Allylic Transposition of Alcohol and Amine Functionality by Thermal or Palladium(II)-Catalyzed Rearrangements of Allylic N-Benzoylbenzimidates

Full text of DOI:10.1021/jo962129q

2288
J . Org. Chem. 1997, 62, 2288-2291
was observed and SN2′ products were not detected. The
N-benzoylbenzimidate intermediates were conveniently
purified by simple flash chromatography on silica gel.
In contrast, Mitsunobu reaction of trans-2-hexen-1-ol
with dibenzamide was not clean and provided a 2.5:1
mixture of O- and N-alkylated products. Numerous
attempts to improve this ratio by modifications of various
reaction parameters were unsuccessful. As a result,
primary allylic alcohols were converted to N-benzoyl-
benzimidate derivatives through imidate exchange with
2-propyl N-benzoylbenzimidate (11, eq 2).7 This ex-
change reaction was most conveniently accomplished by
slowly concentrating (distillation at atmospheric pressure
using a simple Vigreux column) a benzene solution of the
primary allylic alcohol and 1.0 equiv of 11. Final
purification by flash chromatography on silica gel gave
the benzoylbenzimidate products in 81-86% yield (en-
tries 5-8, Table 1).
Allylic Tr a n sp osition of Alcoh ol a n d Am in e
F u n ction a lity by Th er m a l or
P a lla d iu m (II)-Ca ta lyzed Rea r r a n gem en ts
of Allylic N-Ben zoylben zim id a tes
Larry E. Overman* and G. Greg Zipp
Department of Chemistry, 516 Physical Sciences 1,
University of California, Irvine, California 92697-2025
Received November 13, 1996
The 1,3 rearrangement of allylic imidates to allylic
amides allows readily available allylic alcohols to serve
as precursors of less accessible allylic amides and amines.
Especially widely used is the rearrangement of allylic
trichloroacetimidates to allylic trichloroacetamides, which
was introduced by one of us in 1974 (eq 1, R1 ) H, R2 )
CCl3).1 During the course of our current studies to
develop asymmetric catalysts for allylic imidate re-
arrangements,2 we became interested in the related
rearrangement of allylic N-benzoylbenzimidates to allylic
dibenzamides (eq 1, R1 ) Bz, R2 ) Ph). Similar to allylic
trichloroacetimidates, allylic N-benzoylbenzimidates should
be available from allylic alcohol starting materials under
mild, nonacidic conditions.3 Allylic N-benzoylbenz-
imidates would differ from allylic trichloroacetimidates
in their much reduced basicity, which could allow a wider
variety of metals to catalyze their rearrangement to
allylic dibenzamides.4,5
P a lla d iu m (II)-Ca ta lyzed Rea r r a n gem en ts. Ex-
posure of primary N-benzoylbenzimidates 7-9 to 5 mol
% PdCl2(MeCN)2 in CH2Cl2 at rt occasioned rearrange-
ment to the corresponding allylically transposed dibenz-
amides 16-18. However, secondary N-benzoylbenz-
imidates rearranged less efficiently under these condi-
tions. The problem was traced to competing elimination,
which was signaled by the isolation of dibenzamide. The
simple expedient of decreasing the solvent polarity to
toluene reduced this competing process to acceptable
levels. Using toluene as the solvent, N-benzoylbenz-
imidates 3-9 rearranged at rt in the presence of 5%
PdCl2(MeCN)2 to provide dibenzamides 12-18 in 86-
92% yield. The allylic dibenzamide products showed five
diagnostic signals in the 13C NMR spectra for the two
equivalent benzoyl groups. The geraniol-derived benz-
oylbenzimidate 10 was not converted in high yield to
linalyl imide 19 under similar conditions. This latter
reaction was slow and produced up to 35% of geranyl
dibenzamide, the product of 1,3-rearrangement. Since
the rearrangement of 3-methyl-2-butenyl benzimidate 9
to imide 18 took place efficiently (entry 7, Table 1), the
distal double bond of 10 is presumably the cause of the
lower yield of the PdCl2-catalyzed rearrangement of the
geranyl substrate.
Stereoselectivity in forming disubstituted alkene prod-
ucts was extremely high, since only the E isomer of 12
or 13 could be detected by 13C NMR analysis of the crude
rearrangement product. To quantify stereoselection in
the rearrangement of 5 to trisubstituted imide 14, the Z
stereoisomer of 14 was prepared as outlined in Scheme
1. Capillary GLC analysis then established that dia-
stereoselectivity in the PdCl2-catalyzed conversion of 5
f 14 was 98:2.
Th er m a l Rea r r a n gem en ts. The rearrangement of
a representative group of allylic N-benzoylbenzimidates
under thermal conditions was also examined. Refluxing
xylenes (bp 137-144 °C) was required, and yields were
significantly lower than for the PdCl2-catalyzed re-
In this Note we report that allylic N-benzoylbenz-
imidates can be made from a variety of primary and
secondary allylic alcohols by either Mitsunobu displace-
ment or imidate exchange, and that these intermediates
undergo efficient [3,3]-sigmatropic rearrangement to
allylic dibenzamides in the presence of PdCl2(MeCN)2 at
room temperature or thermally at elevated temperatures.
Resu lts a n d Discu ssion
P r ep a r a tion of N-Ben zoylben zim id a tes. Second-
ary allylic alcohols undergo clean O-alkylation with
dibenzamide6 under the Mitsunobu conditions described
by Sammes3c to form allylic N-benzoylbenzimidates in
good yield. In the representative examples summarized
in entries 1-4 of Table 1, less than 4% of N-alkylation
(1) (a) Overman, L. E. J . Am. Chem. Soc. 1974, 96, 597. (b) Overman,
L. E. J . Am. Chem. Soc. 1976, 98, 2901. (c) Overman, L. E. Acc. Chem.
Res. 1980, 13, 218.
(2) Calter, M.; Hollis, K. T.; Overman, L. E.; Ziller, J .; Zipp, G. G.
J . Org. Chem. 1997, 62, 1449.
(3) (a) Mitsunobu, O.; Wada, M.; Sano, T. J . Am. Chem. Soc. 1972,
94, 679. (b) Wada, M.; Sano,T.; Mitsunobu, O. Bull. Chem. Soc. J pn.
1973, 46, 2833. (c) Sammes, P. G.; Thetford, D. J . Chem. Soc., Perkin
Trans. 1 1988, 111.
(4) Mercury(II) salts1 and palladium(II) complexes1c,5 have been
employed most widely to catalyze the rearrangement of allylic imidates.
(5) (a) Ikariya, T.; Ishikawa, Y.; Yoshikawa, S. Chem. Lett. 1982,
1815. (b) Schenck, T. G.; Bosnich, B. J . Am. Chem. Soc. 1985, 107,
2058. (c) Metz, P.; Mues, C.; Schoop, A. Tetrahedron 1992, 48, 1071.
(d) Mehmandoust, M.; Petit, Y.; Larcheveˆque, M. Tetrahedron Lett.
1992, 33, 4313.
(7) Exchange reactions have been employed previously to prepare
simple imidates, see, e.g.: Roberts, R. M.; Higgins, T. D., J r.; Noyes,
P. R. J . Am. Chem. Soc. 1955, 77, 3801.
(6) Titherley, A. W. J . Chem. Soc. 1904, 1673.
S0022-3263(96)02129-9 CCC: $14.00 © 1997 American Chemical Society

Notes
J . Org. Chem., Vol. 62, No. 7, 1997 2289
Ta ble 1. P r ep a r a tion of Allylica lly Rea r r a n ged Diben za m id es fr om Allylic Alcoh ols
Exp er im en ta l Section 8-10
Sch em e 1
Gen er a l P r oced u r e for P r ep a r in g N-Ben zoylb en z-
im id a tes by Mitsu n obu Rea ction . 4-P h en ylbu t-3-en -2-yl
N-Ben zoylben zim id a te (3). Following the general procedure
(8) General experimental details: All reactions were carried out
under an atmosphere of Ar or N2, and concentrations were performed
under reduced pressure using a Bu¨chi rotary evaporator. Tetrahydro-
furan (THF), Et2O and CH2Cl2 were degassed with Ar then passed
through two 4 × 36 in columns of anhydrous neutral A-2 alumina (8
× 14 mesh; LaRoche Chemicals; activated under a flow of Ar at 350
°C for 3 h) to remove water.9 Toluene was degassed with Ar, and then
passed through a 4 × 36 in column of anhydrous neutral A-2 alumina
(8 × 14 mesh; LaRoche Chemicals; activated under a flow of Ar at 350
°C for 3 h) to remove water and then through a 4 × 36 in column of
Q-5 reactant (Englehard; activated under a flow of 5% H2/N2 at 250
°C for 3 h) to remove O2.9 NMR spectra were measured on a Bruker
AC300 FT NMR spectrometer or General Electric GN500 FT NMR
spectrometer. 1H NMR chemical shifts are reported as δ values in ppm,
coupling constants are reported in hertz and refer to apparent
arrangement (Table 1). The one exception was geranyl
imidate 10, which gave the corresponding linalyl imide
19 in slightly higher yield under thermal conditions.
Stereoselection was also high in the thermal rearrange-
ments with 14 being formed as a 98:2 mixture of E and
Z stereoisomers.
Con clu sion . The [3,3]-sigmatropic rearrangement of
allylic N-acylimidates to allylic imides has been demon-
strated for the first time. In the presence of 5% PdCl2-
(MeCN)2 the rearrangement of allylic N-benzoylbenz-
imidates takes place in high yield within hours at rt.
Since the preparation of allylic N-benzoylbenzimidates
and their 1,3 transposition to allylic dibenzamides can
be accomplished under mild, neutral conditions, this
sequence for 1,3-transposition of oxygen and nitrogen
functionality should find application in the synthesis of
nitrogen-containing materials.
multiplicities. Multiplicity is indicated as follows:
s (singlet); d
(doublet); t (triplet); m (multiplet); app t (apparent t); dd (doublet of
doublets), etc. High resolution mass spectra were measured on a
MicroMass Analytical 7070E (EI or CI-isobutane), uncertainty (σ) in
mass measurments is 1.0 millimass unit (molecular weight < 400) or
1.5 millimass units (molecular weight 400-1000). FAB mass spectra
were measured with a MicroMass AutoSpec E spectrometer. Infrared
spectra were recorded using a Perkin Elmer 1600 FTIR spectrometer.
Microanalyses were performed by Atlantic Microlabs, Atlanta, GA. TLC
and column chromatography were performed as described by Still10
using E. Merck silica gel (43-60 µm) with a loading of approximately
30:1 SiO2-substrate. Analytical GLC analyses were performed on a
Hewlet Packard 5890 Series II with a 30 m × 0.32 mm Supelco SPB-1
column.
(9) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J . Organometallics 1996, 15, 1518.
(10) Still, W. C.; Kahn, M.; Mitra, A. J . Org. Chem. 1978, 43, 2923.

2290 J . Org. Chem., Vol. 62, No. 7, 1997
Notes
of Sammes,3c diethyl azodicarboxylate (0.77 mL, 4.9 mmol) was
added dropwise to a precooled (0 °C) solution of dibenzamide
(1.0 g, 4.4 mmol), Ph3P (1.3 g, 4.9 mmol), 4-phenyl-3-buten-2-ol
(0.66 g, 4.4 mmol), and THF (20 mL). The resulting mixture
was maintained for 1 h at 0 °C and then allowed to warm to rt.
After 2 h, the reaction was concentrated, and the residue was
purified by flash chromatography (20:1 hexane-EtOAc) to afford
1.2 g (76%) of 3 as a colorless oil that was homogeneous by TLC
analysis:11 Rf 0.22 (9:1 hexane-EtOAc); 1H NMR (500 MHz,
CDCl3) δ 7.99 (d, J ) 8.0 Hz, 2H), 7.61 (d, J ) 7.3 Hz, 2H), 7.47
(t, J ) 7.3 Hz, 2H), 7.43-7.23 (m, 8H), 7.12 (t, J ) 7.7 Hz, 1H),
6.77 (d, J ) 16.0 Hz, 1H), 6.38 (dd, J ) 16.0, 7.0 Hz, 1H), 5.83
(quin, J ) 6.6 Hz, 1H), 1.64 (d, J ) 6.4 Hz, 3H); 13C NMR (125
MHz, CDCl3) 175.7, 173.4, 157.4, 136.1, 134.0, 132.4, 131.6,
131.4, 130.5, 129.9, 129.3, 128.5, 128.3, 127.8, 127.2, 126.4, 74.1,
20.5 ppm; IR (film) 1657, 1651, 1599 cm-1; MS (EI) m/ z 355.1559
(355.1572 calcd for C24H21NO2).
2H), 2.11 (q, J ) 7.0 Hz, 2H), 1.46 (sextet, J ) 7.4 Hz, 2H), 0.94
(t, J ) 7.4 Hz, 3H); 13C NMR (125 MHz, CDCl3) 175.9, 158.2,
136.9, 134.2, 132.7, 131.6, 130.5, 129.5, 128.5, 123.8, 68.7, 34.4,
22.1, 13.7 ppm; IR (film) 1672, 1654, 1602 cm-1; MS (CI) m/ z
308.1648 (308.1650 calcd for C20H22NO2).
tr a n s-Cin n a m yl N-Ben zoylben zim id a te (8). A colorless
oil that was homogeneous by TLC analysis:11 Rf 0.15 (9:1
1
hexane-EtOAc); H NMR (300 MHz, CDCl3) δ 8.04 (d, J ) 7.2
Hz, 2H), 7.64 (d, J ) 7.3 Hz, 2H), 7.51 (t, J ) 6.1 Hz, 1H), 7.47-
7.25 (m, 10H), 6.82 (d, J ) 15.9 Hz, 1H), 6.51 (dt, J ) 15.9, 6.3
Hz, 1H), 5.09 (d, J ) 6.3 Hz, 2H); 13C NMR (125 MHz, CDCl3)
175.9, 158.1, 136.2, 134.7, 134.1, 132.9, 131.8, 130.4, 129.5, 128.7,
128.5, 128.2, 126.7, 123.1, 68.4 ppm; IR (film) 1674, 1651, 1599
cm-1; MS (EI) m/ z 341.1416 (341.1416 calcd for C23H19NO2).
3-Meth yl-2-bu ten yl N-Ben zoylben zim id a te (9). A color-
less oil that was homogeneous by TLC analysis:11 Rf 0.23 (9:1
1
hexane-EtOAc); H NMR (300 MHz, CDCl3) δ 8.01 (d, J ) 7.2
5-P h en yl-1-p en ten -3-yl N-Ben zoylben zim id a te (4).
A
Hz, 2H), 7.60 (d, J ) 7.2 Hz, 2H), 7.53 (t, J ) 7.3 Hz, 1H), 7.43
(t, J ) 7.6 Hz, 2H), 7.40 (t, J ) 7.3 Hz, 1H), 7.30 (t, J ) 7.4 Hz,
2H), 5.58 (t, J ) 7.1 Hz, 1H), 4.91 (d, J ) 7.1 Hz, 2H), 1.83 (s,
3H), 1.78 (s, 3H); 13C NMR (125 MHz, CDCl3) 176.0, 158.4, 139.5,
134.2, 132.7, 131.5, 130.6, 129.4, 128.5, 128.4, 128.2, 118.5, 64.9,
25.8, 18.3 ppm; IR (film) 1675, 1651, 1600 cm-1; MS (CI) m/ z
294.1474 (294.1494 calcd for C19H20NO2).
colorless oil that was homogeneous by TLC analysis:11 Rf 0.21
(9:1 hexane-EtOAc); 1H NMR (300 MHz, CDCl3) δ 7.97 (d, J )
7.2 Hz, 2H), 7.59 (d, J ) 9.6 Hz, 2H), 7.54 (t, J ) 8.0 Hz, 1H),
7.45-7.41 (m, 3H), 7.35-7.30 (m, 4H), 7.25-7.21 (m, 3H), 6.02
(ddd, J ) 17.2, 10.5, 6.4 Hz, 1H), 5.58 (q, J ) 6.4 Hz, 1H), 5.43
(d, J ) 17.2 Hz, 1H), 5.36 (d, J ) 10.5 Hz, 1H), 2.92-2.73 (m,
2H), 2.34-2.25 (m, 1H), 2.18-2.13 (m, 1H); 13C NMR (125 MHz,
CDCl3) 175.7, 157.5, 141.2, 136.2, 134.2, 132.6, 131.6, 130.6,
129.5, 128.6, 128.5, 128.4, 126.0, 117.6, 35.9, 31.4 ppm (one
carbon, presumed buried under CDCl3, is not observed); IR (film)
1658, 1651, 1600 cm-1; MS (CI) m/ z 370.1799 (370.1807 calcd
for C25H24NO2).
3,7-Dim eth yl-2,6-octa d ien yl N-Ben zoylben zim id a te (10).
A colorless oil that was homogeneous by TLC analysis:11 Rf 0.24
(9:1 hexane-EtOAc); 1H NMR (300 MHz, CDCl3) δ 8.02 (d, J )
6.9 Hz, 2H), 7.60 (d, J ) 9.6 Hz, 2H), 7.53 (t, J ) 5.9 Hz, 1H),
7.50-7.35 (m, 3H), 7.31 (d, J ) 6.4 Hz, 2H), 5.59 (t, J ) 7.0 Hz,
1H), 5.13 (t, J ) 6.5 Hz, 1H), 4.94 (d, J ) 6.9 Hz, 2H), 2.22-
2.17 (m, 4H), 1.78 (s, 3H), 1.70 (s, 3H), 1.63 (s, 3H); 13C NMR
(125 MHz, CDCl3) 175.9, 158.4, 142.7, 134.2, 132.7, 131.8, 131.5,
130.6, 129.5, 129.4, 128.5, 128.4, 123.7, 118.2, 64.8, 39.6, 26.3,
25.7, 17.7, 16.7 ppm; IR (film) 1672, 1654, 1600 cm-1; MS (CI)
m/ z 362.2124 (362.2120 calcd for C24H28NO2).
6-Meth yl-1-h ep ten -3-yl N-Ben zoylben zim id a te (5).
A
colorless oil that was homogeneous by TLC analysis:11 Rf 0.19
(9:1 hexane-EtOAc); 1H NMR (500 MHz, CDCl3) δ 7.98 (d, J )
7.5 Hz, 2H), 7.60 (d, J ) 7.5 Hz, 2H), 7.52 (t, J ) 7.4 Hz, 1H),
7.43-7.38 (m, 3H), 7.31 (t, J ) 7.4, 2H), 5.43 (t, J ) 6.5, 1H),
5.11 (s, 1H), 5.04 (s, 1H), 1.95-1.88 (m, 1H), 1.86 (s, 3H), 1.83-
1.81 (m, 1H), 1.47-1.39 (m, 4H), 0.95 (t, J ) 6.8, 3H); 13C NMR
(125 MHz, CDCl3) 175.6, 157.2, 143.3, 134.2, 132.4, 131.5, 130.7,
129.3, 128.3, 128.2, 128.0, 112.8, 80.5, 32.5, 27.5, 22.5, 18.2, 13.8
ppm; IR (film) 1697, 1654, 1600 cm-1; MS (CI) m/ z 336.1952
(336.1963 calcd for C22H26NO2).
Gen er a l P r oced u r e for P d Cl2-Ca ta lyzed Rea r r a n ge-
m en t of Allylic N-Ben zoylb en zim id a t es. N-(1-E t h en yl-
bu tyl)d iben za m id e (16). A solution of 7 (0.61 g, 2.0 mmol),
PdCl2(MeCN)2 (26 mg, 0.1 mmol), and toluene (4 mL) was
maintained at rt for 6 h and then concentrated. Purification of
the residue by flash chromatography (20:1 hexane-EtOAc)
yielded 0.55 g (90%) of 16 as a colorless oil that was homoge-
2-Cycloh exen yl N-Ben zoylben zim id a te (6). A colorless oil
that was homogeneous by TLC analysis: Rf 0.18 (9:1 hexane-
1
neous by TLC analysis: Rf 0.17 (9:1 hexane-EtOAc); H NMR
1
EtOAc); H NMR (300 MHz, CDCl3) δ 8.02 (d, J ) 8.2 Hz, 2H),
(300 MHz, CDCl3) δ 7.37 (d, J ) 7.2 Hz, 4H), 7.20 (t, J ) 6.6
Hz, 2H), 7.10 (t, J ) 7.7 Hz, 4H), 6.32 (ddd, J ) 17.2, 10.1, 7.9
Hz, 1H), 5.32 (d, J ) 17.2 Hz, 1H), 5.21-5.14 (m, 2H), 2.20-
2.10 (m, 1H), 2.00-1.88 (m, 1H), 1.45 (sextet, J ) 7.2 Hz, 2H),
0.97 (t, J ) 7.3 Hz, 3H); 13C NMR (75 MHz, CDCl3) 173.9, 137.5,
137.1, 131.4, 128.4, 128.0, 117.6, 61.2, 34.5, 19.8, 13.6 ppm; IR
(film) 1696, 1654, 1599 cm-1; MS (CI) m/ z 308.1646 (308.1650
calcd for C20H22NO2). Anal. Calcd for C20H21NO2: C, 78.15; H,
6.89; N, 4.56. Found: C, 78.04; H, 6.88; N, 4.50.
7.58 (d, J ) 8.7 Hz, 2H), 7.54 (t, J ) 6.8 Hz, 1H), 7.45 (t, J ) 6.2
Hz, 2H), 7.40 (t, J ) 7.5 Hz, 1H), 7.29 (t, J ) 6.3 Hz, 2H), 6.11-
5.98 (m, 2H), 5.62-5.55 (m, 1H), 2.24-2.03 (m, 4H), 1.91-1.83
(m, 1H), 1.77-1.69 (m, 1H); 13C NMR (125 MHz, CDCl3) 175.9,
158.4, 134.4, 133.2, 132.7, 131.5, 130.8, 129.4, 128.6, 128.5, 125.3,
71.2, 28.2, 25.0, 18.9 ppm; IR (film) 1672, 1653, 1599 cm-1; MS
(CI) m/ z 306.1486 (306.1494 calcd for C20H20NO2). Anal. Calcd
for C20H19NO2: C, 78.66; H, 6.27; N, 4.59. Found: C, 78.41; H,
6.32; N, 4.47.
N-(1-P h en yl-2(E)-bu ten yl)d iben za m id e (12). A colorless
oil that was homogeneous by TLC analysis: Rf 0.18 (9:1 hexane-
Isop r op yl N-Ben zoylben zim id a te (11). A colorless oil that
was homogeneous by TLC analysis:11 Rf 0.20 (9:1 hexane-
1
EtOAc); H NMR (500 MHz, CDCl3) δ 7.60 (d, J ) 7.8 Hz, 2H),
1
EtOAc); H NMR (300 MHz, CDCl3) δ 8.01 (d, J ) 8.5 Hz, 2H),
7.38-7.33 (m, 6H), 7.25 (d, J ) 7.5, 1H), 7.21 (t, J ) 7.5, 2H),
7.11 (t, J ) 7.8 Hz, 4H), 6.47 (dd, J ) 15.6, 8.7 Hz, 1H), 6.40 (d,
J ) 8.8 Hz, 1H), 5.91 (dq, J ) 15.0, 6.6 Hz, 1H), 1.80 (dd, J )
6.4, 1.2 Hz, 3H); 13C NMR (125 MHz, CDCl3) 173.7, 140.1, 137.6,
137.0, 131.1, 128.6, 128.3, 128.2, 128.0, 127.5, 127.3, 63.4, 17.9
ppm; IR (film) 1698, 1658, 1599, 1581 cm-1; MS (EI) m/ z
355.1567 (355.1572 calcd for C24H21NO2). Anal. Calcd for
7.60-7.47 (m, 3H), 7.47-7.34 (m, 3H), 7.30 (t, J ) 7.0 Hz, 2H),
5.33 (heptet, J ) 6.2 Hz, 1H), 1.48 (d, J ) 6.2 Hz, 6H); 13C NMR
(125 MHz, CDCl3) 175.9, 158.6, 132.6, 131.4, 130.9, 129.4, 128.4,
71.0, 21.8 ppm; IR (film) 1652, 1600 cm-1; MS (CI) m/ z
268.1331(268.1337 calcd for C17H18NO2).
Gen er a l P r oced u r e for F or m in g N-Ben zoylb en zim id -
a tes by Exch a n ge w ith 11. tr a n s-2-Hexen yl N-Ben zoyl-
ben zim id a te (7). A solution of 11 (0.53 g, 2.0 mmol), trans-2-
hexen-1-ol (0.24 mL, 2.0 mmol), and benzene (40.0 mL) was
heated at 80 °C while the benzene/2-propanol azeotrope was
collected using a Vigreux column until the total reaction volume
was ∼5 mL. This solution was concentrated, and the residue
was purified by flash chromatography (20:1 hexane-EtOAc) to
yield 0.51 g (83%) of 7 as a colorless oil that was homogeneous
C
24H21NO2: C, 81.10; H, 5.96; N, 3.94. Found: C, 81.12; H, 6.00;
N, 4.91.
N-(5-P h en yl-2(E)-p en ten yl)d iben za m id e (13). A colorless
oil that was homogeneous by TLC analysis: Rf 0.17 (9:1 hexane-
1
EtOAc); H NMR (300 MHz, CDCl3) δ 7.45 (d, J ) 7.0 Hz, 4H),
7.31-7.11 (m, 11H), 5.89-5.71 (m, 2H), 4.58 (d, J ) 5.2 Hz, 2H),
2.70 (t, J ) 7.6 Hz, 2H), 2.43-2.34 (m, 2H); 13C NMR (125 MHz,
CDCl3) 173.8, 141.4, 136.4, 134.5, 131.6, 128.6, 128.3, 128.1,
125.6, 124.7, 48.5, 35.3, 33.8 ppm; IR (film) 1694, 1682, 1651,
1
by TLC analysis:11 Rf 0.19 (9:1 hexane-EtOAc); H NMR (300
1600 cm-1; MS (CI) m/ z 370.1802 (370.1807 calcd for C25H24
-
MHz, CDCl3) δ 8.01 (d, J ) 8.2 Hz, 2H), 7.60 (d, J ) 5.3 Hz,
2H), 7.54 (t, J ) 6.3 Hz, 1H), 7.44 (t, J ) 7.2 Hz, 2H), 7.42 (t, J
) 13.6 Hz, 1H), 7.30 (t, J ) 7.8 Hz, 2H), 5.92 (dt, J ) 15.4, 6.5
Hz, 1H), 5.79 (dt, J ) 15.4, 6.2 Hz, 1H), 4.87 (d, J ) 6.1 Hz,
NO2). Anal. Calcd for C25H23NO2: C, 81.27; H, 6.27; N, 3.79.
Found: C, 81.34; H, 6.31; N, 3.72.
N-(2-Meth yl-2(E)-h ep ten yl)d iben za m id e (14). A colorless
oil that was homogeneous by TLC analysis. Analytical GLC
analysis indicated 98.0% E (PdCl2-catalyzed rearrangement) and
98.1% E (thermal rearrangement): Rf 0.23 (9:1 hexane-EtOAc);
(11) N-Benzoylbenzimidates were too susceptible to hydrolysis to
obtain correct elemental analyses routinely.

Notes
J . Org. Chem., Vol. 62, No. 7, 1997 2291
1H NMR (300 MHz, CDCl3) δ 7.48 (d, J ) 7.9 Hz, 4H), 7.27 (t,
J ) 7.4 Hz, 2H), 7.18 (t, J ) 6.9 Hz, 4H), 5.43 (t, J ) 7.2 Hz,
1H), 4.56 (s, 2H), 2.01 (q, J ) 6.8 Hz, 2H), 1.75 (s, 3H), 1.33-
1.20 (m, 4H), 0.83 (t, J ) 7.1 Hz, 3H); 13C NMR (125 MHz,
CDCl3) 174.1, 136.5, 131.7, 130.0, 129.0, 128.2, 53.9, 31.5, 27.4,
22.2, 14.8, 13.9 ppm; IR (film) 1698, 1655 cm-1; MS (CI) m/ z
336.1956 (336.1963 calcd for C22H26NO2). Anal. Calcd for
(dd, J ) 17.4, 10.7 Hz, 1H), 5.26 (d, J ) 17.4 Hz, 1H), 5.14 (d, J
) 10.7 Hz, 1H), 1.76 (s, 6H); 13C NMR (125 MHz, CDCl3) 173.4,
144.3, 138.3, 131.6, 128.7, 128.4, 128.1, 111.6, 62.5, 27.3 ppm;
IR (film) 1702, 1658, 1598 cm-1; MS (CI) m/ z 294.1485 (294.1494
calcd for C19H20NO2). Anal. Calcd for C19H19NO2: C, 77.79; H,
6.53; N, 4.77. Found: C, 77.60; H, 6.47; N, 4.72.
N-(1,5-Dim eth yl-1-eth en yl-4-h exen yl)d iben za m id e (19).
A colorless oil that was homogeneous by TLC analysis: 1H NMR
(500 MHz, CDCl3) δ 7.37 (d, J ) 8.2 Hz, 4H), 7.23 (t, J ) 8.3
Hz, 2H), 7.13 (t, J ) 8.2 Hz, 4H), 6.58 (dd, J ) 15.2, 10.4 Hz,
1H), 5.25-5.15 (m, 3H), 2.39-2.32 (m, 1H), 2.23-2.15 (m, 2H),
2.11-2.05 (m, 1H), 1.72 (s, 3H), 1.67 (s, 3H), 1.60 (s, 3H); 13C
NMR (125 MHz, CDCl3) 173.8, 158.2, 143.0, 134.1, 133.0, 131.8,
129.6, 128.5, 118.2, 67.0, 40.1, 26.4, 25.8, 17.6, 16.4 ppm; IR
(film) 1702, 1667, 1602 cm-1; MS (CI) m/ z 362.2118 (362.2120
calcd for C24H28NO2).
C
22H25NO2: C, 78.77; H, 7.51; N, 4.18. Found: C, 78.67; H, 7.54;
N, 4.12.
N-(2-Cycloh exen yl)d iben za m id e (15). A colorless oil that
was homogeneous by TLC analysis: Rf 0.18 (9:1 hexane-EtOAc);
1H NMR (300 MHz, CDCl3) δ 7.39 (d, J ) 6.9 Hz, 4H), 7.23 (t,
J ) 7.4 Hz, 2H), 7.13 (t, J ) 7.0 Hz, 4H), 5.94-5.86 (m, 1H),
5.73-5.66 (m, 1H), 5.43-5.33 (m, 1H), 2.40-2.26 (m, 1H), 2.26-
1.89 (m, 4H), 1.83-1.64 (m, 1H); 13C NMR (125 MHz, CDCl3)
174.0, 137.7, 131.7, 129.5, 128.6, 128.2, 127.6, 55.5, 27.7, 24.3,
22.0 ppm; IR (film) 1698, 1654, 1602 cm-1; MS (CI) m/ z 306.1501
(306.1494 calcd for C20H20NO2). Anal. Calcd for C20H19NO2: C,
78.66; H, 6.27; N, 4.59. Found: C, 78.54; H, 6.33; N, 4.51.
N-(1-P h en yl-2-p r op en yl)d iben za m id e (17). A colorless oil
that was homogeneous by TLC analysis: Rf 0.14 (9:1 hexane-
Ack n ow led gm en t. This research was supported by
National Science Foundation grant CHE-9412266.
G.G.Z. was supported in part by a GAANN grant from
the Department of Education. NMR and mass spectra
were determined using instruments acquired with the
assistance of Shared Instrumentation grants from NSF
and NIH. We thank Dr. J ohn Greaves for assistance
with mass spectral analyses.
1
EtOAc); H NMR (300 MHz, CDCl3) δ 7.62 (d, J ) 7.5 Hz, 2H),
7.38 (d, J ) 7.1 Hz, 5H), 7.26 (t, J ) 7.1 Hz, 2H), 7.21 (t, J ) 6.2
Hz, 2H), 7.11 (t, J ) 7.4 Hz, 4H), 6.78 (ddd, J ) 17.1, 9.9, 8.0
Hz, 1H), 6.45 (d, J ) 8.0 Hz, 1H), 5.45 (d, J ) 17.1 Hz, 1H), 5.41
(d, J ) 9.9 Hz, 1H); 13C NMR (125 MHz, CDCl3) 173.6, 139.2,
137.4, 135.3, 131.7, 128.6, 128.4, 128.2, 127.6, 127.5, 119.4, 63.7
ppm; IR (film) 1697, 1655, 1599 cm-1; MS (EI) m/ z 341.1412
(341.1416 calcd for C23H19NO2). Anal. Calcd for C23H19NO2: C,
80.90; H, 5.61; N, 4.10. Found: C, 80.88; H, 5.67; N, 4.10.
N-(1,1-Dim eth yl-2-p r op en yl)d iben za m id e (18). A color-
less oil that was homogeneous by TLC analysis: Rf 0.19 (9:1
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
3-5, 7-11, and 19 (9 pages). This material is contained in
libraries on microfiche, immediately follows this article in the
microfilm version of the journal, and can be ordered from the
ACS; see any current masthead page for ordering information.
1
hexane-EtOAc); H NMR (300 MHz, CDCl3) δ 7.38 (d, J ) 7.2
Hz, 4H), 7.24 (t, J ) 7.2 Hz, 2H), 7.12 (t, J ) 7.5 Hz, 4H), 6.46
J O962129Q