Synthesis of Primitive Dendrimer Systems Bearing Bicyclo[3,2,0]Hept-6-en-6-yl Groups via Unique Au-catalyzed [2+2] Cyclization

Article abstract of DOI:10.1002/bkcs.11445

Propargylic pivaloates bearing an alkynyl group at a three-carbon tether under the gold catalysis would undergo [3,3] rearrangements of propargylic pivaloates followed by tandem [2+2] cyclization to give the corresponding 6-acylbicyclo[3,2,0]hept-6-ens. In continuing work, we prepared various substrates bearing two arms of alkyne-propargylic pivaloates to explore primitive dendrimer concept bicyclic compounds. Finally, we could obtain a series of diasteromeric compounds bearing two arms of 6-acylbicyclo[3,2,0]hept-6-ene groups in high yields.

Full text of DOI:10.1002/bkcs.11445

Article
DOI: 10.1002/bkcs.11445
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K. H. Lee et al.
KOREAN CHEMICAL SOCIETY
Synthesis of Primitive Dendrimer Systems Bearing Bicyclo[3,2,0]
Hept-6-en-6-yl Groups via Unique Au-catalyzed [2+2] Cyclization
*
Kyu Hwan Lee, Raveendra Jillella, Jaewoong Kim, and Chang Ho Oh
Department of Chemistry and Research Institute of Natural Science, Hanyang University, Seoul 04763,
South Korea. *E-mail: changho@hanyang.ac.kr
Received December 1, 2017, Accepted March 9, 2018
Propargylic pivaloates bearing an alkynyl group at a three-carbon tether under the gold catalysis would
undergo [3,3] rearrangements of propargylic pivaloates followed by tandem [2+2] cyclization to give the
corresponding 6-acylbicyclo[3,2,0]hept-6-ens. In continuing work, we prepared various substrates bearing
two arms of alkyne-propargylic pivaloates to explore primitive dendrimer concept bicyclic compounds.
Finally, we could obtain a series of diasteromeric compounds bearing two arms of 6-acylbicyclo[3,2,0]
hept-6-ene groups in high yields.
Keywords: Gold catalyst, [2+2] cyclization, Propargylic carboxylate, Bicyclo[3,2,0]heptane
Introduction
under metal-catalyzed conditions. And A4–A5 shows non-
shift-cyclization under non-metal and base catalyzed condi-
tion. It has been assumed that acyl migration was occurred
only under [Au and Pt] catalyzed conditions. Toste et al.
reported silver-catalyzed 1,3-acyl migration of a nonterminal
propargylic esters (Type A) to the highly functionalized aro-
matic compounds (Type A1).5 In the same year, we reported
gold-catalyzed allene formation via 1,3-acyl migration of a
nonterminal propargylic esters (Type A), followed by
Myers–Saito-type (C2–C7) enyne–allene cyclization to form
the highly functionalized aromatic compounds (Type A1)
via 6-endo-dig.6 Next, Liu group has reported about a gold-
catalyzed allene formation via 1,3-acyl migration of a pro-
pargyl carbonates (Type A1).7 Here the resulting oxocarbe-
nium ion formed in the gold-catalyzed 6-endo-dig
cyclization step could be further attacked by the aryl moiety,
giving rise to a second cyclization reaction leading to the tet-
racycles (Type A2). In 2014, Chen et al. reported benzoful-
venes via 1,3-acyl migration strategy (Type A3) through a
Schmittel-type (C2–C6) enyne–allene cyclization by
platinum-catalyzed reaction.8 It has been postulated that
Au(I)-catalyzed [3,3]-rearrangement of propargylic esters are
reversible processes that take place via Au(I)-coordinated
cationic intermediates and subsequent formation of the
allenes, which can then undergo further transformations.9
Recently, Liu groups reported base catalyzed Schmittel
enyne–allene cyclization (Type A4).10 As expected, under
non-metal condition, non-shift cyclization was occurred. In
the same year, Zhou et al. reported that p-tosyl alkenyl
substituted (R3) propargylic carboxylates were transformed
to 1,2-dihydrocyclobuta-[b]naphthyl structures under base
catalysts via non-shift [2+2] cycloaddition (Type A5).11
Propargylic carboxylates with an alkynyl group linked
with an alkyl tether have been valuable substrates for vari-
ous gold-catalyzed transformations as summarized in
Gold-catalyzed rearrangement reactions of propargylic esters
offer a highly significant synthetic strategy for their synthetic
utility in a wide variety of fascinating transformations and to
construct complex polycyclic compounds.1 This is mainly
due to the excellent alkynophilicity of gold cations (I or III)
towards propargylic carboxylates. A propargylic carboxylate
upon treatment with the gold cation has been known to
undergo 1,2- and/or 1,3-shift of the carboxylate selectively
depending mainly on the types of substrates.2 Propargylic
carboxylates with a terminal alkyne form the gold-carbene
complexes by 1,2-carboxylate shift,3 those with an internal
alkyne form the allenoates by 1,3-carboxylate shift.4
Scheme 1 shows a schematic summary for cyclization of
propargylic carboxylates (substrate A). A1–A3 shows the
result of the cyclizative products with 1,3-carboxylate shift
Scheme 1. Three types of cyclization of propargylic carboxylate.
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Scheme 2. In continuing our study, we further extended our
methodology to alkynes-propargylic acetates, B and C, for
facile synthesis of benzene derivatives B2 and 2,3-
bisalkylidenecyclohexanones C2. We observed that similar
pathways of A to A1 (1,3-sigmatropic acyl shift, 6-endo-
dig cyclization, and acyl elimination) to afford the corre-
sponding dienes B2 and C2.12 During our study, the stan-
dard conditions towards alkynes-propargylic acetates like
D did not afford the expected diene products, but exhibited
a different mode of reactions to give the [n,2,0]bicyclic
products like D2. This unprecedent Au-catalyzed [2+2]
cyclization of alkyne-propargylic pivaloates to transform
into [3,2,0]bicyclic compounds was quite general with a
wide scope of substrates.13 We have shortly extended this
reaction towards several substrates which have two sets of
alkyne-propargylic pivaloate groups in a molecule linked
by a aryl group to explore a very primitive dendrimer con-
cept.14 If more substituted alkyl chain was linked (longer
and more alkynyl groups), more bicyclic units were
appeared in the occurred macro molecule. In this context,
Fensterbank et al. reported a Schmittel-type 5-exo-dig
enyne–allene cyclization of hepta-1,6-diyn-3-yl esters like
D. Of particular interest, hydrative cyclizations of (Z)-
hepta-4-ene-1,6-diyn-3-yl esters led to aromatic ketones
after 1,3-sigmatropic acyloxy shift, 6-endo-dig cyclization,
and acyl elimination where the acylium ion could be
trapped by the nucleophilic Au C bond of D3, a new kind
of cycloisomerization product D4 would ensue.15 This
could be an efficient method for the preparation of
δ-diketones like D4 based on an Au-triggered 1,5-acyl
shift.4o
Results and Discussion
In this paper, we wish to explore our recent accomplish-
ment in which various substrates bearing two sets of a pro-
pargylic carboxylate and an internal triple bond could
undergo sequential gold-catalyzed cyclizations of 1,3-
sigmatropic acyloxy shift, [2+2] cycloaddition, and acyl
elimination to afford the corresponding dendrimer type
compounds having two arms of a bicyclo[3,2,0]heptane
unit. These are very useful dendrimer application in macro-
molecule system. Initially we have prepared substrates for
our study as the following well-known sequences: Sonoga-
shira cross-coupling, oxidation, alkynylation, and esterifica-
tion to the pivaloates 1a–e (Scheme 3).16
Scheme 3. General procedure for preparing substrates.
Next, we have carried out gold-catalyzed reaction of 1a to
explore the optimal conditions affording to the product 3aa
and 3ab (Scheme 4). In our previous study, we have estab-
lished gold-catalyzed cyclization of one propargylic pivalo-
ate in to a [3,2,0]bicyclic compounds. Here to improve the
importance of method to application part, we started our
study towards bis-propargylic pivaloates and internal alkynes
to obtain bis[3,2,0] bicyclic compounds with our standard
condition (10 mol % of chloro(triphenylphosphine)gold
(I) and 10 mol% of silver hexaflouroantimonate(V) in 1,2-
dichloroethane). In fact, these two propargylic compounds
have two chiral centers, so they produce at least two diaste-
reomeric bicyclic compounds. As a result, since substrate 1a
is also a diastereomeric mixture, the corresponding products
should be a diastereomeric mixture. Diastereomeric mixture
of 3aa and 3ab obtained by the reaction of 1a with Au-
catalyst in 8 h with 70% as shown in Scheme 4. Thus, we
have separated its diastereomers by using preparative HPLC
to give 3aa and 3ab in a ratio of 40 and 30% yields, respec-
tively. The proton NMR of the compound 3aa appears two
different magnetically nonequivalents of chiral protons due
to the center of symmetry and C2-axis of symmetry whereas
3ab appears 4 non equivalents of chiral proton signals due to
the lack of symmetry. The substrate 1b, possessing some-
what labile a Br substituent, successfully proceeded this
reaction in 3 h to give 3ba and 3bb in 39 and 28% yields,
respectively.
Scheme 2. Mechanistic four-pathways of substrates via Au-
catalyzed cyclization.
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Synthesis of Bicyclo[3,2,0]hept-6-en-6-groups via
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22% yields, respectively. The substrates 1e underwent the
present transformation into 3ea and 3eb in 45 and 20%
yields, respectively.
Next, we have prepared two more substrates (Scheme 6).
The substrates 2a and 2b are 1,4-disubstituted benzenes
conjugated with two propargyl pivaloates in 3- and 30-posi-
tion, each of which has a remote triple bond in 7- and 70-
position. These substrates were important to confirm the
mechanistic process including 1,3-migration of cyclization.
Overall, these substrates under our conditions proceeded
smoothly into the corresponding products for 5–6 h at
Scheme 4. Gold reaction of substrates 1a and 1b.
We became to know that the 1c was also composed of
one enantiomeric pair (1ca) and one meso isomer. These
two 1cb compounds were exactly same because of having
a center of symmetry, C2 symmetry group (Figure 1). And
all other substrates have a symmetry plane. Consequently
we could obtain totally three compounds via cyclization,
two enantiomeric compounds and one diastereromeric com-
pound. Scheme 5 shows substrates 1c–e and the corre-
sponding products obtained from the present Au-catalyzed
reactions. The substrates 1a–e are aromatic compounds
conjugated with two alkynyl groups, each of which has a
remote propargyl carboxylate group in 6 and 60-positions.
ꢀ
60 C. Thus 2a gave 4aa and 4ab in 45 and 25% yields;
2b gave 4ba and 4bb in 22 and 37% yields, respectively.
Again, the bromide group was intact during this reaction.
Scheme 6. Gold reaction of substrates 2a and 2b.
The proposed mechanism for the conversion of 2a into
4aa and 4ab is as follows (Scheme 6). The first step would
be Au-catalyzed activation of propargyl group to Aa; then
proceed 1,3-pivaloyl shift into Ba, in which Au(+) would
activate the other triple bond in order to help [2+2] cyclo-
addition to Ca. The two reactive sites of 2a might proceed
sequentially not simultaneously. Finally, the presence of
water upon exposure to workup caused to hydrolyze the Ca
into the products 4aa and 4ab in a different ratio depending
on their stabilities. During hydrolysis of Ca, diastereomeric
ratio would be gained into 4aa and 4ab (Scheme 7).
Scheme 5. Substrates scope of gold reaction.
The substrate 1c, under standard conditions, took 2 h at
room temperature to form two diastereomeric products 3ca
and 3cb in 17 and 18% yields, respectively. The substrates
1d, 2, 7-disubstituted naphtꢀhalene, underwent the present
transformation for 3 h at 60 C into 3da and 3db in 37 and
Scheme 7. Specific mechanism of Au-catalyzed [2+2]
cycloaddition.
Conclusion
In conclusion, we have synthesized a series of dendrimer
type compounds bearing two arms of 7-acylbicyclo[3,2,0]-
hept-6-en-6-yl via rare Au-catalyzed [2+2] cycloaddition.
The tandem gold-catalyzed sequences are composed of 1,3-
Figure 1. Structural analysis of diastereomeric substrate 1c.
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Synthesis of Bicyclo[3,2,0]hept-6-en-6-groups via
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acyl migration, [2+2] cyclization, and hydrolysis of the
resulting enloates.
1.90–1.30 (m, 11H). 13C NMR (100 MHz, CDCl3) δ
209.6, 189.6, 170.3, 154.0, 139.4, 137.4, 136.6, 136.3,
133.5, 131.7, 131.6, 131.0, 130.9, 130.4, 128.7, 127.6,
122.2, 50.5, 46.6, 46.1, 44.7, 30.0, 29.9, 29.6, 26.5, 26.2,
24.2, 23.3; HRMS (ESI) [M + Na]+ calculated for
C34H28Br2O2Na+: 649.0338, found 649.0335.
Experimental
Typical Procedure of Gold-catalyzed Reaction (1a-2b to
3aa-4bb). To a new sealed tube equipped with a stirring bar
a solution of bis-alkyne-propargylic pivaloate (1a–2b,
0.10 mmol) in dried 1,2-dichloroethane (1.0 mL) were added
chlorotriphenylphosphine(I) (AuCl(PPh3)) (0.01 mmol) and
silver hexaflouroantimonate(V) (AgSbF6) (0.01 mmol). The
3ca. IR (NaCl, cm−1): 2943, 2855, 1633, 1597, 1577,
1504, 1446, 1333, 1288, 1233; 1H NMR (400 MHz,
CDCl3): δ 7.89–7.86 (m, 2H), 7.56 (d, J = 8 Hz, 4H),
7.22–7.13 (m, 6H), 6.95 (dd, J = 7.6 6.4 Hz, 4H),
3.82–3.78 (m, 2H), 3.67–3.64 (m, 2H), 2.28–2.24 (m, 2H),
1.80–1.73 (m, 4H), 1.58–1.48 (m, 4H), 1.42–1.32 (m, 2H).
13C NMR (100 MHz, CDCl3): δ 191.3, 154.6, 154.4,
139.3, 137.4, 137.4, 132.2, 132.0, 132.0, 130.8, 130.7,
128.6, 127.7, 127.1, 127.0, 126.2, 126.1, 125.3, 48.9, 48.8,
45.8, 45.7, 26.8, 25.5, 25.4, 23.4. HRMS (ESI) [M + Na]+
calculated for C38H32O2Na+: 543.2295, found 543.2296.
3cb. IR (NaCl, cm−1): 3865, 3744, 1700, 1652, 1558,
1539, 1506, 1456; 1H NMR (400 MHz, CDCl3): δ
7.94–7.92 (d, J = 8.8 Hz, 1H), 7.52–7.48 (m, 4H),
7.29–7.28 (m, 2H), 7.13–7.09 (m, 7H), 6.91–6.86 (m, 2H),
3.84–3.82 (m, 1H), 3.75–3.68 (m, 2H), 3.15–3.12 (m, 1H),
2.30–2.17 (m, 2H), 1.95–1.80 (m, 3H), 1.66–1.65 (m, 2H),
1.52–1.38 (m, 5H). 13C NMR (100 MHz, CDCl3): δ 210.5,
191.7, 191.6, 142.9, 139.9, 137.9, 137.8, 132.2, 128.9,
128.2, 127.8, 127.2, 126.3, 125.9, 125.5, 50.9, 49.0, 45.9,
31.0, 29.1, 27.1, 25.9, 24.2, 23.9. HRMS (ESI) [M + Na]+
calculated for C38H32O2Na+: 543.2295, found 543.2296.
3da. IR (NaCl, cm−1): 2950, 2866, 2248, 1694, 1632,
ꢀ
resulting mixture was stirred at 60 C for 2–8 h. Without
extraction, the solvent was removed under reduced pressure
and the crude residue was purified by column chromatogra-
phy (ethyl acetate: hexane = 1:10) to afford the diastereo-
meric mixtures as a clear oil. These mixtures were separated
by HPLC (ethyl acetate: hexane = 1:10) as a clear oil
(3aa–4bb).
3aa. IR (NaCl, cm−1) 2946, 2855, 2249, 1745, 1631,
1
1601, 1287, 1232, 1119; H NMR (400 MHz, CDCl3): δ
7.97 (d, J = 8.4 Hz, 4H), 7.63–7.60 (m, 8H), 7.55 (s, 4H),
7.47–7.43 (m, 4H), 7.40 (d, J = 7.6 Hz, 2H), 3.68–3.45 (m,
2H), 3.57–3.55 (m, 2H), 1.83–1.79 (m, 4H), 1.73–1.67 (m,
5H), 1.43–1.35 (m, 3H). 13C NMR (100 MHz, CDCl3): δ
190.9, 153.0, 145.4, 140.2, 137.7, 136.8, 133.6, 129.8,
129.1, 128.8, 128.3, 127.4, 127.37, 46.3, 44.7, 31.8, 26.7,
+
26.5, 23.5, 22.8, 14.3; HRMS (ESI) [M + Na] calculated
for C46H38O2Na+: 645.2764, found 645.2764.
3ab. IR (NaCl, cm−1): 2952, 2851, 2247, 1757, 1612,
1
1
1313, 1287, 1187. H NMR (400 MHz, CDCl3): δ 7.99 (d,
1596, 1445, 1230; H NMR (400 MHz, CDCl3): δ 8.09 (s,
J = 8.4 Hz, 2H), 7.65–7.58(m, 7H), 7.54(d, J = 8.4 Hz,
2H), 7.48–7.39(m, 5H), 7.37–7.30(m, 4H), 7.27–7.25(m,
2H), 3.83(t, J = 6.8 Hz, 1H), 3.70(dd, J = 3.2 Hz,
J = 4 Hz, 1H), 3.58(dd, J = 3.6 Hz, J = 3.8 Hz, 1H),
3.09–3.05(m, 1H), 2.13–2.08(m, 1H), 1.93–1.63(m, 8H),
1.44–1.33(m, 3H). 13C NMR (100 MHz, CDCl3): δ 210.1,
190.4, 169.9, 153.0, 145.2, 140.7, 140.5, 140.1, 139.9,
138.1, 137.9, 136.7, 136.1, 134.2, 134.0, 133.6, 131.9,
131.0, 50.6, 46.5, 46.3, 44.5, 30.0, 26.6, 26.5, 26.3, 24.2,
23.3. HRMS (ESI) [M + Na]+ calculated for C46H38O2Na+:
645.2764, found 645.2764.
1H), 7.92 (d, J = 8 Hz, 2H), 7.86 (s, 1H), 7.64 (dd,
J = 2.4, 1.6 Hz, 1H), 7.62 (s, 1H), 7.60–7.56 (m, 1H),
7.53–7.49 (m, 1H), 7.40 (t, J = 7.2 Hz, 2H), 7.29–7.27 (m,
3H), 7.24–7.20 (m, 3H), 3.97–3.93 (m, 1H), 3.71–3.69 (m,
2H), 3.14–3.10 (m, 1H), 2.16–2.11 (m, 1H), 1.95–1.65 (m,
8H), 1.43–1.35 (m, 3H). 13C NMR (100 MHz, CDCl3): δ
210.2, 191.5, 170.7, 153.6, 140.8, 138.3, 137.4, 133.9,
133.4, 132.8, 132.2, 130.8, 129.7, 129.2, 129.1, 129.0,
128.7, 128.9, 127.7, 127.6, 50.76, 46.9, 46.8, 46.2, 46.0,
44.7, 30.2, 26.7, 26.4, 24.3, 23.4. HRMS (ESI) [M + Na]+
calculated for C38H32O2Na+: 543.2295, found 543.2295.
3db. IR (NaCl, cm−1): IR(NaCl cm−1): 2947, 1743,
1635, 1601, 1313, 1287, 1232; 1H NMR (400 MHz,
CDCl3) δ 8.07–8.04(d, J = 8.4 Hz, 2H), 7.93–7.91(d,
J = 7.6 Hz, 4H), 7.63–7.56 (m, 4H), 7.53–7.49 (m, 2H),
7.41–7.37(m, 4H), 3.70–3.68(m, 4H), 1.92–1.89 (m, 2H),
1.85–1.80 (m, 2H), 1.76–1.69 (m, 4H), 1.60–1.55 (m, 2H),
1.44–1.38 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 191.6,
153.9, 153.9, 138.4, 137.0, 137.0, 134.1, 132.7, 132.6,
130.6, 130.6, 129.4, 129.1, 128.6, 127.6, 127.4, 46.0, 44.7,
26.8, 26.4, 23.4; HRMS (ESI) [M + Na]+ calculated for
C38H32O2Na+: 543.2295, found 543.2295.
3ba. IR (NaCl, cm−1): 2932, 2850, 2252, 1736, 1633,
1
1585, 1288, 1228; H NMR (400 MHz, CDCl3): δ 7.76 (d,
J = 8.8 Hz, 4H), 7.65 (d, J = 7.2, Hz, 4H), 7.54 (d,
J = 7.2 Hz, 4H), 3.62–3.60 (m, 2H), 3.57–3.55 (m, 2H),
1.83–1.60 (m, 10H), 1.43–1.35 (m, 2H); 13C NMR
(100 MHz, CDCl3) δ 190.0, 154.0, 137.1, 136.9, 133.6,
132.0, 130.7, 128.8, 127.8, 46.2, 44.8, 29.9, 27.2, 26.7,
26.5, 23.4. HRMS (ESI) [M + Na]+ calculated for
C34H28Br2O2Na+: 649.0338, found 649.0335.
3bb. IR (NaCl, cm−1) 2952, 2867, 2250, 1695, 1633,
1
1584, 1484, 1340, 1229; H NMR (400 MHz, CDCl3) δ
7.75 (d, J = 8.4 Hz, 2H), 7.57 (dd, J = 10.4, 8.4 Hz, 2H),
7.44 (d, J = 8.4 Hz, 2H), 7.24 (d, J = 8.4 Hz, 2H), 7.06 (d,
J = 8.8 Hz, 2H), 3.82–3.79 (m, 1H), 3.65–3.63 (m, 1H),
3.57–3.55 (m, 1H), 3.07–3.04 (m, 1H), 2.94–2.05 (m, 1H),
3ea. IR (NaCl, cm−1): 3059, 2948, 2864, 1694, 1446,
1230, 913; 1H NMR (400 MHz, CDCl3): δ 7.83 (d,
J = 7.6 Hz, 2H), 7.75 (d, J = 7.2 Hz, 2H), 7.50 (d,
J = 8.0 Hz, 3H), 7.37–7.34 (m, 5H), 7.32–7.23 (m, 8H),
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Synthesis of Bicyclo[3,2,0]hept-6-en-6-groups via
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7.18 (d, J = 8.4 Hz, 2H), 7.15–7.13 (m, 2H), 7.05 (dd,
J = 6, 2.8 Hz, 2H), 3.79–3.76 (m, 1H), 3.61 (dd, J = 2.8,
4.0 Hz, 1H), 3.49 (dd, J = 4.0, 3.6 Hz, 1H), 3.04–3.00 (m,
1H), 2.09–2.05 (m, 1H), 1.86–1.57 (m, 7H), 1.49–1.28 (m,
4H). 13C NMR (100 MHz, CDCl3): δ 210.2, 191.0, 169.7,
154.0, 150.2, 147.2, 147.1, 140.1, 138.2, 136.2, 133.1,
132.7, 132.2, 131.2, 129.3, 128.9, 128.8, 128.6, 128.4,
128.3, 128.0, 128.8, 127.7, 127.7, 126.0, 120.2, 65.2, 50.4,
46.1, 45.8, 44.4, 30.0, 29.9, 26.5, 26.2, 24.1, 23.2. HRMS
2H), 3.84–3.80 (m, 1H), 3.64–3.61 (m, 1H), 3.56–3.52 (m,
1H), 3.10–3.07 (m, 1H), 2.11–2.08 (m, 1H), 1.95–1.86 (m,
1H), 1.80–1.60 (m, 6H), 1.53–1.45 (m, 2H), 1.41–1.32 (m,
2H); 13C NMR (100 MHz, CDCl3): δ 190.0, 154.9, 141.0,
136.3, 131.6, 131.1, 130.4, 128.8, 124.5, 45.8, 44.7, 27.2,
27.0, 26.5, 26.4, 26.1, 23.2. HRMS (ESI) [M + Na]+ calcu-
lated for M C34H30O2Na+: 493.2138, found 493.2138.
Acknowledgments. This work was supported by a grant
from the National Research Foundation of Korea (NRF),
funded by the Korean Government, through the Center
for New Directions in Organic Synthesis (NRF-
2014R1A5A1011165).
+
(ESI) [M + Na] calculated for C53H42O2Na+: 733.3077,
found 733.3080.
3eb. IR(NaCl, cm−1); 2943, 2855, 1632, 1598,
1501,1323, 1230, 912; 1H NMR (400 MHz, CDCl3): δ
7.82 (d, J = 6.8 Hz, 4H), 7.74 (d, J = 7.2 Hz, 2H), 7.45 (d,
J = 8.4 Hz, 6H), 7.35 (t, J = 7.4 Hz, 8H), 7.29–7.23 (m,
2H), 7.04 (d, J = 8.4 Hz, 4H), 3.62–3.59 (m, 2H),
3.51–3.48 (m, 2H), 1.83–1.78 (m, 2H), 1.75–1.63 (m, 6H),
1.47–1.41 (m, 2H), 1.36–1.31 (m, 2H). 13C NMR
(100 MHz, CDCl3): δ 191.1, 153.9, 150.3, 147.1, 140.1,
138.2, 136.1, 132.2, 131.1, 128.8, 128.6, 128.3, 127.9,
127.7, 126.1, 120.2, 65.3, 45.7, 44.2, 26.5, 26.3, 23.2.
HRMS (ESI) [M + Na]+ calculated for C53H42O2Na+:
733.3077, found 733.3080.
Supporting Information. Supplementary data (Copies of
1H and 13C NMR spectra for all compounds associated with
this article can be found in the online version).
References
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4aa. IR (NaCl, cm−1) 2943, 2854, 1632, 1562, 1489,
1
1227; H NMR (400 MHz, CDCl3): δ 7.86 (d, J = 0.8 Hz,
4H), 7.60 (t, J = 5.8 Hz, 4H), 7.31–7.26 (m, 6H),
3.62–3.57 (m, 4H), 1.84 (dt, J = 12.4, 5.8 Hz, 2H),
1.78–1.59 (m, 6H), 1.53–1.45 (m, 2H), 1.41–1.32 (m, 2H).
13C NMR (100 MHz, CDCl3): δ 190.6, 155.8, 141.2,
141.1, 135.9, 132.5, 130.1, 129.0, 128.4, 45.7, 44.9, 44.9,
26.6, 26.6, 26.4, 23.4; HRMS (ESI) [M + Na]+ calculated
for M C34H30O2Na+: 493.2138, found 493.2138.
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4ab. IR (NaCl, cm−1): 3059, 2950, 2866, 2248, 1697,
1
1631, 1602, 1346, 1231; H NMR (400 MHz, CDCl3): δ
7.83 (dd, J = 4.8, 3.6 Hz, 2H), 7.57–7.61 (m, 2H),
7.22–7.33 (m, 10H), 3.83–3.87 (m, 1H), 3.54–3.63 (m,
2H), 3.06–3.09 (m, 1H), 2.12–2.07 (m, 1H), 1.94–1.64 (m,
7H), 1.57–1.44 (m, 2H), 1.42–1.31 (m, 2H); 13C NMR
(100 MHz, CDCl3) δ 209.8, 191.3, 172.7, 154.1, 139.6,
137.3, 137.0, 136.6, 135.0, 132.8, 130.0, 129.9, 129.2,
128.9, 128.9, 128.8, 128.4, 50.9, 47.1, 46.0, 45.9, 44.7,
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found 493.2138.
4ba. IR (NaCl, cm−1): 3069, 2945, 2856, 1745, 1633,
1
1582, 1482, 1273; H NMR (400 MHz, CDCl3): δ 7.88 (s,
4H), 7.59–7.55 (m, 4H), 7.43 (d, J = 8.8 Hz, 4H),
3.63–3.60 (m, 2H), 3.58–3.56 (m, 2H), 1.83–1.57 (m,
10H), 1.42–1.32 (m, 2H); 13C NMR (100 MHz, CDCl3): δ
190.1, 154.9, 141.0, 136.3, 131.6, 131.1, 130.4, 128.8,
124.5, 45.8, 44.7, 27.2, 27.0, 26.5, 26.4, 26.2, 23.2; HRMS
+
(ESI) [M + Na]
calculated for M
C34H30O2Na+:
493.2138, found 493.2138.
4bb. IR (NaCl, cm−1): 3054, 2879, 2845, 2013, 1763,
1
1577, 1541, 1462, 1380, 1239. H NMR (400 Hz, CDCl3):
δ 7.86–7.82 (m, 2H), 7.56–7.42 (m, 8H), 7.14–7.12 (m,
Bull. Korean Chem. Soc. 2018
© 2018 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.bkcs.wiley-vch.de
5

Synthesis of Bicyclo[3,2,0]hept-6-en-6-groups via
Au-catalyzed [2+2] Cyclization
BULLETIN OF THE
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