Ring-Closing Metathesis Reactions on Azinium Salts
and 3-butenyl triflate (0.53 g, 2.6 mmol) afforded 0.507 g (82%)
of 11a as a pale-yellow oil: IR (NaCl) νmax (cm-1) 3087, 1621,
1257, 1512, 1161, 1030, 785; 1H NMR (300 MHz, CDCl3) δ 8.92
(d, 1H, J ) 6.2 Hz), 8.39 (t, 1H, J ) 7.9 Hz), 8.02 (d, 1H, J ) 8.2
Hz), 7.90 (t, 1H, J ) 6.4 Hz), 7.13 (dd, 1H, J ) 11.3, 17.0 Hz),
6.28 (dd, 1H, J ) 1.3, 17.0 Hz), 6.13 (dd, 1H, J ) 1.1, 11.2 Hz),
5.84-5.71 (m, 1H), 5.06 (d, 1H, J ) 10.2 Hz), 4.94 (dd, 1H, J )
1.3, 17.0 Hz), 4.79 (t, 2H, J ) 6.9 Hz), 2.65 (dd, 2H, J ) 6.9, 14.1
Hz); 13C NMR (75 MHz, acetone-d6) δ 153.2, 146.6, 133.2, 130.5,
128.3, 127.6, 127.3, 119.7, 58.2, 34.7; MS (ESI+) m/z (relative
intensity) 160 (M+). Anal. Calcd for C12H14NSO3F3: C, 46.60; H,
4.56; N, 4.53; S, 10.37. Found: C, 46.52; H, 4.79; N, 4.44; S, 10.41.
Ring-Closing Metathesis of Dienes 11. General Procedure
for 3,4-Dihydroquinolizinium 10. The ruthenium catalyst G-II
(5 mol %, 0.01 mmol, 8.5 mg) or H-G (5 mol %, 0.01 mmol, 6.2
mg) in CH2Cl2 or ClCH2CH2Cl (1 mL) was added to a solution of
the corresponding diene 11 (0.2 mmol) in dry CH2Cl2 or
ClCH2CH2Cl (1.5 mL) under an argon atmosphere. The reaction
mixture was stirred at room temperature or under heating for the
appropriate time. The solvent was evaporated under reduced
pressure, and the residue was purified by flash chromatography
(eluent: CH2Cl2/MeOH 9.3:0.7).
3,4-Dihydroquinolizinium Triflate (10a). Following the general
procedure, after stirring for 1.5 h, 46.8 mg (83%) of 10a was obtained
as a gray powder: mp 124-125 °C (acetone/Et2O); IR (NaCl) νmax
(cm-1) 3086, 1646, 1507, 1263, 1150, 1031, 808; 1H NMR (300 MHz,
CDCl3) δ 8.92 (d, 1H, J ) 6.2 Hz), 8.33 (t, 1H, J ) 7.8 Hz), 7.80 (t,
1H, J ) 7.1 Hz), 7.65 (d, 1H, J ) 7.9 Hz), 6.89-6.83 (m, 1H), 6.72
(d, 1H, J ) 9.7 Hz), 4.81 (t, 2H, J ) 7.7 Hz), 2.85 (dd, 2H, J ) 7.7,
12.3 Hz); 13C NMR (75 MHz, acetone-d6) δ 146.7, 146.1, 140.6, 126.6,
126.0, 122.1, 53.7, 22.9; MS (ESI+) m/z (relative intensity) 132 (M+).
Anal. Calcd for C10H10NSO3F3: C, 42.71; H, 3.58; N, 4.98; S, 11.40.
Found: C, 42.40; H, 3.76; N, 4.85; S, 11.34.
87). Anal. Calcd for C16H14NSO3F3: C, 53.78; H, 3.95; N, 3.92; S,
8.97. Found: C, 53.97; H, 3.66; N, 4.01; S, 9.18.
1,2-Dimethyl-3,4-dihydroquinolizinium Triflate (10q). Fol-
lowing the general procedure, after heating for 19 h and purified
by chromatography, 37.3 mg (61%) of 10q was obtained as a gray
needles: mp 124-125 °C; IR (KBr) νmax (cm-1) 3081, 1570, 1512,
1258, 1148, 1032, 793; 1H NMR (300 MHz, acetone-d6) δ 8.89 (d,
1H, J ) 6.3 Hz), 8.57 (td, 1H, J ) 1.0, 8.3 Hz), 8.09 (d, 1H, J )
8.2 Hz), 7.92 (t, 1H, J ) 6.5 Hz), 4.83 (t, 2H, J ) 7.5 Hz), 2.88
(t, 2H, J ) 7.7 Hz), 2.22 (t, 3H, J ) 0.8 Hz), 2.18 (s, 3H); 13C
NMR (75 MHz, acetone-d6) δ 150.3, 146.6, 145.9, 145.1, 124.2,
123.3, 121.7 (c, J ) 320.5 Hz), 121.5, 53.5, 20.0, 13.3; MS (ESI+)
m/z (relative intensity) 160 (M+, 100). Anal. Calcd for
C12H14NSO3F3: C, 46.60; H, 4.56; N, 4.53; S, 10.37. Found: C,
46.49; H, 4.51; N, 4.48; S, 10.22.
2-(But-3-enyl)pyridine (19). To a solution of 2-picoline (0.186
g, 2 mmol) in dry THF (2 mL), under argon atmosphere at -78
°C, was added tert-butyllithium (1.235 mL, 2.1 mmol), and the
reaction mixture was stirred for 1 h. Then, allyl bromide was added
dropwise over the cooled solution, and the reaction mixture was
stirred at -78 °C for 30 min and left to stand overnight at room
temperature. Then, the mixture was extracted with water (5 mL)
and EtOAc (2 × 5 mL), the organic phase dried over MgSO4, and
the solvent evaporated under reduced pressure. Compound 19 was
isolated as a yellow oil by flash chromatography on silica gel using
hexane/EtOAc (8:2) as eluent (0.215 g, 81%): IR (NaCl) νmax (cm-1
)
1
2925, 1591, 1474, 1435; H NMR (300 MHz, acetone-d6) δ 8.47
(d, 1H, J ) 4.8 Hz), 7.64 (td, 1H, J ) 1.8, 7.5 Hz), 7.21 (d, 1H,
J ) 7.7 Hz), 7.14 (t, 1H, J ) 4.9 Hz), 5.93-5.80 (m, 1H),
5.06-4.98 (m, 2H), 2.83 (t, 2H, J ) 7.3 Hz), 2.50-2.42 (m, 2H);
13C NMR (200 MHz, acetone-d6) δ 162.0, 149.9, 138.9, 136.8,
123.4, 121.7, 115.0, 38.1, 34.2; HRMS (DIP/QI) m/z calcd for
C9H12N: 134.0968. Found: 134.0970.
2-(But-3-enyl)-1-(2-chloroethyl)pyridinium Triflate (20). To
a solution of 2-chloroethanol (0.105 g, 1.3 mmol) in dry CCl4 (1
mL), under argon atmosphere, was added dry pyridine (0.103 g,
1.3 mmol), and the reaction mixture was stirred at room temperature
for 5-10 min. Then, this solution was added dropwise (5-10 min)
over a cooled solution (-10 °C) of triflic anhydride (0.327 g, 0.219
mL, 1,3 mmol) in dry CCl4 (1.5 mL). The resulting white solid
formed was filtered off through sodium sulfate, and the solution
was added via cannula to a solution of 2-(but-3-enyl)-pyridine 19
(1 mmol) in dry CCl4 (1.5 mL). The reaction mixture was stirred
at room temperature for 24 h. Removal of the solvent under reduced
pressure and purification by flash chromatography on silica gel using
CH2Cl2/MeOH (9.5:0.5) gave 20 (0.307 g, 89%) as a yellow oil:
IR (NaCl) νmax (cm-1) 3087, 1632, 1512, 1454, 1261, 1158, 1030,
779; 1H NMR (200 MHz, acetone-d6) δ 9.14 (d, 1H, J ) 6.4 Hz),
8.68 (td, 1H, J ) 1.3, 9.1 Hz), 8.24 (d, 1H, J ) 8.0 Hz), 8.14 (t,
1H, J ) 6.4 Hz), 6.03-5.89 (m, 1H), 5.30 (t, 2H, J ) 5.7 Hz),
5.17-5.04 (m, 2H), 4.35 (t, 2H, J ) 5.8 Hz), 3.51 (t, 2H, J ) 7.5
Hz), 2.72-2.64 (m, 2H); 13C NMR (300 MHz, acetone-d6) δ 159.6,
147.4, 147.1, 136.4, 130.3, 126.6, 117.4, 58.8, 43.6, 32.5, 32.4;
MS (ESI+) m/z 196 (M+), 198 (M + 2). Anal. Calcd for
C12H15NClSO3F3: C, 41.68; H, 4.37; N, 4.05; S, 9.27. Found: C,
41.37; H, 4.59; N, 4.31; S, 9.15.
2-(But-3-enyl)-1-vinylpyridinium Triflate (9a). To a solution
of 20 (0.086 g, 0.25 mmol) in EtOH/MeOH (3:1) (5 mL) was added
dropwise at -10 °C for 10 min a solution of aqueous NaOH (10
N, 0.275 mmol, 1.1 equiv). The reaction mixture was stirred for
15 min, neutralized with acetic acid, and the solvent removed under
reduced pressure at 20 °C. The residue was filtered off, and the
solution was concentrated under reduced pressure at 20 °C and
purified by flash chromatography on silica gel using CH2Cl2/MeOH
(9.5:0.5) as eluent. Compound 9a (49.0 mg, 64%) was obtained as
a brown oil: IR (NaCl) νmax (cm-1) 3493, 1627, 1497, 1276, 1158,
1031, 787; 1H NMR (300 MHz, acetone-d6) δ 9.07 (d, 1H, J ) 6.2
Hz), 8.69 (td, 1H, J ) 1.5, 8.0 Hz), 8.19 (d, 1H, J ) 8.0 Hz), 8.13
(t, 1H, J ) 7.5 Hz), 7.89 (c, 1H, J ) 8.2 Hz), 6.22 (dd, 1H, J )
2.2, 14.8 Hz), 6.07 (dd, 1H, J ) 2.0, 8.2 Hz), 5.99-5.85 (m, 1H),
9-Bromo-3,4-dihydroquinolizinium Triflate (10b). Following
the general procedure, after stirring for 1 h, 57.6 mg (80%) of 10b
was obtained as a pale-brown solid: mp 145-147 °C (CH2Cl2/Et2O);
IR (NaCl) νmax (cm-1) 3084, 1632, 1477, 1262, 1149, 1029, 784;
1H NMR (300 MHz, CDCl3) δ 9.03 (d, 1H, J ) 5.8 Hz), 8.86 (d,
1H, J ) 8.2 Hz), 7.94 (t, 1H, J ) 8.1 Hz), 7.27-7.17 (m, 2H),
4.97 (t, 2H, J ) 7.5 Hz), 3.02-2.85 (m, 2H); 13C NMR (75 MHz,
acetone-d6) δ 150.1, 147.2, 146.2, 143.8, 126.3, 121.7, 121.2, 55.4,
22.8; MS (ESI+) m/z (relative intensity) 211 (M+), 213 (M + 2).
Anal. Calcd for C10H9NBrSO3F3: C, 33.35; H, 2.52; N, 3.89. Found:
C, 33.12; H, 2.74; N, 3.51.
1-Methyl-3,4-dihydroquinolizinium Triflate (10k). Following
the general procedure, after stirring for 2 h and purified by
precipitation, 53.9 mg (91%) of 10k was obtained as a white solid:
mp 130-132 °C (CH2Cl2/Et2O); IR (NaCl) νmax (cm-1) 3076, 1620,
1510, 1442, 1262, 1149, 1031, 736; 1H NMR (300 MHz, acetone-
d6) δ 8.99 (d, 1H, J ) 6.2 Hz), 8.64 (t, 1H, J ) 7.9 Hz), 8.13 (d,
1H, J ) 8.2 Hz), 8.02 (t, 1H, J ) 7.1 Hz), 6.77 (t, 1H, J ) 4.6
Hz), 4.88 (t, 2H, J ) 7.5 Hz), 2.85 (dd, 2H, J ) 4.6, 7.6 Hz), 2.27
(s, 3H); 13C NMR (75 MHz, acetone-d6) δ 147.0, 146.4, 136.4,
128.3, 126.2, 124.2, 54.7, 22.8, 18.1; MS (ESI+) m/z (relative
intensity) 146 (M+, 100), 147 (M + 1, 25), 441 (2M + OTf, 14).
Anal. Calcd for C11H12NSO3F3: C, 44.74; H, 4.10; N, 4.74; S, 10.86.
Found: C, 44.56; H, 4.32; N, 4.65; S, 10.58.
2-Phenyl-3,4-dihydroquinolizinium Triflate (10m). Following
the general procedure, after heating for 3 h and purified by
chromatography, 49.3 mg (69%) of 10m was obtained as a green
solid: mp 122-123 °C; IR (NaCl) νmax (cm-1) 2924, 1504, 1257,
1225, 1161, 1029, 774; 1H NMR (300 MHz, acetone-d6) δ 8.97 (d,
1H, J ) 6.2 Hz), 8.57 (td, 1H, J ) 1.1, 7.9 Hz), 8.09 (d, 1H, J )
8.0 Hz), 7.96 (td, 1H, J ) 1.1, 7.5 Hz), 7.88-7.85 (m, 2H),
7.55-7.51 (m, 4H), 5.08 (t, 1H, J ) 7.7 Hz), 3.45 (td, 1H, J )
0.9, 8.0 Hz); 13C NMR (75 MHz, acetone-d6) δ 150.5, 146.4, 145.5,
136.9, 131.5, 129.8, 127.2, 127.0, 125.5, 116.8, 113.1, 54.2, 25.4;
MS (ESI+) m/z (relative intensity) 208 (M+, 100), 209 (M + 1,
J. Org. Chem. Vol. 74, No. 11, 2009 4175