PE: EA 10:1) = 0.52; 1H NMR (500 MHz, CD2Cl2): δ = 0.23 (s, 9H), 7.32 – 7.35 (m, 2H), 7.37 – 7.41
(m, 1H), 7.49 – 7.51 (m, 2H) ppm; 13C NMR (125 MHz, CD2Cl2): δ = -0.4 (q, 3C), 74.3 (s), 76.9 (s),
87.9 (s), 91.1 (s), 121.5 (s), 128.9 (d, 2C), 129.9 (d), 133.0 (d, 2C) ppm; IR(reflection): = 3081, 3062,
2961, 2899, 2507, 2207, 2105, 1951, 1882, 1802, 1672, 1595, 1571, 1490, 1442, 1410, 1332, 1292,
1279, 1251, 1178, 1068, 1035, 1020, 1008, 991, 962, 940, 915, 860, 752, 727, 687, 633 cm-1; HR-MS
(EI+): found: m/z = 198.0857, calc. for C13H14Si [M]+: 198.0865.
4-(Iodoethynyl)-1,1'-biphenyl

According to GP2 iodine (820 mg, 3.23 mmol) and morpholine (762 l, 8.79 mmol) were dissolved in
4.0 ml abs. toluene. After 30 min a solution of 4-ethynyl-1,1'-biphenyl (523 mg, 2.93 mmol) in toluene
(6.0 ml) was added dropwise. Flash column chromatography was performed over silica gel with ethyl
acetate. The product obtained was a yellow powder (813 mg, 2.67 mmol, 91%).
1
Rf(EA) = 0.80; H NMR (500 MHz, CD2Cl2): δ = 7.35 – 7.38 (m, 1H), 7.45 (t, J = 7.7 Hz, 2H), 7.50 –
7.52 (m, 2H), 7.57 – 7.61 (m, 4H) ppm; 13C NMR (125 MHz, CD2Cl2): δ = 7.1 (s), 94.2 (s), 122.5 (s),
127.2 (d, 2C), 127.3 (d, 2C), 128.2 (d), 129.3 (d, 2C), 133.1 (d, 2C), 140.4 (s), 141.9 (s) ppm;
IR(reflection): = 3076, 3060, 3030, 1953, 1738, 1682, 1598, 1577, 1549, 1517, 1481, 1446, 1403,
1391, 1334, 1315, 1283, 1261, 1227, 1183, 1155, 1108, 1075, 1038, 1007, 994, 968, 955, 918, 840,
762, 726, 698 cm-1; HR-MS (EI+): found: m/z = 303.9751, calc. for C14H9I [M]+: 303.9749.
[1,1'-Biphenyl]-4-ylbuta-1,3-diyn-1-yl)trimethylsilane 14b
According to GP3 4-(iodoethynyl)-1,1'-biphenyl (762 mg, 2.50
mmol), trimethylsilylacetylene (420 l, 3.00 mmol) and
Pd(PPh3)Cl2 (35.1 mg, 50 mol) were dissolved in 10.0 ml
degassed triethylamine. After 10 min copper iodide (9.50 mg, 50
mol) was added. Flash column chromatography was performed
over silica gel with petroleum ether. The product obtained was a white powder (302 mg, 1.10 mmol,
44%).
Rf(PE: EA 10:1) = 0.65; 1H NMR (500 MHz, CD2Cl2): δ = 0.24 (s, 9H), 7.38 (t, J = 7.3 Hz, 1H), 7.46 (t,
J = 7.3 Hz, 2H), 7.56 – 7.61 (m, 6H) ppm; 13C NMR (125 MHz, CD2Cl2): δ = -0.4 (q, 3C), 74.9 (s), 76.9
(s), 88.0 (s), 91.5 (s), 120.4 (s), 127.4 (d, 2C), 127.5 (d, 2C), 128.3 (d), 133.5 (d, 2C), 140.3 (s), 142.5
(s) ppm; IR(ATR): = 3060, 3033, 2958, 2897, 2205, 2105, 1950, 1913, 1884, 1671, 1600, 1542,
1485, 1447, 1403, 1335, 1290, 1249, 1179, 1108, 1077, 1032, 1009, 978, 944, 913, 837, 759, 724,
697, 632 cm-1; HR-MS (EI+): found: m/z = 274.1153, calc. for C19H18Si [M]+: 274.1178.
1-(Iodoethynyl)-4-methoxybenzene
According to GP2 iodine (2.11 g, 8.33 mmol) and morpholine (1.97 ml, 22.7
mmol) were dissolved in 12.0 ml abs. toluene. After 30 min a solution of
4-ethynylanisole (1.00 g, 7.57 mmol) in toluene (18.0 ml) was added dropwise.
Flash column chromatography was performed over silica gel with ethyl acetate.
The product obtained was a pale brown powder (1.78 g, 6.54 mmol, 86%).
Rf(EA) = 0.75; 1H NMR (500 MHz, CDCl3): δ = 3.81 (s, 3H), 6.83 (d, J = 8.9 Hz, 2H), 7.38 (d, J = 8.9
Hz, 2H) ppm; 13C NMR (125 MHz, CDCl3): δ = 4.0 (s), 55.4 (q), 94.1 (s), 114.0 (d, 2C), 115.7 (s),
133.9 (d, 2C), 160.1 (s) ppm; IR(ATR): = 2929, 2839, 2271, 1722, 1665, 1605, 1509, 1461, 1295,

1256, 1177, 1113, 1034, 944, 838, 812, 791, 751, 693, 671, 646, 614 cm-1; HR-MS (EI+): found: m/z =
257.9535, calc. for C9H7OI [M]+: 257.9542.
(4-Methoxyphenylbuta-1,3-diyn-1-yl)trimethylsilane 14c
According to GP3 1-(iodoethynyl)-4-methoxybenzene (1.74 g, 6.39
mmol), trimethylsilylacetylene (1.06 ml, 7.67 mmol) and Pd(PPh3)Cl2
(90.0 mg, 128 mol) were dissolved in 20.0 ml degassed triethylamine.
After 10 min copper iodide (12.7 mg, 128 mol) was added. Flash
column chromatography was performed over silica gel with petroleum
ether. The product obtained was a yellow oil (535 mg, 2.34 mmol, 37%).
Rf(PE: EA 10:1) = 0.54; 1H NMR (500 MHz, CDCl3): δ = 0.23 (s, 9H), 3.81 (s, 3H), 6.83 (d, J = 8.9 Hz,
2H), 7.43 (d, J = 8.9 Hz, 2H) ppm; 13C NMR (125 MHz, CDCl3): δ = -0.2 (q, 3C), 55.5 (q), 73.2 (s), 77.2
(s), 88.3 (s), 90.0 (s), 113.4 (s), 114.3 (d, 2C), 134.5 (d, 2C), 160.6 (s) ppm; IR(ATR): = 3733, 3797,
3005, 2960, 2900, 2838, 2548, 2202, 2102, 1890, 1749, 1603, 1567, 1509, 1462, 1441, 1416, 1375,
1298, 1250, 1172, 1107, 1029, 1004, 977, 842, 830, 759, 669 cm-1; HR-MS (EI+): found: m/z =
228.0972, calc. for C14H16OSi [M]+: 228.0970.
4 Catalyzed reactions
4.1 Furan-yne cyclization of ethinyl aryl/alkyl ethers
3,6-Dimethyl-2-phenoxyphenol 8a
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg, 12.0
µmol) were dissolved in 2.0 ml abs. DCM. After 10 min (ethynyloxy)benzene 7a
(47.3 mg, 400 mol), 2,5-dimethylfuran (85.3 µl, 800 mol) and 2.0 ml abs.
DCM were added. After 16 h TLC monitoring showed complete conversion. Column chromatography
(SiO2, PE:EA, 100:1) delivered 3,6-dimethyl-2-phenoxyphenol 8a as rose powder (63.8 mg, 298 mol,
75 %).
1
Rf (PE:EA, 10:1)= 0.31; H NMR (CDCl3, 500 MHz): δ = 2.04 (s, 3H), 2.27 (s, 3H), 5.40 (bs, 1H),
6.68 (d, J = 7.5 Hz, 1H), 6.87 (d, J = 7.5 Hz, 2H), 6.92 (d, J = 8.0 Hz, 1H), 7.03 (t, J = 7.5 Hz, 1H),
7.28 (m, 2H) ppm; 13C NMR (CDCl3, 125 MHz): δ = 15.6 (q), 16.2 (q), 115.1 (d, 2 C), 121.8 (d),
122.5 (d), 123.1 (s), 127.3 (d), 128.9 (s), 130.0 (d, 2C), 139.5 (s), 147.2 (s), 157.4 (s) ppm; IR (film):
= 3454, 2925, 1623, 1599, 1491, 1465, 1423, 1348, 1271, 1243, 1218, 1159, 1073, 946, 887, 808,
750, 689, 613 cm-1; HR-MS (EI+): found: m/z = 214.0981, calc. for C14H14O2 [M]+: 214.0994.
2-(4-Methoxyphenoxy)-3,6-dimethylphenol 8b

According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg,
12.0 µmol) were dissolved in 2.0 ml abs. DCM. After 10 min 1-
(ethynyloxy)-4-methoxybenzene
7b
(59.2
mg,
400 mol),
2,5-dimethylfuran (85.3 µl, 800 mol) and 2.0 ml abs. DCM were added.
After 36 h TLC monitoring showed complete conversion. Column chromatography (SiO2, PE:EA, 40:1)
delivered 2-(4-methoxy-phenoxy)-3,6-dimethylphenol 8b as yellow powder (66.4 mg, 272 mol, 68%).
1
Rf (PE:EA, 10:1)= 0.54; H NMR (CDCl3, 500 MHz): δ = 2.04 (s, 3H), 2.26 (s, 3H), 3.75 (s, 3H),
5.46 (bs, 1H), 6.66 (d, J =7.8 Hz, 1H), 6.78 – 6.82 (m, 4H), 6.90 (d, J = 7.8 Hz, 1H) ppm;
13C NMR (CDCl3, 125 MHz): δ = 15.6 (q), 16.2 (q), 55.8 (q), 115.0 (d, 2 C), 115.9 (d, 2 C), 121.8 (d),
123.0 (s), 127.1 (d), 128.9 (s), 140.0 (s), 147.3 (s), 151.4 (s), 155.0 (s) ppm; IR (film) = 3413, 2970,
2926, 1621, 1586, 1506, 1459, 1429, 1285, 1267, 1228, 1212, 1064, 1030, 1015, 822, 812, 797, 732
cm-1; HR-MS (EI+): found: m/z = 244.1099, calc. for C15H16O3 [M]+: 244.1099.
3,6-Dimethyl-2-(o-tolyloxy)phenol 8c
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg, 12.0
µmol) were dissolved in 2.0 ml abs. DCM. After 10 min 1-(ethynyloxy)-2-
methylbenzene 7c (52.8 mg, 400 mol), 2,5-dimethylfuran (85.3 µl, 800 mol)
and 2.0 ml abs. DCM were added. After 24 h TLC monitoring showed complete conversion. Column
chromatography (SiO2, PE:EA, 100:1) delivered 3,6-dimethyl-2-(o-tolyloxy)phenol 8c as yellow oil
(72.1 mg, 316 mol, 79%).
1
Rf (PE:EA, 5:1) = 0.58; H NMR (CD2Cl2, 500 MHz): δ = 1.98 (s, 3H), 2.26 (s, 3H), 2.44 (s, 3H), 5.46
(s, 1H), 6.39 (d, J = 8.0 Hz, 1H), 6.69 (d, J = 8.0 Hz, 1H), 6.91 – 6.95 (m, 2H), 7.01 (ddd, J = 8.1 Hz, J
= 7.4 Hz, J = 1.6 Hz, 1H), 7.24 (dd, J = 7.4 Hz, J = 1.6 Hz, 1H) ppm; 13C NMR (CD2Cl2, 125 MHz):
δ = 15.6 (q), 15.9 (q), 16.4 (q), 112.7 (d), 122.0 (d), 122.5 (d), 123.2 (s), 126.8 (s), 127.2 (d), 127.3 (d),
128.9 (s), 131.6 (d), 140.1 (s), 147.5 (s), 155.7 (s) ppm; IR (reflection) = 3554, 3028, 2950, 2925,
2857, 2735, 1896, 1778, 1628, 1589, 1504, 1488, 1466, 1429, 1380, 1334, 1284, 1267, 1235, 1221,
1207, 1179, 1159, 1115, 1062, 1045, 1016, 986, 943, 830, 799, 749, 711, 687, 617 cm-1; HR-MS (EI+):
found: m/z = 228.1163, calc. for C15H16O2 [M]+: 228.1150.
2-(2-Allylphenoxy)-3,6-dimethylphenol 8e
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg, 12.0
µmol) were dissolved in 2.0 ml abs. DCM. After 10 min 1-allyl-2-
(ethynyloxy)benzene 7e (63.2 mg, 400 mol), 2,5-dimethylfuran (85.3 µl,
800 mol) and 2.0 ml abs. DCM were added. After 36 h TLC monitoring
showed complete conversion. Column chromatography (SiO2, PE:EA, 100:1)
delivered 2-(2-allylphenoxy)-3,6-dimethylphenol 8e as yellow oil (59.5 mg, 234 mol, 59%).

1
Rf (PE:EA, 10:1) = 0.49; H NMR (CD2Cl2, 500 MHz): δ = 2.03 (s, 3H), 2.23 (s, 3H), 3.57 – 3.65 (m,
1H), 5.12 (dd, J = 9.8 Hz, J = 1.8 Hz, 1H), 5.15 (d, J = 1.8 Hz), 1H), 5.47 (s, 1H), 6.15 (ddt, J = 16.8
Hz, J = 10.4 Hz, J = 6.4 Hz, 1H), 6.41 (d, J = 8.1 Hz, 1H), 6.92 (d, J = 8.1 Hz, 1H), 6.98 – 7.00 (m,
1H), 7.06 (td, J = 7.8 Hz, J = 1.5 Hz, 1H), 7.26 (dd, J = 7.4 Hz, J = 1.5 Hz, 1H) ppm; 13C
NMR (CD2Cl2, 125 MHz): δ = 15.6 (q), 16.1 (q), 34.9 (t), 112.7 (t), 115.8 (d), 121.9 (d), 122.6 (d), 123.4
(s), 127.4 (d), 128.0 (d), 128.4 (s), 129.3 (s), 131.1 (d), 138.0 (d), 139.7 (s), 147.4 (s), 155.3 (s) ppm;
IR (reflection) = 3498, 3077, 3059, 3027, 3004, 2977, 2924, 2857, 2736, 2441, 1636, 1603, 1586,
1504, 1486, 1453, 1428, 1379, 1284, 1267, 1234, 1204, 1175, 1120, 1106, 1061, 1041, 997, 945, 915,
829, 800, 750, 689, 651, 616 cm-1; HR-MS (EI+): found: m/z = 254.1300, calc. for C17H16O2 [M]+:
254.1307.
2-(2-(tert-Butyl)phenoxy)-3,6-dimethylphenol 8f
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg, 12.0
µmol) were dissolved in 2.0 ml abs. DCM. After 10 min 1-(tert-butyl)-2-
(ethynyloxy)benzene 7f (69.6 mg, 400 mol), 2,5-dimethylfuran (85.3 µl,
800 mol) and 2.0 ml abs. DCM were added. After 4 d TLC monitoring showed
complete conversion. Column chromatography (SiO2, PE:EA, 200:1) delivered 2-(2-(tert-
butyl)phenoxy)-3,6-dimethylphenol 8f as yellow oil (35.5 mg, 131 mol, 33%).
Rf (PE:EA, 10:1) = 0.52; 1H NMR (CD2Cl2, 500 MHz): δ = 1.54 (s, 9H), 2.04 (s, 3H), 2.24 (s, 3H), 5.19
(s, 1H), 6.42 (dd, J = 7.9 Hz, J = 1.3 Hz, 1H), 6.72 (d, J = 7.8 Hz, 1H), 6.93 (d, J = 7.8 Hz, 1H), 6.97
(td, J = 7.6 Hz, J = 1.3 Hz, 1H), 7.02 (td, J = 7.9 Hz, J = 1.8 Hz, 1H), 7.40 (dd, J = 7.6 Hz, J = 1.8 Hz,
1H) ppm; 13C NMR (CD2Cl2, 125 MHz): δ = 15.6 (q), 16.5 (q), 30.1 (q, 3C), 35.3 (s), 113.0 (d), 122.2
(d), 122.4 (d), 123.5 (s), 127.4 (d), 127.6 (d), 127.8 (d), 129.4 (s), 137.7 (s), 139.3 (s), 147.3 (s), 156.0
(s) ppm; IR (reflection) = 3566, 3057, 2962, 2869, 2738, 2441, 1902, 1781, 1599, 1578, 1485, 1466,
1441, 1392, 1379, 1360, 1333, 1285, 1266, 1233, 1207, 1132, 1091, 1059, 943, 810, 752, 688, 619
cm-1; HR-MS (EI+): found: m/z = 270.1613, calc. for C18H22O2 [M]+: 270.1620.
3,6-Dimethyl-2-(pentyloxy)phenol 8i
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg,
12.0 µmol µmol) were dissolved in 2.0 ml abs. DCM. After 10 min 1-
(ethynyloxy)pentane 7i (44.8 mg, 400 mol), 2,5-dimethylfuran (85.3 µl,
800 mol) and 2.0 ml abs. DCM were added. After 42 h TLC monitoring showed complete conversion.
Column chromatography (SiO2, PE:EA, 100:1) delivered 3,6-dimethyl-2-(pentyloxy)phenol 8i as yellow
oil (21.2 mg, 102 mol, 25%).
Rf (PE:EA, 5:1) = 0.64; 1H NMR (CD2Cl2, 500 MHz): δ = 0.94 (t, J = 7.2 Hz, 3H), 1.36 – 1.49 (m, 4H),
1.77 – 1.83 (m, 2H), 2.18 (s, 3H), 2.23 (s, 3H), 3.83 (t, J = 6.8 Hz, 2H), 5.75 (s, 1H), 6.57 (d, J = 7.8
Hz, 1H), 6.74 (d, J = 7.8 Hz) ppm; 13C NMR (CD2Cl2, 125 MHz): δ = 14.2 (q), 15.5 (q), 16.0 (q), 22.9

(t), 28.6 (t), 30.4 (t), 73.9 (t), 121.7 (d), 122.2 (s), 125.9 (d), 128.2 (s), 144.6 (s), 147.6 (s) ppm; IR
(reflection) = 3529, 3027, 2925, 2860, 2732, 2115, 1724, 1675, 1626, 1587, 1506, 1467, 1429, 1379,
1339, 1281, 1236, 1212, 1159, 1062, 991, 943, 872, 798, 761, 741, 681 cm-1; HR-MS (EI+): found:
m/z = 208.1478, calc. for C13H20O2 [M]+: 208.1463.
3,6-Dimethyl-2-(naphthalen-2-yloxy)phenol 8j
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg,
12.0 µmol 5.3 mg, 6.0 µmol) were dissolved in 2.0 ml abs. DCM. After 10
min 2-(ethynyloxy)-naphthalene 7j (67.2 mg, 400 mol), 2,5-dimethylfuran
(85.3 µl, 800 mol) and 2.0 ml abs. DCM were added. After 18 h TLC monitoring showed complete
conversion. Column chromatography (SiO2, PE:EA, 200:1) delivered 3,6-dimethyl-2-(naphthalen-2-
yloxy)phenol 8j as yellow solid (53.9 mg, 204 mol, 51%).
Rf (PE:EA, 10:1) = 0.53; 1H NMR (CDCl3, 500 MHz): δ = 2.06 (s, 3H), 2.30 (s, 3H), 5.44 (bs, 1H), 6.72
(d, J = 7.8 Hz, 1H), 6.97 (d, J = 7.7 Hz, 1H), 7.00 (d, J = 2 Hz, 1H), 7.28 (dd, J = 9.1 Hz, J =
2.0 Hz, 1H), 7.37 (t, J = 7.5 Hz, 1H), 7.43 (t, J = 7.7 Hz, 1H), 7.63 (d, J = 8.3 Hz, 1H), 7.80 (d, J =
9.4 Hz, 1H), 7.82 (d, J = 9.4 Hz, 1H) ppm; 13C NMR (CDCl3, 125 MHz): δ = 15.7 (q), 16.2 (q),
109.2 (d), 117.5 (d), 121.9 (d), 123.3 (s), 124.5 (d), 126.8 (d), 127.1 (d), 127.4 (d), 127.9 (d), 129.0 (s),
129.9 (s), 130.3 (d), 134.4 (s), 140.0 (s) 147.2 (s), 155.2 (s) ppm; IR (reflection) = 3449, 3059, 2927,
2856, 1633, 1600, 1513, 1463, 1426, 1391, 1360, 1275, 1249, 1211, 1161, 1117, 1061, 1018, 967,
940, 844, 816, 801, 772, 744, 640, 623 cm-1; HR-MS (EI+): found: m/z = 264.1175, calc. for C18H16O2
[M]+: 264.1150.
3,6-Dimethyl-2-(naphthalen-1-yloxy)phenol 8k
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg,
12.0 µmol) were dissolved in 2.0 ml abs. DCM. After 10 min
1-(ethynyloxy)-naphthalene 7k (67.2 mg, 400 mol), 2,5-dimethylfuran
(85.3 µl, 800 mol) and 2.0 ml abs. DCM were added. After 18 h TLC
monitoring showed complete conversion. Column chromatography
(SiO2, PE:EA, 200:1) delivered 3,6-dimethyl-2-(naphthalen-1-yloxy)phenol 8k as yellow oil (58.4 mg,
221 mol, 55%).
Rf (PE:EA, 10:1) = 0.48; 1H NMR (CDCl3, 500 MHz): δ = 2.03 (s, 3H), 2.30 (s, 3H), 5.42 (bs,
1H), 6.52 (d, J = 7.7 Hz, 1H), 6.73 (d, J = 7.7 Hz, 1H), 6.97 (d, J = 7.7 Hz, 1H), 7.26 (t, J = 8.0 Hz, 1H),
7.52 (d, J = 8.0 Hz, 1H), 7.57 – 7.60 (m, 2H), 7.89 (d, J = 6.8 Hz, 1H), 8.49 (d, J = 7 Hz, 1H) ppm;
13C NMR (CDCl3, 125 MHz): δ = 15.7 (q), 16.0 (q), 107.1 (d), 121.8 (d), 121.9 (d), 122.3 (d), 123.3 (s),
125.0 (s), 125.9 (d), 126.0 (d), 126.9 (d), 127.4 (d), 127.9 (d), 128.9 (s), 135.0 (s) 139.7 (s), 147.2 (s),
152.9 (s) ppm; IR (film) = 3554, 3054, 2958, 2924, 2856, 2734, 1920, 1843, 1662, 1629, 1597, 1576,

1508, 1462, 1428, 1393, 1331, 1285, 1261, 1232, 1203, 1157, 1085, 1064, 1041, 1016, 936, 909, 863,
795, 770, 690, 620 cm-1; HR-MS (EI+): found: m/z = 264.1165, calc. for C18H16O2 [M]+: 264.1150.
4.2 Reaction of alkynes with electron-withdrawing substituents
(Z)-2,5-Dimethyl-3-(2-tosylvinyl)furan 11a
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg, 12.0
µmol) were dissolved in 2.0 ml abs. DCM. After 10 min 1-(ethynylsulfonyl)-4-
methyl benzene (72.1 mg, 400 mol), 2,5-dimethylfuran (85.3 µl, 800 mol) and
2.0 ml abs. DCM were added. After 20 h TLC monitoring showed complete
conversion. Column chromatography (SiO2, PE:EA, 200:1) delivered (Z)-2,5-
Dimethyl-3-(2-tosylvinyl)furan 11a as yellow oil (102 mg, 368 mol, 92%).
Rf (PE:EA, 10:1) = 0.48; 1H NMR (CD2Cl2, 500 MHz): δ = 2.52 (s, 3H), 2.29 (s, 3H), 2.42 (s, 3H), 6.11
d, J = 12.1 Hz, 1H), 6.70 (d, J = 12.1 Hz, 1H), 6.87 (s, 1H), 7.34 (d, J = 8.1 Hz, 2H), 7.79 (d, J = 8.1
Hz, 2H) ppm; 13C NMR (CD2Cl2, 125 MHz): δ = 12.1 (q), 13.4 (q), 21.7 (q), 107.7 (d), 116.0 (s), 124.4
(d), 127.3 (d, 2C), 130.1 (d, 2C), 131.5 (d), 139.7 (s), 144.7 (s), 151.4 (s), 156.6 (s) ppm; IR (reflection)
= 3734, 3629, 3463, 3149, 3054, 2922, 1921, 1685, 1622, 1603, 1494, 1448, 1412, 1382, 1313,
1299, 1209, 1183, 1141, 1083, 1039, 1009, 924, 850, 911, 749, 734, 707, 656, 611 cm-1; HR-MS (EI+):
found: m/z = 276.0829, calc. for C15H16O3S [M]+: 276.0820.
(Z)-3-(2,5-Dimethylfuran-3-yl)acrylic acid 11b
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg, 12.0
µmol) were dissolved in 2.0 ml abs. DCM. After 10 min propiolic acid (24.6 l,
400 mol), 2,5-dimethylfuran (85.3 µl, 800 mol) and 2.0 ml abs. DCM were
added. After 18 h TLC monitoring showed complete conversion. Column chromatography (SiO2,
PE:EA, 2:1) delivered (Z)-3-(2,5-dimethylfuran-3-yl)acrylic acid 11b as yellow solid (46.8 mg, 282
mol, 70%).
Rf (PE:EA, 2:1) = 0.22; 1H NMR (CD2Cl2, 400 MHz): δ = 2.25 (s, 3H), 2.33 (s, 3H), 5.67 (d, J = 12.6 Hz,
1H), 6.79 (d, J = 12.6 Hz, 1H), 6.81 (s, 1H), 11.45 (bs, 1H) ppm; 13C NMR (CD2Cl2, 100 MHz): δ = 12.1
(q), 13.4 (q), 107.6 (d), 113.0 (d), 118.1 (s), 136.7 (d), 150.7 (s), 156.2 (s), 172.0 (s) ppm; IR (ATR)
=
2924, 2754, 2568, 1684, 1595, 1463, 1407, 1299, 1208, 1144, 1093, 1040, 1008, 986, 926, 821, 799,
750, 631 cm-1; HR-MS (EI+): found: m/z = 166.0647, calc. for C9H10O3 [M]+: 166.0630.
Ethyl (Z)-3-(2,5-dimethylfuran-3-yl)acrylate 11c
According to GP4 IPr*AuCl (13.7 mg, 12.0 µmol) and NaBArF (10.6 mg, 12.0
µmol) were dissolved in 2.0 ml abs. DCM. After 10 min ethyl propiolate (40.5 l,

400 mol), 2,5-dimethylfuran (85.3 µl, 800 mol) and 2.0 ml abs. DCM were added. After 18 h TLC
monitoring showed complete conversion. Column chromatography (SiO2, PE:EA, 50:1) delivered ethyl
(Z)-3-(2,5-dimethylfuran-3-yl)acrylate 11c as yellow oil (56.7 mg, 292 mol, 73%).
Rf (PE:EA, 5:1) = 0.58; 1H NMR (CD2Cl2, 400 MHz): δ = 1.28 (t, J = 7.2 Hz, 3H), 2.23 (s, 3H), 2.30 (s,
3H), 4.16 (q, J = 7.2 Hz, 2H), 5.63 (d, J = 12.6 Hz, 1H), 6.63 (d, J = 12.6 Hz, 1H), 6.80 (s, 1H) ppm;
13C NMR (CD2Cl2, 100 MHz): δ = 12.0 (q), 13.4 (q), 14.5 (q), 60.2 (t), 107.7 (d), 114.6 (d), 118.0 (s),
133.8 (d), 150.3 (s), 155.0 (s), 166.7 (s) ppm; IR (ATR) = 3149, 2981, 2923, 1719, 1627, 1444, 1400,
1289, 1228, 1179, 1094, 1031, 1007, 950, 924, 831, 745, 630 cm-1; HR-MS (EI+): found: m/z =
194.0957, calc. for C11H14O3 [M]+: 194.0943.
4-Nitrophenyl (Z)-3-(2,5-dimethylfuran-3-yl)acrylate 11d
According
to
GP4
IPr*AuCl (22.8 mg,
20.0 µmol)
and
NaBArF (17.7 mg, 20.0 µmol) were dissolved in 2.0 ml abs. DCM. After
10 min the alkyne derivative (76.4 mg, 400 mol), 2,5-dimethylfuran
(85.3 µl, 800 mol) and 2.0 ml abs. DCM were added. After 5 days
TLC monitoring showed complete conversion. Column chromatography (SiO2, PE:EA, 20:1) delivered
4-nitrophenyl (Z)-3-(2,5-dimethylfuran-3-yl)acrylate 11d as yellow powder (90.7 mg, 316 mol, 79%).
Rf (PE:EA, 5:1) = 0.35; 1H NMR (CD2Cl2, 500 MHz): δ = 2.23 (s, 3H), 2.37 (s, 3H), 5.86 (d, J = 12.6 Hz,
1H), 6.86 (s, 1H), 6.92 (d, J = 12.6 Hz, 1H), 7.35 (d, J = 9.1 Hz, 2H), 8.27 (d, J = 9.1 Hz, 2H) ppm;
13C NMR (CD2Cl2, 125 MHz): δ = 12.2 (q), 13.4 (q), 107.5 (d), 111.5 (d), 118.3 (s), 123.0 (d, 2C),
125.4 (d, 2C), 138.4 (d), 145.5 (s), 150.9 (s), 156.2 (s), 17.0 (s), 164.0 (s) ppm; IR (ATR) = 2954,
2923, 1739, 1614, 1592, 1519, 1490, 1458, 1401, 1377, 1349, 1207, 1160, 1094, 1011, 938, 865, 814,
756, 690, 669, 634, 621 cm-1; HR-MS (EI+): found: m/z = 287.0766, calc. for C15H13O5N [M]+:
287.0794.
4.3 Tandem cyclization of 1,3-diynes
4,7-Dimethyl-2-phenylbenzofuran 16a
According to GP5 IPr*AuCl (22.8 mg, 20.0 µmol) and NaBArF (17.7 mg, 20.0
µmol) were dissolved in 2.0 ml with water-saturated DCM. After 10 min
(phenyl-buta-1,3-diyn-1-yl)trimethylsilane 14a (79.2 mg, 400 mol),
2,5-dimethylfuran (85.3 µl, 800 mol) and 2.0 ml with water-saturated DCM
were added. After 40 h TLC monitoring showed complete conversion. Column chromatography (SiO2,
PE) delivered 4,7-dimethyl-2-phenylbenzofuran 16a as white powder (28.9 mg, 130 mol, 32%).

Rf (PE:EA, 5:1) = 0.71; 1H NMR (CD2Cl2, 500 MHz): δ = 2.51 (s, 3H), 2.54 (s, 3H), 6.94 (d, J = 7.4 Hz,
1H), 6.99 (d, J = 7.4 Hz, 1H), 7.09 (s, 1H), 7.36 (t, J = 7.3 Hz, 1H), 7.45 – 7.49 (m, 2H), 7.91 (d, J =
7.3 Hz, 2H) ppm; 13C NMR (CD2Cl2, 125 MHz): δ = 14.9 (q), 18.5 (q), 100.7 (d), 119.0 (s), 123.6 (d),
125.1 (d, 2C), 125.5 (d), 128.6 (s), 128.7 (d), 128.8 (s), 129.2 (d, 2C), 131.1 (s), 154.0 (s), 155.3 (s)
ppm; IR (reflection) = 3050, 2920, 2858, 1606, 1566, 1511, 1487, 1446, 1379, 1326, 1285, 1247,
1176, 1069, 1021, 976, 912, 804, 763, 747, 724, 688, 659, 623 cm-1; HR-MS (EI+): found: m/z =
222.1019, calc. for C16H14O [M]+: 222.1045.
2-([1,1'-Biphenyl]-4-yl)-4,7-dimethylbenzofuran 16b
According
to
GP5
IPr*AuCl (22.8 mg,
20.0 µmol)
and
NaBArF (17.7 mg, 20.0 µmol) were dissolved in 2.0 ml with water-
saturated DCM. After 10 min ([1,1'-biphenyl]-4-ylbuta-1,3-diyn-1-
yl)trimethylsilane 14b (110 mg, 400 mol), 2,5-dimethylfuran (85.3 µl,
800 mol) and 2.0 ml with water-saturated DCM were added. After 36 h TLC monitoring showed
complete conversion. Column chromatography (SiO2, PE:EA 200:1) delivered 2-([1,1'-biphenyl]-4-yl)-
4,7-dimethylbenzofuran 16b as white powder (40.5 mg, 136 mol, 34%).
Rf (PE:EA, 5:1) = 0.56; 1H NMR (CD2Cl2, 500 MHz): δ = 2.53 (s, 3H), 2.57 (s, 3H), 6.95 (d, J = 7.5 Hz,
1H), 7.01 (d, J = 7.5 Hz, 1H), 7.13 (s, 1H), 7.37 – 7.40 (m, 1H), 7.46 – 7.50 (m, 2H), 7.67 – 7.69 (m,
2H), 7.71 – 7.74 (m, 2H), 7.97 – 7.99 (m, 2H) ppm; 13C NMR (CD2Cl2, 125 MHz): δ = 14.9 (q), 18.5 (q),
100.9 (d), 119.0 (s), 123.6 (d), 125.5 (d, 2C), 125.6 (d), 127.3 (d, 2C), 127.8 (d, 2C), 128.0 (d), 128.6
(s), 128.8 (s), 129.3 (d, 2C), 130.1 (s), 140.7 (s), 141.3 (s), 154.1 (s), 155.1 (s) ppm; IR (ATR)
=
3035, 2917, 2859, 2733, 1953, 1916, 1850, 1675, 1598, 1580, 1523, 1506, 1484, 1450, 1409, 1388,
1378, 1349, 1325, 1289, 1250, 1180, 1117, 1079, 1047, 1031, 1015, 976, 947, 912, 843, 829, 807,
765, 751, 722, 692, 661, 619 cm-1; HR-MS (EI+): found: m/z = 298.1350, calc. for C22H18O [M]+:
298.1358.
2-(4-Methoxyphenyl)-4,7-dimethylbenzofuran 16c
According to GP5 IPr*AuCl (22.8 mg, 20.0 µmol) and NaBArF (17.7 mg,
20.0 µmol) were dissolved in 2.0 ml with water-saturated DCM. After 10
min ((4-methoxyphenyl)buta-1,3-diyn-1-yl)trimethylsilane 14c (91.3 mg,
400 mol), 2,5-dimethylfuran (85.3 µl, 800 mol) and 2.0 ml with water-
saturated DCM were added. After 48 h TLC monitoring showed complete conversion. Column
chromatography (SiO2, PE:EA 200:1) delivered 2-(4-methoxyphenyl)-4,7-dimethylbenzofuran 16c as
yellow powder (19.2 mg, 76.2 mol, 19%).
Rf (PE:EA, 5:1) = 0.56; 1H NMR (CD2Cl2, 500 MHz): δ = 2.49 (s, 3H), 2.53 (s, 3H), 3.86 (s, 3H), 6.91
(d, J = 7.5 Hz, 1H), 6.94 (s, 1H), 6.96 (d, J = 7.5 Hz, 1H), 6.98 – 7.01 (m, 2H), 7.82 – 7.85 (m, 2H)
ppm; 13C NMR (CD2Cl2, 125 MHz): δ = 14.9 (q), 18.5 (q), 55.7 (q), 99.0 (d), 114.6 (d, 2C), 118.7 (s),

123.4 (d), 123.9 (s), 125.0 (d), 126.5 (d, 2C), 128.2 (s), 129.0 (s), 153.7 (s), 155.5 (s), 160.3 (s) ppm;
IR (ATR) = 3122, 3056, 3009, 2974, 2921, 2864, 2842, 2736, 2042, 1897, 1850, 1735, 1657, 1614,
1589, 1517, 1499, 1459, 1440, 1425, 1389, 1378, 1320, 1306, 1285, 1246, 1182, 1173, 1152, 1111,
1081, 1043, 1025, 1008, 977, 948, 913, 835, 800, 752, 660 cm-1; HR-MS (EI+): found: m/z = 252.1158,
calc. for C17H16O2 [M]+: 252.1150.
4,7-Di(n-butyl)-2-phenylbenzofuran 16d
According to GP5 IPr*AuCl (22.8 mg, 20.0 µmol) and NaBArF (17.7 mg,
20.0 µmol) were dissolved in 2.0 ml with water-saturated DCM. After 10
min (phenyl-buta-1,3-diyn-1-yl)trimethylsilane 14a (79.2 mg, 400 mol),
2,5-di(n-butyl)furan (144 mg, 800 mol) and 2.0 ml with water-saturated
DCM were added. After 70 h TLC monitoring showed complete
conversion. Column chromatography (SiO2, PE) delivered 4,7-di(n-butyl)-
2-phenylbenzofuran 16d as yellow oil (32.7 mg, 107 mol, 27%).
Rf (PE:EA, 10:1) = 0.45; 1H NMR (CD2Cl2, 500 MHz): δ = 0.97 (t, J = 7.4 Hz, 3H), 0.99 (t, J = 7.4 Hz,
3H), 1.39 – 1.48 (m, 4H), 1.67 – 1.73 (m, 2H), 1.75 – 1.81 (m, 2H), 2.84 (t, J = 7.7 Hz, 2H), 2.94 (t, J =
7.7 Hz, 2H), 6.96 (d, J = 7.5 Hz, 1H), 7.02 (d, J = 7.5 Hz, 1H), 7.10 (s, 1H), 7.36 (t, J = 7.4 Hz, 1 H),
7.47 (t, J = 7.4 Hz, 1H), 7.90 (d, J =7.4 Hz, 1H) ppm; 13C NMR (CD2Cl2, 125 MHz): δ = 14.1 (q), 14.2
(q), 23.0 (t), 23.1 (t), 29.7 (t), 32.6 (t), 33.2 (t), 33.5 (t), 100.7 (d), 122.8 (d), 124.1 (s), 124.7 (d), 125.1
(d, 2C), 128.4 (s), 128.7 (d), 129.2 (d, 2C), 131.2 (s), 133.8 (s), 153.9 (s), 155.2 (s) ppm; IR (reflection)
= 3039, 2956, 2929, 2858, 1944, 1872, 1608, 1566, 1509, 1487, 1465, 1448, 1396, 1377, 1359,
1337, 1277, 1235, 1172, 1138, 1104, 1071, 1042, 1024, 913, 876, 807, 755, 688, 662 cm-1; HR-MS
(EI+): found: m/z = 306.1988, calc. for C22H26O [M]+: 306.1984.

5 1H NMR and 13C NMR spectra

I
O