Waste-free catalytic propargylation/allenylation of aryl and heteroaryl nucleophiles and synthesis of naphthopyrans

Article abstract of DOI:10.1055/s-0030-1260146

A general method for the substitution of propargylic alcohols with electron-rich aromatic carbocycles and heterocycles has been developed. The reaction occurs under simple, mild conditions, and employs an inexpensive environmentally benign and recoverable

Full text of DOI:10.1055/s-0030-1260146

3152
PAPER
Waste-Free Catalytic Propargylation/Allenylation of Aryl and Heteroaryl
Nucleophiles and Synthesis of Naphthopyrans
Catalytic
P
ropargylatio
A
n/Allenylation of
d
A
ryl and
H
et
a
eroaryl
N
uc
m
leophiles McCubbin,* Costa Nassar, Oleg V. Krokhin
Department of Chemistry, University of Winnipeg, 515 Portage Ave., Winnipeg, MB, R3B 2E9, Canada
Fax +1(204)7752114; E-mail: a.mccubbin@uwinnipeg.ca
Received 16 June 2011
backs still need to be addressed, including the high cost
Abstract: A general method for the substitution of propargylic al-
cohols with electron-rich aromatic carbocycles and heterocycles has
been developed. The reaction occurs under simple, mild conditions,
and employs an inexpensive environmentally benign and recover-
and toxicity associated with transition-metal complexes,
and the harsh nature of strongly Lewis acidic catalysts.
Furthermore, methods to date have focused primarily on
able arylboronic acid catalyst, perfluorophenylboronic acid, pro- secondary alcohol substrates, and yield primarily propar-
ducing water as the only byproduct. High yields and selectivities are
observed for propargyl- or allenyl-substituted products, including
furans, indoles, and pyrroles, as well as methoxy-substituted ben-
principle, allenyl arylation products 4 are also possible.7,8
zenes and naphthalenes. Reaction with 2-naphthol affords substitut-
gyl-substituted products 3. The intermediacy of propar-
gylic cations in many of these reactions suggests that, in
ed naphthopyrans as products. Preliminary evidence suggests a
Friedel–Crafts-like substitution mechanism, which occurs via an in
situ generated carbocation.
R3
R1 R2
R1 R2
Ar
catalyst
R3
and/or
R3
R2
Ar
H
+
Ar
HO
4
2
Key words: organocatalysis, boronic acids, propargylic alcohols,
Friedel–Crafts reaction
3
1
+
H2O
R1
Scheme 1 Direct aromatic substitution of propargylic alcohols
The nucleophilic substitution of propargylic alcohols is a
powerful tool in the synthesis of complex organic struc-
tures. This is due in part to the ease with which diverse
starting materials can be prepared (i.e., by addition of
acetylides to aldehydes and ketones) as well as the variety
of transformations available to manipulate the alkyne or
allene functionality in the products. The cobalt-mediated
Nicholas reaction has therefore found wide application,
particularly in the context of carbon–carbon bond-form-
ing reactions,1 and is featured prominently in several total
syntheses.2 Although a mild and useful method, the reac-
tion suffers from the use of stoichiometric quantities of
Co(CO)8, which is necessary for stabilization of the car-
bocation intermediates. The direct catalytic substitution of
propargylic alcohols with carbon nucleophiles remains a
significant challenge, due in part to the poor leaving group
ability of hydroxide, as well as the propensity of the re-
sulting unstabilized carbocations to form polymerization
products.
Diversely substituted arylboronic acids are inexpensive
and widely available, primarily due to their use as cou-
pling partners in the Suzuki–Miyaura reaction.9 They pos-
sess several useful properties, including air and moisture
stability, high solubility in organic solvents and Lewis
acidity of the boron atom, which can be modulated by ring
substituents.10 Despite this, there are only sporadic reports
of their use as catalysts.11
We have recently reported on the direct coupling of allylic
and benzylic alcohols with electron-rich aromatics and
heteroaromatics catalyzed by an electron-deficient aryl-
boronic acid.12 In our efforts to extend the applicability of
this unique class of organocatalysts, we wish to report its
use in the efficient, regioselective coupling of propargylic
alcohols with electron-rich aromatic and heteroaromatic
rings under simple, mild conditions.13
We began by applying our optimized conditions for the al-
lylation reaction, treating a 1:1 mixture of 2-methylfuran
(5) and diphenyl propargylic alcohol 2a in dichlo-
romethane with 4 Å molecular sieves and perfluorophe-
nylboronic acid (6) at room temperature for 16 hours
(Table 1, entry 1). We were pleased to observe the forma-
tion of propargyl derivative 3a, although in modest yield,
with recovery of starting materials. Heating the same mix-
ture in 1,2-dichloroethane affords the product 3a in good
yield (entry 2). Moderately electron-poor derivative 2b
behaves similarly at room temperature, affording 3b in
comparably modest yield (entry 3). Electron-rich alcohol
2c undergoes coupling much more efficiently under the
same conditions to afford 3c in near quantitative yield (en-
try 4). In all four cases, the propargyl derivatives are
Recently, several reports on catalytic, cobalt-free direct
substitution of propargylic alcohols 2 with aromatic nu-
cleophiles 1 to afford coupled products 3, have emerged
(Scheme 1).3 These studies have focused primarily on the
use of transition-metal complexes,4 and conventional
Brønstead or Lewis acids as catalysts.5 This approach is
particularly attractive, since the aryl nucleophile requires
no pre-activation (halides, etc.) and only water is pro-
duced as stoichiometric waste.6 However, several draw-
SYNTHESIS 2011, No. 19, pp 3152–3160
x
x.
x
x
.
2
0
1
1
Advanced online publication: 01.08.2011
DOI: 10.1055/s-0030-1260146; Art ID: M61711SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Catalytic Propargylation/Allenylation of Aryl and Heteroaryl Nucleophiles
3153
Table 1 Propargylation of 2-Methylfuran (continued)
formed exclusively, with no evidence of isomeric prod-
ucts in the crude reaction mixtures
C6F5B(OH)2
(6, 10 mol%)
R1 R2
O
In contrast, triphenyl tertiary alcohol 2d affords allenyl
derivative 4d exclusively under the same reaction condi-
tions (entry 5). Similarly, the electron-rich tertiary alcohol
2e undergoes substitution to afford tetraarylallene 4e in
high yield (entry 6). The analogous electron-poor deriva-
tive 2f also affords exclusively the allene product 4f, but
in somewhat decreased isolated yield (entry 7).
+
3 or 4
HO
4 Å MS, CH2Cl2
R3
5
2
r.t., 16 h
Entry Alcohol 2
Product 3 or 4
Yielda
(%)
O
11
10
Table 1 Propargylation of 2-Methylfuran
HO
C6F5B(OH)2
(6, 10 mol%)
Ph
Ph
Ph
Ph
R1 R2
O
2j
3j
+
3 or 4
HO
4 Å MS, CH2Cl2
r.t., 16 h
R3
5
2
O
12
38d
HO
Entry Alcohol 2
Product 3 or 4
Yielda
(%)
2k
3k
a Isolated yields.
X
X
b The reaction was run in DCE at reflux.
c 59% yield of dehydration product isolated.
d 57% yield of dehydration product isolated.
O
HO
Non-aryl alkyne substituents at R3 are well tolerated, in-
cluding alkyl 2g (entry 8) and silyl derivatives 2h (entry
9). Similarly to the triaryl derivatives, subjecting 2g or 2h
to the reaction conditions affords exclusively the allenyl
products 4g or 4h, respectively.
Ph
Ph
1
2
3
4
2a: X = H
2a: X = H
2b: X = F
3a: X = H
3a: X = H
3b: X = F
41
79b
43
96
The reaction is notably less effective for cyclic substrates
2i–k. In the case of 2i and 2k, significant amounts of con-
jugated enyne dehydration products are formed (entries
10 and 12). Surprisingly, cyclohexyl derivative 2j failed
to react to any significant extent, with high recovery of
starting materials (entry 11). This lack of reactivity sug-
gests that steric effects arising from the conformation of
the cyclohexane ring in 2j are either inhibiting interaction
with 6, or the resulting carbocation is not in a configura-
tion suitable for elimination or nucleophilic attack. In con-
trast to the acyclic tertiary alcohol substrates 2d–h,
derivatives 2i–k (entries 10–12) react to form the propar-
gylated derivatives 3i–k as the only coupled products.
This marked reversal of selectivity can be attributed to
steric differences between the substrates at R1 and R2
(vide infra), and/or the strain associated with the exocy-
clic allenyl carbocations that would be formed from 2i–k.
For all of the examples shown in Table 1, high selectivity
for either the alkyne or allene products is observed, with
no evidence of the corresponding isomeric products in the
crude reaction mixtures.
2c: X = OMe
3c: X = OMe
X
Ph
O
Ph
Ph
HO
X
Ph
5
6
7
2d: X = H
4d: X = H
91
93
76
2e: X = OMe
2f: X = CF3
4e: X = OMe
4f: X = CF3
C6H13
Ph Ph
HO
O
O
Ph
Ph
8
9
86
98
C6H13
Ph
Ph
2g
4g
4h
TMS
Ph Ph
HO
TMS
When we attempted to extend the scope of the reaction to
include diarylalkyl derivatives 2l–n, however, we ob-
served formation of isomeric mixtures of 3 and 4
(Table 2). In the case of methyl derivative 2l, the alkyne
derivative 3l is favored over the allene derivative 4l by a
factor of 7:3, affording an inseparable mixture of isomeric
products in high combined yield (entry 1). Modification
of the alkyl group from methyl to ethyl to isopropyl (en-
tries 2 and 3), results in a steady decrease in this ratio,
2h
O
10
39c
HO
Ph
Ph
3i
2i
Synthesis 2011, No. 19, 3152–3160 © Thieme Stuttgart · New York

3154
J. A. McCubbin et al.
PAPER
Table 2 Alkyne/Allene Selectivity
Ph
R
Ph
R
Ph
6 (10 mol%)
O
+
5
O
Ph
HO
4 Å MS
CH2Cl2, r.t., 16 h
+
4
3
2
Ph
Ph
R
Entry
R
2
Ratioa 3/4
70:30
Total yieldb (%)
1
2
3
Me
Et
2l
89
93
95
2m
2n
55:45
i-Pr
50:50
a Determined by 1H NMR.
b Isolated yields.
where in the case that R = i-Pr, the allene product 4n is selectivity. Benzene- and naphthalene-based nucleophiles
formed in equal amount with the alkyne product 3n (entry 7d–g all afford allene-substituted products 9d–g, respec-
4).
tively in high to near quantitative yields (entries 4–7).
Such mixtures of allenyl and propargyl products have This method compares favorably with other propargyla-
been observed previously in conventional Friedel–Crafts tion reactions. While it does not compete in terms of cat-
reactions with propargylic electrophiles.14 The carbo- alyst loading with many of the transition-metal-based
cations derived from such substrates have been studied catalysts,4 the lower cost, simplicity, and non-toxic nature
extensively and are well known to exist as resonance of the boronic acid catalyst are significant advantages. A
structures with the corresponding allenyl carbocations.7 comparable Lewis acid, boron trifluoride–diethyl ether
Of the two forms, the sp3 hybridized propargylic carbocat- complex, has only been shown to be effective at mediating
ion is more highly stabilized than the sp2 hybridized allyl- these reactions in stoichiometric quantities.4i Simple
ic one and thus the resonance hybrid should exhibit more Bronstead acids (e.g., TsOH) are effective catalysts, but
positive character at the propargylic position. The results require harsh reaction conditions (refluxing MeCN).5f
from Table 2 suggest that as the steric bulk of R increases,
Previous mechanistic studies on the related reaction of al-
nucleophilic attack at the favored propargylic position is
lylic and benzylic alcohols with aromatic nucleophiles,
inhibited, resulting in attack on the electronically less fa-
under similar conditions are in support of an SN1/Friedel–
vored allenyl position. These observations are also consis-
Crafts-like mechanism,14 involving the intermediacy of a
tent with the results in Table 1. For example, the reversal
resonance-stabilized carbocation. Although alternative
of selectivity observed between reaction of secondary al-
mechanisms have been proposed for similar substitution
cohol 2c with 5, (entry 4) and the tertiary alcohol 2e with
5 (entry 6) can be explained by the lower steric demand of
the hydrogen as compared to the phenyl group.
reactions,5d our results suggest that an SN1-type substitu-
tion mechanism is indeed operative. For example, the ob-
servation that electron-neutral and electron-poor
Having established the scope of the reaction with furan secondary alcohols behave sluggishly in the reaction
substrate 5, we turned our attention to the reaction of var- (Table 1, entries 1 and 3), whereas electron-rich substrates
ious other aromatic heterocycles and carbocycles 7 with a react completely under identical conditions (entry 4) is
propargylic alcohol 2h, in order to test further the selec- consistent with rate-determining carbocation formation
tivity of the reaction (Table 3). Similarly to the reaction of via departure of the hydroxide as a leaving group. Further-
5 with 2h (Table 1, entry 9), pyrrole (7a) affords allenyl more, propargyl- vs. allenyl-substitution product distribu-
products exclusively (entry 1); in this case, an inseparable tions can be attributed to the formation of a delocalized
mixture of C2- and C3-allenylated products 9a and 9a¢ re- propargylic carbocation. This intermediate undergoes nu-
sults in high combined yield. Similarly, thiophene (7b) re- cleophilic attack at one of two positions, depending on the
acts with 2h to form a mixture of allenylated products 9b nature of the substituents, as well as the structure of the
(entry 2), but in this case the minor product is the symmet- nucleophile.
rical disubstituted product 9b¢. The only nucleophile in
Interestingly, reaction of 10 with 2h under these condi-
this series that affords a propargylic product is indole (7c).
tions results in the clean formation of naphthopyran 11a in
It is unclear why some five-membered ring heterocycles
excellent yield (Table 4, entry 1). Given that reaction of
(e.g., 7c) form propargyl products with 2h under these
closely related 7f forms allene product 9f, we propose that
conditions, whereas others (e.g., 5, 7b) form allene prod-
reaction of 10 with 2h results in initial formation of an al-
ucts. However, these results suggest that in addition to the
lene, followed by protonation of the double bond to form
steric and electronic effects discussed above, subtle differ-
a stabilized carbocation and intramolecular attack of oxy-
ences in the nucleophilicity of the heteroaromatic sub-
gen.
strates may be contributing to the divergence in
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Catalytic Propargylation/Allenylation of Aryl and Heteroaryl Nucleophiles
3155
Table 3 Propargylation of Other Nucleophiles
TMS
Ph Ph
HO
6 (10 mol%)
Ph Ph
or
+
Ar
H
Ar
Ph
4 Å MS
CH2Cl2, r.t., 16 h
Ar
TMS
TMS
2h
7
8
9
Ph
Entry
Ar-H
Product
Yielda (%)
TMS
H
N
H
N
85b
52c
Ph
1
2
Ph
7a
S
9a/9a¢
TMS
S
Ph
Ph
Ph
7b
9b
8c
Ph
3
83
TMS
Ph
N
H
N
H
7c
OMe
OMe TMS
OMe TMS
4
5
86
99
MeO
7d
MeO
Ph
9d
OMe
Ph
MeO
OMe
MeO
OMe Ph
7e
9e
TMS
6
7
94
87
Ph
OMe
OMe Ph
9f
7f
Ph
OH
OH
Ph
TMS
7g
9g
a Isolated yields.
b Inseparable 7:3 mixture of C2- and C3-substituted products 9a and 9a¢ as determined by 1H NMR.
c 23% of C2,C4-disubstituted product 9b¢ isolated.
Benzopyran derivatives are of significant biological and substituents 2d,l,o,n lead to regioselective formation of
medicinal value,15 and have useful photochromic proper- naphthopyrans 11b–e in good to excellent yields (entries
ties.16 We therefore attempted a preliminary examination 2–5). Spironaphthopyran products bearing six-, seven-,
the scope of this reaction using a selection of propargylic and five-membered rings 11f–h are also available by this
alcohols 2 (Table 4). Annulation reactions of this type method (entries 6–8). The moderate yield of 11f (entry 7),
have been previously reported, but generally rely on harsh even under reflux heating is consistent with our observa-
conventional Brønstead or Lewis acids that result in mod- tion that 2j has limited reactivity with other nucleophiles
erate yields, or costly transition-metal-based catalysts.17
under these conditions (Table 1, entry 11).
We were pleased to find that tertiary propargylic alcohols In summary, we have developed an efficient, mild, and
bearing various combinations of aliphatic and aromatic catalytic method for the direct propargylation and/or alle-
Synthesis 2011, No. 19, 3152–3160 © Thieme Stuttgart · New York

3156
J. A. McCubbin et al.
PAPER
nylation of a variety of aromatic and heteroaromatic sub-
strates. 2-Naphthols are efficiently annulated under these
conditions. The catalyst is commercially available as well
as being air and moisture stable and does not require any
special handling. A wide variety of propargylic alcohol
substrates are tolerated, the catalyst is recoverable and the
reaction produces only water as a byproduct. Preliminary
evidence suggests a Friedel–Crafts-like mechanism, in-
volving rate-determining carbocation formation. Exten-
sion of the scope of this reaction, and further mechanistic
studies are ongoing in our laboratory and will be reported
in due course.
Table 4 One-Pot Synthesis of Naphthopyrans
R1
R2
R3
6 (10 mol%)
R1 R2
HO
OH
+
O
4 Å MS
CH2Cl2, r.t., 16 h
R3
10
2
11
Entry
2
Product
Yielda (%)
TMS
Ph Ph
1
2
3
4
5
95
HO
Ph
Ph
TMS
O
2h
11a
11b
1H and 13C NMR spectra were recorded using a Bruker Avance III
400 spectrometer at 400 and 100 MHz, respectively. NMR shifts are
reported relative to a TMS or CDCl3 internal standard. IR spectra
were obtained using a Varian Scimitar Series 1000 FT-IR spectro-
photometer. HRMS were obtained using the Manitoba/Sciex proto-
type MALDI quadrupole/TOF (QqTOF) mass spectrometer.18 Flash
chromatography was performed using Merck silica gel Si 60 (40–63
mm) purchased from EMD chemicals. All solvents were purchased
as ACS reagents and used without further purification. All other
chemicals were purchased from Aldrich or Alfa Aesar and were
used as received.
Ph
Ph Ph
97
71
72
88
HO
Ph
Ph
Ph
O
2d
Ph
Ph
HO
Ph
Ph
O
Ph
2l
Acetylenes 3, 8, Allenes 4, 9, and 3H-Naphtho[2,1-b]pyrans 11;
General Procedure
11c
11d
Ph
To a vial containing the alcohol (0.5 mmol) in CH2Cl2 (2.5 mL) was
added freshly dried powdered 4 Å molecular sieves (500 mg), the
nucleophile (1.0 equiv), and pentafluorophenylboronic acid (6, 11
mg, 0.1 equiv). The vial was capped and the mixture allowed to stir
at r.t. for 16 h. The suspension was filtered through a 1-inch plug of
silica gel (CH2Cl2), and the eluent concentrated in vacuo. The resi-
due was purified (if necessary) by flash chromatography (EtOAc–
hexanes).
HO
O
2o
Ph
Ph i-Pr
HO
i-Pr
Ph
2-(1,3-Diphenylprop-2-ynyl)-5-methylfuran (3a)
FTIR (neat): 3057, 2929, 2202, 1960, 1890, 1708, 1598, 1223,
1020, 701 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.50–7.46 (m, 4 H), 7.37–7.32 (m,
2 H), 7.31–7.27 (m, 4 H), 6.13–6.11 (d, J = 3.0 Hz, 1 H), 5.89–5.87
(d, J = 3.0 Hz, 1 H), 5.20 (s, 1 H), 2.24 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 151.9, 151.8, 139.1, 131.7, 128.5,
128.2, 128.0, 127.8, 127.2, 123.3, 107.3, 106.1, 87.7, 83.7, 37.8,
13.6.
Ph
O
2n
11e
11f
11g
Ph
6
7
57b
HO
O
Ph
2j
HRMS: m/z [M]+ calcd for C20H16O: 272.1201; found: 272.1178.
Ph
O
2-[1-(4-Fluorophenyl)-3-phenylprop-2-ynyl]-5-methylfuran
(3b)
79
HO
FTIR (neat): 3060, 2924, 2199, 1599, 1508, 1158, 840, 758 cm–1.
Ph
1H NMR (400 MHz, CDCl3): d = 7.53–7.46 (m, 4 H), 7.35–7.32 (m,
2 H), 7.10–7.04 (t, J = 8.5 Hz, 2 H), 6.18–6.16 (d, J = 2.8 Hz, 1 H),
5.95–5.93 (d, J = 2.8 Hz, 1 H), 5.22 (s, 1 H), 2.28 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 163.2–160.8 (d, J = 246 Hz),
152.0, 151.5, 134.88–134.85 (d, J = 2.9 Hz), 131.7, 129.4–129.3 (d,
J = 8.0 Hz), 128.2–128.15 (d, J = 5.1 Hz), 123.0, 115.5, 115.2,
107.3, 106.2, 87.4, 83.9, 37.1, 13.6.
2i
Ph
O
8
91
HO
Ph
HRMS: m/z [M – H]+ calcd for C20H14FO: 289.1029; found:
289.1015.
2p
11h
a Isolated yields.
2-[1-(4-Methoxyphenyl)-3-phenylprop-2-ynyl]-5-methylfuran
(3c)
b Reaction run at reflux in DCE; product contaminated with conjugat-
ed enyne dehydration product (inseparable; 40% by 1H NMR).
FTIR (neat): 2954, 2836, 2199, 1302, 1109, 1034, 758, 692 cm–1.
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Catalytic Propargylation/Allenylation of Aryl and Heteroaryl Nucleophiles
3157
1H NMR (400 MHz, CDCl3): d = 7.46–7.43 (m, 2 H), 7.40–7.37 (d,
J = 8.5 Hz, 2 H), 7.26–7.23 (m, 3 H), 6.87–6.83 (d, J = 8.5 Hz, 2 H),
6.11–6.09 (d, J = 3.0 Hz, 1 H), 5.87–5.85 (d, J = 3.0 Hz, 1 H), 5.14
(s, 1 H), 3.72 (s, 3 H), 2.20 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 158.9, 152.3, 151.9, 131.8, 131.4,
129.0, 128.3, 128.2, 123.4, 114.1, 107.2, 106.3, 88.3, 83.7, 55.3,
37.2, 13.7.
13C NMR (100 MHz, CDCl3): d = 206.2, 151.9, 148.3, 137.2, 128.5,
128.2, 127.1, 113.5, 107.4, 107.3, 101.6, 31.6, 29.8, 29.1, 28.0,
22.6, 14.0, 13.8.
HRMS: m/z [M – H]+ calcd for C26H27O: 355.2062; found:
355.2045.
2-[3,3-Diphenyl-1-(trimethylsilyl)propa-1,2-dienyl]-5-methyl-
furan (4h)
HRMS: m/z [M – H]+ calcd for C21H17O: 301.1229; found:
301.1221.
FTIR (neat): 3058, 2956, 2855, 1715, 1598, 1250, 1023, 874, 766
cm–1.
2-Methyl-5-(1,3,3-triphenylpropa-1,2-dienyl)furan (4d)
FTIR (neat): 3055, 2928, 1957, 1893, 1715, 1596, 1447, 1273,
1019, 770 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.47–7.44 (d, J = 7.3 Hz, 2 H),
7.39–7.36 (d, J = 7.5 Hz, 4 H), 7.26–7.21 (m, 6 H), 7.20–7.15 (m, 3
H), 6.13–6.11 (d, J = 3.3 Hz, 1 H), 5.92–5.90 (d, J = 3.3 Hz, 1 H),
2.20 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 208.4, 152.4, 146.9, 136.4, 135.0,
128.6, 128.5, 128.4, 128.2, 127.8, 127.5, 113.7, 110.3, 107.5, 104.9,
13.8.
1H NMR (400 MHz, CDCl3): d = 7.64–7.61 (d, J = 7.3 Hz, 4 H),
7.55–7.50 (t, J = 7.3 Hz, 4 H), 7.45–7.41 (t, J = 7.3 Hz, 2 H), 6.45–
6.43 (d, J = 3.0 Hz, 1 H), 6.18–6.16 (d, J = 3.0 Hz, 1 H), 2.47 (s, 3
H), 0.54 (s, 9 H).
13C NMR (100 MHz, CDCl3): d = 209.4, 151.9, 147.5, 137.2, 128.7,
128.5, 127.1, 108.9, 107.9, 107.7, 95.1, 14.0, –0.2.
HRMS: m/z [M]+ calcd for C23H24OSi: 344.1596; found: 344.1583.
1-(5-Methylfuran-2-yl)-1-(phenylethynyl)cycloheptane (3i)
FTIR (neat): 3059, 2929, 2860, 2201, 1598, 1489, 1460, 1274, 757,
691 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.44–7.38 (m, 2 H), 7.29–7.23 (m,
3 H), 6.09–6.07 (d, J = 3.0 Hz, 1 H), 5.86–5.84 (d, J = 3.0 Hz, 1 H),
2.26 (s, 3 H), 2.18–2.12 (m, 2 H), 2.06–1.98 (m, 2 H), 1.88–1.79 (m,
2 H), 1.74–1.67 (m, 2 H), 1.63–1.56 (m, 4 H).
HRMS: m/z [M + H]+ calcd for C26H21O: 349.1592; found:
349.1594.
2-[3-(4-Methoxyphenyl)-1,3-diphenylpropa-1,2-dienyl]-5-
methylfuran (4e)
FTIR (neat): 3055, 2931, 2835, 1715, 1509, 1247, 1032, 831, 697
13C NMR (100 MHz, CDCl3): d = 157.8, 150.7, 131.6, 128.1, 127.5,
cm–1.
123.8, 105.6, 104.2, 93.7, 82.3, 41.0, 39.8, 28.2, 23.4, 13.6.
1H NMR (400 MHz, CDCl3): d = 7.57–7.53 (d, J = 8.5 Hz, 2 H),
7.49–7.45 (d, J = 8.5 Hz, 2 H), 7.41–7.38 (d, J = 8.8 Hz, 2 H), 7.37–
7.32 (m, 4 H), 7.30–7.26 (m, 2 H), 6.90–6.87 (d, J = 9.0 Hz, 2 H),
6.22–6.20 (d, J = 3.3 Hz, 1 H), 6.02–6.00 (d, J = 3.3 Hz, 1 H), 3.79
(s, 3 H), 2.31 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 208.2, 154.1, 152.3, 147.2, 136.7,
135.2, 129.7, 128.62, 128.58, 128.44, 128.39, 128.2, 127.7, 127.5,
113.8, 113.3, 110.1, 107.5, 104.7, 55.3, 13.8.
1-(5-Methylfuran-2-yl)-1-(phenylethynyl)cyclohexane (3j)
FTIR (neat): 3056, 2930, 2856, 2224, 1598, 1490, 1219, 1020, 781,
691 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.52–7.48 (m, 2 H), 7.34–7.31 (m,
3 H), 6.17–6.15 (d, J = 3.0 Hz, 1 H), 5.95–5.93 (d, J = 3.0 Hz, 1 H),
2.33 (s, 3 H), 2.15–2.10 (m, 2 H), 1.91–1.85 (m, 4 H), 1.79–1.72 (m,
4 H).
HRMS: m/z [M + H]+ calcd for C27H23O2: 379.1698; found:
371.1711.
13C NMR (100 MHz, CDCl3): d = 157.5, 150.6, 131.5, 128.1, 127.6,
123.7, 105.8, 104.4, 92.4, 83.5, 38.2, 37.0, 25.8, 22.8, 13.6.
2-{1,3-Diphenyl-3-[4-(trifluoromethyl)phenyl]-propa-1,2-di-
enyl}-5-methylfuran (4f)
1-(5-Methylfuran-2-yl)-1-(phenylethynyl)cyclopentane (3k)
FTIR (neat): 3060, 2953, 2872, 2221, 1598, 1492, 1382, 1318,
1026, 915, 757, 692 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.43–7.40 (m, 2 H), 7.29–7.24 (m,
3 H), 6.14–6.12 (d, J = 3.0 Hz, 1 H), 5.88–5.86 (d, J = 3.0 Hz, 1 H),
2.28 (s, 3 H), 2.20–2.15 (m, 4 H), 1.97–1.91 (m, 2 H), 1.84–1.78 (m,
2 H).
FTIR (neat): 3059, 2927, 1718, 1493, 1326, 1167, 1067, 844, 699
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.63–7.55 (m, 6 H), 7.49–7.45 (d,
J = 7.3 Hz, 2 H), 7.43–7.34 (m, 6 H), 6.27–6.25 (d, J = 3.0 Hz, 1 H),
6.08–6.06 (d, J = 3.0 Hz, 1 H), 2.36 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 208.9, 152.8, 146.4, 140.5, 135.8,
134.6, 130.0–129.0 (q, J = 32.3 Hz), 128.8, 128.7, 128.63, 128.57,
128.3, 128.1, 127.9, 125.5–125.4 (q, J = 3.7 Hz), 122.9, 113.0,
110.9, 107.7, 105.7, 13.9.
HRMS: m/z [M + H]+ calcd for C27H20F3O: 417.1466; found:
417.1477.
13C NMR (100 MHz, CDCl3): d = 155.6, 151.0, 131.6, 128.1, 127.6,
123.8, 105.8, 105.3, 94.0, 81.1, 43.2, 40.2, 24.2, 13.7.
2-(2,4-Diphenylbut-3-yn-2-yl)-5-methylfuran (3l) and 2-(1,3-
Diphenylbuta-1,2-dienyl)-5-methylfuran (4l)
FTIR (neat): 3059, 2985, 1771, 1447, 1267, 1026, 698, 588 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.55–7.47 (m, 4 H), 7.35–7.27 (m,
5 H), 7.25–7.21 (m, 1 H), 6.21–6.19 (d, J = 3.0 Hz, 0.3 H), 6.18–
6.16 (d, J = 3.0 Hz, 0.7 H), 6.02–6.00 (d, J = 3.0 Hz, 0.3 H), 5.91–
5.89 (d, J = 3.0 Hz, 0.7 H), 2.29 (s, 0.9 H), 2.28 (s, 0.9 H), 2.24 (s,
2.1 H), 1.97 (s, 2.1 H).
13C NMR (100 MHz, CDCl3): d = 207.0, 155.4, 152.2, 151.8, 147.5,
144.4, 136.5, 135.6, 131.7, 128.41, 128.37, 128.25, 128.21, 128.15,
127.9, 127.5, 127.1, 126.8, 126.3, 126.0, 123.4, 109.8, 107.3, 106.7,
105.9, 104.8, 103.9, 92.5, 83.5, 41.5, 29.4, 17.1, 13.8, 13.7.
2-[2-(Diphenylvinylidene)heptyl]-5-methylfuran (4g)
FTIR (neat): 3058, 2927, 1710, 1598, 1446, 910, 763, 735, 699
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.43–7.39 (m, 4 H), 7.34–7.29 (m,
4 H), 7.27–7.21 (m, 2 H), 6.19–6.17 (d, J = 3.0 Hz, 1 H), 5.98–5.96
(d, J = 3.0 Hz, 1 H), 2.49–2.44 (t, J = 7.5 Hz, 2 H), 2.26 (s, 3 H),
1.66–1.58 (q, J = 7.5 Hz, 2 H), 1.33–1.24 (m, 2 H), 1.24–1.16 (m, 4
H), 0.82–0.77 (t, J = 7.0 Hz, 3 H).
HRMS: m/z [M – H]+ calcd for C21H17O: 285.1280; found:
285.1266.
Synthesis 2011, No. 19, 3152–3160 © Thieme Stuttgart · New York

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PAPER
2-(1,3-Diphenylpent-1-yn-3-yl)-5-methylfuran (3m) and 2-(1,3-
Diphenylpenta-1,2-dienyl)-5-methylfuran (4m)
FTIR (neat): 3059, 2973, 2877, 1689, 1491, 1220, 1024, 758, 699
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.58–7.48 (m, 4 H), 7.34–7.27 (m,
5 H), 7.24–7.18 (m, 1 H), 6.23–6.21 (d, J = 3.0 Hz, 0.55 H), 6.20–
6.18 (d, J = 3.0 Hz, 0.45 H), 6.01–5.99 (d, J = 3.0 Hz, 0.45 H),
5.90–5.88 (d, J = 3.0 Hz, 0.55 H), 2.65–2.59 (q, J = 7.3 Hz, 0.9 H),
2.45–2.35 (m, 0.55 H), 2.28 (s, 1.35 H), 2.23 (s, 1.65 H), 2.22–2.13
(m, 0.55 H), 1.26–1.21 (t, J = 7.3 Hz, 1.35 H), 1.03–0.97 (t, J = 7.3
Hz, 1.65 H).
13C NMR (100 MHz, CDCl3): d = 206.4, 154.8, 152.1, 151.6, 147.7,
142.9, 136.3, 135.7, 131.7, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9,
127.5, 127.0, 126.9, 126.7, 126.2, 123.5, 111.8, 109.5, 107.32,
107.30, 105.9, 90.9, 85.2, 47.2, 34.1, 23.7, 13.8, 13.7, 12.5, 9.8.
HRMS: m/z [M – H]+ calcd for C22H19O: 299.1436; found:
299.1429.
Disubstituted 9b¢
FTIR (neat): 2957, 2896, 1888, 1596, 1491, 1250, 1074, 768, 692,
626 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.37–7.21 (m, 20 H), 6.88–6.85
(m, 2 H), 0.31 (s, 18 H).
13C NMR (100 MHz, CDCl3): d = 209.8, 139.3, 136.6, 128.5, 128.3,
127.0, 125.3, 107.6, 98.4, –0.2.
3-[1,1-Diphenyl-3-(trimethylsilyl)prop-2-ynyl]-1H-indole (8c)
FTIR (neat): 3401, 3083, 3058, 2959, 2168, 1597, 1352, 1250,
1064, 859, 622 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.86 (s, br, 1 H), 7.51–7.47 (d,
J = 8.0 Hz, 1 H), 7.41–7.37 (m, 4 H), 7.27–7.11 (m, 9 H), 6.50 (s, 1
H), 0.14 (s, 9 H).
13C NMR (100 MHz, CDCl3): d = 144.7, 137.0, 128.7, 128.0, 126.8,
126.2, 124.6, 122.2, 122.1, 121.2, 119.3, 111.2, 110.7, 88.9, 50.5,
0.1.
2-Methyl-5-(4-methyl-1,3-diphenylpent-1-yn-3-yl)-5-methyl-
furan (3n) and 2-Methyl-5-(4-methyl-1,3-diphenylpenta-1,2-di-
enyl)furan (4n)
1-(2,4-Dimethoxyphenyl)-3,3-diphenyl-1-(trimethylsilyl)allene
(9d)
FTIR (neat): 3002, 2966, 2837, 1600, 1503, 1282, 1032, 762, 558
FTIR (neat): 3058, 2965, 2873, 1953, 1449, 1378, 784 cm–1.
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.78–7.74 (d, J = 8.5 Hz, 1 H),
7.58–7.55 (m, 1 H), 7.53–7.47 (m, 2 H), 7.33–7.25 (m, 5 H), 7.22–
7.17 (t, J = 7.3 Hz, 1 H), 6.33–6.31 (d, J = 3.0 Hz, 0.5 H), 6.20–6.18
(d, J = 3.3 Hz, 0.5 H), 6.00 –5.98 (d, J = 3.3 Hz, 0.5 H), 5.85–5.83
(d, J = 3.0 Hz, 0.5 H), 3.06–2.95 (h, J = 6.8 Hz, 0.5 H), 2.86–2.75
(h, J = 6.8 Hz, 0.5 H), 2.28 (s, 1.5 H), 2.26 (s, 1.5 H), 1.27–1.24 (d,
J = 6.8 Hz, 1.5 H), 1.23–1.20 (d, J = 6.8 Hz, 1.5 H), 1.08–1.05 (d,
J = 6.8 Hz, 1.5 H), 0.87–0.84 (d, J = 6.8 Hz, 1.5 H).
13C NMR (100 MHz, CDCl3): d = 205.8, 154.9, 152.1, 151.4, 147.9,
142.7, 136.3, 135.8, 131.8, 128.6, 128.5, 128.4, 128.2, 128.1, 127.5,
127.2, 127.1, 126.9, 126.7, 123.7, 117.4, 109.5, 107.8, 107.4, 106.2,
106.0, 88.9, 87.1, 52.6, 36.9, 29.5, 22.47, 22.46, 19.6, 18.4, 13.9.
1H NMR (400 MHz, CDCl3): d = 7.42–7.38 (m, 4 H), 7.33–7.28 (m,
4 H), 7.22–7.15 (m, 3 H), 6.45–6.42 (m, 2 H), 3.75 (s, 3 H), 3.72 (s,
3 H), 0.19 (s, 9 H).
13C NMR (100 MHz, CDCl3): d = 208.8, 159.9, 157.3, 137.4, 130.3,
128.4, 128.2, 126.5, 118.7, 104.7, 100.4, 98.8, 55.4, 54.9, –0.1.
1,1-Diphenyl-3-(2,4,6-trimethoxyphenyl)-3-(trimethylsilyl)al-
lene (9e)
FTIR (neat): 2996, 2962, 2836, 1597, 1494, 1451, 1257, 1151,
1057, 800, 632 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.59–7.56 (d, J = 7.3 Hz, 4 H),
7.43–7.38 (t, J = 7.3 Hz, 4 H), 7.32–7.27 (t, J = 7.3 Hz, 2 H), 6.22
(s, 2 H), 3.86 (s, 3 H), 3.77 (s, 6 H), 0.25 (s, 9 H).
13C NMR (100 MHz, CDCl3): d = 208.1, 159.8, 157.8, 137.4, 128.4,
128.1, 126.2, 107.0, 103.3, 94.9, 90.9, 55.5, 55.4, –0.3.
HRMS: m/z [M + H]+ calcd for C27H31O3Si: 431.2042; found:
431.2033.
HRMS: m/z [M + H]+ calcd for C23H23O: 315.1749; found:
315.1751.
2-[3,3-Diphenyl-1-(trimethylsilyl)propa-1,2-dienyl]-1H-pyr-
role (9a) 3-[3,3-Diphenyl-1-(trimethylsilyl)propa-1,2-dienyl]-
1H-pyrrole (9a¢)
FTIR (neat): 3058, 2957, 2169, 1598, 1491, 1445, 1248, 842, 754,
698 cm–1.
1-(2-Methoxy-1-naphthyl)-3,3-diphenyl-1-(trimethylsilyl)al-
1H NMR (400 MHz, CDCl3): d = 8.35 (s, br, 0.7 H), 8.29 (s, br, 0.3
H), 7.48–7.44 (m, 3 H), 7.43–7.38 (m, 3 H), 7.38–7.36 (m, 2 H),
7.35–7.31 (m, 2 H), 6.84–6.82 (m, 0.3 H), 6.82–6.79 (m, 0.7 H),
6.33–6.30 (m, 1.4 H), 6.22–6.19 (m, 0.3 H), 5.78–5.75 (m, 0.3 H),
0.42 (s, 6.3 H), 0.33 (s, 2.7 H).
13C NMR (100 MHz, CDCl3): d = 207.1, 197.4, 144.4, 136.7, 133.7,
128.5, 128.2, 128.04, 128.01, 127.0, 124.9, 118.4, 117.5, 109.6,
109.4, 108.9, 108.7, 108.4, 108.2, 96.1, 89.5, 0.0, –0.3.
lene (8f)
FTIR (neat): 3063, 2958, 2835, 1591, 1492, 1453, 1266, 1086, 841,
628, 695 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.86–7.83 (d, J = 8.0 Hz, 1 H),
7.72–7.67 (t, J = 8.0 Hz, 2 H), 7.45–7.41 (m, 4 H), 7.33–7.27 (m, 5
H), 7.27–7.24 (d, J = 7.5 Hz, 1 H), 7.23–7.18 (m, 3 H), 3.85 (s, 3 H),
0.15 (s, 9 H).
13C NMR (100 MHz, CDCl3): d = 206.8, 153.0, 137.1, 132.8, 129.4,
128.6, 128.4, 128.0, 127.9, 126.6, 126.0, 125.9, 123.5, 120.3, 113.3,
104.0, 98.3, 56.2, –0.4.
2-[3,3-Diphenyl-1-(trimethylsilyl)propa-1,2-dienyl]thiophene
(9b) and 2,5-Bis[3,3-diphenyl-1-(trimethylsilyl)propa-1,2-di-
enyl]thiophene (9b¢)
1-(1-Hydroxy-2-naphthyl)-3,3-diphenyl-1-(trimethylsilyl)al-
lene (8g)
Monosubstituted 9b
FTIR (neat): 3058, 2957, 1897, 1598, 1492, 1250, 868, 767, 630
FTIR (neat): 3403, 2956, 2897, 1921, 1738, 1492, 1450, 1149, 910,
cm–1.
638 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.39–7.30 (m, 7 H), 7.27–7.22 (m,
1H NMR (400 MHz, CDCl3): d = 8.33–8.30 (d, J = 8.3 Hz, 1 H),
8.11–8.07 (d, J = 8.5 Hz, 1 H), 7.57–7.51 (m, 5 H), 7.50–7.45 (m, 5
H), 7.40–7.36 (t, J = 7.3 Hz, 2 H), 7.30–7.27 (d, J = 7.5 Hz, 1 H),
6.87–6.84 (d, J = 7.8 Hz, 1 H), 5.61 (s, br, 1 H), 0.34 (s, 9 H).
2 H), 7.16–7.14 (m, 1 H), 6.99–6.95 (m, 2 H), 0.32 (s, 9 H).
13C NMR (100 MHz, CDCl3): d = 209.5, 140.3, 136.6, 128.5, 128.2,
127.4, 127.0, 124.6, 124.4, 107.4, 98.2, –0.3.
Synthesis 2011, No. 19, 3152–3160 © Thieme Stuttgart · New York

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Catalytic Propargylation/Allenylation of Aryl and Heteroaryl Nucleophiles
3159
13C NMR (100 MHz, CDCl3): d = 207.5, 150.3, 137.3, 132.8,
128.54, 128.45, 127.8, 126.8, 126.7, 126.2, 125.3, 125.1, 125.0,
121.9, 108.5, 104.3, 101.6, –0.6.
1¢-Phenylspiro[cyclohexane-1,3¢-naphtho[2,1-b]pyran] (11f)
FTIR (neat): 2853, 2726, 2671, 1625, 1460, 1377, 1234, 816, 722
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.72–7.68 (m, 1.2 H), 7.42–7.39
(m, 0.8 H), 7.29–7.17 (m, 6.4 H), 7.11–7.08 (d, J = 8.5 Hz, 0.6 H),
7.03–6.98 (t, J = 8.0 Hz, 0.6 H), 6.21–6.18 (m, 0.4 H), 5.72 (s, 0.6
H), 2.25–2.19 (m, 0.8 H), 2.15–2.09 (m, 0.8 H), 1.97–1.91 (m, 1.2
H), 1.77–1.48 (m, 6.4 H).
13C NMR (100 MHz, CDCl3): d = 152.8, 141.8, 135.7, 135.2, 131.5,
130.3, 130.2, 130.05, 130.00, 128.45, 128.42, 128.3, 127.9, 127.8,
127.3, 126.4, 125.0, 123.8, 122.9, 120.8, 118.8, 116.8, 91.4, 86.9,
76.4, 34.6, 29.3, 25.8, 25.6, 22.4, 21.9, 21.6.
3,3-Diphenyl-1-(trimethylsilyl)-3H-naphtho[2,1-b]pyran (11a)
FTIR (neat): 3054, 2958, 1949, 1898, 1819, 1600, 1246, 839 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.00–7.97 (d, J = 8.5 Hz, 1 H),
7.64–7.61 (d, J = 7.8 Hz, 1 H), 7.58–7.54 (d, J = 8.5 Hz, 1 H), 7.47–
7.43 (d, J = 7.3 Hz, 4 H), 7.37–7.32 (dd, J = 8.5, 7.0 Hz, 1 H), 7.25–
7.20 (m, 6 H), 7.17–7.12 (t, J = 7.3 Hz, 2 H), 6.55 (s, 1 H), 0.29 (s,
9 H).
13C NMR (100 MHz, CDCl3): d = 150.3, 144.3, 140.3, 135.3, 131.0,
129.7, 129.4, 128.3, 127.9, 127.3, 127.1, 125.5, 125.0, 123.3, 120.9,
119.0, 81.2, 1.4.
1¢-Phenylspiro[cycloheptane-1,3¢-naphtho[2,1-b]pyran] (11g)
FTIR (neat): 3055, 2923, 2852, 1624, 1458, 1240, 1073, 993, 813,
699, 577 cm–1.
HRMS: m/z [M]+ calcd for C28H26OSi: 406.1753; found: 406.1699.
1,3,3-Triphenyl-3H-naphtho[2,1-b]pyran (11b)
FTIR (neat): 3056, 1957, 1622, 1446, 1237, 1071, 959, 697, 526
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.66–7.63 (d, J = 8.8 Hz, 1 H),
7.61–7.58 (d, J = 8.0 Hz, 1 H), 7.56–7.52 (m, 4 H), 7.34–7.27 (m, 6
H), 7.25–7.20 (m, 4 H), 7.17–7.12 (t, J = 7.3 Hz, 2 H), 7.11–7.07
(m, 2 H), 6.97–6.92 (m, 1 H), 6.19 (s, 1 H).
13C NMR (100 MHz, CDCl3): d = 152.7, 144.6, 141.4, 137.3, 131.0,
130.4, 129.9, 129.6, 128.6, 128.5, 128.2, 128.1, 127.8, 127.7, 126.6,
125.2, 123.3, 118.9, 116.7, 82.3.
1H NMR (400 MHz, CDCl3): d = 7.70–7.66 (d, J = 8.5 Hz, 2 H),
7.29–7.24 (m, 3 H), 7.22–7.15 (m, 4 H), 7.10–7.07 (d, J = 8.5 Hz, 1
H), 7.02–6.97 (m, 1 H), 5.71 (s, 1 H), 2.17–2.10 (m, 2 H), 1.90–1.83
(m, 2 H), 1.77–1.64 (m, 4 H), 1.63–1.56 (m, 2 H), 1.52–1.44 (m, 2
H).
13C NMR (100 MHz, CDCl3): d = 152.9, 141.9, 134.8, 131.5, 130.3,
130.2, 129.9, 128.5, 128.4, 127.9, 127.3, 126.4, 125.0, 122.9, 119.0,
116.5, 80.2, 37.8, 29.2, 21.9.
1¢-Phenylspiro[fluorene-9,3¢-naphtho[2,1-b]pyran] (11h)
FTIR (neat): 3052, 1623, 1491, 1369, 1237, 1003, 821, 738, 527
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.84–7.80 (d, J = 8.0 Hz, 1 H),
7.79–7.76 (d, J = 8.8 Hz, 1 H), 7.71–7.68 (d, J = 7.5 Hz, 2 H), 7.50–
7.47 (d, J = 7.5 Hz, 2 H), 7.43–7.39 (t, J = 7.5 Hz, 2 H), 7.38–7.35
(m, 3 H), 7.33–7.31 (m, 3 H), 7.24–7.21 (d, J = 8.8 Hz, 1 H), 7.20–
7.14 (m, 4 H), 5.96 (s, 1 H).
3-Methyl-1,3-diphenyl-3H-naphtho[2,1-b]pyran (11c)
FTIR (neat): 3056, 2931, 1624, 1490, 1344, 1235, 1101, 1073, 825,
698, 523 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.68–7.65 (d, J = 8.8 Hz, 1 H),
7.64–7.61 (d, J = 8.0 Hz, 1 H), 7.59–7.55 (m, 2 H), 7.32–7.27 (m, 5
H), 7.24–7.19 (m, 3 H), 7.14–7.09 (t, J = 8.5 Hz, 2 H), 7.05–7.01 (d,
J = 8.5 Hz, 1 H), 6.97–6.92 (m, 1 H), 6.07 (s, 1 H), 1.83 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 153.1, 141.6, 135.5, 130.6, 130.4,
130.2, 129.9, 128.4, 127.9, 127.3, 126.4, 125.0, 123.0, 118.9, 116.1,
75.4, 26.4.
13C NMR (100 MHz, CDCl3): d = 154.5, 146.3, 141.2, 139.5, 138.1,
130.6, 130.5, 129.9, 129.7, 128.6, 128.4, 128.3, 127.8, 127.6, 126.4,
126.1, 125.2, 125.1, 123.3, 120.0, 118.9, 116.4, 84.4.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.
3,3-Dimethyl-1-phenyl-3H-naphtho[2,1-b]pyran (11d)
FTIR (neat): 3056, 2925, 2856, 1627, 1456, 1264, 1147, 990, 818,
578 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.72–7.69 (d, J = 8.5 Hz, 2 H),
7.30–7.27 (m, 3 H), 7.21–7.16 (m, 4 H), 7.11–7.08 (d, J = 8.3 Hz, 1
H), 7.04–6.99 (m, 1 H), 5.70 (s, 1 H), 1.50 (s, 6 H).
13C NMR (100 MHz, CDCl3): d = 153.1, 141.6, 135.5, 130.6, 130.4,
130.2, 129.9, 128.4, 127.9, 127.3, 126.4, 125.0, 123.0, 118.9, 116.1,
75.4, 26.4.
Acknowledgment
We thank the University of Winnipeg for financial support of this
work in the form of Start-up Funding and a Major Research Grant.
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