Efficient transamination under mild conditions: Preparation of primary amine derivatives from carbonyl compounds via imine isomerization with catalytic amounts of potassium tert-butoxide

Article abstract of DOI:10.1021/jo952124d

1,3-Prototropic rearrangement of N-diphenylmethanimines was successfully performed with a catalytic amount of potassium tert-butoxide. This procedure can also be used with aliphatic and aromatic aldimines and was extended to the isomerization of (1R)-camphorquinone monoimine and N-(4-methoxyphenyl)-4-phenyl-3-iminoazetidin-2-one. The isomerized imines were easily hydrolyzed and isolated as Cbz derivatives.

Full text of DOI:10.1021/jo952124d

5134
J . Org. Chem. 1996, 61, 5134-5139
Efficien t Tr a n sa m in a tion u n d er Mild Con d ition s: P r ep a r a tion of
P r im a r y Am in e Der iva tives fr om Ca r bon yl Com p ou n d s via Im in e
Isom er iza tion w ith Ca ta lytic Am ou n ts of P ota ssiu m ter t-Bu toxid e
Gianfranco Cainelli,* Daria Giacomini,* Alessandra Trere`, and Pietro Pilo Boyl
Dipartimento di Chimica “G. Ciamician”, Universita` di Bologna, Via Selmi 2, I-40126 Bologna, Italy
Received November 30, 1995X
1,3-Prototropic rearrangement of N-diphenylmethanimines was successfully performed with a
catalytic amount of potassium tert-butoxide. This procedure can also be used with aliphatic and
aromatic aldimines and was extended to the isomerization of (1R)-camphorquinone monoimine and
N-(4-methoxyphenyl)-4-phenyl-3-iminoazetidin-2-one. The isomerized imines were easily hydrolyzed
and isolated as Cbz derivatives.
R,R′-Imine isomerization has been recognized as a
demonstrate the usefulness of this method through an
application in â-lactam chemistry.
prototype of the biochemical transamination reaction for
many years. Several attempts have been made to mimic
natural transaminases by converting amines into carbo-
nyl compounds using prototropic rearrangement and
equilibration of Schiff base intermediates.1 The conver-
sion of carbonyl compounds into amines by the same
process has received less attention.2
Resu lts a n d Discu ssion
Our goal was to develop a simple and mild conversion
of carbonyl compounds into amines via imine isomeriza-
tion. The key step of this process is a 1,3-proton shift
which allows the interconversion of the two isomeric
imines. This transformation usually requires severe
reaction conditions and the use of a strong base. More-
over, attempts to prepare 1-alkyl-3-phenyl-2-azaallyl
anion with lithium dialkylamides have failed.4a Phase-
transfer conditions have been successfully used in enan-
tioselective alkylation of glycine imine derivatives.11 We
used N-diphenylmethanamine to form the starting imine
1 to provide a particularly acidic R-proton, which would
then allow us to use milder basic conditions to effect
deprotonation.
The mechanism of base-catalyzed imine tautomerism
was investigated by Cram and Guthrie,3 who showed that
it involves the formation of a delocalized 2-azaallyl anion.
More recently, this intermediate has been generated
through deprotonation of imines with a strong base,4 tin-
lithium exchange of 2-azaallyl stannanes,5 desilylation
of N-(silylmethyl) imines,6 and conrotatory ring opening
of N-metallo aziridines.7 2-Azaallylic anions have found
useful synthetic applications as R-amino carbanion equiva-
lents in alkylation reactions,8 in Michael additions,9 and
as 4π components in cycloaddition reactions.4a
Continuing our studies on the reactivity of the azome-
thine group and the use of imines as a nitrogen source
in the synthesis of natural products,10 we report here our
findings on the use of N-diphenylmethanimines 1 in the
synthesis of primary amine derivatives via transamina-
tion using potassium tert-butoxide as a catalyst. We
X Abstract published in Advance ACS Abstracts, J uly 1, 1996.
(1) (a) Bucklev, T. F.; Rapoport, H. J . Am. Chem. Soc. 1982, 104,
4446. (b) Corey, E. J .; Achiwa, K. J . Am. Chem. Soc. 1969, 91, 1429.
(c) Calo`, V.; Lopez, L.; Todesco, P. E. J . Chem. Soc., Perkin Trans. 1
1972, 1652. (d) J aeger, D. A.; Cram, D. J . J . Am. Chem. Soc. 1971,
93, 5153. (e) Yamada, S.-I.; Hashimoto, S.-I. Tetrahedron Lett. 1976,
997. (f) Babler, J . H.; Invergo, B. J . J . Org. Chem. 1981, 46, 1937.
(2) (a) Yamada, S.-I.; Ikota, N.; Achiwa, K. Tetrahedron Lett. 1976,
1001. (b) Soloshonok, V. A.; Kirilenko, A. G.; Kukhar, V. P.; Resnati,
G. Tetrahedron Lett. 1993, 34, 3621.
(3) (a) Cram, D. J .; Guthrie, R. D. J . Am. Chem. Soc. 1966, 88, 5760.
(b) Guthrie, R. D.; Meister, W.; Cram, D. J . J . Am. Chem. Soc. 1967,
89, 5288. (c) Guthrie, R. D.; J aeger, D. A.; Meister, J . W.; Cram, D. J .
J . Am. Chem. Soc. 1971, 93, 5137.
(4) (a) Kauffmann, T. Angew. Chem., Int. Ed. Engl. 1974, 13, 627.
(b) Ricci, A.; Guerrini, A.; Seconi, G.; Mordini, A.; Constantieux, T.;
Picard, J .-P.; Aizpurua, J .-M.; Palomo, C. Synlett 1994, 955.
(5) (a) Pearson, W. H.; Stevens, P. E. Tetrahedron Lett. 1994, 35,
2641. (b) Pearson, W. H.; Szura, D. P.; Postich, M. J . J . Am. Chem.
Soc. 1992, 114, 1329 and references therein.
Treatment of 1a with 10 mol % of t-BuOK gave 2a .
The starting imines 1a -f were prepared from the cor-
responding aldehydes with diphenylmethanamine in
CH2Cl2 in the presence of MgSO4 as a dehydrating agent.
Generally, the reaction with catalytic t-BuOK proceeds
satisfactorily at room temperature with good yields for
the isomerized products (Table 1). NMR analysis of the
crude products showed almost pure compounds, while
chromatography on silica gel showed a loss of material
(10) (a) Cainelli, G.; Panunzio, M.; Giacomini, D.; Martelli, G.;
Spunta, G.; Bandini, E. Addition of Enolates and Metalloalkyls to
Imines. Stereospecific Synthesis of â-Lactams, amines, aziridines and
aminols. NATO ASI Chemical synthesis: gnosis to prognosis, in press.
(b) Bandini, E.; Cainelli, G.; Giacomini, D.; Martelli, G.; Panunzio, M.;
Spunta, G. Biorg. Med. Chem. Lett. 1993, 3, 2347. (c) Cainelli, G.;
Panunzio, M.; Andreoli, P.; Martelli, G.; Spunta, G.; Giacomini, D.;
Bandini, E. Pure Appl. Chem. 1990, 62, 605. (e) Cainelli G.; Panunzio,
M.; Giacomini, D.; Martelli, G.; Spunta, G. J . Am. Chem. Soc. 1988,
110, 6879.
(6) (a) Tsuge, O.; Kanemasa, S.; Hatada, A.; Matsuda, K. Bull. Chem.
Soc. J pn. 1986, 59, 2537. (b) Tsuge, O.; Kanemasa, S.; Yamada, T.;
Matsuda, K. J . Org. Chem. 1987, 52, 2523.
(7) Kauffmann, T.; Habersaat, K.; Ko¨ppelmann, E. Angew. Chem.,
Int. Ed. Engl. 1972, 11, 291.
(8) Arrowsmith, J . E.; Cook, M. J .; Hardstone, D. J . J . Chem. Soc.,
Perkin Trans. 1 1979, 2364.
(9) Stork, G.; Leong, A. Y. W.; Touzin, A. M. J . Org. Chem. 1976,
41, 3491.
(11) O’Donnell, M. J .; Wu, S.; Huffman, J . C. Tetrahedron 1994, 50,
4507 and references cited therein.
S0022-3263(95)02124-4 CCC: $12.00 © 1996 American Chemical Society

Efficient Transamination under Mild Conditions
J . Org. Chem., Vol. 61, No. 15, 1996 5135
Ta ble 1. Isom er iza tion of Im in es 1a -f
entry
imine
product
t-BuOK equiv
time
yield, %
1
2
3
4
5
6
7
1a
1a
1b
1c
1d
1e
1f
2a
2a
2b
2c
2d
2e
2f
1.2
0.1
0.1
0.1
0.1
1.2
1.2
20 min
20 min
1 h
2 h
50 min
1 h
97
91
87
95
94
60a
71b
1 h
a
b
The remaining 40% is starting material 1e. The remaining
29% is starting material 1f.
due to imine hydrolysis. In the imines 1a -d , the proton
was efficiently shuttled from the R to the R′ position by
t-BuOK. Indeed, the difference in pKa between the
hydrogens in the two positions is the driving force of this
reaction. The imines 1e,f, which are derived from
aromatic aldehydes, gave rise to an equilibrium between
the starting materials and 2e,f, which reflected the fact
that the two positions had similar pKa values. If the
isomerization of 1e,f is performed with 1.2 equiv of
t-BuOK in the presence of an electrophile, a concomitant
irreversible alkylation occurs with an almost quantitative
conversion into the products. In an attempted tandem
isomerization-alkylation reaction with the hexanal imi-
ne 1a , the only product was the isomerized imine 2a ,
even in presence of the electrophile. This suggests that,
in the case of aliphatic aldimines, the intramolecular
protonation of the intermediate 2-azaallyl anion was
faster than its intermolecular alkylation. Various rear-
by a NOE DIFF experiment in CDCl3 (the relevant
correlations used to determine the relative stereochem-
istry are shown in the Experimental Section). This result
demonstrated that t-BuOK attacked from the less-
hindered exo position and shuttled the proton from the
same side. Hydrolysis of 16 under acidic conditions and
treatment with CbzCl gave the corresponding carbamate
17 in 70% yield after flash chromatography.
Following our interest in â-lactam chemistry and
possessing N-(4-methoxyphenyl)-4-phenyl-3-oxoazetidin-
2-one,12 we tested this transamination on the correspond-
ing highly functionalized imine. The product 18 was
obtained as an E,Z mixture (40:60) from the 3-oxoazeti-
dinone. In this isomerization, we observed that the
amount of the base played an important role in the
diastereofacial selectivity. In fact, exposure to 10% mol
of t-BuOK in THF gave a 20:80 cis/ trans mixture of the
two â-lactams 19 and 20 in a quantitative yield. Inter-
estingly, if a stoichiometric amount of potassium tert-
butoxide was used, the ratio of the two isomers was
reversed. The relative stereochemistry of the two isomers
was assigned on the basis of the NMR signals of the
annular protons. In the azetidinone 19, the coupling
constant was 1.8 Hz, which indicates a trans arrange-
ment, while cis isomer 20 showed J ) 4.98 Hz.
These results indicate that this method is useful for
transforming carbonyl compounds to amines under very
mild conditions. This method could be successfully used
with “sensitive” compounds, such as â-lactams, and
represents an improvement over Chiba’s procedure13 for
obtaining 3-aminoazetidin-2-one via oxime reduction.
ranged and alkylated imines were successfully hydro-
lyzed with 1 N HCl in acetone and isolated as carboben-
zyloxy derivatives for complete characterization.
Attempts to isomerize imines of simple ketones such
as 3-methylbutan-2-one with a catalytic amount of t-
BuOK in THF failed. However, in the case of keto imines
activated by a neighboring carbonyl group, such as the
(1R)-camphorquinone monoimine 15, prototropic rear-
rangement was successful and exclusively gave the
rearranged product 16. Imine 15 is the only product
obtained by refluxing (1R)-(-)-camphorquinone and diphe-
nylmethanamine in benzene in a Dean-Stark apparatus.
Treatment with 10 mol % of t-BuOK gave the 3-ami-
nobornan-2-one derivative 16 in good yield. Interest-
ingly, 16 was obtained as the endo isomer, as confirmed
The mechanism of the transamination reaction in
t-BuOK/t-BuOH has been studied thoroughly by Cram
and Guthrie.3c They demonstrated that abstraction of
the proton by the action of t-BuOK solvated by THF and
(12) Cainelli, G.; Panunzio, M.; Giacomini, D.; Di Simone, B.;
Camerini, R. Synthesis 1994, 805.
(13) Chiba, K.; Mori, M.; Ban, Y. Tetrahedron 1985, 41, 387.

5136 J . Org. Chem., Vol. 61, No. 15, 1996
Cainelli et al.
t-BuOH generates an ion pair14 that is coordinated only
by the potassium on the side from which the proton was
abstracted. Collapse to the covalent state then occurs
via a syn proton shift. In the case of imine 18, the face
opposite the 4-phenyl substituent could better accom-
modate the potassium with its ligands. Consistent with
rected. NMR spectra were obtained on 300- and 200-MHz
instruments with TMS as an internal standard. A differential
NOE experiment was performed using NOE DIFF sequences
in NMR tubes degassed using the freeze-pump-thaw tech-
nique. Mass spectra were recorded at an ionization energy of
70 eV.
Im in es 1a -f. Gen er a l P r oced u r e. To a stirred solution
of diphenylmethanamine (10 mmol) in dry CH2Cl2 (25 mL)
under an inert atmosphere at rt were successively added
MgSO4 (2.6 g, 22 mmol) and the aldehyde (10 mmol). The
resulting mixture was stirred at room temperature until the
starting aldehyde was consumed (GC-monitoring). The fil-
tered solution was evaporated to give the crude imine.
N-Hexylid en e-1,1-d ip h en ylm eth yla m in e (1a ) was ob-
tained by the general procedure as a colorless oil (2.597 g, Y
) 98%): m/ z 265 (M+, 0.2), 209 (28), 167 (100), 91 (3), 77 (4);
1
IR (film) 1667 cm-1; H NMR (CDCl3, 300 MHz) δ 0.9 (t, J )
7.2 Hz, 3 H), 1.30-1.65 (m, 6H), 2.38 (dt, J ) 8.1 and 4.8 Hz,
2 H), 5.38 (s, 1H), 7.2-7.4 (m, 10 H), 7.77 (t, J ) 4.8 Hz, 1 H);
13C NMR (CDCl3, 50.3 MHz) δ 13.9, 22.4, 25.6, 31.4, 35.8, 78.1,
126.8, 127.4, 127.5, 128.3, 143.7, 165.6.
N -(C y c lo h e x y lm e t h y lid e n e )-1,1-d ip h e n y lm e t h y l-
a m in e (1b) was obtained by the general procedure as a white
solid (2.216 g, Y ) 80%) crystallized from pentane/CH2Cl2: mp
48-49 °C; m/ z 277 (M+, 1.2), 209 (25), 167 (100), 91 (4.3), 77
(3.0); IR (Nujol) 1660 cm-1; 1H NMR (CDCl3, 200 MHz) δ 1.1-
1.9 (m, 10 H), 2.2 (bs, 1 H), 5.33 (s, 1 H), 7.15-7.60 (m, 10 H),
7.70 (d, J ) 5.6 Hz, 1 H); 13C NMR (CDCl3, 50.3 MHz) δ 25.4,
26.0, 29.7, 43.5, 77.9, 126.7, 127.5, 128.3, 143.9, 169.0. Anal.
Calcd for C20H23N: C, 86.59; H, 8.36; N, 5.05. Found: C, 86.63;
H, 8.40; N, 5.11.
a syn proton transfer, the cis diastereoisomer should be
preferred. Indeed, this was observed with an equimo-
lecular amount of the base, which leads to the quantita-
tive formation of the azaallyl anion which undergoes
rapid prototropic rearrangement. However, the catalytic
protocol favors equilibration to give the thermodynami-
cally more stable trans isomer. The existence of an
equilibrium under these conditions was confirmed by
treatment of the pure cis azetidinone imine 20 with 0.1
equiv of t-BuOK for 12 h to give a 20:80 mixture of cis
and trans â-lactams 20:19 in quantitative yield. The
same cis:trans ratio was obtained when we started from
the pure trans azetidinone imine 19 with 0.1 equiv of
t-BuOK for 12 h.
N -(2,2-Dim e t h ylp r op ylid e n e )-1,1-d ip h e n ylm e t h yl-
a m in e (1c) was obtained by the general procedure as a pure
solid compound and used without further purification (2.134
g,Y ) 85%): mp 44-46 °C; m/ z 251 (M+, 1), 236 (0.5), 194
(0.4), 167 (100), 91 (3.0), 77 (2.9); IR (Nujol) 1667 cm-1 1H
;
NMR (CDCl3, 300 MHz) δ 1.12 (s, 9 H), 5.35 (s, 1 H), 7.20-
7.35 (m, 10 H), 7.8 (s, 1 H); 13C NMR (CDCl3, 75.5 MHz) δ
20.9, 36.4, 77.4, 126.7, 126.9, 127.5, 128.3, 144.2, 171.6. Anal.
Calcd for C18H21N: C, 86.01; H, 8.42; N, 5.57. Found: C, 85.95;
H, 8.36; N, 5.61.
Successful hydrolysis was effected by treating the
isomerized imines 19 and 20 in CH2Cl2 with a 0.5 M
solution of NH2OH‚HCl in EtOH at 40 °C for 5 min to
give, after treatment with CbzCl, the derivatives 21 and
22.
N-(2-Bu ten ylid en e)-1,1-d ip h en ylm eth yla m in e (1d ) was
obtained by the general procedure as a yellow oil (2.279 g),
cis/ trans ) 10:90, Y ) 97%: m/ z 235 (M+, 10), 220 (3), 167
(100), 91 (3), 77 (3.6); IR (film) 1657, 1619 cm-1 1H NMR
;
(CDCl3, 300 MHz) δ 1.18 (d, J ) 6.3 Hz, 3 H cis), 1.9 (d, J )
6.4 Hz, 3 H trans), 5.42 (s, 1H), 6.20-6.44 (m, 2 H), 7.20-
7.45 (m, 10 H) 8.03 (d, J ) 8.0 Hz, 1 H trans), 8.51 (d, J ) 8.5
Hz 1 H cis); 13C NMR (CDCl3, 75.5 MHz) δ 18.3 (trans), 20.9
(cis), 77.8 (trans), 78.0 (cis), 126.7, 127.0, 127.3, 127.5, 128.3,
132.0, 141.2, 143.6, 162.7 (trans), 163.8 (cis).
N-Ben zylid en e-1,1-d ip h en ylm eth yla m in e (1e) was ob-
tained by the general procedure as pale yellow solid (crystal-
lized from pentane), 2.303 g, 85% yield: mp 98-100 °C; m/ z
271 (M+, 10), 270 (4), 194 (3), 167 (100), 90 (4), 77 (7); IR
In summary, N-diphenylmethanimines derived from
alkyl and aryl aldehydes undergo rapid prototropic
rearrangement with a catalytic amount of t-BuOK.
Furthermore, we have shown that this mild protocol for
transamination can be applied to highly functionalized
compounds. In fact, (1R)-camphorquinone monoimine
and 3-oxoazetidinone imine each gave good yields of the
corresponding Cbz derivatives.
(CHCl3) 1637 cm-1 1H NMR (CDCl3, 300 MHz) δ 5.63 (s, 1
;
H), 7.2-7.9 (m, 15 H), 8.45 (s, 1 H); 13C NMR (CDCl3, 50.3
MHz) δ 77.9, 127.0, 127.7, 128.4, 130.7, 136.3, 143.9, 160.8.
Anal. Calcd for C20H17N: C, 88.52; H, 6.31; N, 5.16. Found:
C, 88.47; H, 6.23; N, 5.24.
N -(F u r a n -2-y lm e t h y li d e n e )-1,1-d i p h e n y lm e t h y l-
a m in e (1f) was obtained by the general procedure as white
solid (crystallized from hexane, 2.088 g, 80% yield): mp 96-
98 °C; m/ z 261 (M+, 33), 260 (8), 232 (1), 184 (4), 167 (100);
Exp er im en ta l Section
1
IR (Nujol) 1645 cm-1; H NMR (CDCl3, 200 MHz) δ 5.60 (s, 1
H), 6.50 (dd, J ) 1.8 and J ) 3.5 Hz, 1 H), 6.82 (d, J ) 3.5 Hz,
1 H), 7.2-7.4 (m, 10 H), 7.56 (d, J ) 1.8 Hz, 1 H), 8.22 (s, 1
H); 13C NMR (CDCl3, 50.3 MHz) δ 77.9, 111.6, 114.5, 127.0,
127.7, 128.4, 143.2, 144.8, 149.6, 151.6. Anal. Calcd for
C18H15NO: C, 82.73; H, 5.79; N, 5.36. Found: C, 82.80; H,
5.83; N, 5.34.
Isom er iza tion Rea ction . Gen er a l P r oced u r e. In a 25
mL flask under an inert atmosphere was placed 1 mmol of
the starting imine in THF (10 mL), and 0.1 mL of a 1 M THF
solution of t-BuOK was added, giving a pale rose reaction
mixture. After the starting material disappeared (GC-
Commercially available compounds were used without
further purification, unless otherwise indicated. All reactions
were performed under a positive pressure of argon. CH2Cl2
was distilled from P2O5 immediately prior to use. THF was
distilled from Na/Ph2CdO under argon and diethyl ether, and
benzene was distilled from Na. Final solutions were dried over
Na2SO4 before rotatory evaporation. Melting points are uncor-
(14) For X-ray structure of the 1,3-diphenyl-2-azaallyl anion-
potassium pair, see: Veya, P.; Floriani, C.; Chiesi-Villa, A.; Guastini,
C. J . Chem. Soc., Chem. Commun. 1991, 991.

Efficient Transamination under Mild Conditions
J . Org. Chem., Vol. 61, No. 15, 1996 5137
monitoring), the reaction mixture was quenched with ice and
extracted with CH2Cl2, dried, and evaporated, obtaining the
crude oily isomerized imines which were found to be pure by
1H NMR and GC analysis.
N-(Dip h en ylm eth ylid en e)h exyla m in e (2a ) (0.240 g, 91%
yield) was obtained by the general procedure starting from
0.265 g (1 mmol) of 1a : m/ z 265 (M+, 24), 264 (59), 250 (14),
236 (29), 222 (12), 208 (95), 194 (100), 180 (23), 165 (30), 91
(89), 77 (25); IR (film) 1625 cm-1; 1H NMR (CDCl3, 200 MHz)
δ 0.85 (t, J ) 7.3 Hz, 3 H), 1.2-1.4 (m, 6H), 1.67 (m, 2 H),
3.36 (t, J ) 7.1 Hz, 2 H), 7.10-7.65 (m, 10 H); 13C NMR (CDCl3,
50.3 MHz,) δ 14.0, 22.5, 27.1, 31.1, 31.6, 53.9, 126.8, 127.7,
127.9, 128.2, 129.6, 137.0, 140.0, 167.5.
1.1-2.0 (m, 6 H), 4.43 (dd, J ) 8.7 and J ) 11.7 Hz, 1 H),
7.1-7.8 (m, 15 H); 13C NMR (CDCl3, 50.3 MHz) δ 13.9, 22.5,
28.6, 39.3, 66.6, 126.4, 126.8, 127.5, 127.7, 128.1, 128.3, 129.7,
137.1, 140.0, 145.3, 166.1. Anal. Calcd for C24H25N: C, 88.03;
H, 7.69; N, 4.28. Found: C, 88.11; H, 7.73; N, 4.24.
N-(Diph en ylm eth yliden e)-1-ph en ylpr opylam in e (5) was
obtained as for 3, with ethyl bromide, 89% yield (0.268 g): m/ z
299 (M+, 10), 270 (100), 165 (44), 91 (59), 77 (20); IR (film)
1
1629 cm-1; H NMR (CDCl3, 300 MHz) δ 0.9 (t, J ) 5.0 Hz, 3
H), 2.0 (m, 2 H), 4.37 (dd, J ) 5.6 and J ) 7.5 Hz, 1 H), 7.10-
7.75 (m, 15 H); 13C NMR (CDCl3, 50.3 MHz) δ 11.1, 32.4, 68.07,
126.5-128.5, 137.2, 140.0, 145.1, 166.4. Anal. Calcd for
C22H21N: C, 88.25; H, 7.07; N, 4.68. Found: C, 88.20; H, 6.98;
N, 4.71.
N-(Dip h en ylm et h ylid en e)-1-cycloh exylm et h yla m in e
(2b). Starting from 0.277 g (1 mmol) of 1b by the general
procedure 2b was obtained, 0.240 g 87% yield: m/z 277 (M+,
10), 276 (17.2), 194 (77.4), 180 (9.1), 165 (18.6), 91 (100), 77
(12.9); IR (film) 1620 cm-1; 1H NMR (CDCl3, 200 MHz) δ 0.8-
N-(Diph en ylm eth yliden e)-1-ph en yl-3-bu ten ylam in e (6)
was obtained as for 3, with allyl bromide, 84% yield (0.261 g):
m/ z 311 (M+, 2), 310 (1), 270 (100), 193 (2), 180 (2), 165 (51),
1
91 (10), 77 (11); IR (film) 1620, 1600 cm-1; H NMR (CDCl3,
1.9 (m, 11 H), 3.22 (d, J ) 6.0 Hz, 2 H), 7.1-7.7 (m, 10 H); 13
C
300 MHz) δ 2.7 (m, 2 H), 4.5 (dd, J ) 8.6 Hz and J ) 11.3 Hz,
1 H), 5.05 (m, 2 H), 5.75 (m, 1 H), 7.05-7.90 (m 15 H); 13C
NMR (CDCl3, 75.5 MHz) δ 43.9, 66.5, 116.6, 126.5, 126.6,
127.1, 127.8, 128.2, 128.5, 129.8, 134.4, 135.7, 140.0, 146.3,
166.6. Anal. Calcd for C23H21N: C, 88.71; H, 6.80; N, 4.50.
Found: C, 88.80; H, 6.78; N, 4.61.
NMR (CDCl3, 50.3 MHz) δ 26.1, 26.6, 31.4, 39.7, 60.5, 127.9,
128.0, 128.3, 129.6, 137.1, 140.1, 167.4.
N-(Diph en ylm eth yliden e)-2,2-dim eth ylpr opylam in e (2c)
was obtained by the general procedure starting from 1c, 2.238
g, 95% yield: m/ z 251 (M+, 3), 250 (2), 236 (4), 194 (52), 180
1
(3), 165 (23), 91 (100), 77 (10); IR (film) 1627 cm-1; H NMR
N -(Dip h e n ylm e t h ylid e n e )-1-p h e n yl-2-m e t h ylb u t yl-
a m in e (7) was obtained as for 3, with sec-butyl bromide, 83%
yield (0.271 g) of a 1/1 mixture of syn:anti isomers: m/ z 327
(M+, 6), 326 (1), 270 (100), 165 (27), 91 (4), 77 (2); IR (film)
(CDCl3, 300 MHz) δ 0.9 (s, 9 H), 3.15 (s, 2 H), 7.12-7.70 (m,
10 H); 13C NMR (CDCl3, 75.5 MHz) δ 28.0, 32.8, 65.4, 127.9,
128.0, 128.2, 128.3, 129.6, 137.1, 140.2, 167.2.
N-(Dip h en ylm eth ylid en e)-1-bu ten yla m in e (2d ) was ob-
tained by the general procedure starting from 1d , 0.221 g, 94%
yield: m/ z 235 (M+, 51), 234 (46), 220 (39), 206 (16), 193 (18),
1623 cm-1 1H NMR (CDCl3, 300 MHz) δ 0.7-1.0 (m, 6 H),
;
1.1-2.1 (m, 3 H), 4.08 (d, J ) 5.0 Hz, 1 H, 1° isomer), 4.18 (d,
J ) 4.0 Hz, 1 H, 2° isomer), 7.0-7.9 (m, 15 H); 13C NMR
(CDCl3, 75.5 MHz) δ 11.5, 11.7, 15.3, 15.6, 25.7, 26.2, 42.5,
42.8, 71.0, 72.0, 126.3, 126.4, 126.9, 127.6, 127.9, 128.2, 128.3,
128.7, 129.9, 130.6, 137.1, 137.2, 140.1, 140.1, 143.8, 144.8,
144.1, 144.0, 166.0, 166.1. Anal. Calcd for C24H25N: C, 88.03;
H, 7.69; N, 4.28. Found: C, 88.00; H, 7.75; N, 4.23.
180 (9), 165 (100), 91 (10), 77 (24); IR (film) 1624, 1599 cm-1
;
1H NMR (CDCl3, 200 MHz) δ cis isomer 1.11 (t, J ) 7.5 Hz, 3
H), 2.69 (quintet, J ) 7.5 Hz, 2 H), 5.37 (dt, J ) 7.5 and J )
7.6 Hz, 1 H), 6.64 (dt, J ) 7.6 and J ) 12.9 Hz, 1 H), 7.1-7.8
(m, 10 H); trans isomer 1.02 (t, J ) 7.43 Hz, 3 H), 2.12 (quintet,
J ) 7.36 Hz, 2 H), 6.25 (dt, J ) 7.16 and J ) 12.98 Hz, 1 H),
6.77 (t, J ) 12.98 Hz, 1 H), 7.1-7.8 (m, 10 H); 13C NMR (CDCl3,
75.5 MHz) δ cis isomer 14.2, 19.9, 127.2, 128.0, 128.3, 128.4,
128.6, 129.9, 136.4, 139.7, 139.7, 164.6; trans isomer 13.9, 23.8,
126.7, 127.2, 128.0, 128.3, 128.4, 128.6, 129.9, 136.4, 139.7,
164.6.
N -(D ip h e n y lm e t h y lid e n e )-1-fu r y l-2-p h e n y le t h y l-
a m in e (8) was obtained from 1f following the same protocol
for 3, with benzyl bromide, 90% yield (0.316 g): m/ z 260 (M+
- 91,100), 180 (2), 165 (16), 91 (12), 77 (8); IR (film) 1624 cm-1
;
1H NMR (CDCl3, 200 MHz) δ 3.3 (d, J ) 7.3 Hz, 2 H), 4.68 (t,
J ) 7.3 Hz, 1 H) 6.21 (d, J ) 3.3 Hz, 1 H), 6.35 (dd, J ) 3.4
and J ) 2.2 Hz, 1 H) 7.0-7.5 (m, 1H), 6.6-7.7 (m, 15 H); 13C
NMR (CDCl3, 50.3 MHz) δ 41.5, 62.2, 105.5, 110.1, 126.1,
127.6, 127.9, 128.0, 128.2, 128.4, 128.7, 129.9, 130.0, 132.4,
138.6, 141.5, 156.1, 168.9. Anal. Calcd. for C25H21NO: C,
85.44; H, 6.02; N, 3.99. Found: C, 85.49; H, 6.11; N, 4.06.
N-(Dip h en ylm eth ylid en e)-1-p h en ylm eth yla m in e (2e)
was obtained by the general procedure starting from 1e, 0.163
g, 60% yield: m/ z 271 (M+, 66), 270 (100), 193 (28), 180 (14),
165 (48), 91 (90), 77 (31); IR (film) 1623 cm-1; 1H NMR (CDCl3,
300 MHz) δ 4.67 (s, 2 H); 7.2-7.9 (m, 15 H); 13C NMR (CDCl3,
50.3 MHz) δ 57.3, 126.4, 128.0, 128.2, 128.3, 130.0, 136.6,
149.7, 168.6.
N-(Dip h en ylm eth ylid en e)-1-fu r ylp r op yla m in e (9) was
obtained as for 8, with ethyl bromide, 86% yield (0.248 g): m/z
289 (M+, 74), 260 (100), 165 (35), 157 (13), 128 (12), 109 (31),
81 (12); IR (film) 1620 cm-1; 1H NMR (CDCl3, 200 MHz) δ 0.85
(t, J ) 8.0 Hz, 3 H), 1.98 (m, 2 H), 4.41 (t, J ) 6.4 Hz, 1 H),
6.17 (m, 1 H), 6.31 (m, 1 H), 7.2-7.7 (m, 11 H); 13C NMR
(CDCl3, 50.3 MHz) δ 10.7, 28.3, 61.8, 105.3, 109.9, 128.0, 128.3,
128.7, 130.0, 136.9, 139.9, 141.3, 156.8, 168.4. Anal. Calcd
for C20H19NO: C, 83.01; H, 6.62; N, 4.84. Found: C, 82.94;
H, 6.68; N, 4.76.
Im in e Hyd r olysis. Gen er a l P r oced u r e. The isomerized
imine (1 mmol) was diluted in acetone (7 mL), and 1 N HCl (3
mL) was added. After the starting material disappeared (TLC-
monitoring), H2O (4 mL) was added, the pH was adjusted to
7-8 with solid K2CO3, and CbzCl (0.16 mL, 1.1 mmol) was
added. The resulting mixture was stirred at rt overnight. Then
after evaporation at low pressure of the acetone, the water
phase was extracted with CH2Cl2 (3 × 20 mL). Evaporation
gave a crude product that was purified by flash chromatog-
raphy (eluent cyclohexane/ethyl acetate ) 95:5).
N-(Dip h en ylm eth ylid en e)-1-fu r ylm eth yla m in e (2f) was
obtained by the general procedure starting from 1f, 0.185 g,
71% yield: m/ z 261 (M+, 100), 260 (61), 232 (14), 180 (11),
1
165 (24), 81 (92.0); IR (film) 1625, 1640, 1600 cm-1; H NMR
(CDCl3, 300 MHz) δ 4.57 (s, 2 H), 6.24 (dd, J ) 3.14 and J )
1.1 Hz, 1 H), 6.35 (dd, J ) 3.14 and J ) 1.84 Hz, 1 H), 7.2-
7.7 (m, 10 H); 13C NMR (CDCl3, 50.3 MHz) δ 50.9, 106.2, 110.1,
127.8, 128.1, 128.4, 129.8, 136.1, 139.4, 141.4, 153.6, 169.7.
N-(Dip h en ylm eth ylid en e)-1,2-d ip h en yleth yla m in e (3).
In a 25 mL flask were placed 10 mL of THF and 0.271 g (1
mmol) of 1e. At room temperature were added t-BuOK (1.2
mL, 1 M solution in THF, 1.2 mmol) and 0.15 mL (1.2 mmol.)
of benzyl bromide. After 45 min, the reaction was quenched
with cold water and the solution was extracted with CH2Cl2
(3 × 20 mL). The crude product (0.249 g, 92%) results as a
pure oil by 1H NMR and GC: m/z 360 (0.1), 270 (100), 165
1
(30), 91 (5), 77 (3); IR (film) 1626 cm-1; H NMR (CDCl3, 200
MHz) δ 3.07 (dd, J ) 4.1 and J ) 13.0 Hz, 1 H), 3.26 (dd, J )
9.0 and J ) 13.0, 1 H), 4.54 (dd, J ) 4.1 and J ) 9.0 Hz, 1 H),
6.5-7.7 (m, 20 H); 13C NMR (CDCl3, 50.3 MHz) δ 31.2, 68.8,
125.2-128.6, 139.4, 166.4 Anal. Calcd for C27H23N: C, 89.71;
H, 6.41; N, 3.87. Found: C, 89.80; H, 6.48; N, 3.93.
N-(Ca r boben zyloxy)h exyla m in e (10) was obtained by
the general hydrolysis procedure as low-melting solid starting
from 2a with 80% yield (0.188 g): m/ z 235 (M+, 0.4), 120 (1),
108 (58), 91 (100), 77 (5); IR (Nujol) 3315, 1684 cm-1; 1H NMR
(CDCl3, 300 MHz) δ 0.9 (t, J ) 6.8 Hz, 3 H), 1.2-1.4 (m, 6 H),
1.5 (m, 2 H), 3.2 (dt, J ) 6.81 and 6.6 Hz, 2 H), 4.8 (bs, 1 H),
5.1 (s, 2 H), 7.2-7.5 (m, 5 H); 13C NMR (CDCl3, 75.5 MHz) δ
13.9, 22.5, 26.3, 29.8, 31.4, 41.0, 66.4, 127.2, 127.8, 128.0, 128.2,
N-(Diph en ylm eth yliden e)-1-ph en ylpen tylam in e (4) was
obtained as for 3, with n-butyl bromide (1.2 mmol, 0.108 mL),
98% yield (0.320 g): m/ z 327 (M+, 24), 326 (12), 270 (100),
193 (11), 180 (19), 165 (80), 91 (72), 77 (26); IR (film) 1620
1
cm-1; H NMR (CDCl3, 300 MHz) δ 0.9 (t, J ) 6.8 Hz, 3 H),

5138 J . Org. Chem., Vol. 61, No. 15, 1996
Cainelli et al.
128.5, 136.6, 156.3. Anal. Calcd for C14H21NO2: C, 71.46; H,
8.99; N, 5.95. Found: C, 71.40; H, 9.04; N, 5.91.
g (0.99 mmol) of 16. After silica gel chromatography (cyclo-
hexane/ethyl acetate ) 9:1) we obtain 0.200 g (0.7 mmol) of
N-(Car boben zyloxy)-1-cycloh exylm eth ylam in e (11) was
obtained by the general procedure starting from 2b as white
pure solid compound used without further purification (81%
yield, 0.200 g), mp 89 °C: m/ z 247 (M+, 1), 226 (15), 108 (60),
17 in 70% yield: [R]20 ) +26.3 (c ) 9.405, CHCl3); m/ z 301
D
(M+, 1), 273 (3), 190 (25), 146 (20), 91 (100); IR (film) 3320,
1
1752, 1719 cm-1; H NMR (CDCl3, 200 MHz) δ 0.95 (s, 3 H),
0.97 (s, 3 H), 1.02 (s, 3 H), 1.2-1.8 (m, 4 H), 2.48 (bs, 1 H), 4.3
(t, J ) 5.1 Hz, 1 H), 5.1 (bs, 3 H), 7.3-7.4 (m, 5 H); 13C NMR
(CDCl3, 50.3 MHz) δ 9.2, 18.9, 19.2, 19.6, 32.2, 44.0, 47.9, 58.6,
59.34 66.9, 128.0, 128.3, 136.1, 156.3, 217.0. Anal. Calcd for
91 (100); IR (Nujol) 3345, 1692 cm-1 1H NMR (CDCl3, 200
;
MHz,) δ 0.8-1.8 (m, 11 H), 3.02 (t, J ) 6.9 Hz, 2 H), 5.1 (s, 2
H), 6.0 (d, J ) 6.9 Hz, 1 H), 7.2-7.4 (m, 5 H); 13C NMR (CDCl3,
50.3 MHz) δ 25.7, 26.3, 30.5, 38.1, 66.5, 66.9, 127.1, 127.6,
128.0, 128.5, 141.5, 155.5. Anal. Calcd for C15H21NO2: C,
72.84; H, 8.56; N, 5.66. Found: C, 72.89; H, 8.61; N, 5.61.
N-(Car boben zyloxy)-2,2-dim eth ylpr opylam in e (12) was
obtained as an oil by the general procedure starting from 2c,
76% yield (0.168 g): m/ z 221 (M+, 0.7), 108 (21), 91 (100), 77
(7); IR (Nujol) 3353, 1660 cm-1; 1H NMR (CDCl3, 200 MHz) δ
0.91 (s, 9 H), 3.10 (d, J ) 6.5 Hz, 2 H), 4.84 (bs, 1 H), 5.12 (s,
2 H), 7.35-7.40 (m, 5 H); 13C NMR (CDCl3, 75.5 MHz) δ 26.9,
31.9, 52.4, 66.6, 127.8, 128.0, 128.1, 128.4, 128.6, 136.6, 156.7.
Anal. Calcd for C13H19NO2: C, 70.56; H, 8.65; N, 6.33.
Found: C, 70.50; H, 8.71; N, 6.28.
C
18H23NO3: C, 71.73; H, 7.69; N, 4.65. Found: C, 71.68; H,
7.74; N, 4.60.
N-(4-Met h oxyp h en yl)-3-((d ip h en ylm et h yl)im in o)-4-
p h en yla zetid in -2-on e (18). Under an inert atmosphere in
a 50 mL flask were placed the N-(4-methoxyphenyl)-3-oxo-4-
phenylazetidinone12 (1.340 g, 5 mmol.), 1,1-diphenylmetha-
namine (0.86 mL, 5 mmol), and MgSO4 (1.200 g) in 20 mL of
dry CH2Cl2. The mixture was refluxed for 3 h. The filtered
solution was evaporated, and the crude product was triturated
with pentane and filtered, affording a white solid as a 60:40
mixture of the E:Z imine (1.65 g, 76%): mp 214-215 °C; IR
(Nujol) 1742, 1726 cm-1; m/ z 211 (78), 196 (100), 167 (26),
N-(Ca r boben zyloxy)-1,2-d ip h en yleth yla m in e (13) was
obtained as an oil by the general procedure starting from 3,
66% yield (0.218 g): m/ z 223 (M+ - 107, 1), 178 (1.5), 152 (1),
1
141 (11), 115 (12), 77 (17); H NMR (CDCl3, 200 MHz) δ 3.74
(s, 3 H), 3.77 (s, 3 H), 5.51 (s, 2 H), 5.52 (s, 1 H), 5.56 (s, 1 H),
6.7-7.5 (m, 14 H); 13C NMR (CDCl3, 75.5 MHz) δ 55.4, 67.8,
68.3, 69.2, 69.7, 114.6, 114.6, 119.0, 119.1, 126.9, 127.2, 127.3,
128.0, 128.3, 128.52, 128.9, 129.0, 129.5, 130.5, 134.5, 134.7,
141.7, 142.6, 143.0, 143.1, 157.0, 157.2, 157.2, 160.4, 163.9.
Anal. Calcd for C29H24N2O2: C, 80.53; H, 5.59; N, 6.48.
Found: C, 80.29; H, 5.86; N, 6.43.
1
132 (100), 91 (18.1), 77; IR (Nujol) 3341, 1683 cm-1; H NMR
(CDCl3, 200 MHz) δ 3.1 (d, J ) 4.0 Hz, 2 H), 5.05 (m, 4 H),
7.0-7.5 (m, 5 H); 13C NMR (CDCl3, 75.5 MHz) δ 42.9, 56.3,
66.5, 126.3, 126.4, 127.2, 127.4, 127.9, 128.2, 128.3, 128.7,
129.2, 136.3, 137.1, 141.7, 155.5. Anal. Calcd for C22H21NO2:
C, 79.73; H, 6.39; N, 4.23. Found: C, 79.79; H, 6.30; N, 4.27.
N-(Ca r boben zyloxy)-1-p h en ylp r op yla m in e (14) was ob-
tained as oil by the general procedure starting from 5, 58%
yield (0.156 g): m/ z 240 (M+ - 29, 31), 196 (15), 178 (6.8),
3,4-tr a n s-N-(4-Meth oxyp h en yl)-3-(N′-((d ip h en ylm eth -
ylid en e)a m in o)-4-p h en yla zetid in -2-on e (19) a n d 3,4-cis-
N-(4-Meth oxyph en yl)-3-(N′-(diph en ylm eth yliden e)am in o)-
4-p h en yla zetid in -2-on e (20) were obtained starting from 18
0.434 g, 1 mmol) in THF (5 mL). The general isomerization
procedure using a catalytic amount of t-BuOK resulted in a
19:20 ) 80:20 mixture in 98% yield (0.336 g). After crystal-
lization of the mixture with pentane, the pure trans isomer
19 was isolated (0.210 g, 48% yield). Starting from 18 (1 mmol)
with a stoichiometric amount of t-BuOK (1 mmol, 1 mL, 1M
THF solution), after 3 h at room temperature we obtained a
19:20 ) 20:80 mixture of the two azetidinones in 95% yield.
After crystallization of the latter mixture with pentane, the
pure cis isomer was recovered in a 71% yield (0.308 g). 19:
134 (4), 91 (100), 77; IR (film) 3338, 1656 cm-1 1H NMR
;
(CDCl3, 200 MHz) δ 0.9 (t, J ) 7.9 Hz, 3 H), 1.8 (m, 2 H), 4.6
(m, 1 H), 5.1 (m, 3 H), 7.2-7.4 (m, 5 H); 13C NMR (CDCl3,
50.3 MHz) δ 10.6, 29.5, 56.8, 66.6, 126.3, 127.2, 127.4, 127.7,
128.0, 128.4, 136.4, 155.8. Anal. Calcd for C17H19NO2: C,
75.81; H, 7.11; N, 5.20. Found: C, 75.78; H, 7.19; N, 5.17.
N-(Diph en ylm eth yl)-3-im in o-2,3-bor n an edion e (15). In
a Dean-Stark apparatus were placed dry benzene (27 mL),
diphenylmethanamine (1.33 mL, 7.4 mmol), and camphorquino-
ne (0.664 g, 4 mmol). After 7 h at reflux, the solvent was
evaporated and the crude product was treated with petroleum
ether (40-60 °C), affording 15 as a solid (1.18 g, 3.56 mmol,
1
white solid; mp 198-200 °C; IR (Nujol) 1750, 1612 cm-1; H
89%): mp 102-103 °C; [R]20 ) +80.3 (C ) 3.075, CHCl3); IR
NMR (CDCl3
, 300 MHz) δ 3.75 (s, 3 H), 4.66 (d, J ) 1.8 Hz, 1
D
H), 5.31 (d, J ) 1.8 Hz, 1 H), 6.7-7.7 (m, 19 H); 13C NMR
(CDCl3, 50.3 MHz) δ 55.3, 62.4, 78.5, 114.2, 118.7, 126.4, 128.1,
128.2, 128.9, 129.0, 130.6, 131.0, 135.1, 136.5, 139.4, 156.1,
163.6, 172.7. Anal. Calcd for C29H24N2O2: C, 80.53; H, 5.59;
N, 6.48. Found: C, 80.40; H, 5.89; N, 6.44. 20: white solid;
mp 134-135 °C; IR (Nujol), 1757, 1610 cm-1; 1H NMR (CDCl3,
300 MHz) δ 3.78 (s, 3 H), 5.17 (d, J ) 4.98 Hz, 1 H), 5.23 (d,
J ) 4.98 Hz, 1 H), 6.83-7.65 (m, 19 H); 13C NMR (CDCl3, 50.3
MHz) δ 55.4, 62.4, 71.6, 114.3, 118.6, 127.8, 131.2, 134.6, 135.4,
139.3, 156.1, 163.9, 171.8. Anal. Calcd for C29H24N2O2: C,
80.53; H, 5.59; N, 6.48. Found: C, 80.42; H, 5.77; N, 6.42.
(Nujol) 1754, 1670 cm-1; 1H NMR (CDCl3, 200 MHz) δ 0.75 (s,
3 H), 1.00 (s, 3 H), 1.08 (s, 3 H), 1.20-2.15 (m, 4 H), 3.08 (d,
J ) 4.5 Hz, 1 H), 5.70 (s, 1 H), 7.20-7.46 (m, 10 H); 13C NMR
(CDCl3, 50.3 MHz) δ 9.0, 17.6, 20.6, 23.2, 30.2, 44.2, 49.3, 57.9,
70.3, 126.9, 127.1, 127.4, 127.8, 128.46, 143.0, 143.2, 171.3,
205.1. Anal. Calcd for C23H25NO: C, 83.34; H, 7.60; N, 4.23.
Found: C, 83.40; H, 7.69; N, 4.30.
N-(Dip h en ylm eth ylid en e)-3-a m in obor n a n -2-on e (16)
was obtained after 12 h by the general isomerization procedure
as an oil (0.330 g, 94%) starting from 0.331 g (1 mmol) of 15:
m/ z 331 (M+, 11), 303 (29), 220 (100), 193 (21), 165 (55), 91
1
(25), 77 (13); IR (film) 1754, 1625 cm-1; H NMR (CDCl3, 200
3,4-tr a n s-N-(Ca r boben zyloxy)-3-a m in o-4-p h en yla zeti-
d in -2-on e (21). In a 50 mL flask was placed 0.434 g (1mmol)
of 19 dissolved in 1 mL of CH2Cl2 and 10 mL of 80%
NH2OH‚HCl in EtOH. The mixture was refluxed for 5 min.
The solvent was removed in vacuo, and the mixture was
diluted in acetone (10 mL). Then H2O (10 mL) was added and
the pH was adjusted to 8 with solid Na2CO3; finally CBzCl
(0.18 mL, 1.2 mmol) was added. The resulting mixture was
stirred at room temperature overnight. After evaporation of
the organic solvent at low pressure, the water phase was
extracted with CH2Cl2, dried, and evaporated, affording the
crude product which was purified by flash chromatography
(eluent: cyclohexane/ethyl acetate ) 9:1), obtaining 0.205
g(0.509 mmol, 51%) of a white solid: mp 130-131 °C; m/ z
402 (M+, 7), 294 (2), 253 (4), 212 (35), 196 (11), 149 (22), 91
MHz) δ 0.69 (s, 3 H), 0.96 (s, 3 H), 1.01 (s, 3 H), 1.60-2.1 (m,
4 H), 2.61 (dt, J ) 7.9 and J ) 7.9 Hz, 1 H), 4.11 (d, J ) 4.65
Hz, 1 H), 7.25-7.70 (m, 10 H); 13C NMR (CDCl3, 50.3 MHz) δ
9.6, 19.0, 19.6, 19.9, 31.5, 44.3, 50.4, 58.3, 69.0, 127.3, 127.8,
128.3, 128.4, 128.5, 128.7, 129.9, 132.4, 136.4, 139.6, 170.7,
216.1. NOE effect in compound 16:
(100), 77 (8); IR (Nujol) 3278, 1758, 1690 cm-1 1H NMR
;
(CDCl3, 300 MHz) δ 3.75 (s, 3 H), 4.51 (m, 1 H), 5.15 (s, 2 H),
5.54 (m, 1 H), 6.8-7.4 (m, 14 H); 13C NMR (CDCl3, 50.3 MHz)
δ 55.3, 63.6, 66.9, 67.3, 114.2, 118.8, 126.0, 128.1, 128.5, 128.7,
N-(Ca r boben zyloxy)-3-a m in obor n a n -2-on e (17) was ob-
tained by the general hydrolysis procedure starting from 0.330

Efficient Transamination under Mild Conditions
J . Org. Chem., Vol. 61, No. 15, 1996 5139
129.1, 130.5, 135.8, 136.2, 155.4, 156.2, 163.3. Anal. Calcd
for C24H22N2O4: C, 71.63; H, 5.51; N, 6.96. Found: C, 71.58;
H, 5.54; N, 6.92.
for C24H22N2O4: C, 71.63; H, 5.51; N, 6.96. Found: C, 71.70;
H, 5.48; N, 6.99.
3,4-cis-N-(Ca r boben zyloxy)-3-a m in o-4-p h en yla zetid in -
2-on e (22) was obtained by the same protocol used for 21,
starting from 20 (0.434 g, 1 mmol). The product was a white
solid (0.203 g, 0.504 mmol, 51% yield): mp 134-135 °C; m/ z
402 (M+, 6), 251 (7), 212 (67), 196 (16), 149 (11), 91 (100), 77
Ack n ow led gm en t. Financial support was provided
by MURST (Fondi 40% and 60%) and C.N.R.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
the synthetic intermediates 1d , 2a , 2b, 3c, 2d , 2e, 2f, and 16
(8 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.
(8); IR (Nujol) 3350, 1757, 1706 cm-1 1H NMR (CDCl3, 300
;
MHz) δ 3.76 (s, 3 H), 4.92 (d, J ) 9.0 Hz, 1 H), 4.98 (s, 2 H),
5.35 (d, J ) 6.0 Hz, 1 H), 5.49 (dd, J ) 6.0 and J ) 9.0 Hz, 1
H), 6.75-7.45 (m, 14 H); 13C NMR (CDCl3, 75.5 MHz) δ 55.4,
61.3, 67.0, 67.3, 114.3, 118.6, 126.8, 127.7, 128.1, 128.4, 129.0,
129.1, 130.5, 133.4, 136.8, 155.4, 156.4, 163.02. Anal. Calcd
J O952124D