Trichloroacetylation of some cyclic enamines

Article abstract of DOI:10.1248/cpb.51.444

The pyrrolidine and morpholine enamines of cyclic ketones such as cyclohexanone and cyclopentanone were successfully diacetylated at α- and α′-positions with trichloroacetyl chloride using zinc catalyst. Morpholine enamines of the cyclic ketones gave acetylated morpholine in good yields besides the corresponding diacetylated cyclic enamines. When the same reactions were performed by using triethylamine without using zinc, monoacetylation products of the same enamines were synthesized.

Full text of DOI:10.1248/cpb.51.444

444
Notes
Chem. Pharm. Bull. 51(4) 444—447 (2003)
Vol. 51, No. 4
Trichloroacetylation of Some Cyclic Enamines
Hülya S¸ ENÖZ and Nazan TUNO G˘ LU*
Department of Chemistry, Hacettepe University; 06532 Beytepe, Ankara, Turkey.
Received November 25, 2002; accepted January 20, 2003
The pyrrolidine and morpholine enamines of cyclic ketones such as cyclohexanone and cyclopentanone were
successfully diacetylated at a- and aꢀ-positions with trichloroacetyl chloride using zinc catalyst. Morpholine
enamines of the cyclic ketones gave acetylated morpholine in good yields besides the corresponding diacetylated
cyclic enamines. When the same reactions were performed by using triethylamine without using zinc,
monoacetylation products of the same enamines were synthesized.
Key words monoacetylation; diacetylation; cyclic enamine; trichloroacetyl chloride
The acylation of enamines derived from cyclic ketones is a triethylamine without using zinc gave monoacylation prod-
well-established synthetic method for the synthesis of a-acy- ucts as in the literature.
1)
lated carbonyl compounds. Enamine acylation with acid
The reaction of 1-(1-pyrrolidinyl)cyclohexene (1c) with
chlorides having no a-hydrogen atom appears to be a trichloroacetyl chloride using zinc catalyst yielded 2,6-
straightforward reaction at the enamine carbon. The enamine di(trichloroacetyl)-1-(1-pyrrolidinyl)cyclohexene (10). Even
undergoes acylation to give the corresponding enamino though the product was isolated and characterized, it was
ketone in a moderate yield, which then hydrolyses to 1,3- quite unstable and subsequently hydrolyzed to the corre-
triketone (b-diketone). A number of b-diketones had been sponding a,aꢀ-triketone, 2,6-di(trichloroacetyl)cyclohexanone
2—4)
prepared via acylation of enamines.
(4), when saturated NaHCO solution was added. The less re-
3
Besides the monoacylation of enamines, the diacylation of active morpholine enamine of cyclohexanone (1a) gave a
the same compounds at a- and aꢀ-positions has been shown better result than pyrrolidine enamine (1c) in enamine acyla-
5)
to be a possible reaction course, however, we have rarely tion under similar reaction conditions. A stable a,aꢀ-diacety-
met a,aꢀ-diacylated cyclic enamines in the literature which lated morpholine enamine, 2,6-di(trichloroacetyl)-1-(4-mor-
were synthesized by similar methods. The reaction of 1-(4- pholino)cyclohexene (2), was successfully isolated and it re-
morpholino)cycloheptene with trifluoroacetic acid has been sisted to hydrolysis during the same procedure. Compound 2
reported to give a diacetylated product, where more reactive was hydrolyzed to 4 only by using 5 M NaOH solution under
enamines such as 1-(4-morpholino)cyclopentene has been re- reflux condition. The single crystal X-ray analysis result of 2
6)
ported to react even at low temperatures to give complicated was published elsewhere. The reaction of compound 1a
6)
reaction mixtures.
yielded not only a diacetylated enamine (2) in 43% yield but
Acylation of enamines with acyl chlorides can not only a new product, N-(trichloroacetyl)morpholine (3), was ob-
take place on carbon but acylation on nitrogen is also ob- tained in 15% yield. Formation of the stable compound 3 is a
served. However, in contrast to the N-alkylated products, N- good example to the acylation of enamines on nitrogen to
acylated products are not always stable so that C-acylation is yield N-acylated products. Compound 3 has been directly
1
)
generally the normal mode of the reaction.
synthesized by the reaction of morpholine in chloroform
9)
Herein we report diacylation reactions of pyrrolidine and with hexachloroacetone, in the literature. In case of cy-
morpholine enamines of cyclohexanone and cyclopentanone clopentanone enamines under the same reaction conditions,
with trichloroacetyl chloride, in two different reaction both the 1-(4-morpholino)cyclopentene (1b) and 1-(1-pyrro-
medium, under the presence of zinc catalyst and by using tri- lidinyl)cyclopentene (1d) were converted directly to the cor-
ethylamine to prevent salt-formation, respectively.
responding triketone, 2,6-di(trichloroacetyl)cyclopentanone
In the present study, the first examples of bis(trichloro- (7), in 45 and 55% yields, respectively. The reaction of com-
acetyl) cyclic enamines were synthesized by the reaction of pound 1b also gave N-acetylated product, compound 3, in
cyclic enamines with trichloroacetyl chloride as acylating 35% yield.
agent under the influence of zinc catalyst where the second
When the same enamines (1a—d) reacted with trichloro-
acetyl attack was at the aꢀ-position of the cyclic enamine. acetyl chloride under the presence of triethylamine without
The diacetylation was probably due to the much greater reac- using zinc, new products, monoacylated enamines, were ob-
tivity of the trichloroacetyl chloride when compared to the tained. Monoacylation of compound 1a gave 2-trichloroacetyl-
reactivity of unsubtituted acyl chlorides used very frequently 1-(4-morpholino)cyclohexene (5) and 6-trichloroacetyl-1-(4-
as acylating agents or it might be due to the presence of zinc morpholino)cyclohexene (6) in 50 and 30% yields respec-
which is not an usual catalyst in acylation reactions. Zinc is tively as an isomeric mixture. Their properties were so simi-
normally used in ketene formation reactions, however, we lar that they could be hardly separated and isolated by means
have unexpectedly obtained diacetylated products rather than of HPLC technique. Even though the reaction of trichloro-
subtituted cyclobutanones over ketene formation, by using acetic anhydride in THF with 1-(4-morpholino)cyclohexene
zinc catalyst. On the other hand, high yields are usually ob- and triethylamine has been reported to give 2-trichloroacetyl
10)
served in ordinary acylation reactions when triethylamine is cyclohexanone directly in the literature, we were able to
7)
used as a base to prevent salt formation. The attempts to re- isolate monoacylated morpholine enamines of cyclohexa-
alize the trichloroacetylation of the same enamines by using none (5, 6) by our reaction. A similar reaction of 1b also
*
To whom correspondence should be addressed. e-mail: nazan@hacettepe.edu.tr
© 2003 Pharmaceutical Society of Japan

April 2003
445
Fig. 1
gave an isomeric mixture composed of 2-trichloroacetyl-1- Changes in the environment of the carbonyl can either lower
4-morpholino)cyclopentene (8) and 5-trichloroacetyl-1-(4- or raise the absorption frequency from this “normal” value.
(
morpholino)cyclopentene (9) in 40 and 30% yields respec- The trichloromethyl groups adjacent to the other two identi-
tively. However, each compound 1c and 1d gave only one cal carbonyl groups in compounds 4 and 7 created inductive
isomer, 2-trichloroacetyl-1-(1-pyrrolidinyl)cyclohexene (11) effect which reduced the length of the C=O bond and in-
and 2-trichloroacetyl-1-(1-pyrrolidinyl)cyclopentene (12) in creased the frequency of absorption. Thus, the absorptions of
higher yields, respectively. Thus, there were no trace of the the two similar carbonyl groups, in both cyclohexanone and
second isomers, less conjugated structures, according to the cyclopentanone derivatives, shifted to higher frequencies,
ꢁ1
ꢁ1
HPLC measurements. This result might be due to the higher 1759 cm and 1760 cm , respectively. In the enamino de-
reactivity of pyrrolidinyl enamines rather than morpholine rivatives of cyclohexanone (compounds 2 and 10), a differ-
enamines towards acyl chlorides. It was a surprising result ence in the two carbonyl absorptions was observed because
that we were able to isolate monoacylated products of both of a conjugation of the enamine double bond with one of the
pyrrolidine and morpholine enamines of cyclopentanone.
carbonyls. The resonance effect increased the C=O bond
When the IR spectra of the diacetylated products were length and reduced the frequency of absorption. The uncon-
compared, the absorption frequency of cyclohexanone car- jugated carbonyl absorption was recorded at its normal value
ꢁ1
ꢁ1
bonyl group of compound 4 was recorded at 1715 cm , (1760 cm for compounds 2 and 10) where the conjugated
where the absorption band of the same group of cyclopen- carbonyl absorption was observed at a lower frequency
ꢁ
1
ꢁ1
tanone derivative (compound 7) shifted to a higher stretch- (1715 cm for 2 and 1708 cm for 10) due to the resonance
ꢁ1
ing frequency (1740 cm ) due to angular strain of the effect.
cyclopentanone ring. The absorption frequency of a satu- When the IR spectra of the monoacylated products were
compared, there was also a good correlation between the
ꢁ1
11)
rated aliphatic ketone at 1715 cm is referred “normal”.

446
Vol. 51, No. 4
structures and the frequencies of the carbonyl bands. Even NCH
CH
O), 1.90—2.20 (m, 4H, CH
CH
CH
), 1.65—1.80 (m, 2H,
2
2
2
2
2
1
3
CH CH CH ); C-NMR: d 205 (CꢂO), 180 (conjugated CꢂO), 140
though the C=O stretching frequency of compound 6 was
2
2
2
ꢁ1
(CꢂC), 98 (CHCO), 78 (CCl ), 65 (NCH ), 50 (NCH CH O), 45 (CH –
CꢂC), 35 (CH ), 25 (CH ). Calcd for C H Cl NO : C, 36.71; H, 3.29; N,
3 2 2 2 2
recorded at 1685 cm , the same band of compound 5 ap-
ꢁ1
2
2
14 15
6
3
peared at 1640 cm due to conjugation. The same result was
3
.06. Found: C, 36.56; H, 3.26; N, 3.09.
ꢃ
observed in the IR spectra of compounds 8 and 9. The C=O
Compound 3: mp 83 °C; MS m/z: 231 (M ); IR (KBr): 1680 (amide
CꢂO) cm
4H, NCH CH O); C-NMR: d 168 (CꢂO), 78 (CCl ), 65 (NCH ), 44
NCH CH O). Anal. Calcd for C H Cl O : C, 30.99; H, 3.46; N, 6.02.
ꢁ1
ꢁ1
1
;
H-NMR: d 3.95—4.05 (t, 4H, NCH ), 3.20—3.30 (t,
2
13
band of 9 was at 1680 cm where the conjugated carbonyl
ꢁ1
2
2
3
2
band of 8 was shifted to 1630 cm . The carbonyls of 11 and
2 were in conjugation with the enamine moiety so that C=O
(
2 2 6 8 3 2
1
Found: C, 31.11; H, 3.47; N, 6.00.
,6-Di(trichloroacetyl)cyclohexanone (4) Compound 2 was refluxed in
ꢁ
1
bands shifted to lower frequencies, 1624 and 1640 cm , re-
spectively.
2
5 M NaOH solution for 2 h. The organic layer was separated and the aqueous
layer was extracted with ether. The combined extracts were dried over
MgSO , filtered and the solvent was evaporated. The crude product was re-
crystallized from hexane to give 1.33 g (90%) 4 as a pure white solid.
Compound 4: mp 91 °C; MS m/z: 386 (M ); IR (KBr): 1759 (Cl CCꢂO)
1
The H-NMR spectra supported the IR findings for both
4
diacetylated and monoacetylated compounds. The methine
protons adjacent to acyl carbonyls in all the diacetylated
ꢃ
3
ꢁ1 1
products appeared in the range between dꢂ4.20—4.70. Not and 1715 (cyclohexanone CꢂO) cm ; H-NMR: d 4.20—4.30 (t, H and H,
all but some monoacylation products, compounds 6 and 9, 2CHCO), 2.20—2.50 (m, 4H, CHCH
), 1.60—1.80 (m, 2H, CH CH CH );
2
2
2
2
1
3
C-NMR: d 208 (CꢂO(CCl )), 185 (conjugated CꢂO), 100 (COCHCO),
gave characteristic peaks indicating the structures. These
peaks arised from methine and vinilic protons of 6 and 9.
The vinilic proton of compound 6 appeared at dꢂ4.50—4.60
3
7
8 (CCl ), 44 (CH CH ), 35 (CH CH CH ). Anal. Calcd for C H Cl O : C,
3
2
2
2
2
2
10
8
6
3
3
0.89; H, 2.07. Found: C, 31.14; H, 2.10.
Compound 4 was also obtained by stirring the mixture of compound 10
where the same proton for compound 9 was observed at dꢂ with a saturated NaHCO solution.
3
4.60—4.80. The methine proton adjacent to trichloromethyl
2-Trichloroacetyl-1-(4-morpholino)cyclohexene (5) and 6-Trichloro-
acetyl-1-(4-morpholino)cyclohexene (6) Trichloroacetyl chloride (17.8
mmol, 3.23 g), 1-(4-morpholino)cyclohexene (17.8 mmol, 2.97 g) and triethyl-
amine (17.8 mmol, 1.80 g) yielded 5 and 6 as an isomeric mixture. The
HPLC afforded 1.38 g (50%) pure 5 and 0.83 g (30%) pure 6 as white solids
respectively.
carbonyl in compound 6 was observed at dꢂ4.20—4.30
where the same proton belonging to compound 9 was at dꢂ
4
.30—4.40.
ꢃ
Experimental
Compound 5: mp 99—100 °C; MS m/z: 311 (M ); IR (KBr): 1640
ꢁ1 1
All reactions were performed under an atmosphere of nitrogen. Diethyl (CꢂO), 1540 (CꢂC) cm ; H-NMR : d 3.50—3.60 (t, 4H, NCH ), 3.30—
ether was dried over sodium–potassium alloy and freshly distilled prior to 3.40 (m, 4H, NCH CH O), 1.60—2.10 (m, 8H, CH CH CH CH ); C-
2
13
2
2
2
2
2
2
use. IR spectra were obtained on a Mattson 1000 FTIR spectrometer; ab- NMR: d 175 (CꢂO), 150 (CꢂC), 78 (CCl ), 65 (NCH ), 50 (2C,
3
2
ꢁ1
sorption maxima are reported in wavenumbers (cm ). NMR spectra were NCH CH O), 43 (CH CꢂC), 30 (CH ), 25 (CH ). Anal. Calcd for
2
2
2
2
2
recorded on a Bruker AC-200 (200 MHz) NMR spectrometer; CDCl was
the solvent and tetramethylsilane (TMS) was used as the internal standard.
C H C NO : C, 46.34; H, 5.14; N, 4.50. Found: C, 46.65; H, 4.90; N, 4.21.
12 16 l3 2
ꢃ
3
Compound 6: mp 102—103 °C; MS m/z: 311 (M ); IR (KBr): 1685
ꢁ
1 1
Chemical shifts are reported in ppm (d) downfield from the signal for TMS. (CꢂO), 1580 (CꢂC) cm ; H-NMR: d 4.50—4.60 (t, 1H, CHꢂC), 4.20—
The symbols , t (triplet) and m (multiplet) are used to report the multiplicity
4.30 (t, 1H, CHCO), 3.40—3.60 (t, 4H, NCH ), 3.00—3.20 (t, 4H,
2
13
13
of signals. C-NMR spectra were recorded proton decoupled. GC-MS spec- NCH CH O), 1.20—2.00 (m, 6H, CH CH CH ); C-NMR: d 180 (CꢂO),
2
2
2
2
2
tra were recorded on a 5890 Series Mass Selective Detector Combine Sys- 150 (CꢂC), 98 (CHCO), 78 (CCl ), 65 (NCH ), 50 (NCH CH O), 45 (CH ),
3
2
2
2
2
tem and gave a parent peak and other fragmentations in agreement with
the proposed structures. HPLC measurements were performed by Agilent Found: C, 46.02; H, 4.80; N, 4.05.
LCMSD, with a Phenomex C-18 column using methanol–water (70% : 30%)
2,6-Di(trichloroacetyl)cyclopentanone (7) and N-(Trichloroacetyl)-
35 (CH , CH ). Anal. Calcd for C H Cl NO : C, 46.34; H, 5.14; N, 4.50.
2 2 12 16 3 2
solvent mixture. The flow rate was 1 mm/min. Elemental analyses were de- morpholine (3) The reaction of trichloroacetyl chloride (17.8 mmol, 3.23
termined on a LECO 932 CHNS-O elemental analyzer. Melting points were g), 1-(4-morpholino)cyclopentene (17.8 mmol, 2.97 g) and activated zinc
determined with an electrothermal melting point apparatus and were uncor-
rected. Trichloroacetyl chloride (from Aldrich) was freshly distilled before residue [silica gel, ethyl acetate–hexane (1 : 9)] afforded 1.50 g (45%) 7 as an
(8.9 mmol, 0.58 g) yielded 7 and 3 directly. Column chromatography of the
12)
use and Zn was activated as described previously. The morpholine and
unstable white solid and 1.45 g (35%) 3 as a white solid respectively. Com-
pyrrolidine enamines of cyclohexanone and cyclopentanone were prepared pound 7 was also obtained by the reaction of trichloroacetyl chloride (17.8
3,13)
according to the literature procedures.
Ether was dried by sodium-potas- mmol, 3.23 g) and 1-(1-pyrrolidinyl)cyclopentene (17.8 mmol, 2.69 g) in
sium alloy and purified by distillation prior to use.
55% (1.84 g) yield.
Compound 7: mp 111 °C; MS m/z: 372 (M ), IR (KBr): 1760 (Cl CꢂO),
ꢃ
General Procedure for the Diacetylation and Monoacetylation Reac-
tions of Trichloroacetyl Chloride with Enamines A solution of freshly
distilled trichloroacetyl chloride (17.8 mmol, 3.23 g) in 30 ml dry ether was
added dropwise over a period of 1 h to a cooled mixture (in ice-salt bath) of
activated zinc (8.9 mmol, 0.58 g) and appropriate enamine (17.8 mmol) in
3
ꢁ1
1
1740 (cyclopentanone CꢂO) cm
2CHCO), 1.90—2.10 (m, 4H, CH CH ); C-NMR: d 210 (CꢂO(CCl )),
190 (CꢂO), 98 (CHCO), 78 (CCl ), 45 (CH CH ). Anal. Calcd for
; H-NMR: d 4.30—4.40 (t, H and H,
13
2
2
3
3
2
2
C H Cl O : C, 28.84; H, 1.61. Found: C, 28.75; H, 1.58.
9
6
6
3
5
0 ml anhydrous ether while stirring under nitrogen atmosphere. The reac-
tion mixture was continued to stirring overnight then zinc chloride was re-
moved by filtration and the solvent was evaporated under reduced pressure. mmol, 3.23 g), 1-(4-morpholino)cyclopentene (17.8 mmol, 2.73 g) and tri-
2-Trichloroacetyl-1-(4-morpholino)cyclopentene (8) and 5-Trichloro-
acetyl-1-(4-morpholino)cyclopentene (9) Trichloroacetyl chloride (17.8
The residue was dissolved in hexane, dried over MgSO , filtered and then
the solvent was evaporated.
etylamine (17.8 mmol, 1.80 g) yielded 8 and 9 as an isomeric mixture. The
HPLC afforded 1.06 g (40%) pure 8 and 0.79 g (30%) pure 9 as yellow
4
The same reaction procedure was repeated only by replacing zinc with tri- solids respectively.
ꢃ
ethylamine and removing ammonium chloride instead of zinc chloride for
the monoacetylation reactions.
Compound 8: mp 114—115 °C; MS m/z: 297 (M ); IR (KBr): 1630
(CꢂO), 1540 (CꢂC) cm ; H-NMR: d 3.30—3.40 (t, 4H, NCH ), 2.70—
ꢁ1 1
2
13
2,6-Di(trichloroacetyl)-1-(4-morpholino)cyclohexene (2) and N-(Tri- 2.80 (m, 4H, NCH CH O), 1.80—2.10 (m, 6H, CH CH CH ); C-NMR: d
2 2 2 2 2
chloroacetyl)morpholine (3) Trichloroacetyl chloride (17.8 mmol, 3.23
170 (CꢂO), 145 (CꢂC), 78 (CCl ), 65 (NCH ), 52 (NCH CH O), 43
3 2 2 2
g), 1-(4-morpholino)cyclohexene (17.8 mmol, 2.97 g) and activated zinc (CH CꢂC), 33 (CH ). Anal. Calcd for C H Cl NO : C, 44.46; H, 4.71; N,
2
2
11 14
3
2
(
8.9 mmol, 0.58 g) were used. The column chromatography of the residue
4.71. Found: C, 44.24; H, 4.38; N, 4.58.
Compound 9: mp 117—118 °C; MS m/z: 297 (M ); IR (KBr): 1680
ꢃ
[silica gel, ethyl acetate–hexane (1 : 4)] afforded pure 1.77 g (43%) 2 as a
ꢁ1
1
pure yellow solid and 0.62 g (15% ) 3 as a white solid respectively. Both 2 (CꢂO), 1600 (CꢂC) cm
and 3 were then recrystallized from hexane solution separately.
; H-NMR: d 4.60—4.80 (t, 1H, CHꢂCH2),
4.30—4.40 (t, 1H, CHCO), 3.60—3.70 (t, 4H, NCH ), 3.40—3.50 (t, 4H,
2
ꢃ
Compound 2: mp 125—126 °C; MS m/z: 455 (M ); IR (KBr): 1760
NCH CH O), 3.10—3.25 (m, 1H, CHCO), 1.80—2.00 (m, 4H, CH CH );
2
2
2
2
ꢁ1
1
13
(
4
CꢂO), 1715 (conjugated CꢂO), 1600 (CꢂC) cm ; H-NMR: d 4.40—
C-NMR: d 175 (CꢂO), 145 (CꢂC), 100 (CHCO), 78 (CCl ), 67 (NCH ),
3
2
.50 (t, 1H, CHCO), 3.50—3.70 (t, 4H, NCH ), 2.70—2.90 (t, 4H, 52 (NCH CH O), 43 (CH ), 35 (CH ). Anal. Calcd for C H Cl NO : C,
2
2 2 2 2 11 14 3 2

April 2003
4.46; H, 4.71; N, 4.71. Found: C, 44.15; H, 4.40; N, 4.53.
447
Compound 12: mp 90 °C; MS m/z: 281 (M ); IR (KBr): 1624 (CꢂO),
ꢃ
4
ꢁ1
1
2
,6-Di(trichloroacetyl)-1-(1-pyrolidinyl)cyclohexene (10) and 2,6-Di- 1520 (CꢂC) cm ; H-NMR: d 2.90—3.00 (t, 4H, NCH ), 2.50—2.65 (t,
2
(
trichloroacetyl)cyclohexanone (4) Trichloroacetyl chloride (17.8 mmol,
4H, NCH CH ), 1.90—2.00 (m, 4H, CH CH CH ), 1.75—1.85 (m, 2H,
2
2
2
2
2
1
3
3
.23 g), 1-(1-pyrrolidinyl)cyclohexene (17.8 mmol, 2.69 g) and activated CH CH CH ); C-NMR: d 175 (CꢂO), 145 ( CꢂC), 78 (CCl ), 60 (NCH ),
2
2
2
3
2
zinc (8.9 mmol, 0.58 g) were used. The crude product was recrystallized
40 (NCH CH ), 30 (CH ), 20 (CH ). Anal. Calcd for C H Cl NO: C,
2 2 2 2 11 14 3
from hexane to give 1.57 g (40%) 10 as an unstable yellow solid which sub- 46.97; H, 5.02; N, 4.98. Found: C, 46.62; H, 4.65; N, 4.55.
sequently hydrolyzed to compound 4 by the addition of NaHCO solution.
3
ꢃ
Compound 10: mp 158—160 °C; MS m/z: 439 (M ); IR (KBr): 1758
Acknowledgement The authors wish to express their gratitute to The
ꢁ
1
1
(
4
CꢂO), 1643 (conjugated CꢂO), 1620 (CꢂC) cm ; H-NMR: d 4.60— Scientific and Technical Research Council of Turkey (TÜB I˙ TAK Grant No.
.70 (t, 1H, CHCO), 2.40—2.60 (t, 4H, NCH ), 2.20—2.30 (m, 2H, 2123) for financial support.
CH C(CO)ꢂC), 2.00—2.20 (m, 4H, NCH CH ), 1.40—1.80 (m, 4H,
CH CHCO and CH CH CH ). C-NMR: d 200 (CꢂO), 185 (conjugated
CꢂO), 140 (CꢂC), 98 (CHCO), 78 (CCl ), 58 (NCH ), 45 (CH CꢂC),
2
2
2
2
1
3
2
2
2
2
References
3
2
2
1) Cook A. G., “Enamines: Synthesis, Structure and Reactions,” Marcel
Dekker, London, 1969, pp. 115—168.
Anal. Calcd for C H Cl NO : C, 38.05; H, 3.42; N, 3.17. Found: C, 38.20;
14
15
6
2
H, 3.21; N, 3.31.
-Trichloroacetyl-1-(1-pyrrolidinyl)cyclohexene (11) Trichloroacetyl
chloride (17.8 mmol, 3.23 g), 1-(1-pyrrolidinyl)cyclohexene (17.8 mmol,
.69 g) and triethylamine (17.8 mmol, 1.80 g) were used. The crude product
2) Campbell R. D., Jung J. A., J. Org. Chem., 30, 3711—3714 (1965).
3) Stork G., Brizzolara A., Landesman H., Szmuszkovicz J., Terrel R., J.
Am. Chem. Soc., 85, 207—222 (1963).
4) Hunig S., Salzwedel M., Chem. Ber., 99, 823—842 (1966).
5) Helmers R., Acta Chem. Scan., 19, 2139—2150 (1965).
6) Reinhoudt D. N., Verboom W., J. Org. Chem., 47, 3339—3342 (1982).
7) Alt G. H., Speziale A., J. Org. Chem., 29, 798—800 (1964).
8) Özbey S., S¸ enöz H., Tuno g˘ lu N., Anal. Sci., 16, 1005—1006 (2000).
9) Bew C., Joshi V., Gray J., Kaye P. T., Meakins G. D., J. Chem. Soc.,
Perkin Trans. I., 1982, 945—947 (1982).
10) Morimoto T., Skıya M., Chem. Pharm. Bull., 26, 1586—1591 (1978).
11) Silverstein R. M., Bassler G. C., Morrill T. C., “Spectrometric Idenfi-
cation of Organic Compounds,” John Wiley & Sons, New York, 1981,
pp. 181—212.
12) Krepski L. R., Hassner A., J. Org. Chem., 43, 2879—2882 (1978).
13) Hunig S., Benzing E., Lücke E., Chem. Ber., 90, 2833—2840 (1957).
2
2
was recrystallized from hexane to give 3.30 g (63%) 11 as a pure white
solid.
ꢃ
Compound 11: mp. 85 °C; MS m/z: 295 (M ); IR (KBr): 1640 (CꢂO),
ꢁ
1
1
1
550 (CꢂC) cm ; H-NMR: d 2.70—2.90 (t, 4H, NCH ), 2.40—2.50 (t,
2
4
H, NCH CH ), 1.80—2.00 (m, 4H, CH CH CH CH ), 1.50—1.70 (m, 4H,
2
2
2
2
2
2
1
3
CH CH CH CH ). C-NMR: d 180 (CꢂO), 140 (CꢂC), 78 (CCl ), 60
2
2
2
2
3
(NCH ), 35 (NCH CH ), 30 (CH ), 25 (CH ). Anal. Calcd for C H Cl NO:
2
2
2
2
2
12 16
3
C, 48.81; H, 5.47; N, 4,75. Found: C, 48.50; H, 5.15; N, 4.39.
-Trichloroacetyl-1-(1-pyrrolidinyl)cyclopentene (12) The reaction of
2
trichloroacetyl chloride (17.8 mmol, 3.23 g) and 1-(1-pyrrolidinyl)cyclopen-
tene (17.8 mmol, 2.69 g) and triethylamine (17.8 mmol, 1.80 g) were used.
The crude product was recrystallized from hexane to give 2.75 g (55%) 12 as
a pure yellow solid.