Radical-Enabled Bicyclization Cascades of Oxygen-Tethered 1,7-Enynes Leading to Skeletally Diverse Polycyclic Chromen-2-ones

Article abstract of DOI:10.1002/cjoc.201600571

Catalytic bicyclization cascades of oxygen-tethered 1,7-enynes with simple cycloalkanes or aryl sulfonhydrazides have been established via subsequent multiple C-C bond-forming events from alkynyl/alkenyl functions, delivering a series of densely functiona

Full text of DOI:10.1002/cjoc.201600571

FULL PAPER
DOI: 10.1002/cjoc.201600571
Radical-Enabled Bicyclization Cascades of Oxygen-Tethered
1,7-Enynes Leading to Skeletally Diverse Polycyclic
Chromen-2-ones
Bo Jiang,*,a Jie Li,a Yuanyuan Pan,a Wenjuan Hao,a Guigen Li,b,c and Shujiang Tu*,a
a School of Chemistry and Chemical Engineering, Jiangsu Key Laboratory of Green Synthetic Chemistry for
Functional Materials, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China
b Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
c Institute of Chemistry & BioMedical Sciences, Collaborative Innovation Center of Chemistry for Life Sciences,
Nanjing University, Nanjing, Jiangsu 210093, China
Catalytic bicyclization cascades of oxygen-tethered 1,7-enynes with simple cycloalkanes or aryl sulfonhydra-
zides have been established via subsequent multiple C－C bond-forming events from alkynyl/alkenyl functions, de-
livering a series of densely functionalized tetracyclic chromen-2-ones in a functional-group-compatible manner. In
the former, Fe-catalyzed spiro-bicyclization involves radical addition, 6-exo-dig cyclization, H-abstraction and
5-endo-trig cyclization sequences under mild conditions, resulting in new spiro-fused cyclopenta[c]chromen-2-ones
via dual α,α-C(sp3)-H abstractions. The latter enables in-situ sulfonylation and desulfonylation of oxygen-tethered
1,7-enynes to realize the construction of multiple C－C bonds, thereby leading to the formation of naphtho[2,3-c]-
chromen-6-ones.
Keywords bicyclization, radical reaction, 1,7-enynes, fused chromen-2-ones, C(sp3)-H functionalization
Introduction
nylarylidene)malonates,[9] and recent copper-catalyzed
oxidative bicyclization of 1,7-enynes.[10] Despite these
significant advances, to the best of our knowledge, the
utilization of an oxidative spiro-bicyclization of oxygen-
tethered 1,7-enynes with simple cycloalkanes as radical
precursors for the creation of functionalized cyclopenta-
[c]chromen-2-ones via dual α,α-C(sp3)-H functionaliza-
tion has not yet been documented.
Chromene-fused heterocycles are ubiquitous struc-
tural motifs, found in many natural and pharmaceuti-
cally interesting compounds.[1] Among them, cyclopen-
ta[c]chromene-2-one framework is an important subunit
of natural products, represented by herbertenolide[2]
[3]
(type I, Figure 1), aflatoxin B1 (type II) and aflatoxi-
col B[4] (type III), which showed remarkable biological
activities. Specifically, compounds with a cyclopen-
ta[c]chromene-2-one core have exhibited important bi-
ological activities such as cytotoxicity in vitro against
HTC hepatoma cells and anti-tumor activity in vivo
against KREBS II ascetic tumor.[5] Besides, they are
also reported to have substantial applications as photo-
sensitizers, fluorescent probes, laser dyes and behave as
significant building blocks in organic and medicinal
chemistry.[6] With these attributes in mind, much effort
has been devoted to accessing cyclopenta[c]chromene-
2-ones and their structural analogues. The majority of
synthetic strategies involve BBr3-promoted tandem an-
nulation of 2-(2-methoxyphenyl)cyclopentane-1-carb-
oxylates,[2] Pd-catalyzed cyclization of 2-iodophenyl-
cyclopent-2-ene-1-carboxylates,[7] carboannulation with
allylsilanes,[8] hydroarylation-cyclization of 2-(2-ethy-
OMe
O
H
O
O
O
O
O
O
H
herbertenolide (I)
aflatoxin B1 (II)
OMe
OH
H
O
O
O
O
H
aflatoxicol B (III)
Figure 1 Bioactive cyclopenta[c]chromen-2-one natural prod-
ucts.
1,7-Enynes are privileged building blocks,[11] and
*
E-mail: jiangchem@jsnu.edu.cn, laotu@jsnu.edu.cn; Tel.: 0086-0516-83500065; Fax: 0086-0516-83500065
Received September 5, 2016; accepted October 23, 2016; published online XXXX, 2017.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201600571 or from the author.
Chin. J. Chem. 2017, XX, 1—12
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Jiang et al.
FULL PAPER
methods for their direct radical cyclizations have be-
come an intriguing issue in the synthetic community, as
they allow the simultaneous introduction of different
functional groups via cooperative addition cascades
across the C＝C and C≡C bond system in one step.[12]
For these reasons, considerable efforts have been de-
voted to the use of 1,7-enynes for assembling highly
complex structures of chemical and biomedical im-
portance.[13] Very recently, Li and co-workers reported
an oxidative radical [2＋2＋1] carbocyclization of
1,7-enynes with various cyclic and acyclic ethers, re-
sulting in a series of fused five-membered carbocyclic
hydrocarbons. During these processes, N-linked
1,7-enynes were carefully explored to access spiro-sub-
stituted cyclopenta[c]quinolin-4-ones while only two
examples of cyclopenta[c]chromenes were obtained
using oxygen-linked 1,7-enynes (Scheme 1a).[14] At the
same time, we represented the addition of cycloal-
kanes-derived C-center radicals to the double bond of
N-tethered 1,7-enynes, providing a wide range of spiro-
substituted cyclopenta[c]quinolones (Scheme 1b).[15]
Herein, we would like to report the successful realiza-
tion of the assemble of these spiro-heterocyclic scaf-
folds with two quaternary stereocenters through radical-
triggered bicyclization of oxygen-tethered 1,7-enynes.
Using aryl sulfonhydrazides 4 as an arylsulfonyl radical
precursor to expand the synthetic utility of this method-
ology, similar to our previous study,[13a] this transfor-
mation involved sulfonylation/6-exo-dig/6-exo-trig bi-
cyclization/in situ desulfonylation/5-exo-trig cycliza-
tion/alkyl or alkenyl migration cascades to furnish naph-
tho[2,3-c]chromen-6-ones 5 (Scheme 1d). Both these
bicyclization reactions enabled consecutive multiple
C－C bond-forming events, resulting in the simultane-
ous formation of two new rings including pyran-2-one
and cyclopentene (or cyclohexadiene) rings. Note that in
the former, this special approach allows for high-
efficient access toward spirocyclic cyclopenta[c]chro-
menes by selective functionalization of innate C≡C and
C ＝ C bonds of oxygen-tethered 1,7-enynes and
α,α-C(sp3)-H bifunctionalizations of simple cycloal-
kanes through additional C－C bond-forming reactions
while the latter enables in-situ sulfonylation and desul-
fonylation of oxygen-tethered 1,7-enynes to realize the
construction of multiple C－C bonds.
Scheme 1 Synthesis of polycyclic chromen-2-ones
Results and Discussion
Initial studies were focused on investigating the bi-
cyclization reaction of methacrylates 1a with cyclohex-
ane (2a) using 10 mol% of FeCl3 and 2.0 equiv. of
di-tert-butyl peroxide (DTBP)[16] as an oxidant in neat
conditions at 130 ℃, which gave 50% of desired spiro-
substituted cyclopenta[c]chromene 3a (Table 1, Entry 1).
Switching the catalyst to FeCl2 enhanced the reaction
efficiency to furnish 58% of product 3a (Entry 2). Other
metal salt catalysts, including Cu(acac)2, Cu2O, CuBr,
CuI, Co(acac)2, and AgOTf, exhibited inferior catalytic
activity (Entries 3－8) and the reaction in the absence of
any metal catalyst was sluggish to provide product 3a in
15% yield (Entry 9). Encouraged by the above results,
the same reactions were examined using different oxi-
dants such as dicumyl peroxide (DCP), benzoyl perox-
ide (BPO), anhydrous t-butyl hydroperoxide (TBHP)
(Entries 10－12). Both DCP and BPO led to low yields
of product 3a. The use of TBHP proved to be ineffective
to promote this transformation. After investigating the
effect of amount of cyclohexane and DTBP to our mod-
el reaction (Entries 13－17), we found that the reaction
using 5.0 mL of cyclohexane and 2.0 equiv. of DTBP
gave the best results (74%) (Entry 14). Next, the reac-
tion temperature was examined. It was found that the
reaction temperature critically affected the reaction
efficiency. Lowering the reaction temperature deterio-
rated the experimental outcomes (Entry 18), and no re-
action occurred when the model reaction was carried out
at 110 ℃ (Entry 19).
Inspired by these interesting studies and considering
the significance of cyclopenta[c]chromen-2-ones, we
decided to employ oxygen-tethered 1,7-enynes as a rad-
ical acceptor to capture cycloalkane-derived C-center
radicals, thereby evaluating the feasibility of the for-
mation of cyclopenta[c]chromen-2-ones through cata-
lytic C(sp3)-H bifunctionalization. To our delight, the
reaction proceeded smoothly to give the expected spiro-
substituted cyclopenta[c]chromen-2-ones 3 (Scheme 1c).
With the above conditions in hand, the scope of oxy-
gen-tethered 1,7-enynes 1 was examined by reacting
2
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Chin. J. Chem. 2017, XX, 1—12

Radical-Enabled Bicyclization Cascades of Oxygen-Tethered 1,7-Enynes
Table 1 Optimization of the reaction conditionsa
Scheme 2 Scope of cascade spirocyclization reaction
( )n
R1
R1
FeCl2, DTBP
+
O
130 oC, air
( )n
Me
O
O
n = 0, 1, 2
O
3
Me
1
2
R1
Ph
Entry
1
Cat./mol%
FeCl3 (10)
FeCl2 (10)
Cu(acac)2 (10)
Cu2O (10)
CuBr (10)
CuI (10)
Oxidant (equiv.) t/℃ Yieldb/%
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DCP (2.0)
130
130
130
130
130
130
130
130
130
130
130
130
130
130
130
130
130
120
110
50
58
38
33
29
52
43
50
15
25
21
trace
38
74
57
52
48
48
NR
MeO2C
Me
O
Me
2
O
O
O
3
3l (30%)
3a - 3k
R1
4
3a, R1 = Ph (74%)
5
3b, R1 = 4-MeOPh (43%)
3c, R1 = 3-MeOPh (63%)
3d, R1 = 4-MePh (58%)
3e, R1 = 3-MePh (65%)
3f, R1 = 4-EtPh (66%)
3g, R1 = 4-tBuPh (72%)
3h, R1 = 4-FPh (62%)
3i, R1 = 3-FPh (61%)
3j, R1 = 4-ClPh (64%)
3k, R1 = n-Bu (0%)
6
Me
O
O
7
Co(acac)2 (10)
AgOTf (10)
－
3m - 3q
3m, R1 = Ph (58%)
3n, R1 = 4-MeOPh (41%)
3o, R1 = 4-MePh (50%)
3p, R1 = 4-tBuPh (45%)
3q, R1 = 4-ClPh (56%)
8
9
10
11
12
13c
14d
15e
16d
17d
18d
19d
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
FeCl2 (10)
BPO (2.0)
TBHP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (2.0)
DTBP (3.0)
DTBP (4.0)
DTBP (2.0)
DTBP (2.0)
R1
Me
O
O
3r - 3z
3r, R1 = Ph (45%)
3s, R1 = 4-MeOPh (54%)
3t, R1 = 3-MeOPh (43%)
3u, R1 = 4-MePh (64%)
3v, R1 = 4-EtPh (62%)
3w, R1 = 4-t-BuPh (66%)
3x, R1 = 3-FPh (64%)
3y, R1 = 4-ClPh (62%)
3z, R1 = n-Bu (0%)
a Reaction condition: oxygen-tethered 1,7-enyne 1a (0.20 mmol),
catalyst (0.02 mmol), oxidants in solvent of cyclohexane (3.0
mL), 24 h, air conditions. b Isolated yield based on 1a. c Cyclo-
hexane (2.0 mL) was used. d Cyclohexane (5.0 mL) was used.
e Cyclohexane (7.0 mL) was used.
them with simple cyclohexane 2a (Scheme 2). As antic-
ipated, the substituents on the phenyl ring of arylalkynyl
moiety did not hamper the reaction process. The vari-
ants of substituents on the arylalkynyl moiety including
Me, MeO, Et, t-Bu,F and Cl can tolerate the catalytic
conditions well. It seemed that there was no evident
difference among substrates carrying electron-donating
or electron-withdrawing groups in terms of reactivity,
and all of them offered good yields of the spirocyclic
products except 3b. Therefore, the electronic nature and
the position of the substituents linked to the arylalkynyl
moiety imposed little effect on the reaction efficiency.
Regrettably, substrate with n-butyl substituents at the
terminal position of the triple bond (R1) proved to be
unreactive under these conditions (3k and 3z, Scheme
2), presumably owing to the relative instability of the
alkenyl radicals generated in situ from alkynyl moiety
through 6-exo-trig cyclization. Additionally, a signifi-
cant drop in the yield was observed (30%) when the
strong electron-withdrawing ester group was introduced
(i) Yields of isolated products after column chromatography on silica gel
are given. Oxygen-tethered 1,7-enynes 1 (0.20 mmol), FeCl2 (0.02
mmol), DTBP (0.40 mmol), cycloalkanes (5.0 mL), 130 ℃, 24 h, under
air conditions. (ii) Isolated yield in brackets based on 1.
into the phenyl ring directly bound to the oxygen atom.
To expand the synthetic utility of these processes, other
simple cycloalkanes were employed to react with oxy-
gen-tethered 1,7-enynes (Scheme 2). Using cyclohep-
tane 2b as replacement for cyclohexane 2a, different
substituent groups on the oxygen-tethered 1,7-enynes
were compatible in this radical spiro-bicyclization,
providing the desired products 3m－3q, albeit with
moderate yields (Scheme 2). Alternatively, cyclopentane
2c was suitable for these transformations (3r－3y). The
resulting cyclopenta[c]chromen-2-ones 3 were fully
characterized by their NMR spectroscopy and HRMS.
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3

Jiang et al.
Table 2 Optimization of the reaction conditionsa
FULL PAPER
Furthermore, in the case of 3a, its structure was deter-
mined by X-ray diffraction analysis (Figure 2).
Ph
Me
O
O
TBAI, TBHP
S
HN
+
O
Solvent, t
O
NH2
Me
1a
4a
Ph
Ph
Me
+
O
O
Me
Me
Me
O
O
5a'
5a
Entry TBAI/mol% TBHP (equiv.) Solvent t/℃ Yieldb/%
1
2
3
4
10
10
10
10
10
10
10
10
3.0
3.0
3.0
3.0
4.0
4.0
5.0
5.0
CH3CN 60 20
DCE
DCE
DCE
DCE
DCE
DCE
DCE
60 28
80 35
90 34
80 39
80 43
80 54
80 trace
5
Figure 2 The ORTEP drawing of 3a.
6c
7c
8d
After the successful formation of cyclopenta[c]-
chromen-2-ones 3, we focused our efforts on the evalu-
ation of another radical bicyclization by replacement of
cycloalkanes with aryl sulfonhydrazides as an aryl-
sulfonyl radical precursor. Initially, the reaction of 1a
with tosylhydrazide 4a in a 1∶2 molar ratio was per-
formed in CH3CN at 60 ℃ using TBAI (10 mol%)/
TBHP (3.0 equiv., 5.5 mol/L in decane) system,[13a] but
only 20% total yield of isomers 5a and 5a’ was isolated
(Table 2, Entry 1). Switching the solvent from acetoni-
trile (CH3CN) to 1,2-dichloroethane (DCE) furnished 5a
in a 28% isolated yield (Entry 2). Increasing the reaction
temperature to 80 ℃ led to a slightly higher yield
(35%, Entry 3). The yield leveled off with further in-
crease of reaction temperature (Entry 4). After careful
optimizations, including the dosage of oxidants and
component ratio, we found that using TBAI (10 mol%)
and TBHP (5.0 equiv.) system under Ar conditions, the
reaction of 1a and 4a in 1∶3.5 molar ratio in DCE at
80 ℃ gave the best outcome, in which isomers 5a and
a Reaction condition: oxygen-tethered 1,7-enyne 1a (0.20 mmol),
tosylhydrazide 4a, TBAI (0.02 mmol), TBHP (5.5 mol/L in dec-
ane), solvent (3.0 mL), 24 h, under Ar conditions. b Isolated total
yield based on 1a. c The ratio of 1a∶4a in 1∶3.5. d Under air
conditions.
isomer were afforded in 45%－48% yields whereas
methyl-substituted oxygen-tethered 1,7-enyne 1d was
converted into the corresponding isomers 5c and 5c’ in a
3.6∶1 ratio. Benzenesulfonohydrazide 4c proved to be
a suitable component, transforming into products 5f－
5h with acceptable yields (39%－54%). Alternatively,
sterically encumbered naphthalene-2-sulfonohydrazide
4d was successfully engaged in this radical bicycliza-
tion, giving access in pentacyclic isomers 5i and 5i’ in a
3∶1 ratio. It is worth mentioning that the formation of
three new C－C bonds and two new rings was simulta-
neously achieved via a multi-cyclization, in-situ sul-
fonylation and desulfonylation, and alkyl or alkenyl
migration cascade. The structures were confirmed by a
case of X-ray crystal of 5f (Figure 3).
To gain insight into the reaction mechanism, the re-
actions of substrate 1a under the standard conditions
were conducted in the presence of 2.0 equiv. of 2,2,6,6-
tetramethyl-1-piperidinyloxy (TEMPO) (Scheme 4a). In
this transformation, no conversion to the expected
product 3a was detected, and only the starting material
1a was recovered. Furthermore, the TEMPO−Cy adduct
could be detected by GC-MS (MS 239.2), which points
towards the possibility of a radical mechanism. As a
further support to the radical path of the mechanism, the
reaction was performed with FeCl2 under air without the
use of DTBP. The desired product 3a was not observed
in this reaction (Scheme 4b). These control experiments
suggest that FeCl2 is deficient to form the Cy radical
1
5a’ were in a 1.2∶1 ratio determined by H NMR
analysis (54%, Entry 7). The identical reaction was car-
ried out under air conditions, and only a trace amount of
the desired product 5a was observed, because oxygen
participated in this reaction to form β-hydroxysulfones
via oxysulfonylation of alkene unit of oxygen-tethered
1,7-enynes.[17]
With the established optimal conditions, the general-
ity of this radical bicyclization of oxygen-tethered
1,7-enynes 1 with the other three representative aryl-
sulfonylhydrazides 4b－4d was investigated. As shown
in Scheme 3, 4-methoxyphenylsulfonyl hydrazide 4b
was subjected to reaction of oxygen-tethered 1,7-enynes
1 bearing electron-neutral (H) and electron-rich (methyl,
methoxy, t-butyl) groups residing in the para-position of
arylalkynylmoiety, and products 5b, 5d, and 5e with one
4
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Chin. J. Chem. 2017, XX, 1—12

Radical-Enabled Bicyclization Cascades of Oxygen-Tethered 1,7-Enynes
Scheme 3 Substrate scope for the synthesis of 5
R1
R1
R2
R1
R2
O
O
TBAI, TBHP
DCE, 80 oC, Ar
+
S
HN
+
O
O
O
O
R2
NH2
Me
Me
Me
O
-SO2, -N2
O
- 4c
1
4a
5'
5
4-EtPh
Ph
4-MePh
Ph
O
O
O
O
OMe
OMe
OMe
Me
Me
Me
Me
Me
O
O
O
O
5d (48%, one isomer)
5a (54%, 5a:5a' = 1.2:1)
5c (52%, 5c:5c' = 3.6:1)
5b (47%, one isomer)
4-tBuPh
4-tBuPh
Ph
4-MeOPh
O
O
O
O
OMe
Me
O
Me
O
Me
O
Me
O
5e (45%, one isomer)
5g
(54%)
5h (53%)
5f (39%)
Ph
Ph
Ph
O
TBAI, TBHP
O
+
+
O
DCE, 80 oC, Ar
S
HN
O
O
O
Me
O
Me
-SO2, -N2
NH2
4d
Me
O
5i'
(42%, 5i:5i' = 3:1)
5i
1a
Reaction conditions: 1 (0.20 mmol), 4 (0.7 mmol), TBAI (0.02 mmol), TBHP (5.5 mol/L in decane, 1.0 mmol), DCE (3.0 mL) at 80 ℃, Ar conditions, 24
h. Isolated total yields in brackets were based on 1.
Scheme 4 Mechanistic study for forming products 3
(a) Control Experiments
Ph
Ph
O
N
O
FeCl2, DTBP
+
(a)
+
O
TEMPO (2.0 equiv.)
130 oC
Me
O
Me
Ph
O
3a (Not Detected)
Detected by GC-MS
2a
1a
Ph
Standard conditions
No DTBP
O
(b)
+
Me
O
O
O
Me
3a (Not Detected)
2a
1a
(b) Intermolecular KIE
Ph
D10
Ph
Ph
O
Standard
+
+
+
(c)
Me
O
conditions
D12
Me
O
O
Me
O
O
(1:1)
3a
[D10]-3a
[D12]-2a
2a
1a
KH/KD = 4.81
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5

Jiang et al.
FULL PAPER
Scheme 5 Plausible mechanism for forming 3
t-BuO Ot-Bu
Fe(II)
t-
BuO
Fe(III)
t-BuO
t-BuO
+
t-BuO
H
H
t-BuO
t-BuOH
R1
R1
H
H
O
Me
O
O
O
Me
1
A
R1
R1
H-Abstraction
H
Figure 3 The ORTEP drawing of 5f.
Me
Me
O
O
O
O
through H-abstraction and the radical initiator DTBP is
essential for this transformation. Subsequently, a deu-
terium labelling experiment was also carried out. A
significant kinetic isotope effect (KIE, KIE＝4.81) was
measured in intermolecular competing reaction of 2a
and [D12]-2a, confirming that the rupture of the
C(sp3)-H on the cyclohexane ring was involved in the
rate-determining step (Scheme 4c).
B
C
R1
R1
[O]
-H
Me
O
Me
O
O
O
D
3
On the basis of a literature survey,[14] our previous
report[15] and controlled experimental outcomes, a tenta-
tive mechanism for the formation of products 3 is out-
lined in Scheme 5. tert-Butoxy radical generated in situ
from the Fe(II)-assisted homolysis of DTBP abstracts a
hydrogen atom from the cycloalkane to form a cycloal-
kyl radical. Then, the intermolecular addition of the
in-situ-generated cycloalkyl radical to oxygen-tethered
1,7-conjugated enynes 1 delivers radical intermediates
A, followed by intramolecular 6-exo-dig cyclization and
H-abstraction to afford intermediates C. The 5-endo-trig
cyclization of C gives intermediates D, which undergo
oxidation and deprotonation to yield spiro products 3.
According to experimental results of forming prod-
ucts 5, its mechanism is very similar to our previous
study on radical bicyclization between nitrogen-linked
1,7-enynes and arylsulfonylhydrazides using TBAI/
TBHP system.[13a] Therefore, the mechanism for the
formation of the desired products 5 shown in Scheme 6
was proposed. First, an intermolecular α,β-conjugated
addition of the resulting sulfonyl radicals, from sul-
fonylhydrazides under the oxidative conditions with the
release of N2,[18] onto oxygen-tethered 1,7-enynes 1 fol-
lowed by 6-exo-dig/6-exo-trig bicyclization yields vinyl
radicals G. Next, intermediates G undergo continuous
desulfoylation (G to H)/5-exo-trig cyclization (H to I)
and single electron transfer (SET) oxidation (H to J) to
give spirocylic cation J. Two migration modes of inter-
mediate J could result in intermediates K (path a) and L
(path b), respectively. Subsequent deprotonations of
both K and L lead to access two isomers 5 and 5’. The
regioselectivity of products should be attributed to the
stability of intermediates K and L. Due to the bigger
conjugated system, intermediate K is more stable than L,
thereby occupying higher content of target products,
especially with electron-rich substituents.
Conclusions
In summary, we have established two different radi-
cal-triggered bicyclization cascades of oxygen-tethered
1,7-conjugated enynes, enabling multiple C－C
bond-forming events from alkynyl/alkenyl functions to
deliver skeletally diverse tetracyclic chromen-2-ones in
a functional-group-compatible manner. The former bi-
cyclization reaction provided a practical and facile pro-
tocol toward new spiro-substituted cyclopenta[c]-
chromen-2-ones via Fe-catalyzed oxidative α,α-C(sp3)-
H bifunctionalization of cycloalkanes. In the latter, rad-
ical-enabled bicylization of oxygen-tethered 1,7-enynes
with arylsulfonylhydrazides allowed in-situ sulfonyla-
tion and desulfonylation cascade to the formation of
naphtho[2,3-c]chromen-6-ones. Both bicyclization reac-
tions feature the bond-forming efficiency, functional
group tolerance and mild reaction conditions. Further
investigations aiming at introducing other radicals into
these transformations are currently underway.
Experimental
General procedure for the synthesis of products 3
Example for the synthesis of 3a A mixture of
2-(phenylethynyl)phenyl methacrylate (1a, 1.0 equiv.,
6
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© 2017 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2017, XX, 1—12

Radical-Enabled Bicyclization Cascades of Oxygen-Tethered 1,7-Enynes
Scheme 6 Plausible mechanism for forming 5
0.20 mmol), FeCl2 (10 mol%, 0.02 mmol), and DTBP
(2.0 equiv., 0.40 mmol) in cyclohexane (5.0 mL) was
heated in a sealed tube at 130 ℃. The reaction was
monitored by TLC. After complete consumption of the
reactants, the volatiles were evaporated under vacuum
and the residue was purified by column chromatography
(eluents, petroleum ether/ethyl acetate) to afford the
desired product 3a.
(3b) White solid, m.p. 150－151 ℃; 1H NMR (400
MHz, CDCl3) δ: 7.17－7.13 (m, 1H), 7.05－7.01 (m,
3H), 6.92 (d, J＝8.8 Hz, 2H), 6.81－6.72 (m, 1H), 6.69
－6.67 (m, 1H), 3.84 (s, 3H), 2.49 (d, J＝13.6 Hz, 1H),
2.30 (d, J＝14.0 Hz, 1H), 1.70－1.54 (m, 6H), 1.43 (s,
3H), 1.36－1.29 (m, 2H), 1.22－1.15 (m, 1H), 1.03－
0.96 (m, 1H); 13C NMR (100 MHz, CDCl3) δ: 173.6,
159.0, 151.2, 149.9, 130.3, 130.2, 128.7, 128.0, 127.1,
123.8, 119.5, 116.5, 113.9, 55.2, 52.5, 50.9, 42.8, 37.41,
35.6, 27.0, 25.3, 23.4, 22.4; IR (KBr) ν: 3234, 2930,
2850, 1775, 1637, 1616, 1511, 1480, 1384, 1290, 1209,
1091, 1041, 765, 750, 623 cm1; HRMS (ESI-TOF) m/z
calcd for C25H26NaO3, 397.1780 [M＋Na]＋ ; found
397.1764.
3a'-Methyl-1'-phenyl-3'H-spiro[cyclohexane-1,2'-
cyclopenta[c]chromen]-4'(3a'H)-one (3a)
White
solid, m.p. 207－208 ℃; 1H NMR (400 MHz, CDCl3) δ:
7.41－7.37 (m, 3H), 7.17－7.10 (m, 3H), 7.05－7.03
(m, 1H), 6.78－6.74 (m, 1H), 6.63－6.60 (m, 1H), 2.52
(d, J＝14.0 Hz, 1H), 2.33 (d, J＝14.0 Hz, 1H), 1.74－
1.54 (m, 6H), 1.44 (s, 3H), 1.41－1.32 (m, 2H), 1.21－
1.14 (m, 1H), 1.03－0.93 (m, 1H); 13C NMR (100 MHz,
CDCl3) δ: 173.6, 151.2, 150.1, 136.0, 130.1, 129.2,
128.8, 128.4, 127.5, 127.1, 123.9, 119.3, 116.5, 52.5,
51.1, 42.9, 37.4, 35.6, 27.0, 25.3, 23.4, 22.3; IR (KBr) ν:
2961, 2931, 2864, 2850, 1774, 1637, 1616, 1479, 1449,
1370, 1238, 1209, 1170,1092, 1081, 1046, 752, 621
cm1; HRMS (ESI-TOF) m/z calcd for C24H24NaO2,
367.1674 [M＋Na]＋; found 367.1672.
1'-(3-Methoxyphenyl)-3a'-methyl-3'H-spiro[cy-
clohexane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one
1
(3c) White solid, m.p. 151－152 ℃; H NMR (400
MHz, CDCl3) δ: 7.32－7.28 (m, 1H), 7.17－7.13 (m,
1H), 7.05－7.03 (m, 1H), 6.92－6.89 (m, 1H), 6.81－
6.78 (m, 1H), 6.71－6.64 (m, 3H), 3.80 (s, 3H), 2.50 (d,
J＝14.0 Hz, 1H), 2.32 (d, J＝14.0 Hz, 1H), 1.74－1.51
(m, 6H), 1.44 (s, 3H), 1.41－1.31 (m, 2H), 1.23－1.16
(m, 1H), 1.05－0.94 (m, 1H); 13C NMR (100 MHz,
CDCl3) δ: 173.5, 159.1, 151.2, 149.7, 137.4, 130.1,
129.4, 128.8, 127.2, 123.9, 121.63, 119.3, 116.5, 114.9,
1'-(4-Methoxyphenyl)-3a'-methyl-3'H-spiro[cy-
clohexane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one
Chin. J. Chem. 2017, XX, 1—12
© 2017 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
7

Jiang et al.
FULL PAPER
112.7, 55.3, 52.5, 51.0, 42.9, 37.5, 35.6, 27.0, 25.3, 23.4,
22.4; IR (KBr) ν: 3474, 3235, 3076, 2984, 2959, 2924,
2855, 2828, 1915, 1770, 1637, 1616, 1477, 1456, 1286,
1212, 1161, 1081, 1053, 764, 625 cm1; HRMS
(ESI-TOF) m/z calcd for C25H26NaO3, 397.1780 [M＋
Na]＋; found 397.1780.
6.64－6.61 (m, 1H), 2.50 (d, J＝14.0 Hz, 1H), 2.31 (d,
J＝14.0 Hz, 1H), 1.74－1.53 (m, 6H), 1.43 (s, 3H), 1.41
－1.38 (m, 1H), 1.35 (s, 9H), 1.31 (s, 1H), 1.23－1.17
(m, 1H), 1.05－0.96 (m, 1H); 13C NMR (100 MHz,
CDCl3) δ: 173.7, 151.2, 150.3, 150.3, 132.8, 129.9,
128.7, 128.6, 127.1, 125.2, 123.8, 119.5, 116.4, 52.5,
51.0, 42.8, 37.4, 35.6, 34.6, 31.4, 27.0, 25.3, 23.4, 22.4;
IR (KBr) ν: 3550, 3235, 2929, 2855, 1770, 1637, 1616,
1480, 1455, 1384, 1211, 1169, 1093, 1028, 762, 641
cm1; HRMS (ESI-TOF) m/z calcd for C28H32NaO2,
423.2300 [M＋Na]＋; found 423.2270.
3a'-Methyl-1'-(p-tolyl)-3'H-spiro[cyclohexane-
1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3d) White
solid, m.p. 179－180 ℃; 1H NMR (400 MHz, CDCl3) δ:
7.19－7.12 (m, 3H), 7.05－6.98 (m, 3H), 6.80－6.76
(m, 1H), 6.68－6.63 (m, 1H), 2.49 (d, J＝14.0 Hz, 1H),
2.40 (s, 3H), 2.31 (d, J＝14.0 Hz, 1H), 1.73－1.52 (m,
6H), 1.43 (s, 3H), 1.40－1.28 (m, 2H), 1.21－1.14 (m,
1H), 1.03－0.96 (m, 1H); 13C NMR (100 MHz, CDCl3)
δ: 173.7, 151.2, 150.2, 137.1, 132.9, 129.9, 129.1, 129.0,
128.7, 127.1, 123.8, 119.5, 116.5, 52.5, 51.0, 42.8, 37.4,
35.6, 27.0, 25.3, 23.4, 22.4, 21.3; IR (KBr) ν: 3551,
3235, 2961, 2931, 2848, 1775, 1637, 1616, 1449, 1384,
1210, 1167, 1091, 1081, 760, 747, 626 cm1; HRMS
(ESI-TOF) m/z calcd for C25H26NaO2, 381.1830 [M＋
Na]＋; found 381.1817.
3a'-Methyl-1'-(m-tolyl)-3'H-spiro[cyclohexane-
1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3e) White
solid, m.p. 148－149 ℃; 1H NMR (400 MHz, CDCl3) δ:
7.28－7.25 (m, 2H), 7.18－7.12 (m, 2H), 7.05－7.03
(m, 1H), 6.91 (s, 1H), 6.80－6.76 (m, 1H), 6.65－6.63
(m, 1H), 2.50 (d, J＝14.0 Hz, 1H), 2.36 (s, 3H), 2.32 (d,
J＝14.0 Hz, 1H), 1.70－1.55 (m, 6H), 1.44 (s, 3H), 1.38
－1.31 (m, 2H), 1.22－1.15 (m, 1H), 1.01－0.94 (m,
1H); 13C NMR (100 MHz, CDCl3) δ: 173.6, 151.2,
150.3, 138.0, 135.9, 129.8, 129.6, 128.7, 128.2, 127.2,
126.3, 123.9, 119.5, 119.4, 116.5, 52.5, 51.0, 42.8, 37.5,
35.6, 27.1, 25.3, 23.4, 22.4, 21.6; IR (KBr) ν: 3550,
2948, 2916, 2850, 1760, 1637, 1617, 1479, 1454, 1384,
1208, 1157, 1092, 1081, 764, 626 cm1; HRMS
(ESI-TOF) m/z calcd for C25H26NaO2, 381.1830 [M＋
Na]＋; found 381.1819.
1'-(4-Fluorophenyl)-3a'-methyl-3'H-spiro[cyclo-
hexane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3h)
1
White solid, m.p. 200－201 ℃; H NMR (400 MHz,
CDCl3) δ: 7.18－7.14 (m, 1H), 7.09－7.03 (m, 5H),
6.82－6.78 (m, 1H), 6.62－6.60 (m, 1H), 2.51 (d, J＝
14.0 Hz, 1H), 2.31 (d, J＝14.0 Hz, 1H), 1.71－1.54 (m,
6H), 1.43 (s, 3H), 1.33－1.25 (m, 2H), 1.18－1.11 (m,
1H), 1.03－0.95 (m, 1H); 13C NMR (100 MHz, CDCl3)
δ: 172.4, 161.3 (JCF＝245.1 Hz), 150.2, 147.9, 130.7
(JCF＝3.5 Hz), 129.8 (JCF＝7.8 Hz), 128.0, 126.0, 122.9,
118.1, 115.6, 114.5 (JCF＝21.1 Hz), 51.4, 50.0, 41.8,
36.3, 34.6, 26.0, 24.3, 22.3, 21.3; IR (KBr) ν: 3413,
3235, 2960, 2849, 1771, 1637, 1616, 1482, 1457, 1448,
1384, 1208, 1169, 1156, 1093, 837, 802, 763, 626 cm1;
HRMS (ESI-TOF) m/z calcd for C24H23FNaO2,
385.1580 [M＋Na]＋; found 385.1569.
1'-(3-Fluorophenyl)-3a'-methyl-3'H-spiro[cyclo-
hexane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3i)
White solid, m.p. 174－176 ℃; 1H NMR (400 MHz,
CDCl3) δ: 7.37－7.32 (m, 1H), 7.19－7.15 (m, 1H),
7.09－7.04 (m, 2H), 6.89－6.78 (m, 3H), 6.63 (d, J＝
8.0 Hz, 1H), 2.51 (d, J＝14.0 Hz, 1H), 2.32 (d, J＝14.0
Hz, 1H), 1.72－1.55 (m, 6H), 1.44 (d, J＝1.6 Hz, 3H),
1.37－1.31 (m, 2H), 1.18－1.12 (m, 1H), 1.04－0.97
(m, 1H); 13C NMR (100 MHz, CDCl3) δ: 173.3, 162.7
(JCF＝245.6 Hz), 151.2, 148.4 (JCF＝1.7 Hz), 138.3 (JCF
＝7.7 Hz), 130.8, 130.0 (JCF＝8.5 Hz), 129.1, 127.0,
125.1 (JCF＝2.9 Hz), 124.0, 118.9, 116.6, 116.2 (JCF＝
21.2 Hz), 114.5 (JCF＝20.7 Hz), 52.6, 51.1, 42.8, 37.4,
35.7, 27.0, 25.3, 23.4, 22.3; IR (KBr) ν: 3548, 3235,
2958, 2930, 2850, 1774, 1637, 1616, 1449, 1384, 1210,
1191, 1092, 1081, 753, 625 cm1; HRMS (ESI-TOF)
m/z calcd for C24H23FNaO2, 385.1580 [M＋Na]＋; found
385.1582.
1'-(4-Ethylphenyl)-3a'-methyl-3'H-spiro[cyclohe-
xane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one
(3f)
White solid, m.p. 124－125 ℃; 1H NMR (400 MHz,
CDCl3) δ: 7.20 (d, J＝8.4 Hz, 2H), 7.16－7.12 (m, 1H),
7.04－7.00 (m, 3H), 6.80－6.76 (m, 1H), 6.67－6.64
(m, 1H), 2.73－2.67 (m, 2H), 2.50 (d, J＝14.0 Hz, 1H),
2.31 (d, J＝14.0 Hz, 1H), 1.71－1.54 (m, 6H), 1.43 (s,
3H), 1.41－1.34 (m, 2H), 1.30－1.26 (m, 3H), 1.22－
1.16 (m, 1H), 1.04－0.97 (m, 1H); 13C NMR (100 MHz,
CDCl3) δ: 172.6, 150.1, 149.2, 142.3, 132.0, 128.9,
128.0, 127.6, 126.8, 126.1, 122.8, 118.5, 115.4, 51.5,
49.9, 41.8, 36.4, 34.5, 27.5, 26.0, 24.2, 22.4, 21.3, 14.3;
IR (KBr) ν: 3475, 3414, 2963, 2926, 2850, 1772, 1637,
1616, 1481, 1451, 1384, 1259, 1211, 1161, 1092, 1081,
763, 646 cm1; HRMS (ESI-TOF) m/z calcd for
C26H28NaO2, 395.1987 [M＋Na]＋; found 395.1992.
1'-(4-(tert-Butyl)phenyl)-3a'-methyl-3'H-spiro-
[cyclohexane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-
1'-(4-Chlorophenyl)-3a'-methyl-3'H-spiro[cyclo-
hexane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3j)
1
White solid, m.p. 202－203 ℃; H NMR (400 MHz,
CDCl3) δ: 7.37 (d, J＝8.0 Hz, 2H), 7.19－7.16 (m, 1H),
7.05 (d, J＝8.0 Hz, 3H), 6.83－6.80 (m, 1H), 6.63 (d,
J＝7.6 Hz, 1H), 2.51 (d, J＝14.0 Hz, 1H), 2.31 (d, J＝
14.0 Hz, 1H), 1.71－1.54 (m, 6H), 1.43 (s, 3H), 1.30－
1.26 (m, 2H), 1.16－1.10 (m, 1H), 0.96－0.92 (m, 1H);
13C NMR (100 MHz, CDCl3) δ: 172.23, 150.2, 147.6,
133.4, 132.6, 129.9, 129.6, 128.1, 127.7, 126.0, 122.9,
118.0, 115.6, 51.5, 50.1, 41.8, 36.4, 34.6, 26.0, 24.2,
22.3, 21.3; IR (KBr) ν: 3235, 2960, 2930, 2848, 1773,
1637, 1616, 1480, 1448, 1384, 1260, 1209, 801, 625;
1
one (3g) White solid, m.p. 171－173 ℃; H NMR
(400 MHz, CDCl3) δ: 7.37 (d, J＝8.4 Hz, 2H), 7.16－
7.12 (m, 1H), 7.04－7.00 (m, 3H), 6.79－6.75 (m, 1H),
8
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Chin. J. Chem. 2017, XX, 1—12

Radical-Enabled Bicyclization Cascades of Oxygen-Tethered 1,7-Enynes
HRMS (ESI-TOF) m/z calcd for C24H23ClNaO2,
401.1284 [M＋Na]＋; found 401.1262.
3H), 1.39－1.25 (m, 4H); 13C NMR (100 MHz, CDCl3)
δ: 173.6, 151.2, 151.0, 137.1, 133.3, 129.2, 128.9, 128.8,
128.6, 127.2, 123.8, 119.5, 116.5, 54.9, 50.82, 45.1, 40.6,
40.1, 28.9, 28.6, 26.1, 24.4, 23.7, 21.3; IR (KBr) ν: 3550,
3235, 2961, 2922, 2855, 1773, 1637, 1616, 1510, 1481,
1454, 1384, 1260, 1240, 1210, 1143, 1090, 1021, 819,
748, 624 cm1; HRMS (ESI-TOF) m/z calcd for
C26H28NaO2, 395.1987 [M＋Na]＋; found 395.1978.
1'-(4-(tert-Butyl)phenyl)-3a'-methyl-3'H-spiro[cy-
cloheptane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one
(3p) White solid, m.p. 127－129 ℃; 1H NMR (400
MHz, CDCl3) δ: 7.36 (d, J＝8.4 Hz, 2H), 7.15－7.11 (m,
1H), 7.06－7.01 (m, 3H), 6.78－6.74 (m, 1H), 6.62－
6.60 (m, 1H), 2.51 (d, J＝14.0 Hz, 1H), 2.26 (d, J＝
14.0 Hz, 1H), 1.99－1.88 (m, 2H), 1.68－1.57 (m, 4H),
1.50－1.47 (m, 2H), 1.43 (s, 3H), 1.35 (s, 9H), 1.30－
1.16 (m, 4H); 13C NMR (100 MHz, CDCl3) δ: 173.7,
151.3, 151.1, 150.3, 133.2, 128.8, 128.6, 128.6, 127.2,
125.2, 123.8, 119.5, 116.4, 55.0, 50.8, 44.9, 40.6, 40.1,
34.6, 31.4, 28.8, 28.5, 26.1, 24.4, 23.7; IR (KBr) ν: 3414,
3235, 2926, 2855, 1772, 1637, 1617, 1454, 1384, 1095,
802, 752, 625 cm1; HRMS (ESI-TOF) m/z calcd for
C29H34NaO2, 437.2457 [M＋Na]＋; found 437.2456.
1'-(4-Chlorophenyl)-3a'-methyl-3'H-spiro[cyclo-
heptane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3q)
Methyl 3a'-methyl-4'-oxo-1'-phenyl-3a',4'-dihy-
dro-3'H-spiro[cyclohexane-1,2'-cyclopenta[c]chro-
mene]-8'-carboxylate (3l) White solid, m.p. 217－
218 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.82－7.80 (m,
1H), 7.44－7.38 (m, 3H), 7.32 (d, J＝2.0 Hz, 1H), 7.12
－7.06 (m, 3H), 3.72 (s, 3H), 2.53 (d, J＝14.0 Hz, 1H),
2.34 (d, J＝14.0 Hz, 1H), 1.72－1.55 (m, 6H), 1.43 (s,
3H), 1.41－1.34 (m, 2H), 1.27－1.23 (m, 1H), 1.05－
0.97 (m, 1H); 13C NMR (100 MHz, CDCl3) δ: 172.7,
165.9, 154.3, 151.6, 135.4, 130.2, 129.2 129.19, 129.0,
128.5, 127.7, 125.9, 119.3, 116.6, 52.7, 52.0, 50.9, 42.8,
37.3, 35.5, 26.9, 25.2, 23.4, 22.3; IR (KBr) ν: 3413,
3235, 3052, 2959, 2933, 2852, 1783, 1726, 1637, 1616,
1480, 1439, 1424, 1384, 1283, 1250, 1158, 1129, 1079,
1042, 810,768; HRMS (ESI-TOF) m/z calcd for
C26H26NaO4, 425.1729 [M＋Na]＋; found 425.1744.
3a'-Methyl-1'-phenyl-3'H-spiro[cycloheptane-
1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3m)
1
White solid, m.p. 175－176 ℃; H NMR (400 MHz,
CDCl3) δ: 7.37 (d, J＝5.2 Hz, 3H), 7.16－7.12 (m, 3H),
7.03 (d, J＝8.4 Hz, 1H), 6.78－6.74 (m, 1H), 6.60 (d,
J＝8.0 Hz, 1H), 2.51 (d, J＝13.6 Hz, 1H), 2.29－2.25
(m, 1H), 2.01－1.89 (m, 2H), 1.57 (s, 4H), 1.52－1.49
(m, 2H), 1.44 (d, J＝1.2 Hz, 3H), 1.40 (d, J＝11.6 Hz,
2H), 1.25 (s, 2H); 13C NMR (100 MHz, CDCl3) δ: 173.6,
151.3, 150.8, 136.4, 129.1, 128.7, 128.4, 127.5, 127.1,
123.8, 119.3, 116.5, 55.0, 50.9, 45.1, 40.7, 40.1, 29.0,
28.7, 26.1, 24.3, 23.7; IR (KBr) ν: 3415, 3235, 2963,
2923, 2853, 1773, 1637, 1617, 1479, 1455, 1384, 1261,
1239, 1210, 1168, 1091, 1025, 802, 706, 617; HRMS
(ESI-TOF) m/z calcd for C25H26NaO2, 381.1830 [M＋
Na]＋; found 381.1826.
1
White solid, yield 56%; m.p. 201－202 ℃; H NMR
(400 MHz, CDCl3) δ: 7.36 (d, J＝8.8 Hz, 2H), 7.19－
7.15 (m, 1H), 7.10－7.03 (m, 3H), 6.83－6.79 (m, 1H),
6.63－6.61 (m, 1H), 2.51 (d, J＝14.0 Hz, 1H), 2.27 (d,
J＝14.0 Hz, 1H), 1.95－1.89 (m, 2H), 1.66－1.57 (m,
4H), 1.48－1.46 (m, 2H), 1.43 (s, 3H), 1.36－1.25 (m,
4H); 13C NMR (100 MHz, CDCl3) δ: 173.3, 151.3,
149.4, 134.9, 133.6, 130.5, 129.8, 129.0, 128.8, 127.0,
123.9, 119.0, 116.7, 55.0, 50.9, 45.1, 40.7, 40.1, 28.9,
28.6, 26.1, 24.3, 23.7; IR (KBr) ν: 3448, 2961, 2923,
2854, 1772, 1654, 1648, 1607, 1490, 1480, 1456, 1395,
1384, 1216, 1240, 1212, 1193, 1091, 1015, 801, 750
cm1; HRMS (ESI-TOF) m/z calcd for C25H25ClNaO2,
415.1441 [M＋Na]＋; found 415.1441.
3a-Methyl-1-phenyl-3H-spiro[cyclopenta[c]chro-
mene-2,1'-cyclopentan]-4(3aH)-one (3r) White solid,
m.p. 96－96 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.45－
7.32 (m, 4H), 7.16－7.14 (m, 3H), 7.06－7.04 (m, 1H),
6.80－6.76 (m, 1H), 6.69－6.56 (m, 1H), 2.51 (d, J＝
13.6 Hz, 1H), 2.18 (d, J＝13.6 Hz, 1H), 1.93－1.87 (m,
1H), 1.80－1.64 (m, 4H), 1.56 (s, 2H), 1.46 (s, 3H),
1.40－1.38 (m, 1H); 13C NMR (100 MHz, CDCl3) δ:
173.4, 151.2, 147.4, 136.1, 130.9, 129.2, 128.8, 128.5,
127.5, 127.0, 123.9, 119.2, 116.6, 59.0, 51.2, 48.0, 38.9,
38.3, 26.3, 24.2, 24.0; IR (KBr) ν: 3415, 3235, 2956,
2866, 1770, 1637, 1616, 1454, 1384, 1260, 1210, 1168,
1086, 1049, 766, 707, 622 cm1; HRMS (ESI-TOF) m/z
calcd for C23H22NaO2, 353.1517 [M＋Na]＋ ; found
353.1510.
1'-(4-Methoxyphenyl)-3a'-methyl-3'H-spiro[cy-
cloheptane-1,2'-cyclopenta[c]chromen]-4'(3a'H)-
1
one (3n) White solid, m.p. 135－137 ℃; H NMR
(400 MHz, CDCl3) δ: 7.16－7.12 (m, 1H), 7.07－7.02
(m, 3H), 6.91 (d, J＝8.8 Hz, 2H), 6.81－6.77 (m, 1H),
6.68－6.66 (m, 1H), 3.84 (s, 3H), 2.50 (d, J＝13.6 Hz,
1H), 2.25 (d, J＝14.0 Hz, 1H), 1.98－1.85 (m, 2H),
1.69－1.56 (m, 4H), 1.51－1.46 (m, 2H), 1.42 (s, 3H),
1.39－1.26 (m, 4H); 13C NMR (100 MHz, CDCl3) δ:
173.6, 159.0, 151.3, 150.7, 130.1, 129.1, 128.6, 128.4,
127.2, 123.8, 119.5, 116.5, 113.9, 55.2, 54.9, 50.8, 45.1,
40.7, 40.1, 29.0, 28.7, 26.1, 24.4, 23.7; IR (KBr) ν: 3235,
3035, 2924, 2855, 1773, 1637, 1616, 1510, 1480, 1455,
1384, 1288, 1245, 1210, 1167, 1245, 1210, 1167, 1245,
1210, 1167, 1090, 1038, 838, 762, 750, 624 cm1;
HRMS (ESI-TOF) m/z calcd for C26H28NaO3, 411.1936
[M＋Na]＋; found 411.1938.
3a'-Methyl-1'-(p-tolyl)-3'H-spiro[cycloheptane-
1,2'-cyclopenta[c]chromen]-4'(3a'H)-one (3o) White
solid, m.p. 167－168 ℃; 1H NMR (400 MHz, CDCl3) δ:
7.18－7.12 (m, 3H), 7.04－7.02 (m, 3H), 6.80－6.76
(m, 1H), 6.66－6.64 (m, 1H), 2.50 (d, J＝13.6 Hz, 1H),
2.39 (s, 3H), 2.26 (d, J＝14.0 Hz, 1H), 1.98－1.87 (m,
2H), 1.63－1.58 (m, 4H), 1.49－1.46 (m, 2H), 1.43 (s,
1-(4-Methoxyphenyl)-3a-methyl-3H-spiro[cyclo-
penta[c]chromene-2,1'-cyclopentan]-4(3aH)-one (3s)
Oil; 1H NMR (400 MHz, CDCl3) δ: 7.17－7.12 (m, 1H),
7.07－7 .03 (m, 3H), 6.93－6.90 (m, 2H), 6.82－6.74
Chin. J. Chem. 2017, XX, 1—12
© 2017 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
9

Jiang et al.
FULL PAPER
(m, 2H), 3.83 (s, 3H), 2.49 (d, J＝13.2 Hz, 1H), 2.16 (d,
J＝13.6 Hz, 1H), 1.94－1.86 (m, 1H), 1.78－1.45 (m,
6H), 1.44 (s, 3H), 1.38－1.33 (m, 1H); 13C NMR (100
MHz, CDCl3) δ: 173.5, 159.0, 151.2, 147.3, 130.9,
130.2, 128.7, 128.0, 127.0, 123.9, 119.3, 116.6, 114.0,
58.9, 55.2, 51.0, 48.1, 38.9, 38.3, 26.2, 24.3, 24.1; IR
(KBr) ν: 3404, 2955, 2867, 1770, 1637, 1616, 1509,
1480, 1455, 1384, 1285, 1246, 1209, 1169, 1086, 1049,
622 cm1; HRMS (ESI-TOF) m/z calcd for C24H24NaO3,
383.1623 [M＋Na]＋; found 383.1623.
(3v) White solid, m.p. 139－140 ℃; 1H NMR (400
MHz, CDCl3) δ: 7.38 (d, J＝8.4 Hz, 2H), 7.16－7.12 (m,
1H), 7.07－7.02 (m, 3H), 6.80－6.76 (m, 1H), 6.72－
6.70 (m, 1H), 2.49 (d, J＝13.2 Hz, 1H), 2.17 (d, J＝
13.2 Hz, 1H), 1.93－1.90 (m, 1H), 1.79－1.55 (m, 6H),
1.45 (s, 3H), 1.35 (s, 9H), 1.30－1.16 (m, 1H); 13C
NMR (100 MHz, CDCl3) δ: 173.5, 151.2, 150.4, 147.6,
132.8, 130.7, 128.7, 128.7, 127.0, 125.3, 123.8, 119.4,
116.5, 59.0, 51.1, 48.0, 38.9, 38.2, 34.6, 31.4, 26.3, 24.2,
24.0; IR (KBr) ν: 3235, 3084, 2954, 2869, 1771, 1637,
1617, 1512, 1480, 1456, 1384, 1368, 1263, 1248, 1211,
1168, 1087, 1048, 763, 750, 622 cm1; HRMS
1-(3-Methoxyphenyl)-3a-methyl-3H-spiro[cyclo-
penta[c]chromene-2,1'-cyclopentan]-4(3aH)-one (3t)
1
white solid, m.p. 108－110 ℃; H NMR (400 MHz,
(ESI-TOF) m/z calcd for C27H30NaO2, 409.2143 [M＋
＋
CDCl3) δ: 7.32－7.26 (m, 1H), 7.17－7.13 (m, 1H),
7.04 (d, J＝8.0 Hz, 1H), 6.91－6.88 (m, 1H), 6.82－
6.68 (m, 4H), 3.79 (s, 3H), 2.49 (d, J＝13.6 Hz, 1H),
2.17 (d, J＝13.2 Hz, 1H), 1.96－1.88 (m, 1H), 1.79－
1.52 (m, 6H), 1.45 (s, 3H), 1.39－1.36 (m, 1H); 13C
NMR (100 MHz, CDCl3) δ: 173.4, 159.6, 151.2, 147.2,
137.4, 130.8, 129.6, 128.9, 127.0, 123.9, 121.6, 119.1,
116.5, 114.8, 112.9, 59.0, 55.3, 51.1, 48.0, 39.0, 38.3,
26.3, 24.2, 24.0; IR (KBr) ν: 3503, 3066, 2956, 2867,
1771, 1605, 1575, 1455, 1426, 1287, 1209, 1168, 1046,
902, 785, 749, 730, 692 cm1; HRMS (ESI-TOF) m/z
calcd for C24H24NaO3, 383.1623 [M＋Na]＋ ; found
383.1622.
N a ]
;
f o u n d
4 0 9 . 2 1 6 4 .
1-(3-Fluorophenyl)-3a-methyl-3H-spiro[cyclo-
penta[c]chromene-2,1'-cyclopentan]-4(3aH)-one (3x)
White solid, m.p. 92－93 ℃; H NMR (400 MHz,
1
CDCl3) δ: 7.39－7.32 (m, 1H), 7.20－7.15 (m, 1H),
7.08－7.03 (m, 2H), 6.94－6.87 (m, 2H), 6.83－6.79
(m 1H), 6.71－6.69 (m, 1H), 2.50 (d, J＝13.6 Hz, 1H),
2.18 (d, J＝13.6 Hz, 1H), 1.93－1.85 (m, 1H), 1.79－
1.63 (m, 4H), 1.53－1.48 (m, 1H), 1.45 (s, 3H), 1.42－
1.38 (m, 1H); 13C NMR (100 MHz, CDCl3) δ: 173.2,
162.8 (JCF＝245.6 Hz), 151.2, 145.8, 138.3 (JCF＝7.6
Hz), 131.7, 130.2(JCF＝8.4 Hz), 129.2, 126.9, 125.04
(JCF＝2.9 Hz), 123.98, 118.75, 116.71, 116.2 (JCF＝21.2
Hz), 114.6 (JCF＝20.8 Hz), 59.0, 51.2, 48.0, 38.9, 38.3,
26.2, 24.2, 24.0; IR (KBr) ν: 3510, 3067, 2964, 2868,
1771, 1609, 1579, 1455, 1430, 1370, 1263, 1210, 1167,
1086, 1049, 937, 789, 748, 731, 682 cm1; HRMS
(ESI-TOF) m/z calcd for C23H21FNaO2, 371.1423 [M＋
Na]＋; found 371.1420.
3a-Methyl-1-(p-tolyl)-3H-spiro[cyclopenta[c]ch-
romene-2,1'-cyclopentan]-4(3aH)-one (3u)
white
solid, m.p. 127－128 ℃; 1H NMR (400 MHz, CDCl3) δ:
7.20－7.13 (m 3H), 7.05－6.95 (m, 3H), 6.81－6.71 (m,
2H), 2.50 (d, J＝13.6 Hz, 1H), 2.37 (d, J＝12.4 Hz, 3H),
2.17 (d, J＝13.2 Hz, 1H), 1.95－1.87 (m, 1H), 1.74－
1.51 (m, 6H), 1.45 (s, 3H), 1.38－1.33 (d, J＝9.1 Hz,
1H); 13C NMR (100 MHz, CDCl3) δ: 173.5, 151.2,
147.6, 137.2, 132.9, 130.7, 129.2, 129.0, 128.7, 127.0,
123.8, 119.3, 116.5, 58.9, 51.1, 48.0, 38.9, 38.3, 26.3,
24.3, 24.0, 21.3; IR (KBr) ν: 3445, 3024, 2954, 2867,
1773, 1605, 1577, 1480, 1455, 1369, 1247, 1210, 1169,
1085, 1049, 748, 734 cm1; HRMS (ESI-TOF) m/z calcd
for C24H24NaO2, 367.1674 [M＋Na]＋; found 367.1672.
1-(4-Ethylphenyl)-3a-methyl-3H-spiro[cyclopen-
1-(4-Chlorophenyl)-3a-methyl-3H-spiro[cyclop-
enta[c]chromene-2,1'-cyclopentan]-4(3aH)-one (3y)
White solid, m.p. 165－167 ℃; 1H NMR (400 MHz,
CDCl3) δ: 7.37 (d, J＝8.4 Hz, 2H), 7.20－7.16 (m, 1H),
7.10－7.04 (m, 3H), 6.85－6.81 (m, 1H), 6.70－6.68
(m, 1H), 2.49 (d, J＝13.6 Hz, 1H), 2.16 (d, J＝13.2 Hz,
1H), 1.88－1.50 (m, 7H), 1.45 (s, 3H), 1.39－1.34 (m,
1H); 13C NMR (100 MHz, CDCl3) δ: 173.2, 151.2,
146.0 134.5, 133.7 131.7, 130.6, 129.1, 128.9, 126.9,
124.0, 118.8, 116.7, 58.9, 51.2, 48.0, 38.9, 38.3, 26.2,
24.2, 24.0; IR (KBr) ν: 3082, 2956, 2869, 1717, 1637,
1491, 1454, 1394, 1262, 1248, 1169, 1089, 1016, 938,
ta[c]chromene-2,1'-cyclopentan]-4(3aH)-one
(3v)
1
white solid, m.p. 120－121 ℃; H NMR (400 MHz,
CDCl3) δ: 7.20 (d, J＝8.0 Hz, 2H), 7.17－7.13 (m, 1H),
7.04 (d, J＝8.0 Hz, 3H), 6.81－6.77 (m, 1H), 6.73－
6.66 (m, 12.6 Hz, 1H), 2.72－2.66 (m, 2H), 2.48 (d, J＝
13.6 Hz, 1H), 2.16 (d, J＝13.6 Hz, 1H), 1.92－1.86 (m
1H), 1.76－1.54 (m, 6H), 1.45 (s, 3H), 1.38－1.33 (m,
1H), 1.29－1.26 (m, 3H); 13C NMR (100 MHz, CDCl3)
δ: 173.5, 151.2, 147.6, 143.4, 133.1, 130.7, 129.0, 128.7,
127.9, 127.0, 123.8, 119.3, 116.5, 59.0, 51.1, 48.0, 38.9,
38.2, 28.6, 26.3, 24.2, 24.0, 15.3; IR (KBr) ν: 3235,
2962, 2865, 1769, 1637, 1617, 1508, 1455, 1384, 1261,
1209, 1168, 1087, 801, 763, 623 cm1; HRMS
(ESI-TOF) m/z calcd for C25H26NaO2, 381.1830 [M＋
Na]＋; found 381.1840.
901, 828, 763, 622 cm1; HRMS (ESI-TOF) m/z calcd
for C23H21ClNaO2, 387.1128 [M ＋ Na] ; found
387.1125.
＋
General procedure for the synthesis of products 5
Example for the synthesis of 5a To a 10-mL
Schlenk tube, 2-(phenylethynyl)phenyl methacrylate (1a,
0.20 mmol), tosylhydrazide (4a, 0.7 mmol), TBAI (0.02
mmol), and DCE (3.0 mL) as well as TBHP (5.5 mol/L
in decane, 1.0 mmol) were successively added under
argon conditions. The reaction system was then stirred
at 80 ℃ for 24 h as monitored by TLC. After the com-
pletion of the reaction, the resulting mixture was con-
centrated under vacuum. Purification of the crude prod-
1-(4-(tert-Butyl)phenyl)-3a-methyl-3H-spiro[cy-
clopenta[c]chromene-2,1'-cyclopentan]-4(3aH)-one
10
www.cjc.wiley-vch.de
© 2017 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2017, XX, 1—12

Radical-Enabled Bicyclization Cascades of Oxygen-Tethered 1,7-Enynes
uct by flash column chromatography afforded the prod-
uct 5a (petroleum ether/ethyl acetate as eluent).
(ESI-TOF) m/z calcd for C27H24NaO3, 419.1623 [M＋
Na]＋; found 419.1623.
6a,9-Dimethyl-12-phenyl-6a,7-dihydro-6H-
naphtho[2,3-c]chromen-6-one (5a) (major) White
solid, m.p. 169－170 ℃; H NMR (400 MHz, CDCl3)
12-(4-(tert-Butyl)phenyl)-9-methoxy-6a-methyl-
6a,7-dihydro-6H-naphtho[2,3-c]chromen-6-one (5e)
White solid, m.p. 191－192 ℃; H NMR (400 MHz,
1
1
δ: 7.48－7.40 (m, 3H), 7.34－7.26 (m, 1H), 7.24－7.15
(m, 1H), 7.13－7.01 (m, 3H), 6.94－6.89 (m, 2H), 6.68
－6.59 (m, 2H), 3.57－3.51 (m, 1H), 3.35－3.29 (m,
1H), 2.34 (s, 3H), 1.39 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ: 172.8, 150.3, 138.3, 136.4, 133.6, 131.8,
131.3, 129.8, 129.7, 129.4, 128.8, 128.6, 127.7, 127.5,
127.1, 126.5, 123.7, 120.5, 116.9, 42.9, 37.7, 23.1, 21.2;
IR (KBr) ν: 3026, 2971, 2925, 1760, 1607, 1482, 1448,
1218, 1200, 1089, 1065, 820 cm1; HRMS (ESI-TOF)
m/z calcd for C25H20NaO2, 375.1361 [M＋Na]＋; found
375.1364.
9-Methoxy-6a-methyl-12-phenyl-6a,7-dihydro-
6H-naphtho[2,3-c]chromen-6-one (5b) White solid,
m.p. 203－204 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.46
－7.40 (m, 3H), 7.31－7.26 (m, 2H), 7.11－7.07 (m,
1H), 7.02－6.96 (m, 2H), 6.85 (d, J＝1.6 Hz, 1H), 6.68
－6.64 (m, 2H), 6.59－6.56 (m, 1H), 3.82 (s, 3H), 3.56
(d, J＝16.4 Hz, 1H), 3.31 (d, J＝16.4 Hz, 1H), 1.39 (s,
3H); 13C NMR (100 MHz, CDCl3) δ: 172.7, 159.6,
150.2, 138.6, 136.2, 133.8, 130.2, 129.6, 129.2, 128.6,
128.1, 127.7, 127.0, 125.5, 123.7, 120.6, 116.9, 114.4,
111.7, 55.3, 42.8, 38.0, 23.2; IR (KBr) ν: 3057, 2962,
2925, 1767, 1603, 1445, 1283, 1259, 1242, 1215, 1126,
1088, 1035, 802 cm1; HRMS (ESI-TOF) m/z calcd for
C25H20NaO3, 391.1310 [M＋Na]＋; found 391.1311.
9-Methoxy-6a-methyl-12-(p-tolyl)-6a,7-dihydro-
CDCl3) δ: 7.46 (d, J＝8.4 Hz, 2H), 7.17 (s, 2H), 7.10－
6.99 (m, 3H), 6.84 (d, J＝1.6 Hz, 1H), 6.68－6.60 (m,
2H), 6.53－6.51 (m, 1H), 3.82 (s, 3H), 3.56 (d, J＝16.4
Hz, 1H), 3.30 (d, J＝16.4 Hz, 1H), 1.39 (s, 9H), 1.38 (s,
3H); 13C NMR (100 MHz, CDCl3;) δ: 172.8, 159.5,
150.9, 150.2, 136.3, 135.5, 133.8, 129.8, 129.6, 128.5,
128.1, 127.2, 126.0, 125.4, 123.6, 120.7, 116.8, 114.3,
111.7, 55.3, 42.8, 38.1, 34.7, 31.5, 23.2; IR (KBr) ν:
3025, 2961, 1763, 1607, 1499, 1448, 1363, 1284, 1216,
1097, 1026, 843 cm1; HRMS (ESI-TOF) m/z calcd for
C29H28NaO3, 447.1936 [M＋Na]＋; found 447.1934.
6a-Methyl-12-phenyl-6a,7-dihydro-6H-naphtho-
[2,3-c]chromen-6-one (5f) White solid, m.p. 201－
203 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.47－7.43 (m,
3H), 7.29 (d, J＝6.8 Hz, 2H), 7.24－7.20 (m, 2H), 7.15
－7.03 (m, 4H), 6.69－6.61 (m, 2H), 3.58 (d, J＝16.0
Hz, 1H), 3.36 (d, J＝16.4 Hz, 1H), 1.40 (s, 3H); 13C
NMR (100 MHz, CDCl3) δ: 172.6, 150.4, 138.3, 136.4,
133.8, 131.9, 130.3, 129.8, 129.2, 129.1, 128.6, 128.2,
128.2, 127.8, 126.9, 126.4, 123.8, 120.3, 116.9, 42.9,
37.7, 23.1; IR (KBr) ν: 3056, 2963, 2925, 1759, 1602,
1480, 1445, 1261, 1218, 1093, 1023, 802 cm1; HRMS
(ESI-TOF) m/z calcd for C24H18NaO2, 361.1204 [M＋
Na]＋; found 361.1201.
12-(4-Methoxyphenyl)-6a-methyl-6a,7-dihydro-
6H-naphtho[2,3-c]chromen-6-one (5g) White solid,
m.p. 212－213 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.29
－7.26 (m, 1H), 7.24－7.09 (m, 6H), 7.03－6.99 (m,
3H), 6.74－6.69 (m, 2H), 3.88 (s, 3H), 3.56 (d, J＝16.4
Hz, 1H), 3.34 (d, J＝16.4 Hz, 1H), 1.38 (s, 3H); 13C
NMR (100 MHz, CDCl3) δ: 172.7, 159.2, 150.4, 136.0,
134.2, 131.9, 131.4, 130.3, 129.9, 129.0, 128.6, 128.3,
128.07, 126.8, 126.4, 123.9, 120.5, 116.9, 114.6, 55.3,
43.0, 37.7, 23.1; IR (KBr) ν: 3032, 2968, 1756, 1601,
1508, 1449, 1288, 1232, 1216, 1099, 1026, 776 cm1;
HRMS (ESI-TOF) m/z calcd for C25H20NaO3, 391.1310
[M＋Na]＋; found 391.1308.
6H-naphtho[2,3-c]chromen-6-one
(5c)
(major)
White solid, m.p. 101－102 ℃; 1H NMR (400 MHz,
CDCl3) δ: 7.27 (d, J＝6.8 Hz, 2H), 7.22－7.07 (m, 3H),
7.02－6.98 (m, 2H), 6.84 (d, J＝1.6 Hz, 1H), 6.70－
6.63 (m, 3H), 3.82 (s, 3H), 3.55 (d, J＝16.4 Hz, 1H),
3.30 (d, J＝16.4 Hz, 1H), 2.44 (s, 3H), 1.38 (s, 3H); 13C
NMR (100 MHz, CDCl3) δ: 172.8, 159.5, 150.2, 137.4,
136.3, 135.5, 133.8, 130.0, 129.9, 129.6, 128.5, 128.1,
127.3, 125.3, 123.7, 120.7, 116.8, 114.3, 111.7, 55.3,
42.8, 38.1, 23.2, 21.4; IR (KBr) ν: 3022, 2963, 1758,
1606, 1498, 1448, 1312, 1256, 1214, 1113, 1034, 837
cm1; HRMS (ESI-TOF) m/z calcd for C26H22NaO3,
405.1467 [M＋Na]＋; found 405.1474.
12-(4-(tert-Butyl)phenyl)-6a-methyl-6a,7-dihydro-
6H-naphtho[2,3-c]chromen-6-one (5h) White solid,
m.p. 161－162 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.48
(d, J＝8.4 Hz, 2H), 7.28 (d, J＝7.2 Hz, 1H), 7.24－7.15
(m, 5H), 7.12－7.08 (m, 1H), 7.03－7.00 (m, 1H), 6.66
－6.62 (m, 1H), 6.58－6.55 (m, 1H), 3.58 (d, J＝16.4
Hz, 1H), 3.36 (d, J＝16.4 Hz, 1H), 1.39 (s, 9H), 1.39 (s,
3H); 13C NMR (100 MHz, CDCl3) δ: 172.7, 151.0,
150.4, 136.5, 135.1, 134.0, 131.9, 129.9, 128.9, 128.6,
128.2, 128.1, 126.8, 126.5, 126.0, 124.1, 123.7, 120.5,
116.9, 43.0, 37.7, 34.7, 31.5, 23.1; IR (KBr) ν: 3023,
2962, 2865, 1762, 1062, 1482, 1449, 1366, 1218, 1097,
914 cm1; HRMS (ESI-TOF) m/z calcd for C28H26NaO2,
417.1830 [M＋Na]＋; found 417.1829.
12-(4-Ethylphenyl)-9-methoxy-6a-methyl-6a,7-
dihydro-6H-naphtho[2,3-c]chromen-6-one
(5d)
1
White solid, m.p. 175－176 ℃; H NMR (400 MHz,
CDCl3) δ: 7.29－7.26 (m, 2H), 7.15－7.10 (m, 2H),
7.08－7.06 (m, 1H), 7.02－6.99 (m, 2H), 6.83 (d, J＝
2.0 Hz, 1H), 6.68－6.64 (m, 2H), 6.61－6.58 (m, 1H),
3.82 (s, 3H), 3.55 (d, J＝16.4 Hz, 1H), 3.30 (d, J＝16.0
Hz, 1H), 2.76－2.71 (m, 2H), 1.38 (s, 3H), 1.33－1.29
(m, 3H); 13C NMR (100 MHz, CDCl3) δ: 172.8, 159.5,
150.2, 143.8, 136.3, 135.7, 133.8, 130.0, 129.6, 128.6,
128.5, 128.1, 127.2, 125.4, 123.7, 120.7, 116.8, 114.3,
111.6, 55.3, 42.8, 38.1, 28.7, 23.2, 15.6; IR (KBr) ν:
3022, 2967, 1755, 1607, 1597, 1500, 1448, 1333, 1313,
1285, 1233, 1215, 1114, 1098, 1033, 836 cm1; HRMS
6a-Methyl-14-phenyl-6a,7-dihydro-6H-phenanth-
ro[3,2-c]chromen-6-one (5i) (major) White solid,
Chin. J. Chem. 2017, XX, 1—12
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11

Jiang et al.
FULL PAPER
m.p. 214－216 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.28
(d, J＝8.4 Hz, 1H), 7.81－7.77 (m, 1H), 7.65－7.57 (m,
2H), 7.52－7.44 (m, 4H), 7.41－7.30 (m, 2H), 7.26－
7.23 (m, 1H), 7.15－7.12 (m, 1H), 7.09－7.01 (m, 1H),
6.72－6.65 (m, 2H), 4.14 (d, J＝17.2 Hz, 1H), 3.72－
3.66 (m, 1H), 1.49 (s, 3H); 13C NMR (100 MHz, CDCl3)
δ: 172.8, 150.4, 138.8, 136.8, 133.2, 131.6, 130.7, 130.4,
129.6, 129.3, 129.1, 128.5, 127.9, 127.5, 126.7, 126.5,
126.2, 124.2, 123.9, 123.8, 120.3, 117.0, 42.8, 38.2,
33.2, 23.9; IR (KBr) ν: 3053, 2963, 2925, 1758, 1596,
1507, 1449, 1222, 1102, 815 cm1; HRMS (ESI-TOF)
m/z calcd for C28H20NaO2, 411.1361 [M＋Na]＋; found
411.1365.
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Acknowledgement
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We are grateful for financial support from the NSFC
(Nos. 21232004, 21472071, 21602087), PAPD of
Jiangsu Higher Education Institutions, the Outstanding
Youth Fund of Jiangsu Normal University (No.
YQ2015003), and NSF of Jiangsu Province (No.
BK20151163, BK20160212), the Natural Science
Foundation of JSNU (No. 14XLR005), the Qing Lan
Project and NSF of Jiangsu Education Committee (No.
15KJB150006).
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