The Journal of Organic Chemistry
ARTICLE
diethyl ether (10 mL) and washed with distilled water before drying over
MgSO4. The reaction solution was filtered and concentrated in vacuo to
give the corresponding anilide.
purple foam. After drying, the product (23 or 24) was recovered
(93ꢀ96% yield), and 2.7 mmol was added to a 50 mL round-bottom
flask under inert atmosphere. To this were added chloromethylethy-
lether (3.5 mmol) in 5 mL of THF and a couple of drops of water. This
was stirred at 50 °C for 16 h. The contents were concentrated in vacuo
and purified by silica column chromatography 2% MeOH/DCM. The
resulting residue was sonicated in ether and filtered (45ꢀ47% yield).
These diimines were used without further purification.
N,N0-Bis{2-[1-(trimethyl-silanyl)-ethyl]-phenyl}-ethane-1,
2-diylidenediimine (R,R)-23. 1H NMR (CDCl3): ꢀ0.098 (18H, s),
1.4 (6H, d, J = 7.8), 3.1 (2H, q, J = 7.8), 6.9ꢀ7.1 (2H, m), 7.1ꢀ7.3 (6H,
m), 8.3 (2H, s).
N,N0-Bis[2-(1-phenyl-ethyl)-phenyl]-ethane-1,2-diylidene-
diimine (R,R)-24. 1H NMR (CDCl3): 1.7 (6H, d, J = 7.2), 4.8 (2H, J =
7.2), 6.9ꢀ7.4 (18H, m), 8.2 (2H, s).
2-(1-Phenylethyl)benzenamine (R)-16. 1H NMR (CDCl3):
1.7 (3H, d, J = 7.2), 3.5 (2H, s), 4.1 (1H, q, J = 7.2), 6.7 (1H, dd, J = 1.2,
7.8), 6.9 (1H, dt, J = 1.2, 7.5), 7.1 (1H, dt, J = 1.5, 7.5), 7.2ꢀ7.3 (3H, m),
7.3ꢀ7.4 (3H, m). 13C (CDCl3): 22.0 (CH3), 40.4 (CH), 116.4 (CH),
118.9 (CH), 126.6 (CH), 127.4 (CH), 127.6 (CH), 128.9 (CH), 129.9
(C), 144.5 (C), 145.8 (C). MS (CI/MH+): 198. Anal. Calcd for C14H15N:
C, 85.24; H, 7.66. Found: C, 85.27; H, 7.75.6 er = 95:5.
2-(1-(Trimethylsilyl)ethyl)benzenamine (R)-22. 1H NMR
(CDCl3): 0.0 (9H, s), 1.4 (3H, d, J = 7.5), 2.1 (1H, q, J = 7.5), 3.5
(2H, bs), 6.7 (1H, dd, J = 1.2, 7.8), 6.8 (1H, dt, J = 1.2, 7.5), 6.9ꢀ7.0 (2H,
m). 13C NMR (CDCl3): ꢀ2.7 (CH3), 15.4 (CH3), 22.3 (CH), 116.0
(CH), 119.3 (CH), 125.1 (CH), 127.0 (CH), 131.2 (C), 143.1 (C). MS
(CI/MH+): 194. Anal. Calcd for C11H19NSi: C, 68.33; H, 9.90. Found:
C, 68.23; H, 9.93. er = 94:6.
General Procedure for Sandmeyer Reaction. The following is
revised from the published protocol for a different aniline substrate.9 To
a 50 mL round-bottom flask was added NaNO2 (14.5 mmol) in 10 mL of
DMSO. To this solution were added CuBr (7.0 mmol) and the aniline
substrate 16, (3.9 mmol). The resulting suspension was cooled to 0 °C
and treated dropwise with a solution of HBr (5 mL, 48%) in DMSO
(10 mL). The reaction solution was stirred for an additional 30 min
before warming to room temperature and stirring for 1 h. The reaction
solution was then transferred to a separatory funnel, diluted with water
(50 mL), and washed with diethyl ether (3 ꢁ 20 mL). The combined
organic layers were washed with water (3 ꢁ 15 mL), then dried over
MgSO4, filtered, and concentrated in vacuo.
1,3-Bis{2-[1-(trimethyl-silanyl)-ethyl]-phenyl}-1H-imida-
zolium Chloride (R,R)-10. 1H NMR (CDCl3): ꢀ0.066 (18H, s), 1.4
(6H, d, J = 7.2), 1.9 (2H, q, J = 7.2), 7.2ꢀ7.3 (4H, m), 7.4ꢀ7.5 (2H, m),
7.6ꢀ7.7 (2H, m), 8.2 (2H, d, J = 7.8). 9.4 (1H, s). 13C NMR (CDCl3):
ꢀ2.7 (CH3), 16.6 (CH3), 23.8 (CH), 124.8 (CH), 126.7 (CH), 128.2
(CH), 128.8 (CH), 131.4 (CH), 132.4 (CH), 137.9 (C), 141.7 (C). ESI
(MS/-Cl): 421. Anal. Calcd for C25H37 ClN2Si2: C, 65.68; H, 8.16.
Found: C, 65.41; H, 8.23. Single diastereomer. XRD analysis of 10
resulted in refinement of the Flack parameter to a value of zero,
providing confirmation of the absolute configuration as (R,R).
1,3-Bis[2-(1-phenyl-ethyl)-phenyl]-1H-imidazolium Chloride
(R,R)-25. 1H NMR (CDCl3): 1.6 (6H, d, J = 6.9), 4.3 (2H, q, J = 6.9), 6.9
(4H, m), 7.1ꢀ7.3 (8H, m), 7.4ꢀ7.5(4H, m), 7.5ꢀ7.7 (4H, m), 8.9 (1H, s).
13C NMR (CDCl3): 22.8 (CH3), 39.9 (CH), 124.7 (CH), 127.0 (CH),
127.1 (CH), 127.9 (CH), 128.5 (CH), 129.0 (CH), 129.2 (CH), 131.9
(CH), 133.7 (C), 140.6 (C), 145.6 (C). ESI-FTMS calcd [M+] C31H29N2
[M]+ = 429.2331, found [M]+ = 429.2328. Single diastereomer.
4-Methyl-2,6-bis(1-phenylethyl)benzenamine (mixture of
stereoisomers)-28. A 25 mL round-bottom flask equipped with a stir
bar was charged with toluidine (10.0 mmol), KSF montmorillonite
(1.0 g), and phenyl acetylene (40.0 mmol). The round-bottom was fitted
with a reflux condenser, and the heterogeneous slurry was refluxed with
vigorous stirring at 140 °C for 8 h. The reaction vessel was allowed to
cool to room temperature before dilution with ethyl acetate and
filtration. The solvent was removed from the mother liquor under
reduced pressure, and the resultant red oil was purified via column
chromatography with 50:50 dichloromethane and hexanes. The product
(4-methyl-2,6-bis(1-phenylvinyl)benzenamine) was obtained as an off-
white solid in 88% yield. 1H NMR (CDCl3): 2.2 (3H, s), 3.3 (2H, s), 5.3
and 5.7 (4H, dd), 6.9 (2H, s), 7.1ꢀ7.4 (10H, m). 13C NMR (CDCl3):
20.5, 116.2, 126.5, 127.8, 128.3, 128.7, 131.0, 139.3, 139.9, 147.5. A Parr
shaker was charged with 4-methyl-2,6-bis(1-phenylvinyl)benzena-
mine (8.8 mmol), 10% w/w Pd/C (0.88 mmol), and absolute ethanol
(25 mL). The shaker was thrice purged with hydrogen before it was
pressurized to 90 psi and shaken overnight. The black hetergeneous
solution was filtered, and the solvent was removed from the mother liquor
under reduced pressure to give compound 28 in nearly quantitative yield
(99%) with a diastereomerratioof60:20:20. The details of the preparative
separation of 28 can be found in the Supporting Information.
1-(1-(2-Bromophenyl)ethyl)benzene (R)-17. 1H NMR (CDCl3):
1.7 (3H, d, J = 7.2), 4.7 (1H, q, J = 7.2), 7.1 (1H, m), 7.2ꢀ7.4 (7H, m), 7.6
(1H, dd, J = 1.2, 7.8). 13C NMR (CDCl3): 21.5 (CH3), 43.7 (CH), 125.0
(C), 126.4 (CH), 127.8 (CH), 127.9 (CH), 128.0 (CH), 128.5 (CH), 129.0
(CH), 133.1 (CH), 145.1 (C), 145.6 (C). MS (EI): 260.262. er = 95:5. As
compound 17 was reported in 1973,21 we have included our spectra in the
Supporting Information to provide more detailed characterization.
1,2-Diphenyl-N,N0-bis[(R)-2-(1-phenyl-ethyl)-phenyl]-ethane-
(S,S)-1,2-diamine 18. (New compound synthesized with a previously
published procedure.4a) 1H NMR (CDCl3): 1.6 (6H, d, J = 7.2), 3.9 (2H, q,
J = 7.2), 4.2 (2H, d, J = 6.3), 4.5 (2H, d, J = 6.9), 6.4 (6H, d, J = 7.5), 6.7 (2H,
dt, J=0.6, 7.5), 6.9(4H, m), 7.0(4H, m), 7.1ꢀ7.2(8H, m), 7.3(4H, m). 13C
NMR (CDCl3): 22.3 (CH3), 40.1 (CH), 61.9 (CH), 112.1 (CH), 117.4
(CH), 126.3 (CH), 126.8 (CH), 127.4 (CH), 127.5 (CH), 127.8 (CH),
128.0 (CH), 128.2 (CH), 128.8 (CH), 130.0 (C), 139.2 (C), 144.0 (C),
145.7 (C). MS (ESI/MH+): 573. Anal. Calcd for C42H40N2: C, 88.07; H,
7.04. Found: C, 88.25; H, 7.20. Single diastereomer.
(S,S)-4,5-Diphenyl-1,3-bis[(R)-2-(1-phenyl-ethyl)-phenyl]-
4,5-dihydro-3H-imidazol-1-inium; hexafluorophosphate 9.
(New compound synthesized with a previously published procedure.4b)
1H NMR (CDCl3)1.2 (6H, d, J = 6.9), 3.9 (2H, q, J = 6.9), 5.8 (2H, s),
6.9 (4H, d, J = 7.5), 7.1ꢀ7.4 (22H, m), 7.5 (1H, s). 13C NMR (CDCl3):
22.8 (CH3), 39.5 (CH), 76.5 (CH), 127.2 (CH), 127.5 (CH), 128.6
(CH), 128.7 (CH), 128.8 (CH), 129.2 (CH), 129.3 (CH), 130.0 (CH),
130.8 (CH), 130.8 (CH), 132.1 (C), 132.4 (C), 140.4 (C), 144.8 (C),
N,N0-Bis[4-methyl-2,6-bis(1-phenylethyl)phenyl]-ethane-
1,2-diylidenediimine 29. To a 25 mL round-bottom flask was added
chiral or meso aniline 28 (5.80 mmol) in 3 mL of EtOH. To this were
added 40% glyoxal (2.9 mmol) and one drop of formic acid. The reaction
mixture was sonicated overnight at room temperature. The contents
were then filtered to give a bright yellow solid. The mother liquor was
concentrated and recrystallized from ethanol. These combined batches
yielded the product diimine 29 quantitatively (2.88 mmol) as a single
diastereomer. 1H NMR (CDCl3): 1.6 (12H, d, J = 6.3), 2.3 (6H, s), 4.0
(4H, q, J = 6.5), 7.0 (s, 4H), 7.2 (m, 20H), 7.4 (s, 2H). 13CNMR
157.3 (CH). MS (ESI/-PF6): 583. Anal. Calcd for C42H40N2 1/2 H2O:
3
C, 70.00; H, 5.46. Found: C, 69.83; H, 5.33. XRD analysis of 9 resulted in
refinement of the Flack parameter to a value of zero, providing
confirmation of the absolute configuration as (S,S,R,R).
General Procedure for Glyoxal Condenstion and Cycliza-
tion of 16 and 22. To a 25 mL round-bottom flask was added chiral
aniline 16 or 22 (5.80 mmol) in 3 mL of EtOH. To this was added 40%
glyoxal (2.9 mmol). The reaction mixture was refluxed and monitored
by TLC until all starting material had been consumed, taking approxi-
mately 2 h. The contents were then concentrated in vacuo to a dark
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dx.doi.org/10.1021/jo2012434 |J. Org. Chem. 2011, 76, 7341–7351