Reaction of N-aziridinylimines with alkynylborane reagents. A new route to allenes from aldehydes and ketones

Full text of DOI:10.1021/jo960370z

6018
J . Org. Chem. 1996, 61, 6018-6020
Ta ble 1. Syn th esis of Allen es fr om N-Azir id in ylim in es
Rea ction of N-Azir id in ylim in es w ith
Alk yn ylbor a n e Rea gen ts. A New Rou te to
Allen es fr om Ald eh yd es a n d Keton es
a n d Alk yn ylbor a n esa
Sunggak Kim,* Chang Mook Cho, and J oo-Yong Yoon
Department of Chemistry, Korea Advanced Institute of
Science and Technology, Taejon 305-701, Korea
Received February 22, 1996
Nucleophilic addition of organometallic reagents to
imines is synthetically useful1 but somewhat difficult to
achieve due to both the poor reactivity of imines as
electrophilic acceptors and the tendency of easy enoliza-
tion of imines by organometallic reagents such as Grig-
nard reagents and organolithiums.2 These problems
have been solved by employing activated imine deriva-
tives3 and/or by the use of less basic reagents such as
allylboranes,4 allylstannanes,5 organocopper reagents,6
and organocerium reagents.7
Since Eschenmoser reported that N-aziridinylimines
of R,â-epoxy ketones underwent thermal fragmentation,8
N-aziridinylimines have been widely utilized as precur-
sors of not only diazoalkanes9 and carbenes10 but also
vinyl anions in Shapiro elimination.11 In connection with
our research interest in the synthetic utility of N-
aziridinylimines, we reported the use of N-aziridin-
ylimines in radical cyclizations12 and in the generation
of alkylidene carbenes.13 We next have studied the
feasibility of adding nucleophiles onto N-aziridinylimines
and subsequent consecutive â-elimination to afford re-
ductively alkylated anions as shown in Scheme 1. Initial
studies were performed with alkynyllithium reagents.
When (phenylethynyl)lithium was added to hydrocin-
namaldehyde N-aziridinylimine (2), it failed to undergo
addition onto the N-aziridinylimine and the starting
material was recovered. Furthermore, alkynyl Grignard
reagents, alkynylcuprates, and alkynylcerium reagents
were also unsuccessful. We next turned our attention
to the possibility of using alkynylborane reagents, known
a
All reactions were conducted according to the standard
b
procedure. The yield refers to the isolated yield by column
chromatography.
Sch em e 1
Sch em e 2
(1) Volkmann, R. A. In Comprehensive Organic Synthesis; Trost, B.
M., Fleming, I., Eds.; Pergamon Press: New York, 1991; Vol. 1,
Chapter 1.12.
(2) (a) Stork, G.; Dowd, S. R. J . Am. Chem. Soc. 1963, 85, 2178. (b)
Meyers, A. I.; Williams, D. R.; Druelinger, M. J . Am. Chem. Soc. 1976,
98, 3032. (c) Whitesell, J . K.; Whitesell, M. A. J . Org. Chem. 1977, 42,
377. (d) Alexakis, A.; Lensen, N.; Tranchier, J . P.; Mangeney, P. J .
Org. Chem. 1992, 57, 4563.
(3) (a) Speckamp, W. N.; Hiemstra, H. Tetrahedron 1985, 41, 4367.
(b) Davis, F. A.; Giangiordano, M. A.; Starner, W. E. Tetrahedron Lett.
1986, 27, 3957.
(4) (a) Yamamoto, Y.; Komatsu, T.; Maruyama, K. J . Am. Chem.
Soc. 1984, 106, 5031. (b) Yamamoto, Y.; Nishii, S.; Maruyama, K.;
Komatsu, T.; Ito, W. J . Am. Chem. Soc. 1986, 108, 7778.
(5) Keck, G. E.; Enholm, E. J . J . Org. Chem. 1985, 50, 146.
(6) (a) Bertz, S. H. Tetrahedron Lett. 1980, 21, 3151. (b) Wada, M.;
Sakurai, Y.; Akiba, K. Tetrahedron Lett. 1984, 25, 1079.
(7) Denmark, S. E.; Weber, T.; Piotrowski, D. W. J . Am. Chem. Soc.
1987, 109, 2224.
(8) Felix, D.; Mueller, R. K.; Horn, U.; J oos, R.; Schreiber, J .;
Eschenmoser, A. Helv. Chim. Acta 1972, 55, 1276.
(9) (a) Padwa, A.; Ku, H. J . Org. Chem. 1980, 45, 3756. (b) Schultz,
A. G.; Dittami, J . P.; Eng, K. K. Tetrahedron Lett. 1984, 25, 1255. (c)
J ones, G. B.; Moody, C. J .; Padwa, A.; Kassir, J . M. J . Chem. Soc.,
Perkin Trans. 1 1991, 1721.
(10) (a) Padwa, A.; Gareau, Y.; Xu, S. L. Tetrahedron Lett. 1991,
32, 983. (b) Padwa, A.; Austin, D. J .; Gareau, Y.; Kassir, J . M.; Xu, S.
L. J . Am. Chem. Soc. 1993, 115, 2637. (c) Kim, S.; Cho, C. M.
Heterocycles 1994, 38, 1971.
(11) Evans, D. A.; Nelson, J . V. J . Am. Chem. Soc. 1980, 102, 774.
(12) (a) Kim, S.; Kee, I. S.; Lee, S. J . Am. Chem. Soc. 1991, 113,
9882. (b) Kim, S.; Kee, I. S. Tetrahedron Lett. 1993, 34, 4213.
(13) (a) Kim, S.; Cho, C. M. Tetrahedron Lett. 1994, 35, 8405. (b)
Kim, S.; Cho, C. M. Tetrahedron Lett. 1995, 36, 4845.
to be very effective for additions to aldimines by Akiba.14
Alkynylborane reagents were prepared in situ from
equimolar amounts of alkynyllithium reagent and boron
trifluoride etherate. When an equimolar amount of
(phenylethynyl)borane (1a or 1b) was added to compound
2, allene 5 was obtained in 55% yield. The use of 2 and
3 equiv of alkynylborane reagent gave better results,
yielding allene 5 in 68% and 82% yield, respectively
(Scheme 2). Thus, the remaining reactions were carried
out with 3 equiv of alkynylborane reagents for each mole
of N-aziridinylimines.
Table 1 summarizes the experimental results and
illustrates the efficiency and scope of the present method.
N-Aziridinylimines of aldehydes having R-hydrogens
(14) Wada, M.; Sakurai, Y.; Akiba, K. Tetrahedron Lett. 1984, 25,
1083.
S0022-3263(96)00370-2 CCC: $12.00 © 1996 American Chemical Society

Notes
J . Org. Chem., Vol. 61, No. 17, 1996 6019
143, 125 (100), 124, 111, 91. Anal. Calcd for C14H20Si : C, 77.70;
H, 9.32. Found: C, 77.29; H, 9.17.
reacted readily and gave a good yield of allenes (Table 1,
entries 1-4). The selective 1,2-addition of alkynylborane
reagents to R,â-unsaturated N-aziridinylimines (Table 1,
entries 5 and 6) was observed. It is of interest to note
that the phenylthio group did not undergo elimination
under the reaction conditions (Table 1, entry 8). The
present method reaches a limit with N-aziridinylimine
derived from sterically hindered trimethylacetaldehyde
(Table 1, entry 9). When (phenylethynyl)borane was
added to the N-aziridinylimine of trimethylacetaldehyde
under the same conditions, the desired product was
obtained in only 17% yield. Furthermore, we have
examined the reaction of (phenylethynyl)borane with
N-aziridinylimines of ketones (15a and 15b), and the
reaction afforded the desired allenes (16a and 16b) in
moderate yield (Scheme 2).
1-(Tr im et h ylsilyl)-4-p h en yl-1,2-b u t a d ien e (8): 1H NMR
(200 MHz, CDCl3) δ 0.06 (s, 9H), 3.30 (t, 2H, J ) 5.46 Hz), 4.90-
4.98 (m, 2H), 7.15-7.32 (m, 5H); 13C NMR (50 MHz, CDCl3) δ
-0.9, 34.6, 83.1 (2C), 126.0, 128.2, 128.4, 140.9, 210.1; IR (film)
1938 cm-1
. Anal. Calcd for C13H18Si: C, 77.16; H, 8.97.
Found: C, 76.94; H, 9.11.
1-P h en yl-1,3,4-n on a tr ien e (9): 1H NMR (200 MHz, CDCl3)
δ 0.93 (t, 3H, J ) 7.04 Hz), 1.25-1.49 (m, 4H), 2.01-2.14 (m,
2H), 5.40 (q, 1H, J ) 6.52 Hz), 5.91-6.05 (m, 1H), 6.48-6.65
(m, 2H), 7.19-7.41 (m, 5H); 13C NMR (50 MHz, CDCl3) δ 13.8,
22.1, 28.4, 31.2, 92.6, 94.6, 113.7, 125.6, 126.1, 127.1, 127.7,
128.5, 129.7, 137.4, 208.2; IR (film) 1940 cm-1. Anal. Calcd for
C
15H18: C, 90.85; H, 9.15. Found: C, 90.27; H, 9.69.
1-P h en yl-1,2,4-h exa tr ien e (10): 1H NMR (200 MHz, CDCl3)
δ 1.78 (d, 3H, J ) 6.00 Hz), 5.69-5.99 (m, 2H), 6.17-6.33 (m,
2H), 7.15-7.44 (m, 5H); 13C NMR (50 MHz, CDCl3) δ 18.1, 95.7,
97.7, 125.5, 126.8, 126.9, 128.2, 128.8, 131.4, 208.2; IR (film) 1940
cm-1
. Anal. Calcd for C12H12: C, 92.26; H, 7.74. Found: C,
In summary, addition of alkynylborane reagents to
N-aziridinylimines is a new, useful route to prepare
various allenes from carbonyl compounds. Although
various synthetic methods are available for allene syn-
thesis,15 the present method complements the existing
synthetic methods.
91.97; H, 7.69.
5-Met h yl-1-p h en yl-1,2-p en t a d ien e (11): 1H NMR (200
MHz, CDCl3) δ 1.08 (d, 3H, J ) 6.80 Hz), 1.09 (d, 3H, J ) 6.81
Hz), 2.38-2.48 (m, 1H), 5.58 (t, 1H, J ) 6.14 Hz), 6.14-6.19
(m, 1H), 7.13-7.30 (m, 5H); 13C NMR (50 MHz, CDCl3) δ 22.5,
22.6, 28.3, 95.6, 102.4, 126.4, 126.6, 128.5, 135.2, 203.6; IR (film)
1946 cm-1. Anal. Calcd for C12H14: C, 91.08; H, 8.92. Found:
C, 91.01; H, 8.86.
Exp er im en ta l Section
1-P h en yl-2-(p h en ylth io)-3,4-n on a d ien e (12): 1H NMR (200
MHz, CDCl3) δ 0.80 (t, 3H, J ) 6.82 Hz), 1.06-1.24 (m, 4H),
1.61-1.75 (m, 2H), 2.82-3.09 (m, 2H), 3.70-3.93 (m, 1H), 4.91-
5.11 (m, 2H), 7.16-7.42 (m, 10H); 13C NMR (50 MHz, CDCl3) δ
13.8, 22.0, 28.1, 30.9, 41.1, 50.1, 92.4, 93.0, 126.3, 126.9, 128.1,
128.4, 128.6, 129.2, 132.6, 134.7, 138.9, 204.3; IR (film) 1961
Typ ica l P r oced u r e for Syn th esis of Allen e 5. To a
solution of phenylacetylene (61 mg, 0.6 mmol) in THF (2 mL)
was slowly added n-butyllithium in n-hexane (2.5 M, 0.6 mmol)
at -78 °C under nitrogen with stirring. After being stirred for
30 min, BF3‚OEt2 (74 µL, 0.6 mmol) was added to the solution,
and the mixture was stirred for 10 min to prepare (phenyleth-
ynyl)borane. The N-aziridinylimine (51 mg, 0.2 mmol) of hy-
drocinnamaldehyde in THF (1.0 mL) was then added, and the
reaction mixture was stirred for 20 min at -78 °C and for 2 h
at room temperature. The resulting mixture was diluted with
ether (20 mL) and treated with 10% aqueous NaOH solution.
The organic layer was dried over anhydrous MgSO4, filtered,
and concentrated under reduced pressure. The crude product
was purified by silica gel column chromatography (ethyl acetate:
n-hexane ) 1:50) to afford 1,5-diphenyl-1,2-pentadiene (5) (36
mg) in 82% yield.
cm-1
. Anal. Calcd for C21H24: C, 81.76; H, 7.84. Found: C,
81.83; H, 7.90.
1-P h en yl-4,4-d im eth yl-1,2-p en ta d ien e16 (13): 1H NMR
(200 MHz, CDCl3) δ 1.11 (s, 9H), 5.55 (d, 1H, J ) 6.4 Hz), 6.17
(d, 1H, J ) 6.4 Hz), 7.23-7.28 (m, 5H); 13C NMR (50 MHz,
CDCl3) δ 28.8, 34.5, 89.6, 94.0, 125.6, 127.1, 128.5, 137.4, 205.2;
IR (film) 1947 cm-1
.
1-(1,3-Dith ia n yl)-6-p h en yl-2,3-h exa d ien e (14): 1H NMR
(200 MHz, CDCl3) δ 1.71-1.91 (m, 1H), 2.04-2.15 (m, 1H), 2.28-
2.43 (m, 4H), 2.73 (t, 2H, J ) 7.54 Hz), 2.80-2.86 (m, 4H), 4.02
(t, 1H, J ) 6.87 Hz), 5.12-5.20 (m, 2H), 7.15-7.30 (m, 5H); 13
C
1,5-Diph en yl-1,2-pen tadien e (5): 1H NMR (200 MHz, CDCl3)
δ 2.44-2.56 (m, 2H), 2.81-2.89 (m, 2H), 5.62 (q, 1H, J ) 6.56
Hz), 6.13-6.19 (m, 1H), 7.16-7.37 (m, 10H); 13C NMR (50 MHz,
CDCl3) δ 30.5, 35.4, 94.3, 95.0, 125.9, 126.6, 126.7, 128.3, 128.5,
128.6, 134.8, 141.5, 205.3; IR (film) 1948 cm-1; MS (EI/70 eV)
m/e 220 [M]+, 129 (100), 128, 115, 91; HRMS [M]+ calcd for
NMR (50 MHz, CDCl3) δ 25.8, 30.2, 30.3, 35.3, 35.4, 47.3, 87.3,
91.1, 125.8, 128.2, 128.5, 138.2, 204.9; IR (film) 1942 cm-1. Anal.
Calcd for C16H20S2: C, 69.51; H, 7.29. Found: C, 69.19; H, 7.43.
P r oced u r e for Syn th esis of N-Azir id in ylim in e (15b). To
a stirred methanol solution of 2-butanone (180 µL, 2.0 mmol)
was added N-amino-2-phenylaziridine (2.2 mL, 2.2 mmol, 1.0
M solution in methanol) at 0 °C. After being stirred for 1 h at
room temperature, the reaction mixture was concentrated under
reduced pressure. The crude product was purified by silica gel
column chromatography (ethyl acetate:n-hexane ) 1:5) to afford
316 mg (1.68 mmol, 84%) of 15b as a 4.5:1 mixture of E- and
Z-isomers.
C
17H16 220.3140, found 220.3128. Anal. Calcd for C17H16: C,
92.68; H, 7.32. Found: C, 92.34; H, 7.37.
1
1-P h en yl-3,4-n on a d ien e (6): H NMR (200 MHz, CDCl3) δ
0.81 (t, 3H, J ) 7.00 Hz), 1.22-1.31 (m, 4H), 1.84-1.89 (m, 2H),
2.18-2.27 (m, 2H), 2.65 (t, 2H, J ) 7.74 Hz), 4.99-5.06 (m, 2H),
7.09-7.21 (m, 5H); 13C NMR (50 MHz, CDCl3) δ 13.8, 22.1, 28.5,
30.7, 31.3, 35.5, 90.2, 91.5, 125.7, 128.2, 128.5, 141.9, 204.0; IR
(film) 1961 cm-1; MS (EI/70 eV) m/e 200 [M]+, 109 (100), 108,
95, 91. Anal. Calcd for C15H20: C, 89.94; H, 10.06. Found: C,
89.01; H, 9.82.
Isop r op ylid en e(2-p h en yla zir id in -1-yl)a m in e (15a ): 1H
NMR (200 MHz, CDCl3) δ 1.90 (s, 3H), 1.97 (s, 3H), 2.23 (d, 1H,
J ) 4.6 Hz), 2.35 (d, 1H, J ) 7.5 Hz), 2.81 (dd, 1H, J ) 4.5, 7.5
Hz), 7.19-7.35 (m, 5H); 13C NMR (50 MHz, CDCl3) δ 18.6, 24.6,
40.3, 43.3, 125.9, 126.8, 128.0, 138.8, 166.6; IR (film) 1645, 1606,
1497, 1446, 1366, 699 cm-1; MS (EI/70 eV) m/e 175 [M]+, 104,
91, 78, 70 (100), 42, 41. Anal. Calcd for C11H14N2: C, 75.82; H,
8.10; N, 16.08. Found: C, 75.29; H, 8.21; N, 16.06.
(1-Meth ylpr opyliden e)(2-ph en ylazir idin -1-yl)am in e (15b):
E:Z ) 4.5:1 (1H NMR ratio); 1H NMR (200 MHz, CDCl3) E δ
1.06 (t, 3H, J ) 7.4 Hz), 1.95 (s, 3H), 2.20 (q, 2H, J ) 7.6 Hz),
2.25 (d, 1H, J ) 4.5 Hz), 2.37 (d, 1H, J ) 7.6 Hz), 2.80 (dd, 1H,
J ) 4.6, 7.5 Hz), 7.17-7.34 (m, 5H); Z δ 1.02 (t, 3H, J ) 7.4 Hz),
1.89 (s, 3H), 2.25 (d, 1H, J ) 4.5 Hz), 2.37 (d, 1H, J ) 7.6 Hz),
2.51 (q, 2H, J ) 7.6 Hz), 2.80 (dd, 1H, J ) 4.6, 7.5 Hz), 7.17-
7.34 (m, 5H); 13C NMR (50 MHz, CDCl3) E: δ 10.9, 17.0, 31.6,
40.6, 43.5, 126.0, 126.8, 128.1, 139.0, 170.6; Z δ 10.2, 22.1, 25.4,
40.6, 43.5, 126.0, 126.8, 128.1, 139.0, 170.6; IR (film) 1639, 1606,
1-(Tr im eth ylsilyl)-5-p h en yl-1,2-p en ta d ien e (7): 1H NMR
(200 MHz, CDCl3) δ 0.08 (s, 9H), 2.25-2.32 (m, 2H), 2.70 (t, 2H,
J ) 7.30 Hz), 4.80-4.94 (m, 2H), 7.17-7.27 (m, 5H); 13C NMR
(50 MHz, CDCl3) δ 0.0, 29.7, 36.0, 82.8, 83.0, 125.7, 128.2, 128.4,
141.9, 209.8; IR (film) 1938 cm-1 ; MS (EI/70 eV) m/e 216 [M]+,
(15) (a) Baldwin, J . E.; Adlington, R. M.; Crouch, N. P.; Hill, R. L.;
Laffey, T. G. Tetrahedron Lett. 1995, 36, 7925. (b) Mikami, K.; Yoshida,
A.; Matsumoto, S.; Feng, F.; Matsumoto, Y. Tetrahedron Lett. 1995,
36, 907. (c) Bailey, W. F.; Aspris, P. H. J . Org. Chem. 1995, 60, 754.
(d) Reynolds, K. A.; Dopico, P. G.; Sundermann, M. J .; Hughes, K. A.;
Finn, M. G. J . Org. Chem. 1993, 58, 1298. (e) Danheiser, R. L.; Choi,
Y. M.; Menichincheri, M.; Stoner, E. J . J . Org. Chem. 1993, 58, 322.
(f) Nantz, M. H.; Bender, D. M.; J anaki, S. Synthesis 1993, 577. (g)
Block, E.; Putman, D. J . Am. Chem. Soc. 1990, 112, 4072. (h) Reviews
on the synthesis and reactions of allenes : Shuster, H. F.; Coppola, G.
M. Allenes in Organic Synthesis; Wiley: New York, 1984. Pasto, D. J .
Tetrahedron 1984, 40, 2805. Smadja, W. Chem. Rev. 1983, 83, 263.
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52, 3920.

6020 J . Org. Chem., Vol. 61, No. 17, 1996
Notes
1497, 1458, 1371, 698 cm-1 ; MS (EI/70 eV) m/e 189 [M]+, 104,
91, 84 (100), 78, 56, 41. Anal. Calcd for C12H16N2: C, 76.55; H,
8.57; N, 14.88. Found: C, 76.30; H, 8.50; N, 15.06.
5H); 13C NMR (50 MHz, CDCl3) δ 14.0, 19.3, 26.7, 92.3, 97.5,
125.7, 128.3, 128.5, 135.7, 207.6; IR (film) 1950 cm-1
.
Ack n ow led gm en t. We thank the Organic Chemis-
try Research Center and Korea Advanced Institute of
Science and Technology for financial support of our
research program.
1-P h en yl-3-m eth yl-1,2-bu ta d ien e (16a ): 1H NMR (200
MHz, CDCl3) δ 1.75 (s, 3H), 1.77 (s, 3H), 5.89-5.95 (m, 1H),
7.08-7.28 (m, 5H); 13C NMR (50 MHz, CDCl3) δ 20.7, 21.0, 91.7,
96.1, 126.6, 128.5, 135.0, 208.0; IR (film) 1954 cm-1. Anal. Calcd
for C11H12: C, 91.62; H, 8.38. Found: C, 90.80; H, 8.16.
Registr y n os. p r ovid ed by th e a u th or : 13, 109279-80-3;
16b, 109182-91-4.
1
1-P h en yl-3-m eth yl-1,2-p en ta d ien e16 (16b): H NMR (200
MHz, CDCl3) δ 1.06 (t, 3H, J ) 7.2 Hz), 1.80 (d, 3H, J ) 3.0
Hz), 2.08 (dq, 2H, J ) 7.2, 3.0 Hz), 6.05 (m, 1H), 7.17-7.25 (m,
J O960370Z