J. Liu, C.-H. Wong / Tetrahedron Letters 43 (2002) 3915–3917
3917
2).5 Although it has been reported that Selectfluor™
can electrophilically fluorinate amines,13 the reaction of
Selectfluor™ with aromatic amines was found to be
slow relative to the allylstannation reactions in our
study. After optimizing the reaction conditions, we
found that 1.5 equiv. of amines and 1.5 equiv. of
Selectfluor™ could give acceptable yields (Table 2).14 In
our experiments, 1.0 equiv. of Selectfluor™ was added
to the mixture of aldehyde and amine at first. After 5
min, 1.5 equiv. of allyltributyltin were added. The
second portions of Selectfluor™ (0.5 equiv.) and
allytributyltin (1.5 equiv.) were added after 30 min. The
yields of the one-pot allylstannations ranged from mod-
erate (46% for 1-naphthaldehyde and p-anisidine) to
good (87% for trans-cinnamaldehyde and aniline). The
undesirable coupling of aldehyde and allyltributyltin
was usually less than 10%, except 1-naphthaldehyde
(entry 5, Table 2) where 22% alcohol was isolated,
presumably caused by steric hindrance.
8. Vincent, S. P.; Burkart, M. D.; Tsai, C.-Y.; Zhang, Z.;
Wong, C.-H. J. Org. Chem. 1999, 64, 5264–5279.
9. Shibata, N.; Suzuki, E.; Asahi, T.; Shiro, M. J. Am.
Chem. Soc. 2001, 123, 7001–7009.
10. Liu, J.; Wong, C.-H. Tetrahedron Lett., in press.
11. General procedure for preparation of homoallylic alcohols:
Allyltributyltin (375 mL, 1.2 mmol) was added to a mix-
ture of trans-cinnamaldehyde (100 mL, 0.80 mmol) and
Selectfluor™ (354 mg, 1.0 mmol) in CH3CN (5 mL) at
room temperature. A second portion of allyltributyltin
(375 mL, 1.2 mmol) was added after 30 min. After the
reaction proceeded to completion in 1 h, H2O (10 mL)
was added and the mixture was extracted with CH2Cl2
(10 mL×2). The organic layers were combined, dried
(Na2SO4) and concentrated in vacuo. The residue was
purified by flash chromatography (silica, 12:1 hex-
anes:EtOAc) to afford the product as an oil (130 mg,
1
93%). H NMR (500 MHz, CDCl3) l 7.36 (br. d, J=8.5
Hz, 2H), 7.30 (br. t, J=8.5 Hz, 2H), 7.23 (tt, J=1.1, 7.0
Hz, 1H), 6.58 (d, J=16.1 Hz, 1H), 6.22 (dd, J=6.3, 16.1
Hz, 1H), 5.83 (m, 1H), 5.15 (m, 2H), 4.33 (m, 1H), 2.40
(m, 2H), 2.03 (d, J=2.2 Hz, 1H); 13C NMR (125 MHz,
CDCl3): 136.57, 133.99, 131.49, 130.24, 128.49, 127.58,
126.40, 118.38, 71.64, 41.91; ESI m/e calcd for (M+)
C12H14O: 174; found: 174 (M+).
In summary, we have demonstrated that Selectfluor™
can be used as an excellent promoter for the allylation
reaction of aldehydes and imines with allyltributyltin in
a very straightforward one-step route to afford homo-
allylic alcohols or amines. The reaction is not air or
moisture sensitive. In our experiment, all reactions were
carried out directly from commercial reagents in air.
Because Selectfluor™ is not so toxic and relatively
cheap, we believe that it is a good promoter for the
extensively used allylstannation reaction. Further inves-
tigation of the mechanism and the scope of the utility
of Selectfluor™ is ongoing in our laboratory.
12. Keck, G.; Enholm, E. J. J. Org. Chem. 1985, 50, 146–147.
13. Singh, R. P.; Shreeve, J. M. Chem. Commun. 2001, 13,
1196–1197.
14. General procedure for preparation of homoallylic amines:
Selectfluor™ (283 mg, 0.8 mmol) was added to a mixture
of trans-cinnamaldehyde (100 mL, 0.80 mmol) and aniline
(110 mL, 1.2 mmol) in CH3CN (5 mL) at room tempera-
ture. After the reaction mixture was stirred for 5 min,
allyltributyltin (373 mL, 1.2 mmol) was added. After 30
min, the second portions of Selectfluor™ (142 mg, 0.4
mmol) and allyltributyltin (373 mL, 1.2 mmol) were added
to the mixture. After the reaction proceeded to comple-
tion, H2O (10 mL) was added and the mixture was
extracted with CH2Cl2 (10 mL×2). The organic layers
were combined, dried (Na2SO4) and concentrated in
vacuo. The residue was purified by flash chromatography
(silica, 25:1 hexanes:EtOAc) to afford the product as
References
1. Yamamoto, Y.; Asao, N. Chem. Rev. 1993, 93, 2207–
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3. Aspinall, H. C.; Greeves, N.; McIver, E. G. Tetrahedron
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4. Aspinall, H. C.; Bissett, J. S.; Greeves, N.; Levin, D.
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1
yellow oil (173 mg, 87%). H NMR (600 MHz, CDCl3) l
7.33 (d, J=8.3 Hz, 2H), 7.21 (t, J=7.4 Hz, 2H), 7.16 (t,
J=7.4 Hz, 1H), 7.14 (t, J=7.0 Hz, 2H), 6.68 (t, J=7.6
Hz, 1H), 6.63 (d, J=8.3 Hz, 2H), 6.58 (d, J=15.8, 1H),
6.17 (dd, J=6.1, 15.8 Hz, 1H), 5.83 (m, 1H), 5.15 (m,
2H), 4.03 (m, 1H), 3.82 (s, 1H), 2.45 (m, 2H); 13C NMR
(150 MHz, CDCl3): 147.42, 136.85, 134.34, 131.43,
130.18, 129.12, 128.46, 127.33, 126.31, 118.28, 117.39,
113.46, 54.65, 40.45; HRMS m/e calcd for (M+) C18H19N:
249.1517; found: 272.1412 (M+Na).