Electrophilic addition of propargylic cations to allenes: Formation of crowded chloro- and azido-enynes by trapping of the resulting allylic cations with TMSX (X = Cl, N3): A synthetic and computational study

Article abstract of DOI:10.1002/ejoc.201300553

Propargylic cations, generated by the ionization of propargyl alcohols with catalytic amounts of Bi(OTf)₃, react with aryl-substituted allenes to generate incipient allylic cations that are quenched in the presence of TMSCl to form a number of sterically crowded chloro-enynes as a mixture of Z and E isomers with a strong preference for the Z alkenes. Several other metallic triflates, M(OTf)₃ (M = Sc, Yb, La), as well as bismuth nitrate Bi(NO₃)₃·5H₂O also promote this reaction with similar conversions and stereoselectivity. Although trapping with TMSBr and TMSI gave intractable mixtures, trapping with TMSN₃ in a couple of cases led to the isolation of the corresponding isomeric azido-enynes, albeit in lower isolated yields and lower stereoselectivity. Competitive formation of the Meyer-Schuster rearrangement products was also observed. Sterically crowded chloro-allenes did not form adducts with propargyl alcohols, instead they underwent a skeletal rearrangement under the influence of Bi(OTf)₃ to form 2-chloro-butadienes. The results of DFT calculations indicated that the relative anti/syn energies of the propargyl cation and the energy difference between the Z/E isomeric products are too small to explain the stereochemical preference observed for the enynes. A study of the transition state in the crucial C-C bond-forming step by DFT indicated that rotation of the benzylic portion away from the propargyl cation may be a key factor in favoring the anti isomer of the allylic cation. Propargylic cations generated by the ionization of propargylic alcohols with metallic triflates react with aryl-allenes in the presence of TMSCl to form crowded chloro-enynes Copyright

Full text of DOI:10.1002/ejoc.201300553

FULL PAPER
DOI: 10.1002/ejoc.201300553
Electrophilic Addition of Propargylic Cations to Allenes: Formation of
Crowded Chloro- and Azido-Enynes by Trapping of the Resulting Allylic
Cations with TMSX (X = Cl, N3): A Synthetic and Computational Study
Kenneth K. Laali,*[a] Ganesh C. Nandi,[a] Gabriela L. Borosky,[b] and
G. G. K. S. Narayana Kumar[a]
Keywords: Allenes / Alkynes / Enynes / Density functional calculations / Reaction mechanisms
Propargylic cations, generated by the ionization of propargyl
alcohols with catalytic amounts of Bi(OTf)3, react with aryl-
substituted allenes to generate incipient allylic cations that
are quenched in the presence of TMSCl to form a number
of sterically crowded chloro-enynes as a mixture of Z and E
isomers with a strong preference for the Z alkenes. Several
other metallic triflates, M(OTf)3 (M = Sc, Yb, La), as well as
bismuth nitrate Bi(NO3)3·5H2O also promote this reaction
with similar conversions and stereoselectivity. Although
trapping with TMSBr and TMSI gave intractable mixtures,
trapping with TMSN3 in a couple of cases led to the isolation
of the corresponding isomeric azido-enynes, albeit in lower
isolated yields and lower stereoselectivity. Competitive for-
mation of the Meyer–Schuster rearrangement products was
also observed. Sterically crowded chloro-allenes did not form
adducts with propargyl alcohols, instead they underwent a
skeletal rearrangement under the influence of Bi(OTf)3 to
form 2-chloro-butadienes. The results of DFT calculations
indicated that the relative anti/syn energies of the propargyl
cation and the energy difference between the Z/E isomeric
products are too small to explain the stereochemical prefer-
ence observed for the enynes. A study of the transition state
in the crucial C–C bond-forming step by DFT indicated that
rotation of the benzylic portion away from the propargyl cat-
ion may be a key factor in favoring the anti isomer of the
allylic cation.
catalyst and ionic liquids as solvent[6–9] and our continuing
interest in propargyl/allenyl carbocation generation and
chemistry,[10] we report herein on the reaction of aryl-sub-
stituted allenes with a series of propargylic alcohols by
using metallic triflates as catalyst in the presence of TMSX
to form sterically crowded halo-enyne derivatives. A com-
putational study aimed at probing the origin of the ob-
served stereoselectivity that leads to the formation of Z alk-
enes is also reported.
Introduction
Allenes are being increasingly recognized as powerful
and versatile building blocks in organic synthesis and pro-
gress in this area, in particular in the past two decades, has
rapidly changed their old image of being highly unstable
and difficult to work with.[1,2]
To date, many examples of electrophilic addition to all-
enes with control of regio- and stereoselectivity have been
reported.[3] Lewis acid activation and the formation of in-
cipient allylic cations has led to successful ring-closing reac-
tions for the construction of heterocyclic compounds.[4]
Meng and Ma reported the condensation of allylic
alcohols with 1-aryl- and 1,1-diaryl-substituted allenes in
the presence of ZnX2 to form allylic halides and indenes.[5]
In connection with a number of studies in our laboratory
focusing on C–C bond-forming reactions with propargylic
cations employing metallic triflates or bismuth nitrate as
Results and Discussion
The reaction of allene 1a with propargylic alcohol 2a in
the presence of 1.1 equiv. of TMSCl and 5 mol-% Bi(OTf)3
in DCM at 0 °C gave the corresponding chloro-enyne ad-
duct 3aa (Scheme 1) in 65% isolated yield as a mixture of
Z and E isomers in a ratio of 92:8, as determined by NMR
spectroscopy.
The isomers were identified on the basis of the nuclear
Overhauser difference (NOED) (see Figure 1) and 2D
NMR spectroscopy. For compound 3aa (Z), irradiation of
Hc (δ = 7.02 ppm) resulted in a strong NOE enhancement
of Hd (δ = 5.01 ppm) with no enhancement in Ha/Hb (δ =
4.42/3.99 ppm). Irradiation of Hd (δ = 5.01 ppm) resulted
in a strong NOE enhancement of Hc (δ = 7.02 ppm) and a
very weak enhancement of Ha/Hb. When Ha/Hb (δ = 4.42/
[a] Department of Chemistry, University of North Florida,
1 UNF Drive, Jacksonville, Florida 32224, USA
Fax: +1-904-620-3535
E-mail: kenneth.laali@UNF.edu
Homepage: http://www.unf.edu/coas/chemistry/
[b] Departamento de Matemática y Física, INFIQC, Facultad de
Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad
Universitaria,
Córdoba 5000, Argentina
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201300553.
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Scheme 1. Coupling of aryl-allene 1a with propargylic alcohol 2a.
3.99 ppm) were irradiated separately, strong NOE enhance-
ment of the geminal proton was observed with a very weak
enhancement of Hc (δ = 7.02 ppm) and Hd (δ = 5.01 ppm).
For compound 3ab (E), when Ha/Hb (δ = 3.98/4.12 ppm)
were irradiated separately, a strong NOE enhancement of
the geminal proton was observed and a very weak enhance-
ment of Hc (δ = 6.91 ppm), but no NOE effects were de-
tected between Ha/Hb and Hd (δ = 5.38 ppm). Similarly,
irradiation of Hc (δ = 6.91 ppm) resulted in only a weak
NOE effect on Ha/Hb (δ = 3.98/4.12 ppm) and no NOE
enhancement of Hd (δ = 5.38 ppm). These NOE measure-
ments were corroborated by COSY and HSQC NMR spec-
troscopy. The COSY spectrum of 3aa shows a correlation
between Hc (δ = 7.02 ppm) and Hd (δ = 5.01 ppm), but no
Table 1. Survey of catalysts in the reaction of 1a with 2a to form 3aa.
Entry
Catalyst[a]
T [°C]
Z/E[b]
Yield[c] [%]
1
Bi(OTf)3
Sc(OTf)3
Yb(OTf)3
La(OTf)3
0
0
0
0
0
–20
–40
92:8
90:10
87:13
88:12
90:10
91:9
65
58
56
62
57
55
50
2.
3.
4.
5.
6.
7.
Bi(NO3)·5H2O
Bi(OTf)3
Bi(OTf)3
91:9
[a] Catalyst loading 5 mol-%. [b] Isomer ratios determined by
NMR spectroscopy. [c] Isolated yield.
Table 2. Scope of the reaction of allenes 1 with propargylic alcohols 2.
Entry Allene Propargylic alcohol Product Yield[a] [%] Z/E[b]
1.
2.
3.
4.
5.
6.
7.
8.
1a
1a
1a
1a
1a
1a
1a
1a
1a
1b
1b
1c
1c
2a
2b
2c
2d
2e
2f
2g
2h
2i
3aa
3ab
3ac
3ad
3ae
3af
3ag
3ah
3ai
3bf
3bh
3cc
3ch
65
60
58
63
64
65
59
55
62
52
52
51
51
91:9
92:8
89:11
91:9
92:8
87:13
91:9
89:11
93:7
72:28
80:20
82:18
73:27
9.
10.
11.
12.
13.
2f
2h
2c
2h
[a] Isolated yield. [b] Isomer ratios determined by NMR spectroscopy.
Figure 1. NOE effects in 3aa and 3ab.
Scheme 2. Condensation of propargylic alcohols 2a–2i with aryl-allenes 1a–1c in the presence of TMSCl and catalytic amounts of
Bi(OTf)3.
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Electrophilic Addition of Propargylic Cations to Allenes
interaction with the methylene protons. The HSQC NMR bond-forming transformation works well with all of these
spectrum confirmed the C/H connectivity between CH2 (for catalysts, but with minor variations in the isolated yields
3aa; δ = 42.1 ppm) and Ha/Hb (δ = 4.42/3.99 ppm), and and isomer ratios, although the use of excess Bi(OTf)3
between CH2 (δ = 42.0 ppm) and Hd (δ = 5.01 ppm). The (20 mol-%) gave complex mixtures. Lowering the reaction
Hc proton at δ = 7.02 ppm shows long-range coupling with
the CH signal at δ = 132.3 ppm. High-field proton spectra
provide a diagnostic tool for the detection/identification of
Z/E isomeric products (see selected NMR spectra in Sup-
porting Information).
In the search for other catalysts that could promote this
transformation, the reaction was repeated with other met-
allic triflates (M = Sc, Yb, La) and bismuth nitrate penta-
hydrate. The results (Table 1) demonstrate that this C–C Scheme 3. Formation of compound 4 from propargylic alcohol 2j.
Scheme 4. Reaction of 1a with 2b in the presence of TMSN3 and Bi(OTf)3.
Scheme 5. Reaction of 1b with 2h in the presence of TMSN3 and Bi(OTf)3.
Scheme 6. Reaction of crowded chloro-allene 8a with 2f in the presence of TMSCl and Bi(OTf)3. Formation of chlorobutadiene 10 and
independent synthesis of 10.
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temperature appeared to have no notable influence on the unidentified compounds in complex mixtures that could not
Z/E ratio (Table 1). be separated. A complex mixture was also formed with
Having established the feasibility of this novel C–C TMSCN. With TMSN3, the azido-enyne derivative 5ab was
bond-forming reaction, we set out to determine the scope isolated, albeit in low yield, along with the Meyer–Schuster
of the transformation (Scheme 2 and Table 2). Thus, prop- rearrangement products[11,12] 6a and 6b as an E/Z mixture,
argylic alcohols 2a–2i were treated with aryl-allenes 1a–1c which were separated (Scheme 4). Remarkably, in the case
in the presence of a slight excess of TMSCl and catalytic of 5ab, the proportion of the E isomer was notably higher
amounts of Bi(OTf)3.
(E/Z, 53:47). In addition, the azido-enyne 5ad was obtained
The chloro-enyne derivatives 3aa–3ai were isolated in
yields of 55–65% as Z/E mixtures with a strong preference
for the formation of the Z alkene (typically 9:1). The
chloro-enyne derivatives 3bf, 3bh, 3cc, and 3ch were ob-
tained in similar isolated yields of 51–52%, but with smaller
ratios of Z/E.
In an attempt to induce a Lewis acid catalyzed ZǞE
isomerization, isolated chloro-enyne adduct 3bf was heated
at reflux in 1,2-dichloroethene (DCE) for 5 h in the pres-
ence of Bi(OTf)3, but no noticeable change in the Z/E ratio
was observed by NMR spectroscopy. This suggests that the
Z/E ratios reflect a kinetic distribution and that the forma-
tion of the E isomer by subsequent isomerization of the
initially formed Z isomer is unlikely.
The reaction of aryl-allene 1a with propargylic alcohol
2j did not produce the expected coupling adduct; the allene
remained unreacted (TLC monitoring) and chloro-enyne 4
was isolated in 73% yield (Scheme 3). Compound 4 was
formed by a well-known rearrangement of the α-cy-
clopropyl carbocation derived from 2j and trapping with
TMSCl.[6]
Unfortunately, when TMSCl was replaced by TMSBr or
TMSI, the reactions were no longer clean. Although the
allene was consumed (TLC monitoring), the corresponding
Scheme 7. Formation of 2-chlorobutadienes 10–12 from chloro-all-
halo-enyne was only formed in low yields along with other enes in a) DCM at room temp. and b) in DCE at reflux.
Scheme 8. B3LYP/6-31G* relative energies for the anti and syn configurations of the allyl cation and the derived Z and E chloro-enynes
(values in parentheses were determined by the PCM method with DCM as solvent).
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Electrophilic Addition of Propargylic Cations to Allenes
from the reaction of the same allene 1a with 2d in a modest
In the transition state (TS), the originally linear allene
isolated yield (15%) as an isomeric mixture in which the E starts to bend and the vinyl moiety becomes perpendicular
isomer prevailed (E/Z, 73:27). However, the targeted azido- to the benzyl fragment (Figure 2, structure a). This TS
enyne adduct was not obtained from the reaction of could in principle generate either a syn or anti allyl cation.
fluorophenyl-allene 1b and propargylic alcohol 2h. Instead After the transition state, the reaction proceeds downhill
only the Meyer–Schuster rearrangement products 7a/7b with rotation of the benzyl group away from the propargyl
were isolated (Scheme 5).
moiety to yield the anti isomer of the allylic cation (the
The facile synthesis of crowded halo-allenes (such as 8a reaction profile is shown in Figure 3, a). Rotation in the
in Scheme 6) by the reaction of propargylic alcohols with opposite direction generates repulsive interactions between
[13]
N-halosuccinimide/PPh3
encouraged us to explore their
reaction with propargylic alcohols. We had hoped that the
introduction of steric crowding at the other end of the al-
lenyl moiety may alter the regioselectivity of nucleophilic
attack by TMSCl on the resulting allyl cation, hence form-
ing different types of crowded chloro-enynes, for example,
9af. The reaction of 8a with the propargyl alcohol 2f
(Scheme 6) did not, however, lead to the successful isolation
of the expected coupling adduct 9af. Instead, the chloro-
butadiene 10 was formed by a skeletal rearrangement in-
volving the n-butyl side-chain under the influence of Bi-
(OTf)3 and was isolated in modest yield out of an otherwise
complex reaction mixture that could not be separated. Inde-
pendent control experiments (Scheme 6) confirmed that the
formation of compound 10 is independent of 2f and TMSCl
and only requires the presence of catalytic amounts of Bi-
(OTf)3. The formation of 10 from 8a was also observed by
using Sc(OTf)3.
To check the generality of this transformation, chloro-
allenes 8b and 8c were synthesized[13] and tested (Scheme 7,
a). The corresponding 2-chlorobutadienes 11 and 12 were
formed in the presence of catalytic amounts of Bi(OTf)3 in
DCM and were isolated in low yields. A significant im-
provement in the isolated yields was observed by heating
the chloro-allenes in DCE at reflux and by employing short
reaction times (Scheme 7, b).
Although the mechanistic details have not been estab-
lished for this transformation, it is seemingly a Lewis acid
catalyzed electrocyclic reaction involving a hydride shift
from the n-butyl methylene and migration of the double
bond.
Probing the Origin of the Stereoselectivity in the Formation
of the Chloro-Enynes
The plausible mechanistic pathway depicted in Scheme 8
was evaluated by means of DFT calculations both in the
gas phase and with CH2Cl2 as solvent. The computed ener-
gies of the isomeric chloro-enynes are similar (difference of
less than 1 kcal/mol in the gas phase). The incorporation of
solvation effects (by means of PCM computations) led to
an increase in the energy difference to around 2 kcal/mol in
favor of the Z alkene, but it is still too small to account for
the strong preference for the anti orientation of the allyl
cation and subsequent formation of the Z alkene. To shed
some light on this issue, the kinetics of the process were
considered by characterizing the corresponding transition
state for the formation of the allyl cation, which is the step
determining the anti/syn isomerism.
Figure 2. Intermediate structures going downhill from the transi-
tion for the propargyl cation/allene coupling reaction (a) to the
anti-allylic cation (b). The structures are shown in ball-and-stick
and space-filling modes by using van der Waals radii.
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the proximate hydrogen atoms leading to a higher potential bearing an n-butyl group, which produced 2-chlorobutadi-
energy surface for the formation of the syn allylic cation enes.
(Figure 2, structure b and Figure 3, b). This mechanistic
picture may explain the experimental observations regard-
Experimental Section
ing the preference for the formation of the Z-chloro-enynes,
however, the preferred formation of the E isomer in the case
of the azido derivatives 5ab and 5ad remains a mystery.
Computational Procedures: Calculations were performed with the
Gaussian 09 suite of programs.[14] The structures were fully opti-
mized by DFT using the B3LYP[15] functional and the 6-31G* basis
set. Harmonic vibrational frequency calculations were performed
to characterize all computed stationary points as minima (no imag-
inary frequencies) or transition states (one imaginary frequency).
Solvation effects were considered by performing energy minimiza-
tions in CH2Cl2 (dielectric constant ε = 8.93) using the SCRF-
polarized continuum model (PCM).[16]
General Experimental Methods: The substituted allenes[17] and pro-
pargyl alcohols[18] were synthesized according to the reported
methods. The Lewis acid catalysts employed were purchased and
used without further purification. Reactions were carried out in
10 mL round-bottomed flasks under N2. Dichloromethane (DCM)
was dried with molecular sieves. Column chromatography was per-
formed on silica gel (200–400 mesh). NMR spectra were recorded
in CDCl3 with a Varian 500 MHz NMR spectrometer. The mass
spectra of the isomeric mixtures were recorded by using the ES-
API method at the Mass Spectrometer facility at the University of
South Florida. Owing to their fragile nature, intact molecular ions
were observed only in some cases, typically accompanied by sub-
stantial fragmentation.
General Synthetic Procedure: Trimethylsilyl halide (TMSX) or tri-
methylsilyl azide (TMSN3; 0.60 mmol) followed by Bi(OTf)3
(0.05 mol-%) were added to a mixture of 1-arylallene (0.5 mmol)
and propargylic alcohol (0.5 mmol) in dichloromethane (2 mL) at
0 °C under nitrogen. The reaction mixture was stirred for 4–5 h at
0 °C. After completion (monitored by TLC), the reaction mixture
was directly passed through a column of silica gel and the products
were eluted with hexane. The isomeric mixtures could not be sepa-
rated by column chromatography and were isolated as isomeric
mixtures. The azido-enynes were purified by preparative TLC.
(Z)-2-(Chloromethyl)-3-(4-chlorophenyl)-5-phenyl-1-(p-tolyl)pent-1-
1
en-4-yne (3aa, Z/E = 91:1): Yield: 65%; viscous yellow liquid. H
NMR (CDCl3, 500 MHz): δ = 7.48–7.45 (m, 4 H), 7.37–7.36 (m, 3
H), 7.34–7.32 (m, 2 H), 7.28 (d, J = 8.0 Hz, 2 H), 7.21 (d, J =
8.0 Hz, 2 H), 7.02 (s, 1 H), 5.01 (d, J = 1.0 Hz, 1 H), 4.42 (d, J =
11.5 Hz, 1 H), 3.99 (d, J = 11.5 Hz, 1 H), 2.38 (s, 3 H) ppm. 13C
NMR (CDCl3, 125 MHz): δ = 137.8, 137.6, 136.1, 133.3, 133.0,
132.3, 131.6, 129.7, 129.2, 128.9, 128.6, 128.3, 128.2, 123.0, 88.1,
86.4, 42.1, 42.0, 21.2 ppm. MS (ES-API): m/z = 256 [M –
C8H5Cl]+, 389.0 [M – 1]+, 390.1 [M]+, 391 [M + 1]+, 282, 256, 130.
Minor isomer: 1H NMR (CDCl3, 500 MHz): δ = 5.44 (s), 4.27 (dd),
4.08 (dd) ppm.
Figure 3. Reaction profiles for the coupling reaction: (a) formation
of the anti allylic cation and (b) constraining the geometry of the
reactants in a syn disposition to obtain the syn-allylic cation. The
x axis corresponds to the length (in Å) of the forming bond.
Conclusions
We have shown that the propargylic cations generated by
the ionization of propargylic alcohols with catalytic
amounts of Bi(OTf)3 react with various aryl-substituted all-
enes to form incipient allylic cations that are quenched by
TMSCl to produce a number of sterically crowded chloro-
enynes as Z/E isomeric mixtures with a preference for the
formation of the Z stereoisomer. Two azido-enynes were
also formed by using TMSN3. A study of the transition
state for the crucial C–C bond-forming step by DFT calcu-
lations indicates that rotation of the benzylic portion away
from the propargyl cation may be a key factor in favoring
the anti isomer of the allylic cation. An interesting skeletal
(Z)-2-(Chloromethyl)-3,5-diphenyl-1-(p-tolyl)pent-1-en-4-yne (3ab,
Z/E = 92:8): Yield: 60 %; viscous pale-yellow liquid. 1H NMR
(CDCl3, 500 MHz): δ = 7.51–7.47 (m, 4 H), 7.38–7.37 (m, 3 H),
7.32–7.28 (m, 6 H), 7.19 (d, J = 7.5 Hz, 2 H), 7.05 (s, 1 H), 5.02
(d, J = 1.0 Hz, 1 H), 4.40 (d, J = 11.0 Hz, 1 H), 3.98 (d, J =
11.5 Hz, 1 H), 2.37 (s, 3 H) ppm. 13C NMR (CDCl3, 125 MHz): δ
= 139.4, 137.5, 136.7, 133.4, 132.1, 131.8, 129.3, 128.9, 128.7, 128.5,
128.3, 128.2, 127.5, 123.4, 88.8, 86.2, 42.6, 42.3, 21.3 ppm. MS (ES-
API): m/z = 357 [M + H]+, 279 [M – Ph]+. Minor isomer: 1H NMR
(CDCl3, 500 MHz): δ = 5.48 (s), 4.29 (dd), 4.06 (dd) ppm.
(Z)-2-(Chloromethyl)-5-phenyl-1,3-di(p-tolyl)pent-1-en-4-yne (3ac,
rearrangement was observed in crowded chloro-allenes Z/E = 89:11): Yield: 58%; viscous pale-yellow liquid. 1H NMR
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Electrophilic Addition of Propargylic Cations to Allenes
(CDCl3, 500 MHz): δ = 7.46–7.44 (m, 2 H), 3.37 (d, J = 8.5 Hz, 2
137.1, 136.9, 133.7, 131.5, 129.4, 129.2, 128.7, 128.3, 86.4, 79.4,
H), 7.30–7.26 (m, 5 H), 7.18–7.16 (m, 4 H), 7.04 (s, 1 H), 4.96 (s, 42.3, 41.7, 31.1, 22.1, 21.3, 21.2, 18.8, 13.7 ppm. MS (ES-API): m/z
1 H), 4.38 (d, J = 11.5 Hz, 1 H), 3.95 (d, J = 11.5 Hz, 1 H), 2.35
= 351 [M + H]+, 335, 313, 291, 277. Minor isomer: 1H NMR
(s, 6 H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 137.5, 137.2, (CDCl3, 500 MHz): δ = 5.21 (s), 4.23 (dd), 3.97 (dd) ppm.
136.8, 136.4, 133.5, 131.9, 131.8, 131.7, 129.6, 129.3, 129.0, 128.8,
(Z)-2-(Chloromethyl)-3-(4-fluorophenyl)-1-(p-tolyl)non-1-en-4-yne
128.7, 128.5, 128.4, 128.3, 128.1, 123.5, 89.1, 86.1, 42.3, 42.2, 21.3,
(3ai, Z/E = 93:7): Yield: 62%; viscous pale-yellow liquid. 1H NMR
21.2 ppm. MS (ES-API): m/z = 366/369 [M – H]+, 267, 239, 130.
(CDCl3, 500 MHz): δ = 7.40–7.38 (m, 2 H), 7.25 (d, J = 8.0 Hz, 2
Minor isomer: 1H NMR (CDCl3, 500 MHz): δ = 5.41 (s), 4.28 (dd),
H), 7.19 (d, J = 8.5 Hz, 2 H), 7.05–7.02 (m, 2 H), 6.92 (s, 1 H),
4.04 (dd) ppm.
4.75 (d, J = 1.5 Hz, 1 H), 4.35 (d, J = 11.5 Hz, 1 H), 3.91 (d, J =
(Z)-3-(4-Bromophenyl)-2-(chloromethyl)-5-phenyl-1-(p-tolyl)pent-1-
en-4-yne (3ad, Z/E = 91:1): Yield: 63%; yellow solid. 1H NMR
(CDCl3, 500 MHz): δ = 7.51 (d, J = 8.5 Hz, 2 H), 7.48–7.46 (m, 2
H), 7.39 (d, J = 8.5 Hz, 2 H), 7.33–7.31 (m, 3 H), 7.27 (d, J =
8.5 Hz, 2 H), 7.20 (d, J = 8.5 Hz, 2 H), 7.00 (s, 1 H), 4.99 (d, J =
1.0 Hz, 1 H), 4.40 (d, J = 11.0 Hz, 1 H), 3.98 (d, J = 11.0 Hz, 1
H), 2.37 (s, 3 H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 138.4,
137.6, 136.1, 133.0, 132.4, 131.8, 131.7, 131.6, 130.1, 129.2, 128.6,
128.3, 128.2, 123.0, 121.4, 88.0, 86.4, 42.1, 21.2 ppm. MS (ES-API):
m/z = 435/433/431/429 [M]+, 280, 242, 130. Minor isomer: 1H
NMR (CDCl3, 500 MHz): δ = 5.41 (s), 4.26 (dd), 4.07 (dd) ppm.
11.5 Hz, 1 H), 2.36 (s, 3 H), 2.28 (dt, J1 = 1.5, J2 = 7.0 Hz, 2 H),
1.56–1.52 (m, 2 H), 1.46–1.41 (m, 2 H), 0.92 (t, J = 7.5 Hz, 3
H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 161.9 (d, J = 244.3 Hz),
137.4, 137.0, 135.7, 133.3, 131.7, 129.8 (d, J = 8.3 Hz), 129.2, 128.5,
115.4 (d, J = 21.2 Hz), 86.7, 78.8, 42.1, 41.3, 30.9, 22.0, 21.2, 18.6,
13.6 ppm. 19F NMR (470 MHz, CDCl3): δ = –113.4 (m) ppm. MS
(ES-API): m/z = 353 [M – H]+, 355 [M + H]+, 371. Minor isomer:
1H NMR (CDCl3, 500 MHz): δ = 5.19 (s), 4.21 (dd), 3.97 (dd),
0.89 (t) ppm. 13C NMR (CDCl3, 125 MHz): δ = 135.7, 129.2, 129.0,
128.7 ppm.
(Z)-2-(Chloromethyl)-1-(4-fluorophenyl)-5-phenyl-3-thienylpent-1-
en-4-yne (3bf, Z/E = 72:28): Yield: 52%; viscous pale-yellow liquid.
1H NMR (CDCl3, 500 MHz): δ = 7.42–7.40 (m), 7.31–7.28 (m),
7.26–7.23 (m), 7.19–7.18 (m), 7.06 (d, J = 8.5 Hz), 7.01–6.98 (m),
6.92–6.89 (m), 5.20 (s, 1 H), 4.27 (d, J = 11.5 Hz, 1 H), 4.00 (d, J
= 11.5 Hz, 1 H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 162.2 (d,
J = 246.2 Hz), 142.7, 137.0, 131.76, 131.71, 131.0, 130.4 (d, J =
8.2 Hz), 128.3 (d, J = 6.5 Hz), 126.8, 126.3, 125.3, 125.1, 122.9,
115.5 (d, J = 21.2 Hz), 87.6, 85.9, 41.5, 37.9 ppm. 19F NMR
(470 MHz, CDCl3): δ = –113.6 (m) ppm. MS (ES-API): m/z = 367
(Z)-2-(Chloromethyl)-3-(4-fluorophenyl)-5-phenyl-1-(p-tolyl)pent-1-
en-4-yne (3ae, Z/E = 92:8): Yield: 64%; viscous pale-yellow liquid.
1H NMR (CDCl3, 500 MHz): δ = 7.50–7.47 (m, 4 H), 7.33–7.32
(m, 3 H), 7.28 (d, J = 8.0 Hz, 2 H), 7.20 (d, J = 8.0 Hz, 2 H), 7.09–
7.06 (m, 2 H), 7.01 (s, 1 H), 5.01 (s, 1 H), 4.41 (d, J = 11.5 Hz, 1 H),
3.99 (d, J = 11.5 Hz, 1 H), 2.37 (s, 3 H) ppm. 13C NMR (CDCl3,
125 MHz): δ = 162.2 (d, J = 245.0 Hz), 137.7, 136.6, 133.2, 132.3,
131.8, 130.1 (d, J = 7.3 Hz), 129.3, 128.7, 128.3 (d, J = 10.2 Hz),
123.2, 115.7 (d, J = 21.3 Hz), 88.5, 86.5, 42.2, 42.0, 21.3 ppm. 19F
NMR (470 MHz, CDCl3): δ = –115.1 (m) ppm. MS (ES-API): m/z
1
[M + H]+, 280, 242. Minor isomer: H NMR (CDCl3, 500 MHz):
1
= 373 [M – H]+, 267, 239, 130. Minor isomer: H NMR (CDCl3,
δ = 5.40 (s), 4.32 (dd), 4.13 (dd) ppm. 13C NMR (CDCl3,
125 MHz): δ = 142.2, 136.1, 132.0, 131.9, 130.3 (d, J = 8.3 Hz),
130.0, 128.4, 127.0, 125.7, 122.8, 115.6 (d, J = 21.3 Hz), 87.1, 84.5,
45.1, 34.2 ppm.
500 MHz): δ = 5.44 (s), 4.24 (dd), 4.07 (dd) ppm. 13C NMR
(CDCl3, 125 MHz): δ = 135.19, 135.1, 131.9, 129.5, 128.8,
128.4 ppm.
(Z)-2-(Chloromethyl)-5-phenyl-3-thienyl-1-(p-tolyl)pent-1-en-4-yne
(3af, Z/E = 87:13): Yield: 65 %; viscous pale-yellow liquid. 1H
NMR (CDCl3, 500 MHz): δ = 7.50–7.48 (m), 7.33–7.30 (m), 7.27–
7.26 (m), 7.20 (d), 7.16–7.15 (m), 7.10 (s), 7.00–6.98 (m), 5.29 (s),
4.43 (d), 4.12 (d), 2.37 (s) ppm. 13C NMR (CDCl3, 125 MHz): δ =
143.1, 137.7, 136.2, 133.1, 132.2, 131.8, 129.3, 128.7, 128.4, 126.9,
126.3, 125.3, 123.1, 88.0, 85.9, 42.0, 38.1, 21.4 ppm. Minor isomer:
1H NMR (CDCl3, 500 MHz): δ = 5.52 (s), 4.39 (dd), 4.23 (dd) ppm.
(Z)-2-(Chloromethyl)-1-(4-fluorophenyl)-3-(p-tolyl)non-1-en-4-yne
(3bh, Z/E = 80:20): Yield: 52 %; viscous pale-yellow liquid. 1H
NMR (CDCl3, 500 MHz): δ = 7.35–7.32 (m, 2 H), 7.29 (d, J =
8.0 Hz, 2 H), 7.16 (d, J = 8.0 Hz, 2 H), 7.08–7.04 (m), 6.94 (s, 1
H), 4.72 (d, J = 1.5 Hz, 1 H), 4.27 (d, J = 11.0 Hz, 1 H), 3.88 (d,
J = 11.0 Hz, 1 H), 2.35 (s, 3 H), 2.27 (dt, J1 = 1.5, J2 = 7.0 Hz, 2
H), 1.56–1.51 (m), 1.47–1.41 (m), 0.92 (t, J = 7.5 Hz, 3 H) ppm.
13C NMR (CDCl3, 125 MHz): δ = 162.0 (d, J = 265.0 Hz), 138.3,
137.0, 136.9, 130.5, 130.4 (d, J = 9.2 Hz), 129.5, 128.2, 127.5, 115.5
(d, J = 21.3 Hz), 86.6, 79.2, 41.9, 41.7, 31.1, 22.1, 21.2, 18.7,
13.7 ppm. 19F NMR (470 MHz, CDCl3): δ = –114.3 (m) ppm.
Minor isomer: 1H NMR (CDCl3, 500 MHz): δ = 7.39–7.36 (m),
7.23–7.22 (m), 7.19–7.10 (m), 6.89 (s), 5.09 (s), 4.24 (dd), 3.95 (dd),
2.32 (s), 2.29 (dt), 0.96 (t) ppm. 13C NMR (CDCl3, 125 MHz): δ =
136.8, 135.4, 132.6, 132.5, 130.6, 129.2, 128.7, 115.6 (d, J =
21.3 Hz), 45.4, 37.3, 22.1. 21.1 ppm.
(Z)-2-(Chloromethyl)-3-phenyl-1-(p-tolyl)non-1-en-4-yne (3ag, Z/E
1
= 91:9): Yield: 59%; viscous pale-yellow liquid. H NMR (CDCl3,
500 MHz): δ = 7.43–7.41 (m, 2 H), 7.36–7.33 (m, 2 H), 7.28–7.25
(m, 3 H), 7.18 (d, J = 8.5 Hz, 2 H), 6.96 (s, 1 H), 4.76 (d, J =
1.5 Hz, 1 H), 4.35 (d, J = 11.5 Hz, 1 H), 3.91 (d, J = 11.5 Hz, 1
H), 2.37 (s, 3 H), 2.28 (dt, J1 = 1.5, J2 = 7.0 Hz, 2 H), 1.56–1.51
(m, 2 H), 1.46–1.42 (m, 2 H), 0.92 (t, J = 7.5 Hz, 3 H) ppm. 13C
NMR (CDCl3, 125 MHz): δ = 140.1, 137.4, 137.3, 133.6, 131.6,
129.2, 128.7, 128.7, 128.4, 127.3, 86.6, 79.2, 42.3, 42.1, 31.1, 22.1,
21.3, 18.7, 13.7 ppm. MS (ES-API): m/z = 335 [M – H]+, 337, 353,
267, 239, 130. Minor isomer: 1H NMR (CDCl3, 500 MHz): δ =
5.23 (s), 4.23 (dd), 3.97 (dd) ppm.
(Z)-2-(Chloromethyl)-1,5-diphenyl-3-(p-tolyl)pent-1-en-4-yne (3cc,
Z/E = 82:18): Yield: 51%; viscous pale-yellow liquid. 1H NMR
(CDCl3, 500 MHz): δ = 7.39–7.36 (m, 2 H), 7.32–7.29 (m, 6 H),
7.22–7.19 (m, 4 H), 7.10 (d, J = 7.5 Hz, 2 H), 7.00 (d, J = 1.5 Hz,
1 H), 4.91 (d, J = 1.0 Hz, 1 H), 4.29 (d, J = 11.5 Hz, 1 H), 3.87 (d,
(Z)-2-(Chloromethyl)-1,3-di(p-tolyl)non-1-en-4-yne (3ah, Z/E =
1
89:11): Yield: 55%; viscous pale-yellow liquid. H NMR (CDCl3, J = 11.5 Hz, 1 H), 2.27 (s, 3 H) ppm. 13C NMR (CDCl3, 125 MHz):
500 MHz): δ = 7.30 (d, J = 8.0 Hz, 2 H), 7.26–7.24 (m, 2 H), 7.19–
7.18 (m, 2 H), 7.17–7.14 (m, 4 H), 7.09 (m, 2 H), 6.97 (s, 1 H), 4.72 128.29, 128.25, 128.0, 127.5, 123.3, 88.8, 86.0, 42.0, 21.1 ppm. MS
(d, J = 1.5 Hz, 1 H), 4.34 (d, J = 11.0 Hz, 1 H), 3.90 (d, J =
(ES-API): m/z = 357 [M + H]+, 315, 297. Minor isomer: 1H NMR
δ = 137.4, 137.1, 136.3, 136.2, 131.7, 131.6, 129.5, 128.6, 128.5,
11.0 Hz, 1 H), 2.36 (s, 3 H), 2.34 (s, 3 H), 2.28 (dt, J1 = 1.5, J2 = (CDCl3, 500 MHz): δ = 7.45–7.43 (m), 5.33 (s), 4.23 (dd), 3.97 (dd),
7.0 Hz, 2 H), 1.55–1.52 (m, 2 H), 1.45–1.43 (m, 2 H), 0.93 (t, J =
2.25 (s) ppm. 13C NMR (CDCl3, 125 MHz): δ = 129.2, 128.7,
128.6, 128.3, 128.1, 127.4 ppm.
7.5 Hz, 3 H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 137.4, 137.3,
Eur. J. Org. Chem. 2013, 5455–5463
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5461

K. K. Laali et al.
FULL PAPER
(Z)-2-(Chloromethyl)-1-phenyl-3-(p-tolyl)non-1-en-4-yne (3ch, Z/E
H), 5.88 (t, J = 7.5 Hz, 1 H), 2.37–2.32 (m, 2 H), 1.51–1.47 (m, 2
H), 0.96 (t, J = 7.5 Hz, 3 H) ppm. 13C NMR (CDCl3, 125 MHz):
= 73:27): Yield: 51%; viscous pale-yellow liquid. 1H NMR (CDCl3,
500 MHz): δ = 7.38–7.35 (m, 4 H), 7.31–7.30 (m, 3 H), 7.16 (d, J δ = 136.6, 132.3, 131.9, 130.8, 128.6, 127.7, 126.7, 126.7, 31.1, 21.9,
= 8.0 Hz, 2 H), 7.01 (d, J = 1.0 Hz, 1 H), 4.74 (d, J = 2.0 Hz, 1 13.8 ppm. GC–MS: m/z = 206 [M]+.
H), 4.33 (d, J = 11.0 Hz, 1 H), 3.90 (d, J = 11.0 Hz, 1 H), 2.35 (s,
(1E,3Z)-3-Chloro-1-(p-tolyl)hepta-1,3-diene (11): 1H NMR (CDCl3,
3 H), 2.27 (dt, J = 1.5, J2 = 7.5 Hz, 2 H), 1.54–1.51 (m), 1.47–1.43
500 MHz): δ = 7.32 (d, J = 8.0 Hz, 2 H), 7.13 (d, J = 7.5 Hz, 2 H),
(m), 0.92 (t, J = 7.5 Hz, 3 H) ppm. 13C NMR (CDCl3, 125 MHz):
6.87 (d, J = 15.5 Hz, 1 H), 6.73 (d, J = 15.5 Hz, 1 H), 5.85 (t, J =
δ = 138.1, 137.07, 137.0, 136.6, 131.4, 129.4, 129.2, 128.8, 128.7,
7.5 Hz, 1 H), 2.35–2.32 (m, 5 H), 1.51–1.47 (m, 2 H), 0.96 (t, J =
128.6, 128.5, 128.3, 127.54, 127.52, 86.5, 79.3, 42.2, 41.6, 31.1, 22.1,
7.5 Hz, 3 H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 137.7, 133.8,
21.2, 18.8, 13.7 ppm. MS (ES-API): m/z = 337 [M + H]+, 339, 315,
132.4, 131.3, 130.0, 129.3, 126.6, 125.8, 31.1, 21.9, 21.1, 13.8 ppm.
297. Minor isomer: 1H NMR (CDCl3, 500 MHz): δ = 7.41–7.39
GC–MS: m/z = 220 [M]+.
(m), 7.24 (d), 7.11 (d), 6.95 (s), 5.17 (s), 4.26 (dd), 3.97 (dd), 2.33
(s), 2.30 (dt), 0.96 (t) ppm. 13C NMR (CDCl3, 125 MHz): δ =
(1E,3Z)-3-Chloro-1-(4-fluorophenyl)hepta-1,3-diene (12): 1H NMR
(CDCl3, 500 MHz): δ = 7.39–7.37 (m, 2 H), 7.03–6.96 (m, 2 H),
6.85 (d, J = 15.0 Hz, 1 H), 6.90 (d, J = 15.5 Hz, 1 H), 5.87 (t, J =
7.5 Hz, 1 H), 2.36–2.32 (m, 2 H), 1.51–1.47 (m, 2 H), 0.96 (t, J =
7.5 Hz, 3 H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 162.4 (d, J
= 246.2 Hz), 132.8 (d, J = 3.6 Hz), 132.2, 132.0, 128.8, 128.1 (d, J
= 7.37 Hz), 126.5 (d, J = 1.8 Hz), 115.6 (d, J = 21.2 Hz), 31.1, 21.9,
13.8 ppm. GC–MS: m/z = 224 [M]+.
137.2, 136.7, 135.6, 129.8, 127.4, 45.4, 37.4, 21.1, 13.7 ppm.
(E)-2-(Azidomethyl)-3,5-diphenyl-1-(p-tolyl)pent-1-en-4-yne (5ab,
E/Z = 53:47): Yield: 24%; viscous pale-yellow liquid. 1H NMR
(CDCl3, 500 MHz): δ = 7.47–7.46 (m), 7.44–7.40 (m), 7.35–7.29
(m), 7.28–7.19 (m), 7.15–7.14 (m), 7.09 (s), 6.73 (s, 1 H), 5.36 (s, 1
H), 4.06 (d, J = 13.0 Hz, 1 H), 3.72–3.69 (m, 2 H), 2.28 (s) ppm.
13C NMR (CDCl3, 125 MHz): δ = 139.2, 138.1, 134.8, 133.3, 131.9,
129.4, 128.7, 128.46, 128.40, 128.34, 127.6, 123.3, 87.8, 85.1, 53.3,
37.8, 21.4 ppm. Other isomer: 1H NMR (CDCl3, 500 MHz): δ =
6.99 (s, 1 H), 3.86 (dd, J1 = 1.0, J2 = 14.5 Hz, 1 H), 4.80 (s, 1 H),
2.30 (s, 3 H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 137.5, 135.1,
133.2, 132.5, 131.8, 130.1, 129.2, 128.9, 128.8, 128.3, 128.2, 127.5,
88.5, 86.3, 49.2, 43.9, 21.3 ppm.
Supporting Information (see footnote on the first page of this arti-
1
cle): Selected H and 13C{1H} NMR spectra.
Acknowledgments
(E)-2-(Azidomethyl)-3-(4-bromophenyl)-5-phenyl-1-(p-tolyl)pent-1-
en-4-yne (5ad, E/Z = 73:27): Yield: 15%; viscous pale-yellow liquid.
1H NMR (CDCl3, 500 MHz): δ = 7.55–7.53 (m), 7.51–7.48 (m),
7.46–7.45 (m), 7.40 (d), 7.37–7.35 (m), 7.33–7.32 (m), 7.31–7.29
(m), 7.24 (d), 7.18–7.17 (m), 6.83 (s, 1 H), 5.38 (s, 1 H), 3.92 (dd,
J1 = 1.5, J2 = 15.0 Hz, 1 H), 2.38 (s, 3 H) ppm. 13C NMR (CDCl3,
125 MHz): δ = 137.7, 137.3, 134.3, 133.0, 132.8, 131.9, 131.7, 130.7,
130.0, 129.5, 129.3, 128.5, 123.0, 121.3, 87.2, 85.5, 53.3, 37.4,
21.4 ppm. Minor isomer: 1H NMR (CDCl3, 500 MHz): δ = 7.04
(s), 4.85 (s), 4.15 (d), 3.82–3.78 (m), 2.36 (s) ppm. 13C NMR
(CDCl3, 125 MHz): δ = 138.3, 137.7, 134.7, 133.0, 132.8, 132.5,
132.0, 131.8, 129.3, 128.9, 128.8, 128.4, 123.1, 121.5, 87.8, 86.7,
49.2, 43.4, 21.3 ppm.
The authors thank the University of North Florida for research
support.
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16.0 Hz, 1 H), 7.46 (d, J = 8.0 Hz, 2 H), 7.21 (d, J = 8.0 Hz, 2 H),
6.72 (d, J = 16.0 Hz, 1 H), 2.67 (t, J = 7.0 Hz, 2 H), 2.39 (s, 3 H),
1.69–1.66 (m, 2 H), 1.42–1.37 (m, 2 H), 0.95 (t, J = 7.5 Hz, 3
H) ppm. 13C NMR (CDCl3, 125 MHz): δ = 200.8, 142.3, 140.8,
1
131.8, 129.6, 128.2, 125.3, 40.6, 26.5, 22.4, 21.5, 13.9 ppm. 7b: H
NMR (CDCl3, 500 MHz): δ = 7.48 (d, J = 8.0 Hz, 2 H), 7.16 (d,
J = 8.0 Hz, 2 H), 6.78 (d, J = 12.5 Hz, 1 H), 6.15 (d, J = 12.5 Hz,
1 H), 2.48 (t, J = 7.5 Hz, 2 H), 2.37 (s, 3 H), 1.60–1.57 (m, 2 H),
1.32–1.28 (m, 2 H), 0.88 (t, J = 7.5 Hz, 3 H) ppm. 13C NMR
(CDCl3, 125 MHz): δ = 203.4, 139.9, 139.4, 132.4, 129.7, 128.9,
127.6, 43.4, 26.3, 22.2, 21.4, 13.8 ppm.
6-Chloro-1,3-diphenylhex-3-en-1-yne (4): 1H NMR (CDCl3,
500 MHz): δ = 7.74–7.23 (m, 2 H), 7.60–7.58 (m, 2 H), 7.44–7.39
(m, 5 H), 7.37–7.35 (m, 1 H), 6.54 (t, J = 7.5 Hz, 1 H), 3.77 (t, J
= 7.0 Hz, 2 H), 3.09 (q, J = 7.0 Hz, 2 H) ppm. 13C NMR (CDCl3,
125 MHz): δ = 137.6, 132.9, 131.6, 128.5, 128.5, 128.4, 128.0, 126.2,
126.1, 123.1, 96.2, 86.1, 43.6, 34.4 ppm.
(1E,3Z)-3-Chloro-1-phenylhepta-1,3-diene (10): 1H NMR (CDCl3,
500 MHz): δ = 7.43–7.41 (m, 2 H), 7.34–7.31 (m, 3 H), 7.24 (d, J
= 6.5 Hz, 1 H), 6.90 (d, J = 15.5 Hz, 1 H), 6.77 (d, J = 15.5 Hz, 1
5462
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Eur. J. Org. Chem. 2013, 5455–5463

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