5326
A.K. Srivastava et al. / Tetrahedron 65 (2009) 5322–5327
ArH), 5.20–5.16 (br, 1H, –NH), 4.58–4.37 (m, 2H), 3.86–3.81 (m, 1H),
3.56–3.51 (m, 3H), 2.90 (br, 1H, –OH), 1.68–1.36 (m, 11H), 0.91 (t,
21 (0.016 g, 5 mol %) was added and the reaction mixture was stirred
at the same temperature for 3 h. Afterwards, some additional
amounts of the catalyst (0.01 g, 3 mol %) was added and refluxing
was continued for next 1 h. After completion of the reaction, solvent
was evaporated under reduced pressure and the residue was diluted
with ethyl acetate. The organic layer was washed with NaHCO3 so-
lution followed by brine. The extract was dried over anhydrous
Na2SO4 and evaporated. The residue was chromatographed through
J¼11.1 Hz, 3H); 13C NMR (75 MHz, CDCl3þCCl4)
d 156.2, 138.0, 133.6,
130.1,129.9,128.7,128.4,128.0,127.9, 79.9, 75.4, 72.8, 61.8, 54.2, 28.5,
24.0, 10.0; IR (neat, cmꢀ1) 3687, 3020, 2975, 2361, 1704, 1501, 1216,
761, 670; mass (ESI-MS) m/z; 309.9 (100, [M]þ)ꢃ, 253.9 (83,
t
t
[Mꢀ Bu]þ), 210.1 (94, [Mꢀ Boc]þ). Elemental analysis calcd for
C17H27NO4: C, 65.99; H, 8.80; N, 4.53; found: C, 65.52; H, 8.51; N, 4.23.
silica gel column to furnish tetrahydropyridine 24 as brown syrup
30
4.1.11. tert-Butyl (3S,4R)-4-(benzyloxy)hex-1-en-3-ylcarbamate 23
To a cooled solution of alcohol 15 (2.0 g, 6.4 mmol) in dry DCM
(25 mL) was added PCC (1.65 g, 7.68 mmol). The reaction mixture
was warmed up to room temperature and stirred for 2 h at the
same temperature. After completion of the reaction solid was fil-
tered through Celite bed and the crude aldehyde was used in the
next step without further purification. To the cooled solution of
methyl triphenylphosphonium iodide (8.67 g, 21.4 mmol) in dry
THF at ꢀ78 ꢁC under N2 atmosphere, n-BuLi (8.87 mL) of 1.6 M in
THF was added drop wise. After 15 min the solution of the above
crude aldehyde (2.2 g, 7.1 mmol) in dry THF was added and the
reaction was allowed to come at room temperature and stirring was
continued for overnight. After completion of the reaction EtOAc
was added and the organic layer was washed with water followed
by brine. The organic layer was concentrated and the residue was
(0.06 g, 70%). [
a
]
ꢀ0.8 (c 0.12, CH3OH); Rf 0.7 (5% CH3OH/CHCl3); 1H
D
NMR (300 MHz, CDCl3)
d 7.26–7.10 (m, 5H, ArH), 5.79–5.75 (m, 1H),
5.62–5.58 (m, 1H), 4.50 (s, 2H), 3.51 (s, 1H), 3.27–3.25 (m, 1H), 3.09–
3.05 (m,1H), 2.82–2.79 (m,1H), 2.31 (s,1H),1.92 (s,1H),1.65–1.51 (m,
2H), 0.88 (t, J¼7.4 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d 138.4, 129.0,
128.3,127.9,127.6,127.2,124.7, 82.4, 72.2, 54.9, 41.6, 24.1, 23.2,10.2; IR
(neat, cmꢀ1) 3782, 3696, 3020, 2361,1594,1427,1216, 761, 670; mass
(ESI-MS) m/z; 232.1 (100, [MþH]þ); EI-HRMS: calcd for: C15H21NO:
231.1623, measured 231.1606.
4.1.14. (þ)-
a-Conhydrine 5
To a solution of 24$HCl (0.02 g, 0.085 mmol) in CH3OH, 20%
Pd(OH)2/C (0.001 g) was added and stirred the reaction mixture
under hydrogen atmosphere for 8 h. After completion of the re-
action the catalyst was removed by filtration through Celite and the
filtrate was evaporated. The residue was dissolved in EtOAc and
washed with saturated NaHCO3 solution 2–3 times. The organic
layer was concentrated under reduced pressure and chromato-
graphed over silica gel column to furnish the pure 5 (0.008 g, 74%)
as colourless oil. Spectral data was in accordance with the reported
chromatographed over silica gel column to furnish colourless oil 23
29
(0.96 g, 49% over two steps). [
a
]
D
ꢀ13.6 (c 0.139, CH3OH); Rf 0.6
(15% ethyl acetate/hexane); 1H NMR (300 MHz, CDCl3)
d 7.27–7.18
(m, 5H, ArH), 5.85–5.70 (m, 1H), 5.19–5.07 (m, 2H), 4.80–4.77 (br,
1H), 4.57–4.43 (m, 2H), 4.22 (s,1H), 3.35–3.32 (m,1H),1.61–1.50 (m,
2H), 1.36 (s, 9H), 0.88 (t, J¼7.4 Hz, 3H); 13C NMR (75 MHz, CDCl3)
28
27
one. [
a]
þ8.8 (c 0.85, MeOH); {lit. 19b [
a
]
þ8.9 (c 0.85, EtOH)}; Rf
D
D
d
155.7, 137.9, 134.8, 128.7, 128.6, 128.1, 128.1, 128.0, 115.3, 82.8, 79.6,
0.6 (5% CH3OH/CHCl3). Elemental analysis calcd for C8H17NO: C,
67.09; H, 11.96; N, 9.78; found C, 66.89; H, 11.43; N, 9.27.
72.3, 55.1, 28.7, 23.6, 10.5; IR (neat, cmꢀ1) 3780, 3690, 3021, 2928,
2357, 1708, 1425, 1216, 928, 764, 672; mass (ESI-MS) m/z; 305.9 (63,
ꢃ
t
t
[M]þ) , 250.0 (100, [Mꢀ Bu]þ), 206.1 (35, [Mꢀ Boc]þ); EI-HRMS:
Acknowledgements
calcd for C18H28NO3: 306.2069, measured 306.2060.
Financial support from Department of Science and Technology
(SR/S1/OC-23/2005), New Delhi, India is highly acknowledged.
A.K.S. and S.K.D. thank CSIR for providing fellowships (NET-JRFs).
This has CDRI communication number 7745.
4.1.12. (3S,4R)-4-(Benzyloxy)-N-(but-3-enyl)hex-1-en-3-amine 16
To a solution of compound 23 (0.8 g, 2.6 mmol) in DCM (8.0 mL),
50% TFA in DCM (1.0 mL) was added at 0 ꢁC and stirred for 1 h. After
completion of the reaction solvent was evaporated and the residue
was co-evaporated twice with dry DCM to remove excess TFA. The
crude (0.7 g, 3.39 mmol) was redissolved in dry DMF (5.0 mL) and
homoallylbromide (0.54 g, 4.06 mmol) was added followed by
K2CO3 (1.87 g,13.5 mmol). The reaction mixture was stirred at 45 ꢁC
for 2 h. The DMF was distilled under reduced pressure and the
residue was diluted with ethyl acetate. The solution was washed
with water followed by brine. The organic layer was dried over
sodium sulfate, filtered, concentrated under reduced pressure and
Supplementary data
Supplementary data associated with this article can be found in
References and notes
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the crude was chromatographed over silica gel column to furnish
30
pure colourless oil 16 (0.38 g, 56% over two steps). [
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D
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d 138.9, 137.6,136.5,
128.3, 127.9, 127.7, 117.3, 116.2, 84.1, 72.2, 63.7, 46.5, 34.4, 23.3, 10.5;
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mass (ESI-MS) m/z; 260.1 (100, [M]þ). Elemental analysis calcd for
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4.1.13. (S)-6-((R)-1-(Benzyloxy)propyl)-1,2,3,6-tetrahydro-
pyridine 24
To a solution of compound 16 (0.10 g, 0.38 mmol) in dry DCM
(5.0 mL), equimolar amount of PTSA (0.073 g, 0.38 mmol) was added
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45 ꢁC. To this refluxing solution, Grubb’s second generation catalyst
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