Different reactivities of Alkoxy- And Thiocarbene complexes of fischer-type: Formation of (N-Enamino)ethoxycarbene complexes and Quinolines, respectively

Article abstract of DOI:10.1021/om900807s

Alkoxy- and thiocarbene complexes of chromium and tungsten afford different type of products on reaction with (N-aryl)imidoyl chlorides. The (n-butyl)ethoxycarbene complex [(OC)₅W=C(OEt)_n-Bu] and (N-aryl)imidoyl chlorides t-BuClC=NC₆H₄R⁴ (R⁴ = H, OMe) undergo a rearrangement to (N-enamino)ethoxycarbene complexes, whereas quinolines are obtained from the corresponding reaction of(alkyl)thiocarbene complexes [(OC)₅M=C(SEt)CH₂R] (M = W, Cr; R = n-Pr,Me)with (N-aryl)imidoyl chlorides R¹ClC=NC ₆H₂R₂R³R⁴ (R¹ = t-Bu, Ph; R², R³ = H, HC=CH-CH=CH; R⁴ = H, OMe, Me) by β-cyclization.

Full text of DOI:10.1021/om900807s

Organometallics 2010, 29, 801–805 801
DOI: 10.1021/om900807s
Different Reactivities of Alkoxy- and Thiocarbene Complexes of
Fischer-Type: Formation of (N-Enamino)ethoxycarbene Complexes and
Quinolines, Respectively†
Betul Karatas-*,‡,§ and Rudolf Aumann‡
€
‡
€
€
Organish-Chemisches Institut der Universitat Munster, Corrensstrasse 40, 48149 Munster, Germany.
€
§ Current address: Department of Chemistry, Ahi Evran University, 40200 Kırs-ehir, Turkey.
Received September 15, 2009
Alkoxy- and thiocarbene complexes of chromium and tungsten afford different type of products on
reaction with (N-aryl)imidoyl chlorides. The (n-butyl)ethoxycarbene complex [(OC)5WdC(OEt)n-Bu]
and (N-aryl)imidoyl chlorides t-BuClCdNC6H4R4 (R4 = H, OMe) undergo a rearrangement to
(N-enamino)ethoxycarbene complexes, whereas quinolines are obtained from the corresponding
reaction of (alkyl)thiocarbene complexes [(OC)5MdC(SEt)CH2R] (M = W, Cr; R = n-Pr, Me) with
(N-aryl)imidoyl chlorides R1ClCdNC6H2R2R3R4 (R1 = t-Bu, Ph; R2, R3 = H, HCdCH-CHdCH;
R4 = H, OMe, Me) by β-cyclization.
3
4
€
Introduction
blocks in this context. Cyclopropanation, Dotz benzannula-
tion,5 and Hegedus reactions6 of Fischer carbene complexes
have been extensively investigated for the construction of both
carbocyclic and N-heterocyclic compounds. Elaborate combi-
nations of Fischer carbene complexes with N-H and/or CdN
bond containing reagents lead to novel Fischer carbene com-
plexes or N-heterocyclic compounds.7 Quinoline rings are
important members of the latter and attract, therefore, the
interest of both synthetic and medicinal chemists.8,9 They are
synthetically useful building blocks in the preparation of several
alkaloids and also find applications as pharmaceuticals and
agrochemicals. The structural core of quinoline has generally
Efficient ring construction has continued to be a challenge in
organic synthesis. Although a variety of success has been
achieved over the decades,1 much effort is still contributed to
the development of novel synthetic methodologies and new
building blocks for this purpose. Organometallic compounds
are usually considered as potential building blocks for rings that
cannot be readily constructed by conventional methods.2
Fischer carbene complexes have been found very useful building
† Organic Synthesis via Transition Metal Complexes, Part 123. For Part
122 see ref 16a.
*Corresponding author. E-mail: bkaratas@ahievran.edu.tr.
(1) (a) Negishi, E. In Comrehensive Organic Synthesis; Trost, B. M.,
Fleming I., Eds.; Pergamon: Oxford, 1991; Vol. 5, p 1163; (b) Corey, E. J.;
Cheng, X. The Logic of Chemical Synthesis; Wiley-Interscience: New York,
1989.
been synthesized by various conventional named reactions such
as Skraup,10 Doebner von Miller,11 Combes,11 Friedlander,
12
€
Pfitzinger,13 and Conrad-Limpach14 syntheses, but due to its
biological importance, new synthetic methods still remain an
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(alkyl)thiocarbene complexes [(OC)5MdC(SEt)CH2R] 2
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C. M. Curr. Org. Chem. 2005, 9, 141–161.
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Fananas-Mastral, M.; Aznar, F.; Valdes, C. Angew. Chem., Int. Ed.
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€
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2010 American Chemical Society
Published on Web 01/25/2010 pubs.acs.org/Organometallics

802 Organometallics, Vol. 29, No. 4, 2010
Karatas- and Aumann
Scheme 1. Influence of Heteroatom X on the Reaction of
(Alkyl)ethoxycarbene Complexes and (Alkyl)thiocarbene
Complexes with (N-Alkyl)imidoyl Chlorides 3 to Give
(N-Enamino)ethoxycarbene Complexes 4 and Pyrroles 5 and 6,
Respectively16a
(Scheme 3). Compounds 13 are transferred into quinolines
11 by β-cyclization. Ethanthiol, eliminated in this reaction,
forms the corresponding thioesters R1(EtS)CdNC6H2-
R2R3R4 12 with imidoyl chlorides 7a-e.
The conversion of vinylidenes into quinolines resembles
the Povarov reaction17, which involves [4þ2] cycloaddition
of N-aryl imines (Schiff bases) to nucleophilic olefins cata-
lyzed by a Lewis acid,18 Bronsted acid19, or lanthanide
e
triflate20 (Scheme 4). The Povarov reaction is a one-pot,
but multicomponent reaction. Where the synthesis of sub-
stituted quinolines from (alkyl)thiocarbene complexes 2a-c
is concerned, fewer components and reaction steps are
required; thus it can be considered as an alternative to the
Povarov reaction. Moreover, substitutions at C-3 and C-4
positions of quinolines are less common and often suffer
from harsh reaction conditions, expensive reagents, or
both.17,21 However, substituted quinolines at C-2 and C-3
positions could be conveniently synthesized by our method.
The isolated yields of quinolines 11a-g (40-58%) are not as
high as that of (N-enamino)ethoxycarbene complexes 10a,b
(75-80%) (Scheme 2). However, in our syntheses, quinolines
are obtained under milder conditions than applied for the
common Skraup synthesis performed in the presence of a
concentrated acid and an oxidizing agent. The (alkyl)thio-
carbene complexes 2a-c are more reactive than (n-butyl)-
ethoxycarbene complex 1a toward (N-aryl)imidoyl chlorides 7.
The latter compounds are consumed in several days at 20 °C.
Therefore, the reaction is accelerated by using catalytic amounts
of N,N-dimethylamino pyridine. The former compounds, on the
other hand, are consumed within minutes at -40 °C.
(M = W, Cr; R = n-Pr, Me, c-C7H7, c-C6H7Fe(CO)3)
toward (N-alkyl)imidoyl chlorides R1ClCdNCHR2R3
3
(R1 = t-Bu, Ph, 2-furyl; R2 = H, Me; R3 = Me, Et, Ph).
(Alkyl)ethoxycarbene complexes 1 and imidoyl chlorides
3 give (N-enamino)ethoxycarbene complexes16b 4 by a
metalla(di-π-methane) skeletal rearrangement,16c whereas
2H-pyrroles 5 and 1H-pyrroles 6 are obtained from the
corresponding reaction of (alkyl)thiocarbene complexes by
R-cyclization (Scheme 1). We now report on an extension of
the cyclization to pyrroles to the formation of quinolines.
Results and Discussion
Conclusion
The (n-butyl)ethoxycarbene complex [(OC)5WdC(OEt)n-
Bu] (1a) reacts with (N-aryl)imidoyl chlorides t-BuClCd
NC6H4R4 (7a,b; R4 = H, OMe) in the presence of triethyl-
amine to afford (N-enamino)ethoxycarbene complexes 10a,b
(Scheme 2, path 1), whereas quinolines 11a-g are obtained
from the corresponding reaction of compounds R1ClCd
NC6H2R2R3R4 (7a-e; R1 = t-Bu, Ph; R2, R3 = H, HCd
CH-CHdCH; R4 = H, OMe, Me) with (alkyl)thiocarbene
complexes[(OC)5MdC(SEt)CH2R] (2a-c;M = W,Cr;R =
n-Pr, Me) (Scheme 2, path 2).
It is suggested that (β-imino)heterocarbene complexes 8a,b
(X = O) and 9a-h (X = S) generated by addition of the
imidoyl chlorides 7a-e to (n-butyl)ethoxycarbene complex 1a
and (alkyl)thiocarbene complexes 2a-c are precursors com-
mon to reaction paths (Scheme 2). Compounds8a,b afford (N-
enamino)ethoxycarbene complexes 10a,b by metalla(di-π-
methane) skeletal rearrangement. The reaction involves for-
mation of a new bond between the carbene carbon and the
nitrogen atom of the β-imino group and breaking of the bond
between the R-carbon and the carbene carbon atom.16c In our
earlier experiments, the formation of syn- and anti-isomers was
observed among four possible isomers. However, in the pre-
sent case, only the anti-isomer is generated apparently due to
stronger sterical interaction of the aryl substituent and the tert-
butyl group in the syn-isomer as compared to the anti-isomer.
The (β-imino)heterocarbene complexes 8a,b (X = O) and
9a-h (X = S) are assumed to undergo different multistep
processes.16a (N-Enamino)ethoxycarbene complexes 10 are
generated as a result of an associative process by a nucleo-
philic addition of the β-imino nitrogen atom to the carbene
carbon atom, while (β-imino)thiocarbene complexes 9a-h
undergo a dissociative process resulting in vinylidenes 13
We could show the influence of N-aryl substituents on the
reaction of (alkyl)thiocarbene complexes [(OC)5MdC(SEt)-
CH2R] (2a-c; M = Cr, W; R = n-Pr, Me) with (N-aryl)-
imidoyl chlorides R1ClCdNC6H2R2R3R4 (7a-e; R1 = t-Bu,
Ph; R2, R3 = H, HCdCH-CHdCH; R4 = H, OMe, Me) to
give quinolines 11a-g by β-cyclization of the vinylidenes 13.
On the other hand, the (n-butyl)ethoxycarbene complex
[(OC)5WdC(OEt)(n-Bu)] (1a) and N-aryl-substituted imidoyl
chlorides t-BuClCdNC6H4R4 (7a,b; R4 = H, OMe) afforded
(N-enamino)ethoxycarbene complexes 10a,b by metalla(di-π-
methane) skeletal rearrangement. Thus, the use of (N-
aryl)imidoyl chlorides only affects the product formation when
they are reacted with (alkyl)thiocarbene complexes.
Experimental Section
Reagents and solvents obtained from commercial suppliers
were used without further purification unless otherwise noted.
(17) Recent review concerning the Povarov reaction: Kouznetsov,
V. V. Tetrahedron 2009, 65, 2721–2750.
(18) (a) Dobbelaar, P. H.; Marzabadi, C. H. Tetrahedron Lett. 2010,
51, 201–204. (b) Melendez Gomez, C. M.; Kouznetsov, V. V.; Sortino, M. A.;
Alvarez, S. L.; Zacchino, S. A. Bioorg. Med. Chem. 2008, 16, 7908–7920.
(c) Geng, X.; Li, S.; Bian, X.; Xie, Z.; Wang, C. ARKIVOC 2008, 14, 50–57.
(19) (a) Liu, H.; Dagousset, G.; Masson, G.; Retailleau, P.; Zhu, J. J.
Am. Chem. Soc. 2009, 131, 4598–4599. (b) Akiyama, T.; Morita, H.;
Fuchibe, K. J. Am. Chem. Soc. 2006, 128, 13070–13071.
(20) (a) Demaude, T.; Knerr, L.; Pasau, P. J Comb. Chem. 2004, 6,
768–775. (b) Makioka, Y.; Shindo, T.; Taniguchi, Y.; Takaki, K.; Fujiwara, Y.
Synthesis 1995, 801–4.
(21) Cho, C. S.; Kim, B. T.; Choi, H. J.; Shim, S. C. Tetrahedron 2003,
59, 7997–8002.

Article
Organometallics, Vol. 29, No. 4, 2010 803
Scheme 2. (N-Enamino)ethoxycarbene Complexes 10 and Quinolines 11, Respectively, from (n-Butyl)ethoxycarbene Complex 1a and
(Alkyl)thiocarbene Complexes 2a-c
a Isolated chemical yields of compounds 10 and 11 in [%].
Scheme 3. Formation of Quinolines 11 from (β-Imino)thiocarbene Complexes 9a-h by β-Cyclization
Scheme 4. Representative Quinoline Synthesis via Our Method
(route 1) and the Povarov Reaction (route 2)a
60F240, were viewed by UV light (254 nm). Rf values refer to TLC
tests. Flash chromatographic purification was performed on Merck
silica gel 60 under a pressure of argon. 1H and13C NMR spectra were
recorded on Bruker ARX 300, Bruker AMX 400, Inova 500, and
Varian Unity Plus 600 instruments. Chemical shifts are reported in
ppm against TMS (δ = 0) as the internal standard. AB signals in the
1H NMR spectra are denoted by the symbol “)”. IR spectra were
recorded on a Bruker Vector 22 FT-IR spectrometer. EI mass spectra
were obtained on a double beam focusing Sektorfeld-MS MAT 8200
(Thermo-Finnigan-MAT) spectrometer, and HRMS spectra were
obtained by electron spray ionization mass spectrometry (ESI-MS)
a EDG = electron-donating group.
All reactions were performed under a static pressure of argon.
Analytical TLC plates, Merck TLC aluminum sheets with silica gel

804 Organometallics, Vol. 29, No. 4, 2010
Karatas- and Aumann
using a Bruker MicroTOF instrument. Elemental analyses were
obtained using a Elementar Vario EL III instrument. 2a-c16a were
prepared according to literature methods, and the syntheses of (N-
aryl)imidoyl chlorides 7a-e22 were achieved analogous to the synth-
esis of N-phenylbenzimidoyl chloride.
triethylamine (101 mg, 1.00 mmol) in diethyl ether (0.5 mL) with
stirring at -40 °C. The reaction was continued for 10-15 min at
this temperature. After the consumption of 2a (controlled by
TLC), diethyl ether (50 mL) was added and the reaction mixture
was extracted with water (3 ꢀ 30 mL). Then the organic phase
was extracted with HCl solution (1.0 M, 3 ꢀ 30 mL). After the
extraction, the rest of the organic phase was dried over magne-
sium sulfate and the solvent was removed to give compound 12a.
Afterward, sodium hydroxide solution (1.0 M) was added to the
aqueous phase until a turbid and basic solution was obtained.
Finally, the aqueous phase was extracted with ether (3 ꢀ 50 mL)
and the combined organic phases were dried over magnesium
sulfate. The solvent was removed under reduced pressure to give
compound 11a (108 mg, 48%, Rf = 0.6 in n-pentane/dichloro-
methane, 4:1, yellowish oil).
(4E)-[2-Ethoxy-3-phenylamino-4-tert-butyl]-3-aza-1-penta-
carbonyltungstaocta-1,4-diene (anti-10a). To pentacarbonyl-
[1-ethoxypentylidene]tungsten (1a) (219 mg, 0.50 mmol) in di-
chloromethane (1 mL) in a 5 mL screw-top vessel was first added
a mixture of 2,2-dimethyl-N-phenylpropionimidoyl chloride (7a)
(196 mg, 1.00 mmol) and N,N-dimethylamino pyridine (6 mg,
0.05 mmol) in dichloromethane (2 mL) at 20 °C. Triethylamine
(51 mg, 0.50 mmol) in dichloromethane (0.5 mL) was dropwise
added, and the reaction progress was controlled by TLC. After
1 day at 20 °C, the starting carbene complex 1a was consumed
completely. Diethyl ether (10-15 mL) was added, and the
precipitate was discarded after centrifugation. The solvent was
removed at reduced pressure. Chromatography at 25 °C on silica
gel (column 20 ꢀ 2 cm, n-pentane/dichloromethane, 4:1) afforded
compound 10a (223 mg, 75%, Rf = 0.7 in n-pentane/dichloro-
methane, 4:1, pale yellow oil).
11a. 1H NMR (400 MHz, CDCl3, 25 °C): δ 7.99 (dd, br, 3J =
8.3 and 4J = 0.6 Hz, 1H; 8-H), 7.85 (s, 1H; 4-H), 7.66 (dd, br,
3J = 8.1 and 4J = 1.2 Hz, 1H; 5-H), 7.56 and 7.40 (each m,
each 1H; 6-H and 7-H), 2.94 (m, 2H; CH2CH2CH3), 1.72 (m,
2H; CH2CH3), 1.54 [s, 9H; C(CH3)3], 1.07 (t, 3J = 7.5 Hz, 3H;
CH2CH3). 13C NMR (100 MHz, CDCl3): 166.3 (Cq, C2), 145.3
and 126.8 (each Cq, C4a and C8a), 136.9 (CH, C4), 134.6 (Cq,
C3), 129.2 and 126.2 (each CH, C5 and C8), 128.0 and 125.6
(each CH, C6 and C7), 39.8 [Cq, C(CH3)3], 35.5 (CH2,
CH2CH2CH3), 30.5 [C(CH3)3], 25.6 (CH2, CH2CH3), 14.9
(CH3, CH2CH3) ppm. MS (70 eV, EI): m/z (%) 227 (44) [M]þ,
212 (100), 182 (17), 170 (28), 143 (17). HRMS (ESIþ): m/z calcd
for C16H21NH, 228.1747; found, 228.1741 [M þ H]þ.
anti-10a. 1H NMR (400 MHz, CDCl3, 25 °C): δ 7.42-7.31 (m,
br, 5H; o-, m-, p-H Ph), 5.19 (t, 3J = 8.1 Hz, 1H; CdCH), 4.73)
(q, 3J = 7.1 Hz, 1H; OCHA) 4.65) (q, 3J = 7.1 Hz, 1H;
OCHB), 2.27 and 2.12 (each m, each 1H; CH2CH2CH3), 1.46 (t,
3J = 7.1 Hz, 3H; OCH2CH3), 1.40 (m, 2H; CH2CH3), 1.19 [s,
9H; C(CH3)3], 0.89 (t, 3J = 7.4 Hz, 3H; CH2CH3). 13C NMR
(100 MHz, CDCl3): δ 234.4 (Cq, WdC), 200.8 and 198.0 [Cq, 1:4
C; trans- and cis-CO of W(CO)5], 151.6 (Cq, CdCH), 146.3 (Cq,
i-Ph), 130.7 (CH, CdCH) 129.1, 128.9, and 128.1 (each CH, br,
o-, m-, and p-C Ph), 73.7 (OCH2), 35.2 [Cq, C(CH3)3], 30.4 (CH2,
CH2CH2CH3), 30.4 [C(CH3)3], 22.7 (CH2, CH2CH3), 15.5
(OCH2CH3), 13.7 (CH3, CH2CH3) ppm. IR (cyclohexane): ν~
2064.1 (10), 1931.6 (100), 1922.5 (50) cm-1 (CtO). MS (70 eV,
EI): m/z (%) 597 (8) [M]þ, 569 (14) [M - CO]þ, 513 (100) [M -
3CO]þ, 397 (29). Anal. Calcd (%) for C23H27O6NW (597.3): C
46.25, H 4.56, N 2.34. Found: C 46.31, H 4.44, N 2.37.
(4E)-[2-Ethoxy-3-(4-methoxyphenyl)amino-4-tert-butyl]-3-aza-
1-pentacarbonyltungstaocta-1,4-diene (anti-10b). Pentacarbonyl-
[1-ethoxypentylidene]tungsten (1a) (219 mg, 0.50 mmol), N-(4-
methoxyphenyl)-2,2-dimethylpropionimidoyl chloride (7b) (226
mg, 1.00 mmol), N,N-dimethylaminopyridine (6 mg, 0.05 mmol),
and triethylamine (51 mg, 0.50 mmol) were reacted for 1 day as
described above to give compound 10b (250 mg, 80%, Rf = 0.5
in n-pentane/dichloromethane, 4:1, pale yellow oil).
12a. 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.24, 6.99, and 6.91
(eachm, 2:1:2H;o-, m-, p-HPh), 2.10(q, 3J = 7.3 Hz, 2H; SCH2),
1.30 [s, 9H; C(CH3)3], 0.95 (t, 3J = 7.3 Hz, 3H; SCH2CH3).
2-tert-Butyl-6-methoxy-3-propylquinoline (11b) and N-(4-
Methoxyphenyl)-2,2-dimethylthiopropionimidic Acid Ethyl Ester
(12b). Pentacarbonyl[1-(ethylthio)pentylidene]tungsten (2a)
(454 mg, 1.00 mmol), N-(4-methoxyphenyl)-2,2-dimethylpro-
pionimidoyl chloride (7b) (451 mg, 2.00 mmol), and triethyl-
amine (101 mg, 1.00 mmol) were reacted as described above to
give compounds 11b (132 mg, 51%, Rf = 0.4 in n-pentane/
dichloromethane, 2:1, yellowish oil) and 12b.
11b. 1H NMR (600 MHz, CDCl3, 25 °C): δ 7.88 (d, 3J = 9.2
Hz, 1H; 8-H), 7.76 (s, 1H; 4-H), 6.94 (d, 4J = 2.7 Hz, 1H; 5-H),
7.23 (dd, br, 3J = 9.2 and 4J = 2.7 Hz, 1H; 7-H), 3.85 (s, 3H;
OCH3), 2.91 (m, 2H; CH2CH2CH3), 1.71 (m, 2H; CH2CH3),
1.52 [s, 9H; C(CH3)3], 1.06 (t, 3J = 7.3 Hz, 3H; CH2CH3). 13
C
NMR (150 MHz, CDCl3): 163.6 (Cq, C2), 157.2 (Cq, C6), 141.3
(Cq, C8a), 135.9 (CH, C4), 134.8 (Cq, C3), 130.6 (CH, C8), 127.5
(Cq, C4a), 120.6 (CH, C7), 103.8 (CH, C5), 55.3 (OCH3), 39.4
[Cq, C(CH3)3], 35.4 (CH2, CH2CH2CH3), 35.4 [C(CH3)3], 25.6
(CH2, CH2CH3), 14.4 (CH3, CH2CH3) ppm. MS (70 eV, EI): m/
z (%) 257 (41) [M]þ, 242 (100), 215 (16), 200 (24), 187 (28), 134
(40), 57 (20), HRMS (ESIþ): m/z calcd for C17H23ONH,
258.1852; found, 258.1837 [M þ H]þ.
anti-10b. 1H NMR (500 MHz, CDCl3, 25 °C): δ 7.28 (s, br, 2H;
Ar-H), 6.90 (d, 3J = 9.0 Hz, 2H; Ar-H), 5.16 (t, 3J = 7.9 Hz,
1H; CdCH), 4.70) (q, 3J = 7.1 Hz, 1H; OCHA) 4.63) (q, 3J =
7.1 Hz, 1H; OCHB), 3.82 (s, 3H; OCH3), 2.27 and 2.12 (each m,
each 1H; CH2CH2CH3), 1.46 (t, 3J = 7.1 Hz, 3H; OCH2CH3),
1.41 (m, 2H; CH2CH3), 1.18 [s, 9H; C(CH3)3], 0.90 (t, 3J = 7.4
Hz, 3H, CH2CH3). 13C NMR (125 MHz, CDCl3): δ 234.1 (Cq,
WdC), 201.0 and 198.1 [Cq, 1:4 C; trans- and cis-CO of W(CO)5],
159.1 (Cq, C-OCH3), 151.7 (Cq, CdCH), 139.5 (Cq, C-N), 130.1
(CH, CdCH) 129.9 and 114.2 (each CH, br, Ar-C), 73.6 (OCH2),
55.5 (OCH3), 35.1 [Cq, C(CH3)3], 30.4 (CH2, CH2CH2CH3), 30.3
[C(CH3)3], 22.8 (CH2, CH2CH3), 15.6 (OCH2CH3), 13.8 (CH3,
CH2CH3) ppm. IR (cyclohexane): ν~ 2063.3 (10), 1930.2 (100),
1920.5 (50) cm-1 (CtO). MS (70 eV, EI): m/z (%) 627 (8) [M]þ,
599 [M - CO]þ, 543(100) [M - 3CO]þ, 427 (27). Anal. Calcd (%)
for C24H29O7NW (627.4): C 45.95, H 4.66, N 2.23. Found: C
46.00, H 4.51, N 2.12.
12b. 1H NMR (300 MHz, CDCl3, 25 °C): δ 6.89) (d, 3J = 9.0
Hz, 2H; Ar-HA) 6.82) (d, 3J = 9.0 Hz, 2H; Ar-HB), 3.77 (s, 3H;
OCH3), 2.09 (q, 3J = 7.3 Hz, 2H; SCH2), 1.29 [s, 9H; C(CH3)3],
0.95 (t, 3J = 7.3 Hz, 3H; SCH2CH3).
2-tert-Butyl-6-methyl-3-propylquinoline (11c) and 2,2-Dimeth-
yl-N-p-tolylthiopropionimidic Acid Ethyl Ester (12c) (from 2a).
Pentacarbonyl[1-(ethylthio)pentylidene]tungsten (2a) (454 mg,
1.00 mmol), 2,2-dimethyl-N-p-tolylpropionimidoyl chloride
(7c) (419 mg, 2.00 mmol), and triethylamine (101 mg, 1.00
mmol) were reacted as described above to give compounds 11c
(109 mg, 45%, Rf = 0.5 in n-pentane/dichloromethane, 4:1,
yellowish oil) and 12c.
2-tert-Butyl-3-propylquinoline (11a) and 2,2-Dimethyl-N-phe-
nylthiopropionimidic Acid Ethyl Ester (12a). To a mixture of
pentacarbonyl[1-(ethylthio)pentylidene]tungsten (2a) (454 mg,
1.00 mmol) and 2,2-dimethyl-N-phenylpropionimidoyl chloride
(7a) (391 mg, 2.00 mmol) in diethyl ether (3 mL) was added
11c. 1H NMR (400 MHz, CDCl3, 25 °C): δ 7.87 (d, 3J = 8.5
Hz, 8-H), 7.77 (s, 1H; 4-H), 7.42 (s, 1H; 5-H), 7.39 (dd, br, 3J =
8.5 and 4J = 1.5 Hz, 1H; 7-H), 2.93 (m, 2H; CH2CH2CH3), 2.48
(s, 3H; CH3), 1.71 (m, 2H; CH2CH3), 1.52 [s, 9H; C(CH3)3], 1.06
(t, 3J = 7.5 Hz, 3H; CH2CH3). 13C NMR (100 MHz, CDCl3):
165.3 (Cq, C2), 143.9 and 126.8 (each Cq, C4a and C8a), 136.3
(22) (a) Nerdel, F.; Weyerstahl, P.; Dahl, R. Liebigs Ann. Chem. 1968,
716, 127–134.

Article
Organometallics, Vol. 29, No. 4, 2010 805
(CH, C4), 135.3 (Cq, C6), 134.5 (Cq, C3), 130.2 (CH, C7), 128.9
(CH, C8), 125.1 (CH, C5), 39.6 [Cq, C(CH3)3], 35.5 (CH2,
CH2CH2CH3), 30.5 [C(CH3)3], 25.7 (CH2, CH2CH3), 21.5
(CH3), 14.4 (CH3, CH2CH3) ppm. MS (70 eV, EI): m/z (%):
241 (41) [M]þ, 226 (100), 184 (28), 171 (32), 157 (15). HRMS
(ESIþ): m/z calcd for C17H23NH, 242.1903; found, 242.1903
[M þ H]þ.
220 (29), 207 (35). HRMS (ESIþ): m/z calcd for C20H23NH,
278.1903; found, 278.1894 [M þ H]þ.
2-tert-Butyl-3,6-dimethylquinoline (11f) and Ethyl 2,2-Dimethyl-
N-p-tolylthiopropionimidic Acid Ethyl Ester (12c). Penta-
carbonyl[1-(ethylthio)propylidene]tungsten (2b) (426 mg,
1.00 mmol), 2,2-dimethyl-N-p-tolylpropionimidoyl chloride
(7c) (419 mg, 2.00 mmol), and triethylamine (101 mg, 1.00
mmol) were reacted as described above to give compounds
11f (124 mg, 58%, Rf = 0.5 in n-pentane/dichloromethane,
4:1, yellowish oil) and 12c.
12c. 1H NMR (400 MHz, CDCl3, 25 °C): δ 7.08) (d, 3J = 8.2
Hz, 2H; Ar-HA), 6.81) (d, 3J = 8.2 Hz, 2H; Ar-HB), 2.31 (s, 3H;
CH3), 2.13 (q, 3J = 7.3 Hz, 2H; SCH2), 1.32 [s, 9H; C(CH3)3],
0.97 (t, 3J = 7.3 Hz, 3H; SCH2CH3).
11f. 1H NMR (400 MHz, CDCl3, 25 °C): δ 7.88 (d, 3J = 8.0
Hz, 8-H), 7.65 (s, 1H; 4-H), 7.38 (dd, br, 3J = 8.0 and 4J = 2.0
Hz, 1H; 7-H), 7.37 (s, 1H; 5-H), 2.62 (s, 3H; CH3), 2.46 (s, 3H;
CH3), 1.52 [s, 9H; C(CH3)3]. 13C NMR (100 MHz, CDCl3):
165.7 (Cq, C2), 144.1 and 126.9 (each Cq, C4a and C8a), 137.5
(CH, C4), 135.3 (Cq, C6), 130.2 (CH, C7), 129.3 (Cq, C3), 128.9
(CH, C8), 125.0 (CH, C5), 39.6 [Cq, C(CH3)3], 29.8 [C(CH3)3],
22.4 and 21.5 (each CH3) ppm. HRMS (ESIþ): m/z calcd for
C15H19NH, 214.1590; found, 214.1591 [M þ H]þ. Anal. Calcd
(%) for C15H19N (213.3): C 84.46, H 8.98, N 6.57. Found: C
84.40, H 8.92, N 6.60.
12c. See the above synthesis of 11c for spectroscopic data.
2-tert-Butyl-3-methylquinoline (11g) and 2,2-Dimethyl-N-
phenylthiopropionimidic Acid Ethyl Ester (12a). Pentacarbonyl-
[1-(ethylthio)propylidene]tungsten (2b) (213 mg, 0.50 mmol),
2,2-dimethyl-N-phenylpropionimidoyl chloride (7a) (196 mg,
1.00 mmol), and triethylamine (51 mg, 0.50 mmol) were reacted
as described above to give compounds 11g (53 mg, 53%, Rf =
0.5 in n-pentane/dichloromethane, 4:1, yellowish oil) and 12a.
11g. 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.99 (d, br, 3J =
8.3 Hz, 1H; 8-H), 7.77 (s, 1H; 4-H), 7.65 (d, br, 3J = 8.1 Hz, 1H;
5-H), 7.57 (m, 1H; 6-H), 7.41 (m, 1H; 7-H), 1.53 [s, 9H; C-
(CH3)3], 1.07 (s, 3H, CH3). 13C NMR (75 MHz, CDCl3): 166.7
(Cq, C2), 145.4 and 126.8 (each Cq, C4a and C8a), 138.1 (CH,
C4), 129.4 (Cq, C3), 129.1 and 126.1 (each CH, C5 and C8),
128.0 and 125.7 (each CH, C6 and C7), 39.7 [Cq, C(CH3)3], 29.7
[C(CH3)3], 22.5 (CH3) ppm. HRMS (ESIþ): m/z calcd for
C14H17NH, 200.1434; found, 200.1436 [M þ H]þ. Anal. Calcd
(%) for C14H17N (199.3): C 84.37, H 8.60, N 7.03. Found: C
84.27, H 8.42, N 6.91.
2-Phenyl-3-propylquinoline (11d) and N-Phenylthiobenzimidic
Acid Ethyl Ester (12d). Pentacarbonyl[1-(ethylthio)pentyl-
idene]tungsten (2a) (454 mg, 1.00 mmol), N-phenylbenzimidoyl
chloride (7d) (431 mg, 2.00 mmol), and triethylamine (101 mg,
1.00 mmol) were reacted as described above to give compounds
11d (108 mg, 44%, Rf = 0.7 in n-pentane/ether, 1:1, yellowish
oil) and 12d.
11d. 1H NMR (400 MHz, CDCl3, 25 °C): δ 8.13 (d, 3J = 8.3
Hz, 1H; 8-H), 8.0 (s, 1H; 4-H), 7.78 (d, 3J = 8.0 Hz, 1H; 5-H),
7.64 (m, 1H; 7-H), 7.55-7.39 (m, 6H; 6-H and o-, m-, p-H Ph),
2.74 (m, 2H; CH2CH2CH3), 1.56 (m, 2H; CH2CH3), 0.85 (t,
3J = 7.3 Hz, 3H; CH2CH3). 13C NMR (100 MHz, CDCl3):
160.7 (Cq, C2), 146.4 (Cq, C8a), 141.0 (Cq, i-Ph), 135.6 (CH, C4),
133.7 (Cq, C3), 129.2 (CH, C8), 128.7 (CH, C7), 128.7, 128.2,
and 127.9 (each CH, o-, m-, p-C Ph), 127.5 (Cq, C4a), 126.8 (CH,
C5), 126.3 (CH, C6), 34.8 (CH2, CH2CH2CH3), 23.6 (CH2,
CH2CH3), 13.8 (CH3, CH2CH3) ppm. MS (70 eV, EI): m/z (%):
247 (99) [M]þ, 232 (100), 127 (38) 57 (15). HRMS (ESI): m/z
calcd for C18H17NH, 248.1434; found, 248.1442 [M þ H]þ.
12d. 1H NMR (300 MHz, CDCl3, 25 °C): δ 7.56-7.14 (m, 10
3
H; o-, m-, p-H Ph), 1.95 (q, J = 7.4 Hz, 2H; SCH2), 0.74 (t,
3J = 7.4 Hz, 3H; SCH2CH3).
2-tert-Butyl-3-propylbenzo[h]quinoline (11e). Pentacarbonyl-
[1-(ethylthio)pentylidene]tungsten (2a) (454 mg, 1.00 mmol),
2,2-dimethyl-N-naphthalen-1-ylpropionimidoyl chloride (7e)
(491 mg, 2.00 mmol), and triethylamine (101 mg, 1.00 mmol)
were reacted as described above. Chromatographic purification
of the crude reaction mixture at 25 °C on silica gel (column 2 ꢀ
20 cm, n-pentane/dichloromethane, 4:1) afforded compound
11e (140 mg, 51%, Rf = 0.9 in n-pentane/dichloromethane,
4:1, oil). Compound 12e could not be obtained due to the
hydrolysis on silica gel.
12a. See the above synthesis of 11a for spectroscopic data.
2-tert-Butyl-6-methyl-3-propylquinoline (11c) and 2,2-Dimethyl-
N-p-tolylthiopropionimidic Acid Ethyl Ester (12c) (from 2c).
Pentacarbonyl[1-(ethylthio)pentylidene]chromium (2c) (322
mg, 1.00 mmol), 2,2-dimethyl-N-p-tolylpropionimidoyl chlo-
ride (7c) (419 mg, 2.00 mmol), and triethylamine (101 mg, 1.00
mmol) were reacted as described above to give compounds 11c
(96 mg, 40%) and 12c.
11e. 1H NMR (400 MHz, CDCl3, 25 °C): δ 9.30 (dd, br, 3J =
8.0 and 4J = 0.5 Hz, 1H; 10-H), 7.88 (s, 1H; 4-H), 7.83 (d, 3J =
7.7, 1H; 7-H), 7.69) (d, 3J = 8.8 Hz, 1H; 5-HA), 7.56) (d, 3J =
8.8 Hz, 1H; 6-HB), 7.67 (m, 1H; 8-H), 7.60 (m, 1H; 9-H), 2.98 (m,
2H; CH2CH2CH3), 1.75 (m, 2H; CH2CH3), 1.62 [s, 9H; C-
3
(CH3)3], 1.08 (t, J = 7.3 Hz, 3H; CH2CH3). 13C NMR (100
11c and 12c. See the above synthesis of 11c for spectroscopic
data.
MHz, CDCl3): 164.5 (Cq, C2), 142.5, 133.4, 132.1, and 124.5
(each Cq), 137.3 (CH, C4), 135.0 (Cq, C3), 127.6 (CH, C7), 127.3
(CH, C8), 126.8 (CH, C6), 126.6 (CH, C9), 124.6 (CH, C5),
124.4 (CH, C10), 40.2 [Cq, C(CH3)3], 35.4 (CH2, CH2CH2CH3),
30.7 [C(CH3)3], 25.7 (CH2, CH2CH3), 14.5 (CH3, CH2CH3)
ppm. MS (70 eV, EI): m/z (%) 277 (53) [M]þ, 262 (100), 232 (18),
Acknowledgment. The authors thank Organish-Che-
€
misches Institut der Universitat Munster for financial
€
support.