Unprecedented Negishi coupling at C-Br in the presence of a stannyl group as a convenient approach to pyridinylstannanes and their application in liquid crystal synthesis

Article abstract of DOI:10.1021/jo701812t

(Chemical Equation Presented) The 2-bromo-5(or 6)-tri-n- butylstannylpyridines, prepared from dibromopyridines and i-PrMgCl at room temperature, undergo Negishi coupling with either alkyl or arylzinc chlorides. The new alkyl- and aryl-substituted pyridylstannanes produced are shown to be suitable for further functionalization by Stille coupling. A group of new liquid crystalline materials with aromatic cores comprised of pyridine and thiophene rings were prepared utilizing these new pyridinylstannanes as key intermediates.

Full text of DOI:10.1021/jo701812t

Supporting Information for
Unprecedented Negishi coupling at C-Br in the presence of a stannyl group
as a convenient approach to pyridinylstannanes and their application in
liquid crystal synthesis
Y. A. Getmanenko, R. J. Twieg
Department of Chemistry
Kent State University
Kent, OH 44242 USA
rtwieg@lci.kent.edu
Table of Contents
1. Synthesis of 2-alkyl-5-tri-n-butylstannylpyridines 6b-e
1.1. 2-n-Hexyl-5-(tri-n-butylstannyl)-pyridine (6b)
1.2. 2-n-Nonyl-5-(tri-n-butylstannyl)-pyridine (6c)
1.3. 2-n-Decyl-5-(tri-n-butylstannyl)-pyridine (6d)
1.3.1.Synthesis of 6d from 2-n-decyl-5-bromopyridine (7a)
1.3.2. Synthesis of 6d from 2-bromo-5-(tri-n-butylstannyl)-pyridine (1)
1.4. 2-n-Tridecyl-5-(tri-n-butylstannyl)-pyridine (6e)
2. 2-n-Decyl-5-bromopyridine (7a)
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3. Preparation of 2-(5-n-alkylthien-2-yl)-5-(tri-n-butylstannyl)-pyridines 8b,c
3.1. 2-(5-n-Nonylthien-2-yl)-5-(tri-n-butylstannyl)-pyridine (8b)
3.2. 2-(5-n-Tridecylthien-2-yl)-5-(tri-n-butylstannyl)-pyridine (8c)
4. Preparation of 2-alkylthiophenes 9a-d and 2-bromo-5-alkylthiophenes 10a-d
4.1. 2-n-Heptylthiophene (9a)
4.2. 2-n-Nonylthiophene (9b)
4.3. 2-n-Tridecylthiophene (9c)
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4.4. 2-n-Undecylthiophene (9d)
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4.5. 2-Bromo-5-n-heptylthiophene (10a)
4.6. 2-Bromo-5-n-nonylthiophene (10b)
4.7. 2-Bromo-5-n-tridecylthiophene (10c)
4.8. 2-Bromo-5-n-undecylthiophene (10d)
5. 1-n-Heptyloxy-4-bromobenzene (12)
6. Preparation of 3-alkylpyridines 13a-c
6.1. 3-n-Hexylpyridine (13a)
6.2. 3-n-Octylpyridine (13b)
6.3. 3-n-Decylpyridine (13c)
7. Synthesis of 2-tri-n-butylstannyl-5-alkylpyridines 14a,c
7.1. 2-Tri-n-butylstannyl-5-n-hexylpyridine (14a)
7.2. 2-Tri-n-butylstannyl-5-n-decylpyridine (14c)
8.1 2-n-Pentyl-6-(tri-n-butylstannyl)-pyridine (15a)
8.2. 2-n-Decyl-6-(tri-n-butylstannyl)-pyridine (15b)
9.1 6-(5-n-Tridecylthien-2-yl)-2-(tri-n-butylstannyl)-pyridine (16)
9.2. Isolation of 17: protio-de-stannylation of 6-(5-n-tridecylthien-2-yl)-2-(tri-n-
butylstannyl)-pyridine (16)
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10. Stille coupling of pyridinyl stannanes with aryl halides
10.1. 2,5-Bis-(2-n-tridecylpyridin-5-yl)-thiophene (18)
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10.2. Preparation of 2,5-bis-(2-(5-nonylthiophen-2-yl)-pyridin-5-yl)-thiophene (19) S33
10.3. Scheme 1. Three synthetic approaches evaluated for the preparation
of terpyridine liquid crystal 20
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10.4. 2,5-Di-(2-n-hexylpyridin-5-yl)-pyridine (20)
10.5. 2,5-Di-(2-n-hexylpyridin-5-yl)-pyridine (20): Negishi coupling
of 2,5-dibromopyridine (4) with 2-n-hexylpyridin-5-ylzinc chloride
10.6. 2,5-Di-(2-n-hexylpyridin-5-yl)-pyridine (20): Negishi coupling of
2-bromo-5-iodopyridine (22) with 2-n-hexyl-pyridin-5-ylzinc chloride
10.7. 2,5-Di-(5-n-hexylpyridin-2-yl)-pyridine (23)
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10.8. Preparation of thiophene-bypyridine LCs 26a,b
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10.8.1. Scheme 2. Stille coupling of 2-n-decyl-5-tri-n-butylstannylpyridine (6d)
with aryl halides 25 producing thiophene-bipyridine liquid crystals 26a,b
10.8.2. 2-(5-n-Nonylthiophen-2-yl)-5-bromopyridine (25a)
10.8.3. 5-Bromo-2-(5-n-undecylthien-2-yl)-pyridine (25b)
10.8.4. 6'-n-Decyl-6-(5-n-nonylthiophen-2-yl)-[3,3']-bipyridinyl (26a)
10.9. 5-Heptyl-6'-(4-heptyloxy-phenyl)-[2,3']-bipyridinyl (27)
10.10. 2-(5-n-Nonylthiophen-2-yl)-5-(5-n-undecylthiophen-2-yl)-pyridine (29)
10.11. 6-(5-n-Tridecylthiophen-2-yl)-6'-(5-n-undecylthiophen-2-yl)-
[3,3']-bipyridinyl (30)
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10.12. 2,5-Di-(6-n-pentylpyridin-2-yl)-thiophene (31)
10.13. 5,5’-Bis-(6-n-decylpyridin-2-yl)-2,2’-bithiophene (33)
11. 5,5’-Dibromo-2,2’-bithiophene (32)
12. Figure 1. DSC analysis of terpyridine LC 20: enlarged region with weak
1st/2nd order transitions (marked as 1, 2, and 3)
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13. Figure 2. DSC thermogram of terpyridine 23
14. NMR spectra of the synthesized materials
14.1. 1H NMR spectrum of 2-bromo-5-(tri-n-butylstannyl)-pyridine (1)
14.2. 13C NMR spectrum of 2-bromo-5-(tri-n-butylstannyl)-pyridine (1)
14.3. 1H NMR spectrum of 2-bromo-6-(tri-n-butylstannyl)-pyridine (2)
14.4. 13C NMR spectrum of 2-bromo-6-(tri-n-butylstannyl)-pyridine (2)
14.5. 1H NMR spectrum of 2-(tri-n-butylstannyl)-5-bromopyridine (3)
14.6. 13C NMR spectrum of 2-(tri-n-butylstannyl)-5-bromopyridine (3)
14.7. 1H NMR spectrum of 2-n-pentyl-5-(tri-n-butylstannyl)-pyridine (6a)
14.8. 13C NMR spectrum of 2-n-pentyl-5-(tri-n-butylstannyl)-pyridine (6a)
14.9. 1H NMR spectrum of 2-n-hexyl-5-(tri-n-butylstannyl)-pyridine (6b)
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14.10. 13C NMR spectrum of 2-n-hexyl-5-(tri-n-butylstannyl)-pyridine (6b)
14.11. 1H NMR spectrum of 2-n-nonyl-5-(tri-n-butylstannyl)-pyridine (6c)
14.12. 13C NMR spectrum of 2-n-nonyl-5-(tri-n-butylstannyl)-pyridine (6c)
14.13. 1H NMR spectrum of 2-n-decyl-5-(tri-n-butylstannyl)-pyridine (6d)
14.14. Aromatic region of 1H NMR spectrum of 2-n-decyl-5-(tri-n-butylstannyl)-
pyridine (6d)
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14.15. 13C NMR spectrum of 2-n-decyl-5-(tri-n-butylstannyl)-pyridine (6d)
14.16. 1H NMR spectrum of 2-n-tridecyl-5-(tri-n-butylstannyl)-pyridine (6e)
14.17. Aromatic region of 1H NMR spectrum of 2-n-tridecyl-5-(tri-n-butylstannyl)-
pyridine (6e)
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14.18. 13C NMR spectrum of 2-n-tridecyl-5-(tri-n-butylstannyl)-pyridine (6e)
14.19. 1H NMR spectrum of 2-n-decyl-5-bromopyridine (7a)
14.20. Aromatic region of 1H NMR spectrum 2-n-decyl-5-bromopyridine (7a)
14.21. 1H NMR spectrum of 2-(5-n-heptylthien-2-yl)-5-(tri-n-butylstannyl)-
pyridine (8a)
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14.22. Aromatic region of 1H NMR spectrum of 2-(5-n-heptylthien-2-yl)-5-
(tri-n-butylstannyl)-pyridine (8a)
14.23. 13C NMR spectrum of 2-(5-n-heptylthien-2-yl)-5-(tri-n-butylstannyl)-
pyridine (8a)
14.24. 1H NMR spectrum of 2-(5-n-nonylthien-2-yl)-5-(tri-n-butylstannyl)-
pyridine (8b)
14.25. Aromatic region of 1H NMR spectrum of 2-(5-n-nonylthien-2-yl)-
5-(tri-n-butylstannyl)-pyridine (8b)
14.26. 13C NMR spectrum of 2-(5-n-nonylthien-2-yl)-5-(tri-n-butylstannyl)-
pyridine (8b)
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14.27. 1H NMR spectrum of 2-(5-n-tridecylthien-2-yl)-5-(tri-n-butylstannyl)-
pyridine (8c)
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14.28. 13C NMR spectrum of 2-(5-n-tridecylthien-2-yl)-5-(tri-n-butylstannyl)-
pyridine (8c)
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14.29. 1H NMR spectrum of 2-bromo-5-n-tridecylthiophene (10c)
14.30. 13C NMR spectrum of 2-bromo-5-n-tridecylthiophene (10c)
14.31. 1H NMR spectrum of 2-(4-n-heptyloxyphenyl)-5-(tri-n-butylstannyl)-
pyridine (11)
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14.32. 13C NMR spectrum of 2-(4-n-heptyloxyphenyl)-5-(tri-n-butylstannyl)-
pyridine (11)
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14.33. 1H NMR spectrum of 2-tri-n-butylstannyl-5-n-hexylpyridine (14a)
14.34. 13C NMR spectrum of 2-tri-n-butylstannyl-5-n-hexylpyridine (14a)
14.35. 1H NMR spectrum of 2-tri-n-butylstannyl-5-n-octylpyridine (14b)
14.36. 1H NMR spectrum of 2-tri-n-butylstannyl-5-n-decylpyridine (14c)
14.37. 13C NMR spectrum of 2-tri-n-butylstannyl-5-n-decylpyridine (14c)
14.38. 1H NMR spectrum of 2-n-pentyl-6-(tri-n-butylstannyl)-pyridine (15a)
14.39. Aromatic region of 1H NMR spectrum of 2-n-pentyl-6-
(tri-n-butylstannyl)-pyridine (15a)
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14.40. 13C NMR spectrum of 2-n-pentyl-6-(tri-n-butylstannyl)-pyridine (15a)
14.41. 1H NMR spectrum of 2-n-decyl-6-(tri-n-butylstannyl)-pyridine (15b)
14.42. Aromatic region of 1H NMR spectrum of 2-n-decyl-6-(tri-n-butylstannyl)-
pyridine (15b)
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14.43. 13C NMR spectrum of 2-n-decyl-6-(tri-n-butylstannyl)-pyridine (15b)
14.44. 1H NMR spectrum of 6-(5-n-tridecylthien-2-yl)-2-(tri-n-butylstannyl)-
pyridine (16)
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14.45. Aromatic region of 1H NMR spectrum of 6-(5-n-tridecylthien-2-yl)-
2-(tri-n-butylstannyl)-pyridine (16)
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14.46. 13C NMR spectrum of 6-(5-n-tridecylthien-2-yl)-2-(tri-n-butylstannyl)-
pyridine (16)
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14.47. 1H NMR spectrum of 2-(5-tridecylthiophen-2-yl)-pyridine (17)
14.48. Aromatic region of 1H NMR spectrum of 2-(5-tridecylthiophen-2-yl)-
pyridine (17)
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14.49. 13C NMR spectrum of -(5-tridecylthiophen-2-yl)-
pyridine (17)
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14.50. 1H NMR spectrum of 2,5-bis-(2-n-tridecylpyridin-5-yl)-thiophene (18)
14.51. Aromatic region of 1H NMR spectrum of 2,5-bis-(2-n-tridecylpyridin-
5-yl)-thiophene (18)
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14.52. 13C NMR spectrum of 2,5-bis-(2-n-tridecylpyridin-5-yl)-thiophene (18)
14.53. 1H NMR spectrum of 2,5-bis-(2-(5-nonylthiophen-2-yl)-pyridin-5-yl)-
thiophene (19)
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14.54. 13C NMR spectrum of 2,5-bis-(2-(5-nonylthiophen-2-yl)-pyridin-5-yl)-
thiophene (19)
14.55. Aromatic region of 13C NMR spectrum of 2,5-bis-(2-(5-nonylthiophen-
2-yl)-pyridin-5-yl)-thiophene (19)
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14.56. 1H NMR spectrum of 2,5-di-(2-n-hexylpyridin-5-yl)-pyridine (20)
14.57. Aromatic region of 1H NMR spectrum of 2,5-di-(2-n-hexylpyridin-5-yl)-
pyridine (20)
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14.58. 13C NMR spectrum of 2,5-di-(2-n-hexylpyridin-5-yl)-pyridine (20)
14.59. Aromatic region of 13C NMR spectrum of 2,5-di-(2-n-hexylpyridin-5-yl)-
pyridine (20)
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14.60. 1H NMR spectrum of 2,5-di-(5-n-hexylpyridin-2-yl)-pyridine (23)
14.61. Aromatic region of 1H NMR spectrum of 2,5-di-(5-n-hexylpyridin-2-yl)-
pyridine (23)
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14.62. 13C NMR spectrum of 2,5-di-(5-n-hexylpyridin-2-yl)-pyridine (23)
14.63. Aromatic region of 13C NMR spectrum of 2,5-di-(5-n-hexylpyridin-2-yl)-
pyridine (23)
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14.64. 1H NMR spectrum of 2-(5-n-nonylthiophen-2-yl)-5-bromopyridine (25a)
14.65. 13C NMR spectrum of 2-(5-n-nonylthiophen-2-yl)-5-bromopyridine (25a)
14.66. 1H NMR spectrum of 5-bromo-2-(5-n-undecylthien-2-yl)-pyridine (25b)
14.67. 1H NMR spectrum of 6'-n-decyl-6-(5-n-nonylthiophen-2-yl)-[3,3']-
bipyridinyl (26a)
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14.68. Aromatic region of 1H NMR spectrum of 6'-n-decyl-6-
(5-n-nonylthiophen-2-yl)-[3,3']-bipyridinyl (26a)
14.69. 13C NMR spectrum of 6'-n-decyl-6-(5-n-nonylthiophen-2-yl)-[3,3']-
bipyridinyl (26a)
14.70. 1H NMR spectrum of 6'-decyl-6-(5-undecylthiophen-2-yl)-[3,3']-
bipyridinyl (26b)
14.71. Aromatic region of 1H NMR spectrum of 6'-decyl-6-
(5-undecylthiophen-2-yl)-[3,3']-bipyridinyl (26b)
14.72. 13C NMR spectrum of 6'-decyl-6-(5-undecylthiophen-2-yl)-[3,3']-
bipyridinyl (26b)
14.73. 1H NMR spectrum of 5-heptyl-6'-(4-heptyloxy-phenyl)-[2,3']-bipyridinyl (27) S91
14.74. Aromatic region of 1H NMR spectrum of 5-heptyl-6'-(4-heptyloxy-
phenyl)-[2,3']-bipyridinyl (27)
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14.75. 1H NMR spectrum of 2-(5-n-nonylthiophen-2-yl)-5-(5-n-undecylthiophen-
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2-yl)-pyridine (29)
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14.76. Aromatic region of 1H NMR spectrum of 2-(5-n-nonylthiophen-2-yl)-
5-(5-n-undecylthiophen-2-yl)-pyridine (29)
14.77. 13C NMR spectrum of 2-(5-n-nonylthiophen-2-yl)-5-(5-n-undecylthiophen-
2-yl)-pyridine (29)
14.78. 1H NMR spectrum of 6-(5-n-tridecylthiophen-2-yl)-6'-(5-n-undecylthiophen-
2-yl)-[3,3']-bipyridinyl (30)
14.79. Aromatic region of 1H NMR spectrum of 6-(5-n-tridecylthiophen-2-yl)-
6'-(5-n-undecylthiophen-2-yl)-[3,3']-bipyridinyl (30)
14.80. 13C NMR spectrum of 6-(5-n-tridecylthiophen-2-yl)-6'-
(5-n-undecylthiophen-2-yl)-[3,3']-bipyridinyl (30)
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14.81. 1H NMR spectrum of 2,5-di-(6-n-pentylpyridin-2-yl)-thiophene (31)
14.82. 13C NMR spectrum of 2,5-di-(6-n-pentylpyridin-2-yl)-thiophene (31)
14.83. 1H NMR spectrum of 5,5’-bis-(6-n-decylpyridin-2-yl)-2,2’-bithiophene (33) S97
14.84. Aromatic region of 1H NMR spectrum of 5,5’-bis-(6-n-decylpyridin-2-yl)-
2,2’-bithiophene (33)
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14.85. 13C NMR spectrum of 5,5’-bis-(6-n-decylpyridin-2-yl)-2,2’-bithiophene (33) S98
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Synthesis of 2-alkyl-5-(tri-n-butylstannyl)-pyridines 6b-e
RZnCl
Pd(PPh3)4, rt
Bu3Sn
R
Bu3Sn
Br
N
N
6b-e
1
2-n-Hexyl-5-(tri-n-butylstannyl)-pyridine (6b). An alkyl Grignard was prepared from 1-
bromohexane (1.5 equiv., 0.0266 mol, 4.39g) and Mg turnings (0.0319 mol, 0.78 g) in 25 ml
of anhydrous THF. This freshly prepared Grignard was added dropwise to the solution of
ZnCl2 (0.0319 mol, 4.35 g) in 32 ml of anhydrous THF (ice-water bath). A white precipitate
formed after several minutes of stirring, and the reaction mixture was stirred for an additional
hour at room temperature. Next, 2-bromo-5-(tri-n-butylstannyl)-pyridine (1) (0.0177 mol,
7.92 g), Pd(PPh3)4 (0.5 mol%, 0.0885 mmol, 0.10 g) and 20ml of anhydrous THF were mixed
in an oven-dried three-necked flask under a nitrogen atmosphere (clear yellow solution
formed), and n-hexylzinc chloride solution (47 ml, 1.25 equiv.) was added dropwise via
syringe to the yellow reaction mixture. The light yellow reaction mixture with a white
precipitate was stirred overnight, transferred to another round bottom flask, and the solvent
was removed by rotary evaporation. The residue was treated with 50 ml of water and 50 ml
of petroleum ether, and the resulting mixture was vacuum filtered to remove insoluble matter.
The organic phase was separated and the aqueous phase was extracted with petroleum ether
(4×25 ml). The combined organic phases were dried with brine, then over MgSO4 and after
filtration the solvent was removed by rotary evaporation to give 8.10 g of crude material.
The product was purified by Kugelrohr distillation (150-164 ºC/0.055-0.065 mm Hg), and the
desired material was isolated as yellow oil in 74.3% yield (5.95 g). MS analysis (APCI):
454.19, 456.63 (calculated FW 453.2417). FT-IR (cm-1): 3061, 2957, 2927, 2865, 2853,
1
1572, 1542, 1462, 1377, 1344, 1086, 1072, 1015, 877, 862, 816, 692. H NMR (CDCl3, 400
MHz): δ 0.84-0.91 (t, J=7.16 Hz, 12H), 1.03-1.10 (m, 6H), 1.24-1.40 (m, 12H), 1.50-1.60 (m,
6H), 1.64-1.77 (m, 2H), 2.71-2.78 (t, J=7.85 Hz, 2H), 7.07-7.12 (dd, J=7.66 Hz, 0.65 Hz,
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1H), 7.63-7.67 (dd, J=7.49 Hz, 1.66 Hz, 1H), 8.48-8.55 (s, 1H); 13C NMR (CDCl3, 100
MHz): δ 9.55, 13.64, 14.07, 22.58, 27.32, 29.02, 29.16, 29.84, 31.73, 38.41, 122.86 (CH),
132.87 (quaternary C), 144.31 (CH), 155.47 (CH), 161.82 (quaternary C).
2-n-Nonyl-5-(tri-n-butylstannyl)-pyridine (6c). An alkyl Grignard was prepared from 1-
bromononane (0.0225 mol, 4.66 g) and Mg turnings (0.027 mol, 0.65 g) in 25 ml of
anhydrous THF. This freshly prepared Grignard was added dropwise to the solution of ZnCl2
(0.027 mol, 4.41 g) in 30 ml of anhydrous THF (ice-water bath). A white precipitate formed,
and the reaction mixture was stirred for additional hour under room temperature conditions.
2-Bromo-5-(tri-n-butylstannyl)-pyridine (1) (0.015 mol, 6.70 g), Pd(PPh3)4 (0.5 mol%, 0.075
mmol, 0.087 g) and 30 ml of anhydrous THF were mixed in an oven-dried three-necked flask
under nitrogen atmosphere (clear yellow solution formed), and n-nonylzinc chloride solution
was added dropwise via syringe to the bright yellow reaction mixture. After addition of the
n-nonylzinc chloride the mixture became light yellow with white precipitate and warm to the
touch. After addition of 44 ml of n-nonylzinc chloride (1.5 equivalent in 55 ml of THF was
prepared) and stirring for an hour the 2-bromo-5-(tri-n-butylstannyl)-pyridine (1) was
consumed (analyzed by TLC, CH2Cl2 + several drops of EtOAc as eluant), and the reaction
mixture was quenched with 25 ml of water. Organic solvents were removed by rotary
evaporation, 50 ml of hexanes was added and the resulting mixture was vacuum filtered to
remove white insoluble matter. The organic phase was separated, and the aqueous phase was
extracted with hexanes (2×50 ml, then 3×25 ml). The combined organic phases were dried
with brine and then over MgSO4. The solvent was removed by rotary evaporation and the
yellowish cloudy oil was chromatographed (225 g of silica gel, CH2Cl2 first, then
CH2Cl2:EtOAc=50:1). The product was isolated in 46.6% yield (73-75% reaction yield).
MS (APCI): 494.1, 496.1 (with satellites at 492.1, 493.1, 495.1) (calculated FW 495.2887).
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FT-IR (cm-1): 3061, 2957, 2924, 2870, 2853, 1572, 1542, 1462, 1377, 1344, 1067, 1015, 862,
1
691. H NMR (CDCl3, 400 MHz): δ 0.83-0.91 (m, 12H), 1.03-1.10 (m, 6H), 1.20-1.40 (m,
18H), 1.48-1.60 (m, 6H), 1.63-1.74 (m, 2H), 2.67-2.80 (m, 2H), 7.07-7.12 (dd, J=7.54 Hz,
0.84 Hz, 1H), 7.62-7.66 (dd, J=7.51 Hz, 1.62 Hz, 1H), 8.47-8.53 (m, 1H); 13C NMR (CDCl3,
75 MHz): δ 9.56, 13.66, 14.12, 22.69, 27.33, 29.03, 29.32, 29.51, 29.53, 29.89, 31.90, 38.44,
122.87 (CH), 132.88 (quaternary C), 144.31 (CH), 155.50 (CH), 161.85 (quaternary C).
2-n-Decyl-5-(tri-n-butylstannyl)-pyridine (6d)
Synthesis of 6d from 2-n-decyl-5-bromopyridine (7a)
1) n-BuLi, -72 ºC
THF-hexanes
Br
C10H21
Bu3Sn
C10H21
2) n-Bu3SnCl
-70 ºC, 15 min;
rt, 2 hours
N
N
7a
6d
(R= n-C10H21)
An oven-dried three-necked flask was charged with 2-n-decyl-5-bromopyridine (7a) (9.05
mmol, 2.70 g) and 60 ml of anhydrous THF. The reaction mixture was cooled in an
acetone/CO2 bath, and n-BuLi (2.5M in hexanes, 9.05 mmol, 3.62 ml) was added dropwise to
the suspension of white solid (the starting material precipitated upon cooling). The reaction
mixture turned yellow, and then orange during addition of n-BuLi (the internal temperature
was kept at –73–72 ºC). The red mixture was stirred for about half an hour, analyzed by TLC
(CH2Cl2 as eluant, several drops of the reaction mixture was quenched with water, the
organic matter was extracted with hexanes and analyzed) and a solution of tri-n-butyltin
chloride (9.05 mmol, 2.95 g) in 8 ml of anhydrous THF was added dropwise (the internal
temperature was kept at –70 ºC). The red reaction mixture became lighter in color during
addition of tri-n-butyltin chloride, and turned light yellow-orange after completion of
addition. The reaction was stirred for 15 minutes, the cooling bath was removed and the
mixture was warmed to room temperature. After stirring for two and a half hours the clear
S11

orange mixture was quenched with 15 ml of water and the organic solvent was removed by
rotary evaporation. The organic matter was extracted with diethyl ether (50 ml, and 2×15
ml). The combined organic phases were washed with brine and then dried over MgSO4. The
solvent was removed by rotary evaporation and the orange-brown oil (4.80 g, ~80% purity by
NMR) was purified by column chromatography. Crude material (2.50 g) was applied to the
top of the column (50 g of silica gel) and the product was eluted CH2Cl2 first, then with
CH2Cl2:EtOAc~50:1. The purified material was isolated as yellowish oil (1.95 g, 74%
recovery, 77.2% reaction yield). The product can be further purified by Kugelrohr distillation
(140 ºC/0.15 mm Hg). MS (APCI): 509.0, 510.6 (calculated FW 509.3043). 1H NMR
(CDCl3, 400 MHz): δ 0.85-0.91 (m, 12H), 1.03-1.11 (m, 6H), 1.22-1.40 (m, 20H), 1.48-1.58
(m, 6H), 1.68-1.76 (m, 2H), 2.71-2.76 (m, 2H), 7.06-7.12 (dd, J=7.55 Hz, 0.82 Hz, 1H), 7.61-
13
7.68 (dd, J=7.51 Hz, 1.63 Hz, 1H), 8.48-8.53 (m, 1H); C NMR (CDCl3, 75 MHz): δ 9.55,
13.64, 14.11, 22.69, 27.32, 29.03, 29.33, 29.51, 29.52, 29.58, 29.61, 29.89, 31.91, 38.42,
122.86 (CH), 132.86 (quaternary C), 144.30 (CH), 155.48 (CH), 161.84 (quaternary C).
Synthesis of 6d from 2-bromo-5-(tri-n-butylstannyl)-pyridine (1)
An alkyl Grignard was prepared from 1-bromodecane (0.0105 mol, 2.32 g) and Mg
turnings (0.0126 mol, 0.31 g) in 10 ml of anhydrous THF. This freshly prepared Grignard
was added dropwise to the solution of ZnCl2 (0.0126 mol, 1.72 g) in 12 ml of anhydrous THF
(ice-water bath). Precipitation took place after several minutes of stirring, and the reaction
mixture was stirred for additional hour under room temperature conditions. 2-Bromo-5-(tri-n-
butylstannyl)-pyridine (1) (0.007 mol, 3.13 g), Pd(PPh3)4 (1 mol%, 0.07 mmol, 0.081 g) and
20 ml of anhydrous THF were mixed in an oven-dried three-necked flask under nitrogen, and
n-decylzinc chloride solution was added dropwise via syringe to the yellow reaction mixture.
After addition of the n-decylzinc chloride the mixture turned orange for several seconds, but
S12

then the color changed back to yellowish (the mixture is cloudy; the initial n-decylzinc
chloride had lots precipitate in it). After addition of 25 ml of n-decylzinc chloride (32 ml was
the initial volume) and stirring for 35 minutes all the starting material was consumed
(analyzed by TLC, CH2Cl2:hexanes=2:1 as eluant), and the reaction mixture was quenched
with 20 ml of water. Organic solvents were removed by rotary evaporation, 50 ml of hexanes
was added and the resulting mixture was vacuum filtered to remove white insoluble matter.
The organic phase was separated and the aqueous phase was extracted with hexanes (50 ml,
then 4×25 ml). The combined organic phases were dried over MgSO4, the solvent was
removed by rotary evaporation, and the yellowish cloudy oil was chromatographed (100 g of
silica gel, CH2Cl2 first, then CH2Cl2:EtOAc=30:1). The yellowish oil was isolated in 79.4%
yield (2.72 g).
The NMR analysis matched the analysis of 2-n-decyl-5-tri-n-
butylstannylpyridine (6d) synthesized by a different method, described above.
2-n-Tridecyl-5-(tri-n-butylstannyl)-pyridine (6e). An alkyl Grignard was prepared from 1-
bromotridecane (0.0225 mol, 5.92 g), Mg turnings (0.027 mol, 0.66) in 22.5 ml of anhydrous
THF. This freshly prepared Grignard was added dropwise to the solution of dried ZnCl2
(0.027 mol, 3.68 g) in 22 ml of anhydrous THF (ice-water bath). White precipitate formed
after several minutes of stirring, and the reaction mixture was stirred for additional hour
under room temperature conditions. 2-Bromo-5-(tri-n-butylstannyl)-pyridine (1) (0.015 mol,
6.71 g), Pd(PPh3)4 (0.5 mol%, 0.075 mmol, 0.087 g) and 30ml of anhydrous THF were mixed
in an oven-dried three-necked flask under a nitrogen atmosphere (a clear yellow solution
formed), and n-tridecylzinc chloride solution (48 ml, 1.3 equiv.) was added dropwise via
syringe to the yellow reaction mixture. The light yellow reaction mixture with white
precipitate was stirred overnight, transferred to the round bottom flask, and the solvent was
removed by rotary evaporation. The residue was treated with 25 ml of water and 50 ml of
S13

petroleum ether, and the resulting mixture was vacuum filtered to remove insoluble mater.
The organic phase was removed and the aqueous phase was extracted with petroleum ether
(3×25 ml). The combined organic phases were dried with brine, and then over dried over
MgSO4, and the solvent was removed by rotary evaporation to give 10.3 g of crude material.
After storage of the crude material in the refrigerator some solid formed. A Kugelrohr
distillation was attempted (150-158 ºC/0.095 mm Hg), but it was very slow on a big scale
(and higher pressure of 0.12 mm Hg) and was accompanied by decomposition. The
distillation was terminated and the residual material was chromatographed (75 g of silica gel,
CH2Cl2:EtOAc=50:1 as eluant) and a light yellow oil was isolated in 42.6% yield (3.60 g).
The reaction was repeated with omission of the Kugelrohr distillation and in this case the
material was isolated in 65.4% yield using only column chromatography (silica gel, CH2Cl2,
then CH2Cl2:EtOAc=50:1) as a purification step. MS (APCI): 550.2, 552.1 (calculated FW
1
551.3513). H NMR (CDCl3, 300 MHz): δ 0.85-0.90 (t, J=7.28 Hz, 12H), 1.02-1.10 (m, 6H),
1.20-1.40 (m, 26H), 1.50-1.61 (m, 6H), 1.65-1.78 (m, 2H), 2.70-2.77 (t, 2H), 7.08-7.12 (d,
13
J=7.50 Hz, 1H), 7.60-7.68 (dd, J=7.47 Hz, 1.58 Hz, 1H), 8.50-8.53 (d, J=0.75 Hz, 1H); C
NMR (CDCl3, 75 MHz): δ 9.70, 13.79, 14.27, 22.85, 27.09, 29.04, 29.18, 29.31, 29.51,
29.68, 29.73, 30.04, 32.08, 38.56, 123.02 (CH), 133.03 (quaternary C), 144.47 (CH), 155.61
(CH), 161.98 (quaternary C).
2-n-Decyl-5-bromopyridine (7a). A Grignard reagent was prepared from 1-bromodecane
(0.03525 mol, 7.79 g) and Mg turnings (0.0423 mol, 1.03 g) in 40 ml of anhydrous THF.
This freshly prepared n-decylmagnesium bromide was added dropwise to a flask containing
ZnCl2 (0.0423 mol, 5.76 g) in 40 ml of anhydrous THF (ice-water cooling bath) and a white
precipitate was obtained. The cooling bath was removed and the reaction mixture with a
considerable amount of white precipitate was stirred for 1h. The resulting n-decylzinc
S14

chloride (55 ml, 0.024 mol, 1.2 equiv.) was added dropwise to a solution of 2,5-
dibromopyridine (4) (0.02 mol) and Pd(PPh3)4 (0.5 mol%, 0.12 g) in 10 ml of freshly distilled
THF. The reaction mixture was stirred overnight at room temperature, poured into 20 ml of
water, and 20 ml of CH2Cl2 was added. The resulting solution was vacuum filtered to
separate a small amount of insoluble white solid, the organic phase was separated, and the
aqueous phase was extracted with CH2Cl2. The organic phases were combined, washed with
brine and then dried over MgSO4. The solvent was removed by rotary evaporation and the
product was purified by Kugelrohr distillation (colorless oil, 100-105 ºC/0.095-0.10 mm Hg,
4.92 g, 82.6% yield). MS (APCI): 298.1, 300.0 (1:1 intensity ratio) (calculated FW
1
297.1092). H NMR (CDCl3, 400 MHz): δ 0.85-0.0.91 (t, J=6.88 Hz, 3H, CH3), 1.22-1.38
(m, 14H), 1.63-1.75 (m, 2H), 2.70-2.76 (t, J=7.78 Hz, 2H), 7.02-7.07 (d, J=8.27 Hz, 1H),
7.67-7.72 (dd, J=8.28 Hz, 2.42 Hz, 1H), 8.56-8.60 (d, J=2.31 Hz, 1H); 13C NMR (CDCl3, 75
MHz): δ 14.28, 22.84, 29.45, 29.60, 29.69, 29.74, 29.86, 29.93, 32.05, 37.87, 117.87 (C-Br),
124.23 (CH), 138.99 (CH), 150.25 (CH), 161.24 (quaternary C).
Preparation of 2-(5-n-alkylthien-2-yl)-5-(tri-n-butylstannyl)-pyridines 8b,c
R1
ZnCl
S
SnBu3
Br
SnBu3
S
R1
Pd(PPh3)4, THF, rt
N
N
8b-c
1
2-(5-n-Nonylthien-2-yl)-5-(tri-n-butylstannyl)-pyridine (8b). An oven-dried three-necked
flask was charged with 2-bromo-5-n-nonylthiophene (10b) (7.16 mmol, 2.07 g), anhydrous
THF (25 ml) was added, and the resulting mixture was cooled in an acetone/CO2 bath under
nitrogen atmosphere. n-BuLi (2.5M in hexanes, 7.16 mmol, 2.9 ml) was added dropwise to a
clear colorless solution (-75-70 ºC internal temperature). The light yellow reaction mixture
was stirred for half an hour, analyzed by TLC, and an additional 0.6 ml of n-BuLi (20 mol%)
was added since some unreacted starting material was detected. After stirring for an
S15

additional 10 minutes (the starting bromide 10b was consumed as confirmed by TLC
analysis) solution of ZnCl2 (8.6 mmol, 1.17 g) in 10 ml of anhydrous THF was added
dropwise. After completion of the addition of ZnCl2 solution the cooling bath was removed,
and the reaction mixture was stirred for 3 hours. 2-Bromo-5-(tri-n-butylstannyl)-pyridine (1)
(6.82 mmol, 3.05 g) and Pd(PPh3)4 (0.5 mol%, 0.034 mmol, 0.039 g) were added in one
portion. After stirring for several minutes the solution became yellow with noticeable
fluorescence.
The reaction mixture was stirred for an hour, analyzed by TLC
(hexanes:CH2Cl2=2:1 as eluant), the yellow solution was transferred to the round bottom
flask, 20 ml of water was added and the organic solvents were removed by rotary
evaporation. The organic matter was extracted with organic solvents (3×50 ml of hexanes,
2×20 ml of hexanes, 2×10 ml of CH2Cl2), the organic phases were combined, washed with
brine, then dried over MgSO4, and the solvents were removed by rotary evaporation. The
orange oil was chromatographed (80 g of silica gel, hexanes:CH2Cl2=2:1 as eluant). The
purified product was isolated as light yellow oil (3.05 g, 77.6% yield). MS (APCI): 576.6,
1
577.5, 578.3 (calculated FW 577.2764). H NMR (CDCl3, 400 MHz): δ 0.84-0.91 (m, 12H),
1.05-1.11 (m, 6H), 1.22-1.40 (m, 18H), 1.48-1.60 (m, 6H), 1.3-1.74 (m, 2H), 2.80-2.86 (t,
J=7.53 Hz, 2H), 6.75-6.79 (d, J=3.67 Hz, 1H), 7.37-7.41 (d, J=3.62 Hz, 1H), 7.52-7.56 (dd,
13
J=7.75 Hz, 0.95 Hz, 1H), 7.65-7.75 (dd, J=7.75 Hz, 1.55 Hz, 1H), 8.50-8.55 (m, 1H); C
NMR (CDCl3, 100 MHz): δ 9.66, 13.67, 14.12, 22.69, 27.34, 29.05, 29.33, 29.40, 29.52,
30.44, 31.57, 31.90, 118.23 (CH), 124.07 (CH), 125.14 (CH), 134.39 (quaternary C), 142.40
(quaternary C), 144.51 (CH), 148.36 (quaternary C), 152.20 (quaternary C), 155.72 (CH).
2-(5-n-Tridecylthien-2-yl)-5-(tri-n-butylstannyl)-pyridine (8c). An oven-dried three-
necked flask was charged with 2-bromo-5-n-tridecylthiophene 10c (1.1 equiv., 7.7 mmol,
2.66 g), anhydrous THF (15 ml) was added, and the resulting mixture was cooled in an
S16

acetone/CO2 bath under nitrogen atmosphere. n-BuLi (2.5M in hexanes, 7.7 mmol, 3.1 ml)
was added dropwise to the white suspension of 10c. The reaction mixture was stirred for 10
minutes, and then the cooling bath was removed for 10 minutes (the precipitate dissolved),
and cooled again in acetone/CO2 bath for 10 minutes (reprecipitation took place). A solution
of ZnCl2 (9.24 mmol, 1.26 g) in 10 ml of anhydrous THF was added dropwise (the precipitate
started to dissolve), the cooling bath was removed, and the mixture was stirred for an hour
and a half. This freshly prepared arylzinc chloride solution was added to the flask charged
with 2-bromo-5-(tri-n-butylstannyl)-pyridine (1) (7.0 mmol, 3.13 g), Pd(PPh3)4 (0.5 mol%,
0.035 mmol, 0.040 g) and 10 ml of anhydrous THF (the flask became warm to the touch).
The reaction mixture was stirred for an hour and a half, transferred to a round bottom flask,
treated with 10 ml of water and the solvents were removed by rotary evaporation. The
residue was treated with 20 ml of water and 50 ml of hexanes and vacuum filtered to remove
insoluble matter. The organic phase was removed, the aqueous phase was extracted with
hexanes (4×25 ml), and the combined organic phases were washed with brine, and then dried
over MgSO4. The solvents were removed by rotary evaporation to give the crude product as
a yellow oil which was purified by column chromatography (120 g of silica gel,
hexanes:CH2Cl2 as eluant). The purified product was isolated as light yellow oil (3.40 g, 53.7
% yield). First two fractions collected were contaminated (1.35 g of mixture, ~1.1 g of 8c),
but were repurified (4.5 g total yield, 70.6% reaction yield). MS (APCI): 632.4, 634.3
(calculated FW 633.3390). 1H NMR (CDCl3, 400 MHz): δ 0.88-0.95 (m, 12H), 1.10-1.16
(m, 6H), 1.27-1.40 (m, 26H), 1.52-1.62 (m, 6H), 1.68-1.78 (m, 2H), 2.83-2.89 (t, 2H), 6.77-
6.82 (d, J=3.62 Hz, 1H), 7.40-7.43 (d, J=3.62 Hz, 1H), 7.54-7.60 (m, 1H), 7.70-7.80 (dd,
J=7.72 Hz, 1.46 Hz, 1H), 8.54-8.60 (m, 1H); 13C NMR (CDCl3, 75 MHz): δ 9.66, 13.67,
14.14, 22.72, 27.34, 29.05, 29.39, 29.40, 29.57, 29.68, 30.44, 31.57, 31.95, 118.23 (CH),
124.07 (CH), 125.13 (CH), 134.37 (quaternary C), 142.40 (quaternary C), 144.50 (CH),
S17

148.35 (quaternary C), 152.20 (quaternary C), 155.72 (CH) (aromatic C(H) carbons showed
satellite signals).
Preparation of 2-alkylthiophenes 9a-d and 2-bromo-5-alkylthiophenes 10a-d
2-n-Heptylthiophene (9a) was prepared using a literature procedure1 from thiophene (0.18
mol, 15.14 g), n-BuLi (2.5M in hexanes, 0.15 mol, 93.75 ml) and 1-bromoheptane (0.15 mol,
26.86 g). The crude material was purified by vacuum distillation (18.45 g, 67.5%, b.p. 57-60
1
ºC/0.11 mm Hg; lit. b.p. 81.5 ºC/0.3 mm Hg2). H NMR (CDCl3, 300 MHz): δ 0.82-0.93 (t,
J=6.89 Hz, 3H), 1.17-1.40 (m, 8H), 1.60-1.72 (m, 2H), 2.75-2.85 (t, J=8.07 Hz, 2H), 6.74-
6.78 (m, 1H), 6.88-6.92 (dd, J=5.11 Hz, 3.40 Hz, 1H), 7.08-7.11 (dd, J=5.12 Hz, 1.22 Hz,
13
1H); C NMR (CDCl3, 75 MHz): δ 14.28, 22.84, 29.23, 29.28, 30.10, 31.97, 122.87 (CH),
124.04 (CH), 126.79 (CH), 146.06 (quaternary C).
2-n-Nonylthiophene (9b) was prepared using a literature procedure1 from thiophene (0.12
mol, 10.10 g), n-BuLi (2.5M in hexanes, 0.10 mol, 62.5 ml) and 1-bromononane (0.10 mol,
20.70 g). The crude material was purified by vacuum distillation (colorless oil, 12.0 g, 56%,
b.p. 78-83 ºC/0.14 mm Hg, lit. b.p. 128-131 ºC/1 mm Hg3). MS (APCI): 211.1 (calculated
1
FW 210.1442). H NMR (CDCl3, 300 MHz): δ 0.82-0.92 (t, J=6.72 Hz, 3H), 1.15-1.40 (m,
12H), 1.58-1.72 (m, 2H), 2.75-2.85 (t, J=7.92 Hz, 2H), 6.74-6.78 (dd, J=4.37 Hz, 1.00 Hz,
13
1H), 6.87-6.92 (dd, J=5.11 Hz, 3.39 Hz, 1H), 7.07-7.10 (dd, J=5.14 Hz, 1.16 Hz, 1H); C
NMR (CDCl3, 75 MHz): δ 14.31, 22.88, 29.34, 29.51, 29.58, 29.72, 30.11, 32.02, 32.09,
122.87 (CH), 124.04 (CH), 126.79 (CH), 146.05 (quaternary C).
(1) Endtner J.M.; Effenberger F.; Hartschuh A.; Port H. J. Am. Chem. Soc., 2000, 122, 3037.
(2) Jeffery G.H.; Parker R.; Vogel A.I. J. Chem. Soc., 1961, 570.
(3) Campaigne, E.; Diedrich, J. L. J. Am. Chem. Soc., 1948, 70, 391.
S18

2-n-Tridecylthiophene (9c) was prepared using a slightly modified literature procedure1.
Anhydrous THF (75 ml) was mixed with n-BuLi (2.5M in hexanes, 0.15 mol, 60 ml), and the
mixture was cooled down to -25ºC (nitrogen atmosphere). Thiophene (0.15 mol, 12.62 g)
was added (-25-15 ºC), and the clear yellow reaction mixture was allowed to warm up to
room temperature. The mixture was stirred for 2 hours and 1-bromotridecane (0.0125 mol,
32.91 g) was added. After completion of addition of 1-bromotridecane (no exotherm was
observed) the reaction mixture was heated overnight at reflux (an exothermic reaction started
when the bath temperature reached ~40-45 ºC). The orange reaction mixture with a white
precipitate was transferred to a round bottom flask, several ml of water was added and the
organic solvents were removed by rotary evaporation. Additional water was added, and the
product was extracted with hexanes. The combined organic phases were dried with brine,
then over MgSO4, and the solvent was removed by rotary evaporation. The low boiling point
impurities were removed by distillation using a water aspirator, and the product was vacuum
distilled (115-118 ºC/0.095 mm Hg). The purified material was isolated as yellowish oil in
1
79.0% yield (26.30 g). MS analysis (APCI): 267.25 (FW 266.2068). H NMR (CDCl3, 400
MHz): δ 0.90-1.00 (t, 3H), 1.30-1.50 (m, 20H), 1.70-1.80 (m, 2H), 2.83-2.92 (t, 2H), 6.83-
6.86 (dd, J=3.39 Hz, 1.01 Hz, 1H), 6.96-6.99 (dd, J=5.12 Hz, 3.40 Hz, 1H), 7.15-7.17 (dd,
13
J=5.12 Hz, 1.19 Hz, 1H); C NMR (CDCl3, 100 MHz): δ 14.21, 22.81, 29.25, 29.49, 29.68,
29.78, 30.02, 31.92, 32.05, 122.73 (CH), 123.91 (CH), 126.64 (CH), 145.88 (quaternary C)
(the 1H NMR of this compound without resolution of signals in aromatic region was reported
in the literature4).
2-n-Undecylthiophene (9d) was prepared by an adapted literature procedure1. The flask was
charged with anhydrous THF (75 ml) and n-BuLi (0.15 mol, 60 ml), and the solution was
(4) Pomonis, J. G.; Fatland, C.L.; Taylor, F.R. J. Chem. Eng. Data., 1976, 233-236.
S19

cooled (acetone/CO2 bath). Thiophene (0.165 mol, 13.88 g) was added, and the internal
temperature quickly increased from –60 ºC up to –5 ºC. The mixture was allowed to warm
up to room temperature and stirred for 2.5 hours. Half of this freshly prepared solution was
treated with 1-iodoundecane (0.073 mol, 20.60 g), and the mixture was heated up. An
exothermic reaction started once the mixture was heated, and after several minutes white
precipitate formed. The mixture was refluxed for 16 hours, cooled to room temperature and
the yellow solution with white precipitate was transferred to a round bottom flask. The
solvent was removed by rotary evaporation; the residue (dark brown) was treated with 25 ml
of water and 25 ml of hexanes. The organic phase was separated; the aqueous phase was
extracted with hexanes (3×15 ml, 3×10 ml). The combined organic extracts were dried over
MgSO4, and the solvent was removed from yellow solution by rotary evaporation to give
crude material as yellow oil (29 g). Purified material was obtained by the Kugelrohr
1
distillation (126-134 ºC/0.2 mm Hg) in 80.5% yield (14.0 g). H NMR (CDCl3, 400 MHz): δ
0.83-0.91 (t, J=6.88 Hz, 3H), 1.21-1.40 (m, 16H), 1.62-1.71 (m, 2H), 2.68-2.83 (t, J=7.99 Hz,
2H), 6.76-6.79 (m, 1H), 6.89-6.93 (dd, J=5.12 Hz, 3.39 Hz, 1H), 7.08-7.11 (dd, J=5.15 Hz,
1.19 Hz, 1H); 13C NMR (CDCl3, 100 MHz): δ 14.13, 22.70, 29.15, 29.36, 29.38, 29.57,
29.63, 29.65, 29.93, 31.82, 31.93, 122.70 (CH), 123.88 (CH), 126.63 (CH), 145.91
(quaternary C).
2-Bromo-5-n-heptylthiophene (10a). An oven-dried three-necked flask equipped with
magnetic stir bar, additional funnel, and bubbler was charged with 2-n-heptylthiophene (9a)
(0.06 mol, 10.94 g) and anhydrous DMF (40 ml) under nitrogen atmosphere (ice-water bath).
A solution of N-bromosuccinimide (1.1 equiv., 0.066 mol, 11.75 g) in 30 ml of anhydrous
DMF was added dropwise to the colorless solution of 2-n-heptylthiophene (9a) over a half an
hour period, and the cooling bath was removed. The yellow mixture was stirred for 45
S20

minutes and poured into 200 ml of ice water. The product was extracted with hexanes (50
ml, then 10×25 ml), the combined organic phases were dried with brine, then over MgSO4,
and the solvent was removed by rotary evaporation. The residual solvent was removed by
vacuum distillation (water aspirator), and the crude material was purified by vacuum
distillation (90 ºC/0.1 mm Hg) to give the product as colorless oil in 88.8% yield (13.92 g).
1H NMR (CDCl3, 300 MHz): δ 0.82-0.0.90 (t, J=6.78 Hz, 3H), 1.20-1.40 (m, 8H), 1.53-1.64
(m, 2H), 2.70-2.75 (t, J=7.52 Hz, 2H), 6.50-6.54 (d, J=3.69 Hz, 1H), 6.81-6.85 (d, J=3.64 Hz,
13
1H); C NMR (CDCl3, 75 MHz): δ 14.26, 22.82, 29.13, 29.17, 30.51, 31.64, 31.93, 108.72
(C-Br), 124.49 (CH), 129.53 (CH), 147.82 (quaternary C) (no characterization was reported
for this known material5).
2-Bromo-5-n-nonylthiophene (10b). An oven-dried three-necked flask equipped with
magnetic stir bar, additional funnel, and bubbler was charged with 2-n-nonylthiophene (9b)
(0.057 mol, 12.0 g) and anhydrous DMF (35 ml) under nitrogen atmosphere. N-
bromosuccinimide (1.1 equiv., 0.0627 mol, 11.16 g) was dissolved in 30 ml of anhydrous
DMF under nitrogen atmosphere, the yellow solution was transferred via syringe to the
additional funnel and added dropwise to the colorless solution of 2-n-nonylthiophene over a
half an hour period. The reaction was analyzed by TLC (hexanes as eluant, the product is
less polar than starting material) after 15 minutes of stirring, and the yellow mixture was
poured into 150 ml of ice water. The product was extracted with hexanes (3×50 ml, then
6×20 ml), the combined organic phases were dried over MgSO4, and the solvent was
removed by rotary evaporation. The bright yellow oil was filtered thought silica gel (25 g,
petroleum ether). The light yellow solution was collected, and the solvent was removed by
rotary evaporation and then by distillation using water aspirator. The product was distilled at
(5) Bartle, K.; Camplbell, N.; Duffy, W.L.; Kelly, S.; Minter, V.; O’Neill, M.; Tuffin, R.P. Mol. Cryst. Liq.
Cryst., 2001, 364, 881.
S21

117 ºC/0.12 mm Hg as colorless oil (13.15 g, 79.7% yield). A bulb used to increase the space
in case of foaming was removed and additional amount of the product was collected (1.35 g,
8.2%). The purified material was isolated in 89.7% (total 14.50 g). MS (APCI): 290.0, 291.4
1
(calculated FW 288.0547). H NMR (CDCl3, 300 MHz): δ 0.86-0.0.95 (t, J=6.70 Hz, 3H),
1.20-1.40 (m, 12H), 1.55-1.65 (m, 2H), 2.70-2.75 (t, J=7.51 Hz, 2H), 6.50-6.55 (d, J=3.61
13
Hz, 1H), 6.80-6.85 (d, J=3.64 Hz, 1H); C NMR (CDCl3, 75 MHz): δ 14.30, 22.86, 29.17,
29.48, 29.50, 29.68, 30.51, 31.64, 32.06, 108.72 (C-Br), 124.48 (CH), 129.52 (CH), 147.81
(quaternary C).
2-Bromo-5-n-tridecylthiophene (10c). An oven-dried three-necked flask equipped with
magnetic stir bar, nitrogen inlet, and a bubbler was charged with 2-n-tridecylthiophene (9c)
(0.05 mol, 13.32 g) and anhydrous DMF (40 ml) under nitrogen atmosphere. N-
bromosuccinimide (1.1 equiv., 0.055 mol, 9.79 g) was dissolved in 20 ml of anhydrous DMF
under nitrogen atmosphere, and the solution was added dropwise to the reaction mixture
cooled in an ice-water bath. After completion of addition of the N-bromosuccinimide
solution the cooling bath was removed, the bright yellow cloudy mixture was stirred for an
hour (two phases formed once the stirring was stopped) and poured into 200 ml of ice water.
The product was extracted with hexanes (8×75 ml), the yellow organic phases were
combined, washed with brine, then dried over MgSO4, and the solvent was removed by rotary
evaporation. The crude product was vacuum distilled (145-148 ºC/0.085-0.090 mm Hg), and
the purified material was collected as yellow oil (14.97 g, 86.7% yield). MS analysis (APCI):
345.56, 347.13 (1:1 ratio) (calculated FW 344.117). 1H NMR (CDCl3, 400 MHz): δ 0.87-
0.94 (t, J=6.86 Hz, 3H), 1.23-1.40 (m, 20H), 1.60-1.67 (m, 2H), 2.71-2.77 (t, J=7.95 Hz, 2H),
6.53-6.56 (m, 1H), 6.80-6.85 (d, J=3.63 Hz, 1H); 13C NMR (CDCl3, 100 MHz): δ 14.15,
22.73, 29.01, 29.34, 29.39, 29.55, 29.68, 29.70, 30.35, 31.48, 31.96, 108.56 (C-Br), 124.33
S22

(CH), 129.37 (CH), 147.67 (quaternary C) (two signal for alkyl carbon are missing due to
overlap)
2-Bromo-5-n-undecylthiophene (10d). An oven-dried three-necked flask equipped with
magnetic stir bar, additional funnel, and bubbler was charged with 2-n-undecylthiophene (9d)
(0.0658 mol, 15.70 g) and anhydrous DMF (40 ml) under nitrogen atmosphere. N-
bromosuccinimide (1.1 equiv., 0.072 mol, 12.89 g) was dissolved in 30 ml of anhydrous
DMF under nitrogen atmosphere, the yellow solution was transferred via syringe to the
additional funnel and added dropwise to the colorless solution of 2-n-undecylthiophene over
a one hour period. The reaction was analyzed by TLC (hexanes as eluant, the product is less
polar than starting material) after several minutes, and the orange mixture was poured into
200 ml of ice water. The product was extracted with hexanes (3×100 ml), then with
dichloromethane (3×25 ml). The combined organic phases were brine, then over MgSO4, and
the solvents were removed by rotary evaporation. DMF was removed by vacuum distillation
(water aspirator, 55 ºC). The brown oil was filtered thought silica gel (30 g, petroleum ether).
The light yellow solution was collected (the brown strip appeared on the very top of the
column with a pink strip a bit below the brown on), and the solvent was removed by rotary
evaporation. Crude material was isolated in 27.8 g (theoretical yield 20.89 g, probably some
solvent was left). The crude material was transferred to the vacuum distillation flask, the
round bottom flask was rinsed with several ml of hexanes, and the solvent was removed by
vacuum distillation (water aspirator). The product was collected at 138-139 ºC/0.095-0.1 mm
Hg as colorless oil (18.93 g, 90.6% yield). 1H NMR (CDCl3, 300 MHz): δ 0.83-0.90 (t,
J=6.70 Hz, 3H), 1.20-1.40 (m, 16H), 1.55-1.65 (m, 2H), 2.65-2.75 (t, J=8.00 Hz, 2H), 6.50-
6.55 (m, 1H), 6.80-6.85 (d, J=3.67 Hz, 2H); 13C NMR (CDCl3, 75 MHz): δ 14.29, 22.86,
S23

29.14, 29.48, 29.51, 29.69, 29.79, 30.49, 31.62, 32.08, 108.7, 124.48, 129.52, 147.82 (one
signal for alkyl carbon is missing due to overlap).
1-n-Heptyloxy-4-bromobenzene (12). The reagents 4-bromophenol (0.105 mol, 18.17 g), 1-
bromoheptane (0.1 mol, 17.9 g), K2CO3 (0.21 mol, 29.0g) and NMP (25 ml) were placed into
a round bottom flask. This reaction mixture was heated for 90 minutes (115-120 ºC internal
temperature), cooled to room temperature and poured into 200 ml of ice water. The organic
material was extracted with hexanes (2×75 ml, then 3×25 ml) and the combined organic
phases were dried with brine and then over MgSO4. The solvent was removed by rotary
evaporation, low boiling point impurities were removed by distillation using a water aspirator
and then the product was distilled (100 ºC/0.085-0.090 mm Hg; lit. b.p. 127 ºC/1 mm Hg6).
The product was isolated as colorless oil in 81.5% yield (22.10 g). MS (APCI): 270.3, 272.0
(calculated FW 270.0619). 1H NMR (CDCl3, 300 MHz): δ 0.83-1.00 (t, J=6.76 Hz, 3H),
1.25-50 (m, 8H), 1.73-1.80 (m, 2H), 3.80-4.00 (t, J=6.55 Hz, 2H), 6.73-6.80 (m, 2H), 7.30-
7.37 (m, 2H); 13C NMR (CDCl3, 75 MHz): δ 14.25, 22.78, 26.14, 29.22, 29.35, 31.94, 68.15,
112.70 (C-Br), 116.45 (2 CH), 132.34 (2 CH), 158.42 (C-O).
Preparation of 3-alkyl-pyridines 13a-c. A slightly modified literature procedure7 was used
for the preparation of 3-alkylpyridines.
Br
R
RMgBr
NiCl2(dppe)
N
N
3-Hexylpyridine (13a). Magnesium turnings (0.12 mol, 2.91 g) and freshly distilled Et2O
(30 ml) were placed into an oven-dried three-necked round bottom flask, equipped with a
condenser and an additional funnel (N2 atmosphere). The solution of 1-bromohexane (0.11
(6) Bumagin N.A., Luzikova E.V., Beletskaya I.P., Russ. J. Org. Chem., 1995, 31, 11, 1480.
(7) Tamao, K., Kodama, S., Nakajima, I., Kumada, M., Minato, A., Suzuki, K. Tetrahedron, 1982, 38, 3347.
S24

mol, 18.16 g) in 120 ml of anhydrous Et2O was added dropwise via the additional funnel, the
reaction mixture was refluxed for half an hour and then cooled down to room temperature.
This freshly prepared Grignard solution was added dropwise via a syringe into the three-
necked found bottom flask charged with 3-bromopyridine (0.1 mol, 15.8 g), NiCl2(dppe) (0.5
mol%, 0.5 mmol, 0.264 g), and 50 ml of freshly distilled Et2O. After the addition of the
several drops of the Grignard the reaction mixture became yellow-orange and the
precipitation of the white solid took place. The reaction mixture was refluxed for several
hours after the completion of the additions of Grignard reagent, cooled to room temperature
and poured into ice water. The organic layer was separated; the water layer was extracted
with Et2O (3×30 ml). The combined organic extracts were washed with brine, and then dried
over MgSO4. Evaporation of the solvent gave the crude product (14.3 g, 87.5%), which was
vacuum distilled (60-61 ºC/0.09-0.13 mm Hg) to give title compound as a colorless oil (11.0
1
g, 67.3%). H NMR (CDCl3, 300 MHz): δ 0.85-0.90 (t, J=6.56 Hz, 3H), 1.05-1.48 (m, 5H),
1.50-1.80 (m, 2H), 2.50-2.70 (t, J=7.75 Hz, 2H), 7.10-7.21 (m, 1H), 7.45-7.51 (m, 1H), 8.40-
8.45 (m, 2H); 13C NMR (CDCl3, 75 MHz): δ 14.18, 22.69, 28.94, 31.23, 31.73, 33.14,
123.35, 135.91, 138.11, 147.25, 150.06.
3-n-Octylpyridine (13b). The title compound was prepared in a similar way described for
1
(13a) (colorless oil, 44.5% yield, b.p. 95-96 ºC/0.3 mm Hg). H NMR (CDCl3, 300 MHz): δ
0.85-0.90 (t, J=6.52 Hz, 3H), 1.20-1.45 (m, 10 H), 1.50-1.70 (m, 2H), 2.51-2.62 (t, J=7.73
Hz, 2H), 7.16-7.22 (dd J=4.85 Hz, J=7.73 Hz, 1H), 7.46-7.51 (m, 1H), 8.40-8.45 (m, 2H); 13C
(CDCl3, 75 MHz): δ 14.21, 22.78, 29.28, 29.35, 29.51, 31.29, 31.97, 33.14, 123.31 (CH),
135.84 (CH), 138.07 (quaternary C), 147.29 (CH), 150.11 (CH).
S25

3-n-Decylpyridine (13c). The title compound was prepared in a similar way described for
(13a) from 3-bromopyridine (0.075 mol, 11.85 g), NiCl2(dppe) (5 mol%, 0.375 mmol, 1.98
g) and Grignard prepared from 1-bromodecane (1.3 eq., 0.0975 mol, 21.56 g), Mg turnings
(1.2 eq., 0.117 mol, 2.84 g) and anhydrous THF (75 ml). The crude material was purified by
vacuum distillation (98-100 ºC/0.1 mm Hg) and the title compound was isolated as colorless
oil with unpleasant smell (11.13 g, 67.7% yield). MS (APCI): 220.2 (calculated FW
1
219.1987). H NMR (CDCl3, 400 MHz): δ 0.77-0.85 (t, J=6.82 Hz, 3H), 1.15-1.30 (m, 14
H), 1.49-1.58 (m, 2H), 2.48-2.55 (t, J=7.73 Hz, 2H), 7.08-7.13 (dd, J=7.73 Hz, J=4.82 Hz,
1H), 7.38-7.42 (m, 1H), 8.33-38 (m, 2H); 13C NMR (CDCl3, 100 MHz): δ 14.09, 22.67,
29.15, 29.31, 29.40, 29.54, 29.70, 31.14, 31.88, 33.01, 123.17 (CH), 135.70 (CH), 137.93
(quaternary C), 147.15 (CH), 149.97 (CH) (this compound was reported in the literature8, but
no spectral data was found).
Synthesis of 2-tri-n-butylstannyl-5-alkylpyridines 14a,c
1) n-BuLi-LiDMAE
-40-30 ºC, hexanes
R
Bu3Sn
R
2) n-Bu3SnCl
-70 ºC, 1-4 h
N
N
14a,c
13a,c
2-Tri-n-butylstannyl-5-n-hexylpyridine (14a). N,N-Dimethylaminoethanol (0.075 mol,
6.69 g) and 65 ml of hexanes were placed into an oven-dried three-necked round bottom
flask. n-BuLi (2.5M in hexanes, 0.15 mol, 60 ml) was added slowly (–60–0 ºC, acetone/CO2
bath), the reaction mixture was stirred for half an hour (~0 ºC), and cooled down to –45 ºC.
The solution of 3-n-hexylpyridine (13a) (0.025 mol, 4.08 g) in 6 ml of hexanes was added
dropwise (–42–40 ºC internal temperature), and the color of the reaction changed from
colorless to orange and then deep red. The reaction mixture was stirred for an hour, cooled
down to –70 ºC and a solution of tri-n-butyltin chloride (3.5 eq., 0.0875 mol, 28.5 g) in
(8) Tereshko, A.B.; Tarasevich, V.A.; Kozlov, N.G. Zhurnal Org. Khim., 1995, 31, 289.
S26

anhydrous THF (75 ml) was added dropwise (–70–55 ºC internal temperature during
addition), and the color of the mixture changed from red to bright yellow with white
precipitate. The reaction mixture was stirred for 4 hours, the cooling bath was removed and
the mixture was allowed to warm up to room temperature. The yellow reaction mixture with
white precipitate was transferred to a round bottom flask, and the solvents were removed by
rotary evaporation. The residue (yellow oil with white solid) was treated with 75 ml of water,
and the organic matter was extracted with hexanes (25 ml, then 4×10 ml). The light yellow
combined organic extracts were dried over MgSO4, and the solvent was removed by rotary
evaporation. The crude material isolated as light yellow oil was subjected to Kugelrohr
distillation, and the contaminated product was collected at 160-170 ºC/0.14 mm Hg (7.91 g),
while the last fraction (1.1 g) contained pure compound. The contaminated product (7.91 g)
was further purified by column chromatography (40 g of silica gel was mixed with a solution
of Et3N in 125 ml for the slurry preparation; hexanes:EtOAc = 10:1 as eluant). The solvent
was removed by rotary evaporation to give almost colorless oil (5 g), which was Kugelrohr
distilled (155-167 ºC/0.12 mm) to give product (4.95 g) (total yield of 6.05 g (53 %), 85%
purity by NMR). FT-IR (cm-1): 3054, 2957, 2928, 2872, 2854, 1545, 1462, 1377, 1340,
1
1291, 1248, 1072, 1024, 960, 878, 745, 692. H NMR (CDCl3, 400 MHz): δ 0.82-0.91 (m,
12H*), 1.08-1.13 (m, 6H), 1.24-1.40 (m, 12H*), 1.45-1.60 (m, 8H*), 2.50-2.57 (t, J=7.61 Hz,
2H), 7.28-7.33 (m, 2H), 8.58-8.60 (appears as s, 1H) (* - the observed integration is higher
due to inseparable impurity); 13C NMR (CDCl3, 100 MHz): δ 9.74, 13.67, 14.05, 22.58,
27.36, 28.90, 31.09, 31.65, 31.65, 33.11, 131.89 (CH), 133.25 (CH), 136.08 (quaternary C),
151.00 (CH), 169.96 (CH).
2-Tri-n-butylstannyl-5-n-decylpyridine (14c) was prepared in the same manner as
described for 14a using N,N-dimethylaminoethanol (0.045 mol, 4.01 g), 15 ml of hexanes, n-
S27

BuLi (2.5M in hexanes, 0.09 mol, 36 ml), 3-n-decylpyridine (13c) (0.015 mol, 3.29 g), and
solution of tri-n-butyltin chloride (0.0525 mol, 17.09 g) in 45 ml of anhydrous THF. The
crude material was subjected to Kugelrohr distillation, and the product was collected as
yellowish oil at 170 ºC/0.1 mm Hg (2.28 g, 30% yield). MS (APCI): 508.4, 510.2 (calculated
1
FW 509.3043). H NMR (CDCl3, 400 MHz): δ 0.84-0.91 (m, 15H), 1.09-1.13 (m, 6H), 1.22-
1.38 (m, 17H), 1.52-1.63 (m, 8H), 2.51-2.57 (m, 2H), 7.28-7.33 (d, J=1.62 Hz, 2H), 8.57-8.61
(appears as t, J=1.44 Hz, 1H); 13C NMR (CDCl3, 100 MHz): δ 9.74, 13.69, 14.12, 22.69,
27.36, 29.10, 29.23, 29.33, 29.45, 29.57, 29.60, 31.12, 31.90, 33.11, 131.91 (CH), 133.30
(CH), 136.12 (quaternary C), 150.98 (CH), 169.92 (CH).
2-n-Pentyl-6-(tri-n-butylstannyl)-pyridine (15a). An alkyl Grignard was prepared from 1-
bromopentane (2 equiv., 0.014 mol, 2.11 g), Mg turnings (0.0168 mol, 0.41 g) and 14 ml of
anhydrous THF. This freshly prepared Grignard was added dropwise to a solution of ZnCl2
(0.0168 mol, 2.29 g) in 17 ml of anhydrous THF (ice-water bath). A white precipitate formed
after several minutes of stirring, and the reaction mixture was stirred for additional hour at
room temperature. Next, 2-bromo-6-(tri-n-butylstannyl)-pyridine (2) (0.007 mol, 3.13 g),
Pd(PPh3)4 (0.5 mol%, 0.035 mmol, 0.04 g) and 7 ml of anhydrous THF were mixed in an
oven-dried three-necked flask under a nitrogen atmosphere (clear yellow solution formed),
and the freshly prepared n-pentylzinc chloride solution (~1.5 equiv., ~23 ml) was added
dropwise via syringe to the yellow reaction mixture (the flask became warm to touch). The
reaction mixture was stirred for 3 hours at room temperature, transferred to another round
bottom flask, and the solvent was removed by rotary evaporation. The residue was treated
with 25 ml of water and 50 ml of petroleum ether, and the resulting mixture was vacuum
filtered to remove insoluble matter. The organic phase was separated and the aqueous phase
was extracted with petroleum ether (4×10ml). The combined organic phases were dried over
S28

MgSO4, and the solvent was removed by rotary evaporation to give 3.37 g of light yellow oil
as crude material. The product was purified by Kugelrohr distillation (120-125 ºC/0.16 mm
Hg), and the desired material was isolated as yellowish oil in 66.0% yield (2.02 g). MS
1
(APCI): 438.8, 440.2 (calculated FW 439.2261). H NMR (CDCl3, 400 MHz): δ 0.85-0.91
(m, 12H), 1.05-1.11 (m, 6H), 1.28-1.38 (m, 10H), 1.53-1.61 (m, 6H), 1.68-1.77 (m, 2H),
2.73-2.78 (m, 2H), 6.90-6.95 (dd, J=7.81 Hz, 1.19 Hz, 1H), 7.14-7.21 (dd, J=7.29 Hz, 1.19
Hz, 1H), 7.32-7.39 (m, 1H); 13C NMR (CDCl3, 100 MHz): δ 9.55, 13.72, 14.05, 22.61, 27.34,
29.11, 29.39, 31.58, 38.55, 120.83 (CH), 129.40 (CH), 133.16 (CH), 162.47 (quaternary C),
172.97 (quaternary C).
2-n-Decyl-6-(tri-n-butylstannyl)-pyridine (15b). An alkyl Grignard reagent was prepared
from 1-bromodecane (1.5 equiv., 0.0105 mol, 2.32 g), Mg turnings (0.0126 mol, 0.31 g) and
17 ml of anhydrous THF. This freshly prepared Grignard was added dropwise to the solution
of ZnCl2 (0.0126 mol, 1.72 g) in 13 ml of anhydrous THF (ice-water bath). A white
precipitate formed after several minutes of stirring, and the reaction mixture was stirred for
additional hour at room temperature. Next, 2-bromo-6-(tri-n-butylstannyl)-pyridine (2)
(0.007 mol, 3.13 g), Pd(PPh3)4 (1 mol%, 0.07 mmol, 0.08 g) and 4 ml of anhydrous THF
were mixed in an oven-dried three-necked flask under a nitrogen atmosphere (clear yellow
solution formed), and the freshly prepared n-decylzinc chloride solution) was added dropwise
via syringe to give a clear bright yellow reaction mixture (the flask became warm to the
touch). The reaction mixture was stirred for 2 hours at room temperature, transferred to
another round bottom flask, and the solvent was removed by rotary evaporation. The residue
was treated with 25 ml of water and 25 ml of petroleum ether, and the resulting mixture was
vacuum filtered to remove insoluble matter. The organic phase was separated and the
aqueous phase was extracted with petroleum ether (4×10ml). The combined organic phases
S29

were dried over MgSO4, and the solvent was removed by rotary evaporation to give 4.7 g of
light yellow oil as crude material. The product was purified by Kugelrohr distillation (135-
145 ºC/0.16 mm Hg), and the desired material was isolated as yellowish oil in 73.6% yield
(2.62 g). MS (APCI): 508.8, 510.4 (calculated FW 509.3043). FT-IR (cm-1): 3043 (weak),
2957, 2923, 2878, 2852, 1572, 1554, 1463, 1435, 1072, 877, 785, 748, 693. 1H NMR
(CDCl3, 400 MHz): δ 0.85-0.91 (m, 12H), 1.06-1.12 (m, 6H), 1.24-1.39 (m, 20H), 1.53-1.62
(m, 6H), 1.67-1.77 (m, 2H), 2.73-2.78 (m, 2H), 6.90-6.95 (dd, J=7.83 Hz, 1.19 Hz, 1H), 7.15-
7.21 (dd, J=7.27 Hz, 1.22 Hz, 1H), 7.31-7.39 (m, 1H); 13C NMR (CDCl3, 100 MHz): δ 9.92,
13.73, 14.13, 22.72, 27.35, 29.12, 29.40, 29.66, 29.69, 29.72, 31.95, 38.60, 120.83 (CH),
129.39 (CH), 133.16 (CH), 162.48 (quaternary C), 172.96 (quaternary C).
6-(5-n-Tridecylthien-2-yl)-2-(tri-n-butylstannyl)-pyridine (16)
C13H27
ZnCl
S
S
Br
N
SnBu3
N
SnBu3
C13H27
Pd(PPh3)4
THF, rt
2
16
An oven-dried three-necked flask was charged with 2-bromo-5-n-tridecylthiophene (10c) (7.7
mmol), anhydrous THF (15 ml) was added, and the resulting mixture was cooled in an
acetone/CO2 bath under a nitrogen atmosphere. n-BuLi (2.5M in hexanes, 18 mmol, 7.2 ml)
was added dropwise to the white suspension of 10c, and the cooling bath was removed for 10
minutes to warm the reaction mixture. The clear solution was then cooled again
(acetone/CO2 bath), and the solution of ZnCl2 (9.24 mmol, 1.26 g) in 10 ml of anhydrous
THF was added to the suspension (precipitate formed on cooling). After completion of
addition the precipitate started to dissolve, and the cooling bath was removed. The reaction
mixture was stirred for an hour and a half, and the 6-bromo-2-(tri-n-butylstannyl)-pyridine
(2) (0.007 mol, 3.13 g) was added via syringe followed by Pd(PPh3)4 (0.5 mol%, 0.035 mmol,
S30