Synthesis of Carbazoles and Carbazole-Containing Heterocycles via Rhodium-Catalyzed Tandem Carbonylative Benzannulations

Article abstract of DOI:10.1021/acs.joc.6b00212

Polycyclic aromatic compounds are important constituents of pharmaceuticals and other materials. We have developed a series of Rh-catalyzed tandem carbonylative benzannulations for the synthesis of tri-, tetra-, and pentacyclic heterocycles from different types of aryl propargylic alcohols. These tandem reactions provide efficient access to highly substituted carbazoles, furocarbazoles, pyrrolocarbazoles, thiophenocarbazoles, and indolocarbazoles. While tricyclic heterocycles could be derived from vinyl aryl propargylic alcohols, tetra- and pentacyclic heterocycles were synthesized from diaryl propargylic alcohols. The tandem carbonylative benzannulation is initiated by a π-acidic rhodium(I) catalyst-mediated nucleophilic addition to alkyne to generate a key metal-carbene intermediate, which is then trapped by carbon monoxide to form a ketene species for 6π electrocyclization. Overall, three bonds and two rings are formed in all of these tandem carbonylative benzannulation reactions.

Full text of DOI:10.1021/acs.joc.6b00212

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Article
Synthesis of Carbazoles and Carbazole-containing Heterocycles
via Rhodium-Catalyzed Tandem Carbonylative Benzannulations
Wangze Song, Xiaoxun Li, Ka Yang, Xian-liang Zhao, Daniel A. Glazier, Bao-min Xi, and Weiping Tang
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b00212 • Publication Date (Web): 10 Mar 2016
Downloaded from http://pubs.acs.org on March 11, 2016
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The Journal of Organic Chemistry
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Synthesis of Carbazoles and Carbazole-containing Heterocycles via
Rhodium-Catalyzed Tandem Carbonylative Benzannulations
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Wangze Song,† Xiaoxun Li,† Ka Yang,† Xianꢀliang Zhao,† Daniel A. Glazier,‡ Baoꢀmin Xi§,* and
Weiping Tang†,‡,*
† School of Pharmacy, University of WisconsinꢀMadison, Madison, 53705, United States
§ Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical
University, Guangzhou, Guangdong Province 510515, PR China
‡ Department of Chemistry, University of WisconsinꢀMadison, Madison, 53706, United States
ABSTRACT: Polycyclic aromatic compounds are important constituents of pharmaceuticals and other materials. We have develꢀ
oped a series of Rhꢀcatalyzed tandem carbonylative benzannulations for the synthesis of triꢀ, tetraꢀ, and pentacyclic heterocycles
from different types of aryl propargylic alcohols. These tandem reactions provide efficient access to highly substituted carbazoles,
furocarbazoles, pyrrolocarbazoles, thiophenocarbazoles, and indolocarbazoles. While tricyclic heterocycles could be derived from
vinyl aryl propargylic alcohols, tetraꢀ and pentacyclic heterocycles were synthesized from diaryl propargylic alcohols. The tandem
carbonylative benzannulation is initiated by a πꢀacidic rhodium (I) catalystꢀmediated nucleophilic addition to alkyne to generate a
key metalꢀcarbene intermediate, which is then trapped by carbon monoxide to form a ketene species for 6π electrocyclization.
Overall, three bonds and two rings are formed in all of these tandem carbonylative benzannulation reactions.
1. INTRODUCTION
The majority of topꢀselling drugs and many bioactive compounds contain a benzene ring, which is often fused with one or more
additional rings, comprising a polycyclic system. Electrophilic aromatic substitutions are the most widely used methods for the
synthesis of substituted benzene derivatives. However, these methods often rely on the strong directing groups for regioselective
substitution. De novo synthesis of benzene ring by benzannulation will complement existing methods for the synthesis of both
monoꢀ and polycyclic aromatic systems. Very few strategies for de novo synthesis of benzene rings are available and even fewer of
them are general enough for the preparation of various highly substituted polycyclic heterocycles.1 One of the exceptions is Dötzꢀ
Wulff carbonylative benzannulation,2 which has been widely applied to the synthesis of various aromatic compounds including
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complex natural products.3 However, stoichiometric amount of toxic Fischer carbenes are generally employed in this powerful benꢀ
zannulation reaction.
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Tricyclic carbazoles and their related analogues have diverse biological activities.4 For example, natural products glycosinine 1
showed significant antiꢀHIV activity (Figure 1).5 Heptapylline 2 and its derivatives had remarkably selective and potent anticancer
activity.6 Synthetic carbazole DCAP 3 targets bacteria membrane and has broadꢀspectrum antibiotic activity.7 KL001 4 can prevent
ubiquitinꢀdependent degradation of cryptochrome (CRY) by binding to CRY and is a useful small molecule tool for the study of
CRYꢀdependent physiology such as diabetes.8
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Carbazoles often fuse with one or more additional rings to form complex polycyclic systems. For example, mahanimbine 5 has
an additional 2Hꢀpyran ring and this compound showed antiꢀhyperglycemic/antiꢀlipidemic effects in diabetic and obese rats.9 In
addition to pyran ring, carbazole can be fused with other heterocycles such as furan in furostifoline 610 and eustifolineꢀD 7,10a indole
in ancorinazole 8,11 and pyrrole in dictyodendrin A 9.12
We recently reported a Rhꢀcatalyzed tandem annulation and [5+1] cycloaddition for the synthesis of highly substituted carbazoles
11 (Scheme 1).13 The 3ꢀhydroxyꢀ1,4ꢀenyne moiety highlighted in 10 served as the novel fiveꢀcarbon component for the [5+1] cyꢀ
cloaddition. We proposed that intermediates 12, 13, and 14 might be involved in this tandem process. Overall, three bonds and two
rings are formed in the tandem carbonylative benzannulation of vinyl aryl propargylic alcohols.
In the oxidative cyclization step, the OH group in 12 is the leaving group while Bocꢀactivated aniline serves as nucleophile. In
our previous communication,13 the activating group for the aniline nucleophile was limited to Boc in all examples. In this article,
we try to further expand the scope of the activating group to different sulfonamides and found that the tandem reaction worked well
for terminal alkynes. Interestingly, we observed unexpected product 16 for substrates with an internal alkyne such as 15 in Scheme
2.
More importantly, we discovered that the alkene moiety in 10 could be replaced by an aromatic ring in substrates 17 and 19 when
sulfonamide was employed as the nucleophile (Scheme 2). The scope of the tandem carbonylative benzannulation is now expanded
from the formation of tricyclic carbazoles to the construction of tetracyclic furocarbazoles 18a, thiophenocarbazole 18b, pyrroloꢀ
carbazole 18c, and even pentacyclic indolocarbazole 20. Being able to replace the vinyl group in propargylic alcohol 10 with the
aromatic ring in substrates 17 and 19 also suggests that there are other potential mechanistic pathways besides the oxidative cyclizaꢀ
tion mechanism shown in Scheme 1.
In this article, we report the full scope of the Rhꢀcatalyzed tandem carbonylative benzannulation for the synthesis of tricyclic carꢀ
bazoles from vinyl aryl propargylic alcohols, the synthesis tetraꢀ and pentacyclic heterocycles from diaryl propargylic alcohols for
the first time, and potential mechanisms involving metal carbene intermediates that can account for all of our experimental results.14
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Figure 1. Selected Carbazoles and Carbazole-containing Heterocycles
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Scheme 1. 3-Hydroxy-1,4-enyne as a New 5-Carbon Building Block for [5+1] Cycloaddition
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(E = aryl sulfonyl group)
Rx
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Rx
OH
CO
Rh(I) cat.
N
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Ph
E
NHE
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Ph
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OH
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Rh(I) cat.
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E
17a, X = O
17b, X = S
18a, X = O
18b, X = S
Rx
Rx
OH
N
Ts
N
CO
Ts
Rh(I) cat.
N
HO
NHE
NHE
17c
E
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E'
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Rx
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OH
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Rh(I) cat.
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E
HO
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Scheme 2. Polycyclic Heterocycles Derived from Vinyl Aryl Propargylic Alcohols and Diaryl Propargylic Alcohols
2. RESULTS AND DISCUSSION
As reported in our previous communication,13 substrate 21a was prepared by sequential addition of vinyl and alkynyl Grignard
reagents to the corresponding carboxylic acid derivative (Table 1). Among all conditions we screened, we found that product 22a
was prepared in good yields in the presence of [Rh(CO)2Cl]2 catalyst and CO (1 atm). The scope of the tandem annulation and
[5+1] cycloaddition was investigated for the synthesis of various substituted carbazoles and related heterocycles. Various substituꢀ
ents including alkyl, cyclopropyl, and aryl groups could be tolerated on the alkene termini. Substrate 21b is one of many examples.
It is worth to point out that it would be difficult to introduce some of these substituents to carbazoles by existing methods.4a,4b Variꢀ
ous substituents on the aniline ring such as bromine, methoxy, and trifluoromethyl groups could all be tolerated.13 We also found
that electronꢀpoor ligand (CF3CH2O)3P was beneficial for the formation of product 22c and 22d.15 No desired product was obtained
when both alkene and alkyne have a substituent as shown in substrate 21e. Phenol 23 could also participate in this tandem carꢀ
bonylative benzannulation to afford dibenzofuran product 24.
Table 1. Representative Examples for the Rh-Catalyzed Tandem Annulation and [5+1] Cycloaddition Using Boc-Aniline as
Nucleophiles for the Synthesis of Carbazoles and Dibenzofurans13
Substrate
Product
Yield (%)a
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21a
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22b
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OH
Ar
NHBoc
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21b, Ar = pFC6H4
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21c, R = CH3
21d, R = Ph
36,a 81b
56b
22c
22d
-
21e, Ar = pFC6H4
ꢀ
Complexa,b
67c
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a. Unless noted otherwise, Condition A: [Rh(CO)2Cl]2 (5 mol %), DCE, CO (1 atm), 60 oC. Yields were isolated yields. Condition B:
b.
o
c.
[Rh(CO)2Cl]2 (5 mol %), (CF3CH2O)3P (20 mol %), THF, CO (1 atm), 60 C. Condition C: [Rh(CO)2Cl]2 (5 mol%), dioxane, CO (1
atm), 60 oC.
Under condition A in Table 1, product 22f (Scheme 3) was isolated in 52% yield. When we examined this substrate in the presꢀ
ence of (CF3CH2O)3P ligand, byproduct 22f’ was isolated in 32% yield in addition to 56% of the desired product 22f. Substrates 25
with two methyl groups on the terminal position of the alkene afforded cyclohexadienones 26 efficiently in 75% yield.
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Scheme 3. Generation of non-Carbazole Products from 3-Hydroxy-1,4-enynes13
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A number of carbazole alkaloids have a hydroxy or alkoxy substituent on the 2ꢀposition.4a,4b Our tandem annulation [5+1] cyꢀ
cloaddition method is well suited for these natural products. To demonstrate this, we prepared natural products 27, 1, and 5 as
shown in Scheme 4.16 The synthesis of natural product 2ꢀmethoxyꢀ3ꢀmethylcarbazole 2717 represents a formal synthesis of glyꢀ
cosinine 1 (or Oꢀmethylmukonal),17a,17b,18 which has significant antiꢀHIV activity.5 Intermediate 28 could be converted to bioactive
natural product mahanimbine 59,19 by annulation with citral using ethylenediammonium diacetate (EDDA) reagent.20 The last annuꢀ
lation step was reported for the synthesis of 5,19 but the yield was only 35%. Ma and his coworkers recently reported the preparation
of natural products mukoenineꢀA 29 and heptaphylline 2 from intermediate 28.21 The transformations included either a sequence of
Oꢀallylation and Claisen rearrangement or sequential Oꢀallylation, DDQ oxidation, and Claisen rearrangement. We thus realized the
formal syntheses of these two important bioactive natural products as well.6
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Scheme 4. Synthesis of Carbazole Cores in Natural Products
We have seen dramatically different behaviors between Boc and Ts activated anilines in Rhꢀcatalyzed reactions recently.22 We
next prepared three sulfonamides substrates 30aꢀc for the tandem annulation [5+1] cycloaddition (Table 2). Surprisingly, the reacꢀ
tion occurred smoothly at room temperature. Previously, heating was required when Boc was employed as the activating group in
substrate 21a. The isolated yields of products 31a and 31c were slightly higher than that of 31b. We then further tested substrates
30d and 30e and found that they behaved similarly.
When we had phenyl substituted internal alkyne in substrate 21d, product 22d was isolated in moderate yield. We then prepared
sulfonamides 30f and 30g to test if the yield of the tandem annulation [5+1] cycloaddition can be improved for substrates with a
phenyl substituted internal alkyne. Surprisingly, products with a cyclopentadiene moiety were formed. We did not observe any
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[5+1] benzannulation product. When we have substituents on both the alkene and alkyne, similar cyclopentadiene product 33 was
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isolated in 78% yield.
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Table 2. Using Sulfonamides as Nucleophilesa
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substrate
Product
Yield (%)
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30a, R = CH3, R’ =H
30b, R = NO2, R’ = H
30c, R = CH3O, R’ = H
30d, R = R’ = CH3
81
70
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86
82
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31b
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31e
30e, R = CH3O, R’ =
CH3
30f, R = CH3
57b
58b
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32b
30g, R = CH3O
78
30h
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a. Unless noted otherwise, Condition A: [Rh(CO)2Cl]2 (5 mol %), DCE, CO (1 atm), rt, 8ꢀ12 h. Yields are isolated yields. b. Condition
B: [Rh(CO)2Cl]2 (5 mol %), (CF3CH2O)3P (20 mol %), DCE, CO (1 atm), 60 oC, 8ꢀ12 h.
As discussed at the beginning, many polycyclic heterocycles have carbazoles fused with additional carboꢀ or heterocycles. We
envisioned that we might be able to access tetracyclic heterocycles by replacing the alkene moiety of 3ꢀhydroxyꢀ1,4ꢀenyne with an
aromatic ring (Scheme 5). When substrate 3423 was treated with Rhꢀcatalyst in the presence of a CO balloon, only trace amount of
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tetracyclic product 35 was observed, which was very encouraging because a challenging dearomatization step was involved in this
process. Under 10 atm of CO, phenyl fused carbazole product 35 could be isolated in 66% yield.
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Scheme 5. Rh-catalyzed Carbonylative Benzannulation of Diaryl Propargylic Alcohols
We reasoned that breaking the aromaticity of a nonꢀbenzene heterocycle would be easier than benzene ring itself.24 Substrate
36a25 with a furan ring was then prepared (Table 3). In the presence of just a CO balloon, product 37a was obtained in 60% yield
(entry 1, Table 3). Simply lowering the temperature to room temperature, the yield based on 1H NMR was improved to 79% (entry
2).
No or trace amount of desired product was observed for cationic [Rh(COD)2]BF4 or Wilkinson’s catalyst Rh(Ph3P)3Cl (entries 3
and 4). Lower yields were obtained in the presence of phosphine ligand (4ꢀCF3C6H4)3P (entries 5 and 6). The highest yield was
obtained in DCE among all solvents we screened including DCM, CHCl3, THF, dioxane and toluene. We also investigated a few
other catalysts. However, no desired product was observed in the presence of [Ir(COD)Cl]2, [Ir(CO)(PPh3)2Cl], Pd(OAc)2, PtCl2, or
Au(PPh3)Cl (entries 7ꢀ11).
Table 3. Screening of Conditions for Substrate 36aa
entry
conditions
yield of 37a (%)b
1
2
3
4
5
[Rh(CO)2Cl]2 (5 mol %), 60 oC
[Rh(CO)2Cl]2 (5 mol %), rt
[Rh(COD)2]BF4 (5 mol %), rt
[Rh(PPh3)3Cl] (5 mol %), rt
[Rh(COD)Cl]2 (5 mol %),
60
79
0
trace
trace
(4ꢀCF3C6H4)3P (30 mol %), rt
[Rh(COD)Cl]2 (5 mol %),
6
32
(4ꢀCF3C6H4)3P (30 mol %), 60 oC
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7
[Ir(COD)Cl]2 (5 mol %)
[Ir(CO)(PPh3)2Cl] (5 mol %)
Pd(OAc)2 (5 mol %)
PtCl2 (5 mol %)
0
0
0
0
0
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5
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11
Au(PPh3)Cl (5 mol %)
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12
b.
1
a. Conditions: 1,2ꢀdichloroethane (DCE), CO (1 atm), 6 h, unless noted otherwise. The yield was determined by H NMR of crude
product using CH2Br2 as the internal standard.
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A variety of diaryl propargylic alcohols were prepared to explore the scope of the Rhꢀcatalyzed carbonylative benzannulation for
the synthesis of tetraꢀ and even pentacyclic heterocycles (Table 4). Furocarbazoles 37a was isolated in 73% yield under condition
A. The effect of the activating group was examined by replacing the Ts group in 36a with paraꢀnitrobenzene sulfonamide or paraꢀ
methoxybenzene sulfonamide in 36b or 36c, respectively. It was found that the electronꢀdonating sulfonamide worked better and
afforded 76% yield of product 37c, comparable to the yield of 37a.
Substrates 36dꢀ36g were prepared to examine the effect of substituents on the furan ring. The yields were generally higher for
products 37dꢀ37f under heating conditions. An unexpected fragmentation reaction occurred for more electronꢀdeficient furan in
substrate 36g and afforded ketone 37g at room temperature.
Substrates 36hꢀ36k were prepared to examine the effect of substituents on the benzene motif of aniline. Having an alkyl substituꢀ
ent on the orthoꢀposition did not impact the reaction much. Both electronꢀwithdrawing and electronꢀdonating groups could be tolerꢀ
ated. The bromine substituent in product 37k remained unchanged and could be further functionalized by Pdꢀcatalyzed crossꢀ
coupling reactions.
We then explored heterocycles beyond furan. Carbazoles fused with a thiophene such as 37l and 37m could be prepared successꢀ
fully. No desired product was observed for substrate 36n bearing a 2ꢀsubstituted Nꢀmethyl pyrrole. On the other hand, product 37o
could be prepared from substrate 36o with a 3ꢀsubstituted Nꢀtosyl pyrrole. Indolyl fused carbazole 37p was prepared from substrate
36p in 71% yield, demonstrating the feasibility of synthesizing pentacyclic heterocycles from relative simple diaryl propargylic
alcohols by this tandem reaction. We did not observe any desired product for substrates 36q and 36r with an internal alkyne, reꢀ
gardless of the activating group on aniline nitrogen.
Table 4. Scope of Tandem Annulation and [5+1] Cycloaddition for the Synthesis of Polycyclic Heterocyclesa
substrate
36a
36b
36c
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(Ar = pNO2C6H4)
(Ar = pCH3OC6H4)
36d
36e
1
2
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5
6
7
product
37b
37c
37a
37e
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9
37d
(Ar = pNO2C6H4)
(Ar = pCH3OC6H4)
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yield (%)
73
42
76
64b
55b
substrate
36f
36g
36h
36j
36i
37g
product
37h
37j
37f
37i
yield (%)
61b
51
54
58
44
substrate
36o
36l
36m
36k
36n
_
37m
product
37o
37l
37k
yield (%)
substrate
60
63
53
_
55b
36p
36q
36r
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product
-
-
1
2
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5
6
37p
7
8
yield (%)
71
Complex mixture
Complex mixture
9
a. Unless otherwise noted, Condition A was employed: [Rh(CO)2Cl]2 (5 mol%), DCE, CO (1 atm), rt, 6ꢀ12h. Yields were isolated yields.
b. Condition B: 60 oC.
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Previously, we26 and others27 have demonstrated that 3ꢀacyloxyꢀ1,4ꢀenyne 38 can serve as the fiveꢀcarbon component in Rhꢀ
catalyzed [5+1] cycloaddition and we also extended it to [5+2] cycloaddition15,28 as shown in Scheme 6A. DFT calculations sugꢀ
gested a rhodiumꢀmediated concerted oxidative cyclization accompanied by 1,2ꢀacyloxy migration as shown in 39 for the formation
of metallacycle 40 from ester 38.29 Based on this, we proposed the mechanism for the tandem annulation and [5+1] cycloaddition in
Scheme 6B. A new metallacycle 42 might be generated for cycloadditions by replacing the ester group in enyne 39 by a OH leaving
group and a BocNH nucleophile in 1,4ꢀenyne 41. Insertion of CO will produce cyclohexadiene intermediate 43, which can immediꢀ
ately undergo aromatization to yield products 22a or 31a. Alternatively, a 6π electrocyclic ring opening can afford carbene 44,
which can undergo CO insertion to afford ketene 45.
An alternative mechanism involving the formation of Rh(I) carbene 44 by eliminating water from intermediate 47 can also be
proposed (Scheme 6C). Previously, we30 and others31 have generated metal carbenes from propargylic ethers by eliminating methaꢀ
nol from a similar intermediate. The dienyl metal carbene 44 can then undergo CO insertion, 6π electrocyclization, and aromatizaꢀ
tion to yield products 22a or 31a. The formation of lactone byproduct 22e’ from substrate 21e may be explained by the generation
of ketene 48, carboxylic acid 49, and a relatively stable tertiary carbocation 50 (Scheme 6D). The isolation of byproduct 22e’ supꢀ
ports the involvement of metal carbene and ketene intermediates.
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Scheme 6. Proposed Mechanisms for the Tandem Annulation [5+1] Cycloaddition of 3-Hydroxy-1,4-Enynes with CO
We observed the formation of product 32a from substrate 30f with a tosyl amide and a phenylacetylene moiety (Scheme 7). Apꢀ
parently, the CO insertion to metallacycle 52 or the corresponding metal carbene intermediate 51 is much slower than the reductive
elimination of metallacycle 52. Interestingly, when the nitrogen nucleophile was switched to Bocꢀaniline in substrate 21d, the deꢀ
sired tandem annulation [5+1] cycloaddition product 22d was obtained. We hypothesize that the coordination of carbonyl oxygen in
53 prevents the formation of the corresponding metallacyclohexadiene.22 Carbazole fused with a fiveꢀmembered ring product was
therefore not observed.
In the case of diaryl propargylic alcohol substrate 36a, the furan moiety is less likely to coordinate to rhodium metal than the isoꢀ
lated alkene in enynes 21a or 30a. The mechanism for the tandem carbonylative benzannulation of substrate 36a is then proposed in
Scheme 8 based on Scheme 6C. The tandem reaction is initiated by acidic Rhꢀmediated nucleophilic addition of sulfonamide nitroꢀ
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gen to alkyne as shown in complex 55. Elimination of a water molecule from intermediate 56 will afford Rh(I) carbene 57. Inserꢀ
tion of CO, 6π electrophilic ring closure accompanied by dearomatization of the furan ring, and reꢀaromatization will furnish final
product 37a. FriedelꢀCrafts acylation through intermediate 60 is also a possible pathway.
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Scheme 7. Proposed Mechanism for the Divergent Reactivity of Metal Carbenes Derived from 3-Hydroxy-1,4-enynes
Scheme 8. Proposed Mechanism for Rh-catalyzed Carbonylative Benzannulation of Diaryl Propargylic Alcohols
3. CONCLUSION
In summary, we have developed a series of carbonylative benzannulation for the synthesis of substituted carbazoles and carbaꢀ
zoles fused with various heterocycles from relative simple propargylic alcohols. In most of these transformations, one CꢀN bond
and two CꢀC bonds are formed, while classical cycloadditions generally involve the construction of just two bonds. The strategy of
using propargylic alcohol as the Rh(I) carbene precursor should have broad implications in transition metal catalysis and metal carꢀ
bene chemistry.
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4. EXPERIMENTAL SECTION
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General Information. Unless otherwise noted, all reactions in nonꢀaqueous media were conducted under dry argon in glassware
that had been ovenꢀdried prior to use. Anhydrous solutions of reaction mixtures were transferred via an ovenꢀdried syringe or canꢀ
nula. All solvents were dried prior to use. Thin layer chromatography was performed using precoated silica gel plates. Flash column
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chromatography was performed with silica gel (40ꢀ63µm). Infrared spectra (IR) were obtained as neat oils. H and 13C Nuclear
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magnetic resonance spectra (NMR) were obtained on 400 MHz or 500 MHz recorded in ppm (δ) downfield of TMS (δ = 0) in
CDCl3. Signal splitting patterns were described as singlet (s), doublet (d), triplet (t), quartet (q), quintet (quint), or multiplet (m),
with coupling constants (J) in hertz. High resolution mass spectra (HRMS) were performed on an Electron Spray Injection (ESI)
TOF mass spectrometer. The preparation procedures and characterization data for all substrates and products in Table 1, Schemes 3
and 4 except 21e have been reported in our communication.13 Substrate 21e was prepared according to previously reported proceꢀ
dure.13
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(E)-tert-butyl (2-(1-(4-fluorophenyl)-3-hydroxyhex-1-en-4-yn-3-yl)phenyl)carbamateb (21e)
106 mg, 56% over 2 steps. Yellow oil. 1H NMR (400 MHz, CDCl3, TMS): δ 8.10 (s, 1H), 7.87 (d, J = 8.0 Hz, 1H), 7.71 (d, J = 8.0
Hz, 1H), 7.36 ꢀ7.29 (m, 3H), 7.05 (t, J = 7.6 Hz, 1H), 6.98 (t, J = 8.8 Hz, 2H), 6.787 (d, J = 15.6 Hz, 1H), 6.29 (d, J = 15.6 Hz, 1H),
3.15 (s, 1H), 1.98 (s, 3H), 1.37 (s, 9H). 13C NMR (100 MHz, CDCl3): δ 162.7 (d, J = 246.0 Hz), 153.4, 137.1, 132.4 (d, J = 3.3 Hz),
130.8, 130.7 (d, J = 2.0 Hz), 129.3, 128.7, 128.6, 128.5, 127.4, 123.1, 115.6 (d, J = 21.5 Hz), 85.8, 80.2, 79.3, 73.6, 28.4, 4.1. IR
(neat) ν 3377, 2981, 1587, 1509, 1445, 1265, 1231, 1158. HRMS (ESI) m/z calcd for C23H24FNO3 (M+Na)+ 404.1632, found
404.1638.
General strategy for the preparation of substrates 30a-30h in Table 2 is show in Scheme 9:
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Scheme 9. Synthesis of Substrates 30h and 30f and Intermediates for Other Substrates in Table 2
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Procedures for the preparation of 30h and 30f: To a stirred solution of commercially available 2ꢀanimobenzoic acid E1 (2.1 g,
o
10 mmol) in anhydrous THF (80 mL) was added 1,1'ꢀcarbonyldiimidazole (1.6g, 10 mmol) at 0 C under argon atmosphere. The
reaction mixture was allowed to warm to room temperature and stirred for 2 h, then a suspension of N,Oꢀdimethylhydroxylamine
hydrochloride (0.97g, 10 mmol) and Et3N (1.0g, 10 mmol) in THF (20 mL) was added and the reaction mixture was stirred overꢀ
night. When the reaction was complete as determined by TLC, the volatile solvent was removed under reduced pressure. The resiꢀ
due was poured into H2O (100 mL). The pH was adjusted to neutral with 5% NaOH solution. The mixture was extracted with ethyl
acetate (3 × 50 mL). The combined organic layers were washed with brine (1 × 100 mL), dried over anhydrous Na2SO4, filtered and
concentrated in vacuo. The residue was purified by flash column chromatography (hexane/ethyl acetate = 50 : 50) to yield Weinreb
amide E2 (2.2g, 86%) as a white solid.
To a stirred solution of the above Weinreb amide E2 (2.2 g, 8.6 mmol) in anhydrous THF (80 mL) was added Boc anhydride
(1.8g, 9.0 mmol) at room temperature. The reaction mixture was stirred overnight under reflux. When the reaction was complete as
determined by TLC, the volatile solvent was removed under reduced pressure. The residue was purified by flash column chromaꢀ
tography (hexane/ethyl acetate = 85 : 15) to give the corresponding Bocꢀaniline product E3 (2.5 g, 90%) as a white solid.
To a stirred solution of Weinreb amide E2 (360 mg, 2 mmol) in pyridine (2.5 mL) was added tosyl chloride (477 mg) and the reꢀ
sulting solution was stirred at 105 oC overnight under argon. The reaction mixture was cooled to room temperature and diluted with
EtOAc. The mixture was washed with 3M HCl and brine, dried over Na2SO4 and concentrated under vacuum. The resulting residue
was purified with flash column chromatography (10ꢀ30% EtOAc in hexanes) to give the pure product E4 (541 mg, 81%) as a white
solid.
To a stirred solution of Weinreb amide E2 (360 mg, 2 mmol) in pyridine (2.5 mL) was added pꢀnitrobenzenesulfonyl chloride
(553 mg) and the resulting solution was stirred at 105 oC overnight under argon. The reaction mixture was cooled to room temperaꢀ
ture and diluted with EtOAc. The mixture was washed with 3M HCl and brine, dried over Na2SO4 and concentrated under vacuum.
The resulting residue was purified with flash column chromatography (10ꢀ30% EtOAc in hexanes) to give the pure product E5 (613
mg, 84%) as a white solid.
To a stirred solution of Weinreb amide E2 (360 mg, 2 mmol) in pyridine (2.5 mL) was added pꢀmethoxybenzenesulfonyl chloꢀ
ride (517 mg) and the resulting solution was stirred at 105 oC overnight under argon. The reaction mixture was cooled to room temꢀ
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perature and diluted with EtOAc. The mixture was washed with 3M HCl and brine, dried over Na2SO4 and concentrated under vacꢀ
uum. The resulting residue was purified with flash column chromatography (10ꢀ30% EtOAc in hexanes) to give the pure product
E6 (560 mg, 80%) as a white solid.
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To a stirred solution of amide E4 (0.43 g, 1.5 mmol) in anhydrous THF (20 mL) was added 1ꢀpropynylmagnesium bromide soluꢀ
tion in THF (0.5 M, 10.0 mL, 5.0 mmol) at 0oC. The reaction mixture was allowed to warm to room temperature and stirred overꢀ
night. When the reaction was completed as determined by TLC, the reaction mixture was poured into iceꢀHCl (4 M) and extracted
with ethyl acetate (3 × 20 mL). The combined organic layers were washed with brine (1 × 60 mL), dried over anhydrous Na2SO4,
filtered and concentrated in vacuo. The residue was purified by flash column chromatography (25% EtOAc in hexanes) to yield the
ynone intermediate (224 mg, 50%) as a yellow solid. To a stirred solution of this ynone (115 mg, 0.38 mmol) in THF (5 mL) was
added 1ꢀpropenylmagnesium bromide solution in THF (0.5 M, 6.0 mL, 3.0 mmol) at ꢀ78oC. After the addition was completed, the
reaction was stirred for 7h at room temperature. When the reaction was completed as determined by TLC, the reaction mixture was
quenched by addition of saturated aqueous ammonium chloride (5 mL) and extracted with Et2O (3×10 mL). The combined organic
layers were washed with brine, dried over anhydrous Na2SO4, and concentrated in vacuo. The residue was purified by flash column
chromatography (25 % EtOAc in hexanes) to yield pure product 30h (105 mg, 78%) as a colorless oil.
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To a stirred solution of amide E4 (0.56 g, 2.0 mmol) in anhydrous THF (40 mL) was added vinylmagnesium bromide solution in
THF (1.0 M, 6.0 mL, 6.0 mmol) at 0oC. The reaction mixture was allowed to warm to room temperature and stirred for 4 h. When
the reaction was completed as determined by TLC, the reaction mixture was poured into saturated aqueous ammonium chloride
(100 mL) and extracted with ethyl acetate (3 × 50 mL). The combined organic layers were washed with brine (1 × 100 mL), dried
over anhydrous Na2SO4, filtered and concentrated in vacuo. The residue was purified by flash column chromatography (10%
EtOAc in hexanes) to yield the enone intermediate (420 mg, 86%) as a colorless oil. To a stirred solution of phenylacetylene (345
mg, 4.2 mmol) in anhydrous THF (30 mL) was added nꢀBuLi in hexane (2.5 M, 1.7 mL, 4.2 mmol) at ꢀ78 oC. After stirring for 30
min at ꢀ78 oC, the enone intermediate (511 mg, 1.7 mmol) in THF (5 mL) was added to the reaction mixture dropwise. After the
addition was completed, the reaction was stirred for 2 h at ꢀ78 oC. When the reaction was completed as determined by TLC, the
reaction mixture was quenched by addition of saturated aqueous ammonium chloride (100 mL) and extracted with Et2O (3×50 mL).
The combined organic layers were washed with brine, dried over anhydrous Na2SO4, and concentrated in vacuo. The residue was
purified by flash column chromatography (15% EtOAc in hexanes) to yield pure product 30f (582 mg, 85%) as a colorless oil.
Other substrates in Table 2 were prepared according to the above procedures.
N-(2-(3-hydroxypent-1-en-4-yn-3-yl)phenyl)-4-methylbenzenesulfonamide (30a) 176 mg, 54% over 4 steps. Colorless oil. 1H
NMR (500 MHz, CDCl3, TMS): δ 8.69 (s, 1H), 7.74 (d, J = 10.0 Hz, 2H), 7.60 (d, J = 10.5 Hz, 1H), 7.51 (d, J = 9.5 Hz, 1H), 7.26ꢀ
7.21 (m, 3H), 7.01 (t, J = 10.0 Hz, 1H), 5.90 (dd, J = 21.0, 12.5 Hz, 1H), 5.49 (d, J = 21.5 Hz, 1H), 5.17 (d, J = 12.5 Hz, 1H), 2.96
(s, 1H), 2.82 (s, 1H), 2.37 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 143.9, 138.7, 137.3, 136.2, 129.8, 129.7, 128.8, 128.3, 127.7,
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123.7, 120.2, 116.4, 83.0, 77.6, 74.4, 21.8. IR (neat) ν 3055, 2359, 1622, 1475, 1367, 1266, 1119, 1091, 953, 813. HRMS (ESI) m/z
calcd for C18H17NO3S (M+Na)+ 350.0821, found 350.0818.
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N-(2-(3-hydroxypent-1-en-4-yn-3-yl)phenyl)-4-nitrobenzenesulfonamide (30b) 200 mg, 56% over 4 steps. Yellow oil. H
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NMR (500 MHz, CDCl3, TMS): δ 8.93 (s, 1H), 8.27 (d, J = 9.0 Hz, 2H), 8.02 (d, J = 8.5 Hz, 2H), 7.63 (d, J = 8.0 Hz, 1H), 7.51 (d,
J = 8.0 Hz, 1H), 7.29 (t, J = 7.5 Hz, 1H), 7.08 (t, J = 7.5 Hz, 1H), 5.92 (dd, J = 17.0, 10.0 Hz, 1H), 5.49 (d, J = 17.0 Hz, 1H), 5.18
(d, J = 10.0 Hz, 1H), 3.00 (s, 1H), 2.80 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 150.4, 145.9, 138.7, 135.3, 130.0, 129.3, 128.9,
128.7, 124.7, 124.3, 120.5, 116.7, 82.7, 77.8, 74.4. IR (neat) ν 3055, 2360, 1600, 1470, 1267, 1108, 1094, 940, 831. HRMS (ESI)
m/z calcd for C17H14N2O5S (M+Na)+ 381.0521, found 381.0529.
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N-(2-(3-hydroxypent-1-en-4-yn-3-yl)phenyl)-4-methoxybenzenesulfonamide (30c) 182 mg, 53% over 4 steps. Colorless oil.
1H NMR (500 MHz, CDCl3, TMS): δ 8.63 (s, 1H), 7.79 (d, J = 9.0 Hz, 2H), 7.60 (d, J = 8.5 Hz, 1H), 7.54 (d, J = 8.0 Hz, 1H), 7.26ꢀ
7.24 (m, 1H), 7.01 (t, J = 7.5 Hz, 1H), 6.89 (d, J = 9.0 Hz, 2H), 5.93 (dd, J = 17.0, 10.0 Hz, 1H), 5.51 (d, J = 17.0 Hz, 1H), 5.20 (d,
J = 10.0 Hz, 1H), 3.82 (s, 3H), 2.87 (s, 1H), 2.84 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 163.1, 138.5, 136.1, 131.7, 129.6, 128.6,
128.1, 123.4, 120.0, 116.2, 114.1, 82.8, 77.3, 74.2, 55.6. IR (neat) ν 3299, 3055, 1581, 1497, 1264, 1157, 1096, 939, 835. HRMS
(ESI) m/z calcd for C18H17NO4S (M+Na)+ 366.0770, found 366.0757.
N-(2-(3-hydroxyhex-4-en-1-yn-3-yl)phenyl)-4-methylbenzenesulfonamide (30d) 170 mg, 50% over 4 steps. Colorless oil. E/Z
= 2:1 1H NMR (400 MHz, CDCl3, TMS): δ major isomer: 8.80 (s, 1H), 7.75 (d, J = 10.8 Hz, 2H), 7.58 (d, J = 8.0 Hz, 1H), 7.51 (d,
J = 8.0 Hz, 1H), 7.26ꢀ7.19 (m, 3H), 7.02ꢀ6.97 (m, 1H), 5.99 (dq, J = 15.4, 6.4 Hz, 1H), 5.60 (d, J = 15.6 Hz, 1H), 2.88 (s, 1H), 2.79
(s, 1H), 2.37 (s, 3H), 1.69 (d, J = 6.8 Hz, 3H) . 13C NMR (125 MHz, CDCl3): δ 143.9, 137.4, 136.1, 130.4, 132.2, 129.8, 129.6,
128.5, 128.3, 127.6, 123.6, 120.0, 83.6, 77.2, 74.2, 21.8, 17.6. IR (neat) ν 2349, 1642, 1469, 1334, 1265, 1161, 1093, 897. HRMS
(ESI) m/z calcd for C19H19NO3S (M+Na)+ 364.0977, found 364.0964.
N-(2-(3-hydroxyhex-4-en-1-yn-3-yl)phenyl)-4-methoxybenzenesulfonamide (30e) 164 mg, 46% over 4 steps. Colorless oil.
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E/Z = 4:1 (The two isomers were partially separated after column chromatography.) H NMR (500 MHz, CDCl3, TMS): δ major
isomer: 8.73 (s, 1H), 7.81 (d, J = 11.5 Hz, 2H), 7.58 (d, J = 8.0 Hz, 1H), 7.51 (d, J = 8.0 Hz, 1H), 7.22 (t, J = 8.0 Hz, 1H), 7.00 (t, J
= 7.5 Hz, 1H), 6.89 (d, J = 12.0 Hz, 2H), 6.03ꢀ5.98 (m, 1H), 5.60 (d, J = 15.5 Hz, 1H), 3.82 (s, 3H), 2.81 (s, 1H), 2.75 (s, 1H), 1.71
(d, J = 7.0 Hz, 3H) . 13C NMR (125 MHz, CDCl3): δ 163.3, 136.2, 132.2, 132.0, 129.8, 129.6, 129.4, 128.6, 128.3, 123.5, 120.0,
114.3, 83.6, 77.2, 74.2, 55.8, 17.6. IR (neat) ν 3055, 1586, 1468, 1254, 1158, 1046, 835. HRMS (ESI) m/z calcd for C19H19NO4S
(M+Na)+ 380.0932, found 380.0927.
N-(2-(3-hydroxy-5-phenylpent-1-en-4-yn-3-yl)phenyl)-4-methylbenzenesulfonamide (30f) 582 mg, 50% over 4 steps. Colorꢀ
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less oil. H NMR (500 MHz, CDCl3, TMS): δ 8.83 (s, 1H), 7.74 (d, J = 8.5 Hz, 2H), 7.61ꢀ7.58 (m, 2H), 7.48ꢀ7.46 (m, 2H), 7.35ꢀ
7.31 (m, 3H), 7.23 (t, J = 8.0 Hz, 1H), 7.15 (d, J = 8.0 Hz, 2H), 7.02 (t, J = 7.5 Hz, 1H), 5.99 (dd, J = 17.0, 10.0 Hz, 1H), 5.53 (d, J
= 17.0 Hz, 1H), 5.18 (d, J = 10.5 Hz, 1H), 3.05 (s, 1H), 2.33 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 143.9, 139.1, 137.3, 136.3,
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132.0, 129.9, 129.7, 129.7, 129.3, 128.4, 127.7, 127.5, 123.6, 121.9, 119.9, 116.0, 89.3, 88.1, 74.9, 21.7. IR (neat) ν 3239, 2924,
1584, 1492, 1333, 1166, 1090, 813, 755. HRMS (ESI) m/z calcd for C24H21NO3S (M+Na)+ 426.1134, found 426.1117.
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N-(2-(3-hydroxy-5-phenylpent-1-en-4-yn-3-yl)phenyl)-4-methoxybenzenesulfonamide (30g) 210 mg, 50% over 4 steps. Yelꢀ
low oil. 1H NMR (400 MHz, CDCl3, TMS): δ 8.81 (s, 1H), 7.79 (d, J = 8.8 Hz, 2H), 7.60 (d, J = 8.4 Hz, 2H), 7.48 (d, J = 7.2 Hz,
2H), 7.37ꢀ7.33 (m, 3H), 7.24 (t, J = 8.8 Hz, 1H), 7.02 (t, J = 8.4 Hz, 1H), 6.81 (d, J = 8.8 Hz, 2H), 6.01 (dd, J = 16.8, 10.0 Hz, 1H),
5.54 (d, J = 16.8 Hz, 1H), 5.21 (d, J = 10.0 Hz, 1H), 3.78 (s, 3H), 3.09 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 163.2, 139.2, 136.3,
132.0, 131.8, 129.8, 129.7, 129.3, 129.3, 128.7, 128.4, 123.5, 121.9, 119.8, 116.0, 114.2, 89.3, 88.1, 74.8, 55.8. IR (neat) ν 3053,
2987, 1581, 1497, 1158, 1095, 834. HRMS (ESI) m/z calcd for C24H21NO4S (M+Na)+ 442.1083, found 442.1069.
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N-(2-(4-hydroxyhept-2-en-5-yn-4-yl)phenyl)-4-methylbenzenesulfonamide (30h) 105 mg, 27% over 4 steps. White solid. mp
= 121ꢀ123 oC. E/Z = 2.5:1, 1H NMR (400 MHz, CDCl3, TMS): δ major isomer: 8.46 (s, 1H), 7.77ꢀ7.69 (m, 3H), 7.63 (d, J = 8.0 Hz,
1H), 7.53 (dd, J = 12.0, 7.8 Hz, 1H), 7.26ꢀ7.19 (m, 2H), 7.03ꢀ6.99 (m, 1H), 5.52ꢀ5.49 (m, 1H), 5.41ꢀ5.35 (m, 1H), 2.61 (s, 1H), 2.37
(s, 3H), 1.94 (s, 3H), 1.51 (d, J = 7.2 Hz, 3H). 13C NMR (125 MHz, CDCl3): δ 143.8, 137.4, 136.0, 133.2, 132.2, 129.6, 129.4,
129.3, 128.2, 127.5, 123.5, 120.3, 85.1, 80.0, 72.6, 21.7, 13.9, 4.0. IR (neat) ν 3054, 2987, 1584, 1369, 1161, 1092, 894. HRMS
(ESI) m/z calcd for C20H21NO3S (M+Na)+ 378.1134, found 378.1120.
General strategy for the preparation of substrates in Table 4 (Scheme 10):
Scheme 10. Synthesis of Substrates 36a
Procedures for the preparation of substrate 36a:25 To a solution of furan (0.72 mL, 10.0 mmol) in THF (20 mL) was added tꢀ
BuLi (1.25 mL, 1.6 M in hexanes, 2.0 mmol) dropwise at ꢀ78 oC. The solution was then allowed to warm to 0oC and stirred 1h. To
this solution was added amide E4 (0.34 g, 1.0 mmol) in THF (2 mL). After the addition was complete, the reaction was stirred at 0
oC for 4h. Reaction was diluted with EtOAc and quenched with saturated aqueous NH4Cl. The aqueous phase was extracted with
EtOAc and the combined organic layers were washed with brine and dried over Na2SO4. The solvent was removed under vacuum
and the resulting residue was purified by flash column chromatography (10ꢀ30% EtOAc in hexanes) to give product E7 (0.25 g,
74%) as colorless oil.
To a solution of the above ketone E7 (341 mg, 1 mmol) in THF (20 mL) was added ethynylmagnesium bromide (10 mL, 0.5 M
in THF) at 0 oC. Then the mixture was allowed to warm up to room temperature, and stirred overnight. The reaction was quenched
by saturated aqueous NH4Cl. The mixture was extracted with EtOAc and the combined organic layers were washed with brine and
dried over Na2SO4. The solvent was removed under vacuum and the resulting residue was purified by flash column chromatography
(10ꢀ30% EtOAc in hexanes) to give product 36a (253 mg, 69%) as white solid.
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Other substrates in Table 4 (36bꢀ36n and 36p) were prepared according to the above procedure.
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N-(2-(1-(furan-2-yl)-1-hydroxyprop-2-yn-1-yl)phenyl)-4-nitrobenzenesulfonamide (36b) 146 mg, 37% over 4 steps. Brown
solid. mp = 138ꢀ140 oC. 1H NMR (400 MHz, CDCl3, TMS): δ 9.02 (s, 1H), 8.21 (d, J = 8.8 Hz, 2H), 7.93 (d, J = 9.2 Hz, 2H), 7.68
(d, J = 8.4 Hz, 1H), 7.37ꢀ7.29 (m, 3H), 7.06 (t, J = 8.8 Hz, 1H), 6.26ꢀ6.24 (m, 1H), 6.12ꢀ6.10 (m, 1H), 3.74 (s, 1H), 2.83 (s, 1H).
13C NMR (100 MHz, CDCl3): δ 152.9, 150.3, 145.6, 143.9, 135.5, 130.3, 129.4, 128.8, 128.2, 124.5, 124.3, 120.3, 110.8, 109.0,
82.3, 77.1, 71.5. IR (neat) ν 2922, 1606, 1529, 1348, 1162, 1090, 1013, 854, 737. HRMS (ESI) m/z calcd for C19H14N2O6S
(M+Na)+ 421.0464, found 421.0463.
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N-(2-(1-(furan-2-yl)-1-hydroxyprop-2-yn-1-yl)phenyl)-4-methoxybenzenesulfonamide (36c) 134 mg, 35% over 4 steps.
White solid. mp = 125ꢀ127 oC. 1H NMR (400 MHz, CDCl3, TMS): δ 8.78 (s, broad, 1H), 7.70 (d, J = 8.8 Hz, 2H), 7.60 (d, J = 8.0
Hz, 1H), 7.37ꢀ7.33 (m, 2H), 7.24 (t, J = 8.4 Hz, 1H), 6.98 (t, J = 8.0 Hz, 1H), 6.84 (d, J = 8.8 Hz, 2H), 6.28 (dd, J = 3.2, 1.6 Hz,
1H), 6.16 (d, J = 3.6 Hz, 1H), 3.79 (s, 3H), 2.83 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 163.2, 153.0, 143.7, 136.5, 131.4, 130.0,
129.8, 128.9, 127.6, 123.3, 119.5, 114.2, 110.8, 109.0, 82.5, 76.8, 71.3, 55.8. IR (neat) ν 3295, 2360, 1596, 1497, 1335, 1155, 1094,
944, 833. HRMS (ESI) m/z calcd for C20H17NO5S (M+Na)+ 406.0719, found 406.0707.
N-(2-(1-hydroxy-1-(5-methylfuran-2-yl)prop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36d) 128 mg, 34% over 4
steps. White solid. mp = 69ꢀ71 oC. 1H NMR (500 MHz, CDCl3, TMS): δ 8.75 (s, 1H), 7.69 (d, J = 8.0 Hz, 2H), 7.60 (d, J = 8.5 Hz,
1H), 7.36 (d, J = 8.0 Hz, 1H), 7.25 (d, J = 8.0 Hz, 1H), 7.19 (d, J = 8.5 Hz, 2H), 6.98 (t, J = 7.5 Hz, 1H), 5.99 (d, J = 3.5 Hz, 1H),
5.87ꢀ5.86 (m, 1H), 3.48 (s, 1H), 2.79 (s, 1H), 2.36 (s, 3H), 2.27 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 153.9, 150.8, 143.8, 137.1,
136.5, 130.0, 129.7, 128.9, 127.7, 123.3, 119.5, 110.2, 106.8, 82.6, 76.0, 71.2, 21.8, 13.9. IR (neat) ν 2361, 1600, 1495, 1333, 1158,
1092, 978, 736. HRMS (ESI) m/z calcd for C21H19NO4S (M+Na)+ 404.0927, found 404.0926.
N-(2-(1-(4,5-dimethylfuran-2-yl)-1-hydroxyprop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36e) 127 mg, 32% over 4
steps. White solid. mp = 82ꢀ84 oC. 1H NMR (500 MHz, CDCl3, TMS): δ 8.73 (s, 1H), 7.70 (d, J = 8.0 Hz, 2H), 7.61 (d, J = 8.0 Hz,
1H), 7.38 (d, J = 8.0 Hz, 1H), 7.26ꢀ7.22 (m, 1H), 7.19 (d, J = 8.0 Hz, 2H), 6.98 (t, J = 8.0 Hz, 1H), 5.91 (s, 1H), 3.36 (s, 1H), 2.79
(s, 1H), 2.36 (s, 3H), 2.18 (s, 3H), 1.87 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 149.5, 149.3, 143.8, 137.2, 136.5, 130.0, 129.7,
129.0, 127.7, 127.6, 123.3, 119.4, 115.3, 112.6, 82.8, 76.5, 71.2, 21.8, 11.8, 10.0. IR (neat) ν 2369, 2339, 1495, 1326, 1159, 1091,
865, 815. HRMS (ESI) m/z calcd for C22H21NO4S (M+Na)+ 418.1083, found 418.1080.
N-(2-(1-(5-(((tert-butyldimethylsilyl)oxy)methyl)furan-2-yl)-1-hydroxyprop-2-yn-1-yl)phenyl)-4-
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methylbenzenesulfonamide (36f) 171 mg, 33% over 4 steps. Yellow oil. H NMR (400 MHz, CDCl3, TMS): δ 8.74 (s, 1H), 7.69
(d, J = 8.4 Hz, 2H), 7.61 (d, J = 8.4 Hz, 1H), 7.33 (d, J = 8.0 Hz, 1H), 7.26ꢀ7.22 (m, 1H), 7.19 (d, J = 8.4 Hz, 2H), 6.98 (t, J = 7.6
Hz, 1H), 6.12 (d, J = 3.2 Hz, 1H), 6.05 (d, J = 3.2 Hz, 1H), 4.60 (s, 2H), 3.55 (s, 1H), 2.79 (s, 1H), 2.37 (s, 3H), 0.88 (s, 9H), 0.05
(s, 6H). 13C NMR (100 MHz, CDCl3): δ 156.0, 152.1, 143.8, 137.2, 136.5, 130.1, 129.7, 129.0, 127.7, 127.6, 123.4, 119.7, 109.8,
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108.1, 82.5, 76.8, 71.3, 58.4, 26.1, 21.8, 18.6, ꢀ4.9. IR (neat) ν 2931, 2858, 1599, 1496, 1409, 1334, 1253, 1158, 1068, 835. HRMS
(ESI) m/z calcd for C27H33NO5SSi (M+Na)+ 534.1740, found 534.1746.
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N-(2-(1-(4-bromofuran-2-yl)-1-hydroxyprop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36g) 159 mg, 36% over 4
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steps. Yellow oil. H NMR (500 MHz, CDCl3, TMS): δ 8.41 (s, 1H), 7.65 (d, J = 8.0 Hz, 2H), 7.56 (t, J = 7.5 Hz, 2H), 7.29ꢀ7.25
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(m, 2H), 7.19 (d, J = 8.0 Hz, 2H), 7.04 (t, J = 7.5 Hz, 1H), 6.39 (d, J = 2.0 Hz, 1H), 3.66 (s, 1H), 2.95 (s, 1H), 2.37 (s, 3H). 13C
NMR (100 MHz, CDCl3): δ 147.4, 143.9, 142.5, 137.3, 136.6, 130.5, 129.8, 129.3, 127.6, 126.8, 123.4, 119.6, 116.2, 97.7, 81.2,
78.3, 71.7, 21.8. IR (neat) ν 3381, 2944, 1734, 1587, 1501, 1312, 1157, 1025, 732. HRMS (ESI) m/z calcd for C20H16BrNO4S
(M+Na)+ 467.9881, found 467.9885.
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N-(2-(1-(furan-2-yl)-1-hydroxyprop-2-yn-1-yl)-6-methylphenyl)-4-methylbenzenesulfonamide (36h) 152 mg, 40% over 4
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steps. White solid. mp = 108ꢀ110 C. H NMR (400 MHz, CDCl3, TMS): δ 7.73 (d, J = 8.4 Hz, 2H), 7.63 (s, 1H), 7.43ꢀ7.42 (m,
1H), 7.31ꢀ7.27 (m, 3H), 7.18ꢀ7.14 (m, 2H), 6.46ꢀ6.45 (m, 1H), 6.41ꢀ6.39 (m, 1H), 4.38 (s, 1H), 2.91 (s, 1H), 2.43 (s, 3H), 1.97 (s,
3H). 13C NMR (125 MHz, CDCl3): δ 153.9, 143.9, 143.2, 138.4, 138.1, 136.8, 133.4, 132.6, 129.7, 127.5, 127.4, 127.1, 110.9,
109.1, 83.7, 76.5, 71.1, 21.8, 20.0. IR (neat) ν 3258, 2877, 2253, 1761, 1137, 1088, 917, 717. HRMS (ESI) m/z calcd for
C21H19NO4S (MꢀH)ꢀ 380.0962, found 380.0953.
N-(2-(1-(furan-2-yl)-1-hydroxyprop-2-yn-1-yl)-4-(trifluoromethyl)phenyl)-4-methylbenzenesulfonamide (36i) 152 mg, 35%
over 4 steps. Yellow oil. 1H NMR (400 MHz, CDCl3, TMS): δ 8.91 (s, 1H), 7.91 (s, 1H), 7.68 (d, J = 8.4 Hz, 2H), 7.45 (d, J = 8.4
Hz, 1H), 7.38ꢀ7.37 (m, 1H), 7.22ꢀ7.20 (m, 3H), 6.33ꢀ6.31 (m, 1H), 6.25ꢀ6.24 (m, 1H), 3.84 (s, 1H), 2.87 (s, 1H), 2.37 (s, 3H). 13C
NMR (100 MHz, CDCl3): δ 152.2, 144.4, 144.0, 137.1, 136.3, 132.2 (q, J = 32.7 Hz), 130.8, 129.9, 129.5, 127.9, 123.7 (q, J =
271.2 Hz), 119.84 (q, J = 3.7 Hz), 116.18 (q, J = 4.0 Hz), 110.9, 109.5, 81.8, 77.4, 71.0, 21.8. IR (neat) ν 3286, 1706, 1587, 1408,
1331, 1264, 1160, 1089, 814, 714. HRMS (ESI) m/z calcd for C21H16F3NO4S (M+Na)+ 458.0644, found 458.0640.
N-(2-(1-(furan-2-yl)-1-hydroxyprop-2-yn-1-yl)-4,5-dimethoxyphenyl)-4-methylbenzenesulfonamide (36j) 166 mg, 39%
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over 4 steps. Yellow solid. mp = 90ꢀ92 C. H NMR (500 MHz, CDCl3, TMS): δ 8.38 (s, 1H), 7.63 (d, J = 8.5 Hz, 2H), 7.36 (s,
1H), 7.25 (s, 1H), 7.18 (d, J = 8.0 Hz, 2H), 6.89 (s, 1H), 6.26ꢀ6.25 (m, 1H), 6.09ꢀ6.08 (m, 1H), 3.84 (s, 3H), 3.75 (s, 3H), 3.47 (s,
1H), 2.81 (s, 1H), 2.38 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 153.2, 149.7, 145.0, 143.9, 143.7, 137.0, 129.724, 129.673, 127.8,
120.3, 112.1, 110.8, 108.9, 105.1, 82.8, 76.5, 70.8, 56.2, 21.8. IR (neat) ν 2928, 1759, 1520, 1357, 1163, 1089, 1011, 839. HRMS
(ESI) m/z calcd for C22H21NO6S (MꢀH)ꢀ 426.1016, found 426.1014.
N-(4-bromo-2-(1-(furan-2-yl)-1-hydroxyprop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36k) 155 mg, 35% over 4
steps. White solid. mp = 127ꢀ129 oC. 1H NMR (500 MHz, CDCl3, TMS): δ 8.65 (s, 1H), 7.65 (d, J = 8.0 Hz, 2H), 7.53 (d, J = 9.0
Hz, 1H), 7.49 (d, J = 2.0 Hz, 1H), 7.39ꢀ7.35 (m, 2H), 7.21 (d, J = 8.5 Hz, 2H), 6.31ꢀ6.30 (m, 1H), 6.22ꢀ6.20 (m, 1H), 3.57 (s, 1H),
2.86 (s, 1H), 2.38(s, 3H). 13C NMR (100 MHz, CDCl3): δ 152.2, 144.2, 144.1, 136.7, 135.6, 133.0, 131.7, 129.8, 129.5, 127.7,
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121.2, 116.3, 111.0, 109.4, 81.8, 77.4, 70.7, 21.8. IR (neat) ν 3281, 2944, 1704, 1515, 1350, 1161, 1087, 720. HRMS (ESI) m/z
calcd for C20H16BrNO4S (M+Na)+ 467.9881, found 467.9879.
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N-(2-(1-hydroxy-1-(thiophen-2-yl)prop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36l) 157 mg, 41% over 4 steps.
Yellow solid, mp = 148ꢀ150oC. 1H NMR (400 MHz, CDCl3, TMS): δ 8.67 (s, 1H), 7.61 (d, J = 8.0 Hz, 1H), 7.52ꢀ7.49 (m, 3H), 7.29
(dd, J = 5.2, 1.2 Hz, 1H), 7.27ꢀ7.22 (m, 1H), 7.12 (d, J = 8.0 Hz, 2H), 6.99 (t, J = 7.6 Hz, 1H), 6.87ꢀ6.84 (m, 1H), 6.82ꢀ6.80 (m,
1H), 3.71 (s, 1H), 2.90 (s, 1H), 2.35 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 147.2, 143.7, 136.8, 136.2, 130.1, 129.9, 129.7, 128.6,
127.6, 127.0, 126.4, 123.3, 119.5, 84.1, 77.3, 73.0, 21.7. IR (neat) ν 3371, 3288, 1634, 1587, 1494, 1372, 1168, 1081. HRMS (ESI)
m/z calcd for C20H17NO3S2 (M+Na)+ 406.0548, found 406.0544.
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N-(2-(1-hydroxy-1-(thiophen-2-yl)prop-2-yn-1-yl)-6-methylphenyl)-4-methylbenzenesulfonamide (36m) 151 mg, 38% over
4 steps. White solid. mp = 153ꢀ155 oC. 1H NMR (400 MHz, CD3OD): δ 7.61 (d, J = 8.4 Hz, 2H), 7.34ꢀ7.32 (m, 2H), 7.28 (d, J = 8.0
Hz, 2H), 7.16 (d, J = 6.8 Hz, 1H), 7.05 (t, J = 7.6 Hz, 1H), 6.88ꢀ6.87 (m, 2H), 3.24 (s, 1H), 2.41 (s, 3H), 2.15 (s, 1H), 2.08 (s, 3H).
13C NMR (100 MHz, CDCl3): δ 148.4, 143.8, 138.8, 138.5, 138.2, 133.4, 132.6, 129.7, 127.4, 127.3, 126.9, 126.8, 126.8, 126.6,
85.5, 76.9, 72.7, 21.8, 20.2. IR (neat) ν 2967, 2891, 1701, 1507, 1336, 1157, 1037, 848. HRMS (ESI) m/z calcd for C21H19NO3S2
(M+H)+ 398.0879, found 398.0877.
N-(2-(1-hydroxy-1-(1-methyl-1H-pyrrol-2-yl)prop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36n) 152 mg, 40% over
4 steps. Colorless oil. 1H NMR (500 MHz, (CD3)2CO): δ 9.42 (s, 1H), 7.71ꢀ7.69 (m, 3H), 7.32 (d, J = 8.0 Hz, 2H), 7.28 (t, J = 8.5
Hz, 1H), 7.11 (d, J = 8.0 Hz, 1H), 6.96 (t, J = 8.0 Hz, 1H), 6.75 (t, J = 2.5 Hz, 1H), 6.19 (dd, J = 4.0, 2.0 Hz, 1H), 5.99 (dd, J = 3.5,
2.5 Hz, 1H), 3.39 (s, 1H), 3.35 (s, 3H), 2.94 (s, 1H), 2.38 (s, 3H). 13C NMR (125 MHz, (CD3)2CO): δ 144.6, 137.5, 137.4, 132.1,
130.3, 130.2, 129.9, 129.0, 128.5, 126.5, 123.5, 118.9, 111.1, 106.8, 84.7, 77.0, 71.4, 35.6, 21.4. IR (neat) ν 2905, 1608, 1406,
1375, 1250, 1159, 1091, 933. HRMS (ESI) m/z calcd for C21H20N2O3S (M+Na)+ 403.1087, found 403.1080.
N-(2-(1-hydroxy-1-(1-(phenylsulfonyl)-1H-indol-2-yl)prop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36p) 233 mg,
42% over 4 steps. White solid. mp = 126ꢀ128 oC. 1H NMR (500 MHz, CDCl3, TMS): δ 9.33 (s, 1H), 7.95 (d, J = 8.5 Hz, 1H), 7.84
(d, J = 7.5 Hz, 2H), 7.70 (d, J = 8.0 Hz, 1H), 7.65ꢀ7.62 (m, 1H), 7.58ꢀ7.56 (m, 1H), 7.55ꢀ7.40 (m, 4H), 7.33 (t, J = 8.5 Hz, 1H),
7.28 (t, J = 8.5 Hz, 1H), 7.17 (t, J = 7.5 Hz, 1H), 7.15ꢀ7.12 (m, 1H), 7.03 (t, J = 7.5 Hz, 1H), 6.96 (d, J = 8.0 Hz, 2H), 6.69 (s, 1H),
5.78 (s, 1H), 2.98 (s, 1H), 2.27 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 143.7, 141.5, 138.5, 138.2, 137.2, 137.0, 134.5, 130.3,
129.8, 129.7, 129.6, 129.3, 128.0, 127.4, 126.7, 126.4, 124.4, 123.4, 122.3, 119.6, 116.2, 115.3, 82.9, 78.7, 72.9, 21.8. IR (neat) ν
3354, 2962, 1612, 1538, 1206, 1122, 1010, 896. HRMS (ESI) m/z calcd for C30H24N2O5S2 (M+Na)+ 579.1024, found 579.1019.
N-(2-(1-(furan-2-yl)-1-hydroxybut-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36q)
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156 mg, 41% over 4 steps. Colorless oil. H NMR (500 MHz, CDCl3, TMS): δ 8.80 (s, 1H), 7.67 (d, J = 8.0 Hz, 2H), 7.56 (d, J =
8.5 Hz, 1H), 7.35ꢀ7.34 (m, 2H), 7.2ꢀ7.16 (m, 3H), 6.97 (t, J = 7.5 Hz, 1H), 6.26 (dd, J = 3.0, 1.5 Hz, 1H), 6.12 (d, J = 3.0 Hz, 1H),
3.40 (s, 1H), 2.36 (s, 3H), 1.93 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 153.9, 143.8, 143.4, 137.1, 136.4, 129.8, 129.7, 128.9,
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128.5, 127.7, 123.2, 119.2, 110.7, 108.6, 85.6, 78.4, 71.4, 21.7, 4.1. IR (neat) ν 2255, 1585, 1494, 1333, 1158, 1092, 907, 813.
HRMS (ESI) m/z calcd for C21H19NO4S (M+Na)+ 404.0927, found 404.0938.
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147 mg, 45% over 4 steps. White solid. mp = 45ꢀ46 oC. 1H NMR (500 MHz, CDCl3, TMS): δ 8.00 (s, 1H), 7.87 (d, J = 8.0 Hz, 1H),
7.46 (d, J = 7.5 Hz, 1H), 7.39 (s, 1H), 7.32 (t, J = 8.0 Hz, 1H), 7.03 (t, J = 7.5 Hz, 1H), 6.31 (dd, J = 3.0, 2.0 Hz, 1H), 6.24 (d, J =
3.5 Hz, 1H), 3.29 (s, 1H), 1.96 (s, 3H), 1.44 (s, 9H). 13C NMR (100 MHz, CDCl3): δ 154.3, 153.4, 143.2, 137.3, 130.0, 129.6,
127.8, 123.2, 123.0, 110.6, 108.0, 85.1, 80.1, 78.6, 70.9, 28.6, 4.1. IR (neat) ν 2364, 1709, 1589, 1521, 1301, 1158, 1004, 750.
HRMS (ESI) m/z calcd for C19H21NO4 (M+Na)+ 350.1363, found 350.1370.
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Strategy for the preparation of substrate 36o in Table 4 is outline in Scheme 11:
Scheme 11. Synthesis of Substrates 36o
Compound E8 was prepared following literature procedure.32 To a stirred suspension of anhydrous aluminum trichloride (100
mg, 7.5 mmol) in anhydrous dichloromethane (6 mL) at 0oC and under argon, was added oꢀnitrobenzoyl chloride (0.13 mL, 0.7
mmol) and the mixture was stirred for 10 min. A solution of 1ꢀ(4ꢀmethylphenyl)sulfonylꢀ1Hꢀpyrrole (112 mg, 0.5 mmol) in anhyꢀ
drous dichloromethane (3 mL) was added dropwise, then the temperature allowed to reach room temperature for 1h. The reaction
mixture was poured into ice water (13 mL), and the aqueous layer extracted with dichloromethane (3*10 mL). The combined orꢀ
ganic layers were treated with saturated NaHCO3, washed with brine, dried over Na2SO4, and evaporated under reduced pressure to
give a dark oil. The residue was subjected to column chromatography (10% EtOAc in hexanes) to give [1ꢀ[(4ꢀ
methylphenyl)sulfonyl]ꢀ1Hꢀpyrrolꢀ3ꢀyl](2ꢀnitrophenyl)methanone E8 (73 mg, 40%) as a white solid.
To a solution of above ketone E8 (73 mg, 0.2 mmol) in ethanol (3 mL), was added Pd/C (10%) (20.4 mg) and the mixture was alꢀ
lowed to stir under H2 (1 atm) for 5h. The reaction mixture was filtered over a pad of celite and concentrated to give crude amine
E9 (68 mg, 99%) which was used in next step without purification.
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To a stirred solution of the above crude amine E9 (68 mg, 0.2 mmol) in pyridine (1 mL) was added tosyl chloride (47.5 mg) and
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the resulting solution was stirred at 105 C overnight. The reaction mixture was cooled to room temperature and diluted with
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EtOAc. The mixture was washed with 3M HCl and brine, dried over Na2SO4 and concentrated under vacuum. The resulting residue
was purified by flash column chromatography (10ꢀ30% EtOAc in hexanes) to give the pure product E10 (72 mg, 75%) as a colorꢀ
less oil.
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To a solution of E10 (72 mg, 0.15 mmol) in THF (3 mL) was added ethynylmagnesium bromide (1.5 mL, 0.5 M in THF) at 0 oC.
Then the mixture was allowed to warm up to room temperature, and stirred overnight. The reaction was quenched by saturated
aqueous NH4Cl. The mixture was extracted with EtOAc and the combined organic layers were washed with brine and dried over
Na2SO4. The solvent was removed under vacuum and the resulting residue was purified by flash column chromatography (10ꢀ30%
EtOAc in hexanes) to give product 36o (55 mg, 70%) as a colorless oil.
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N-(2-(1-hydroxy-1-(1-tosyl-1H-pyrrol-3-yl)prop-2-yn-1-yl)phenyl)-4-methylbenzenesulfonamide (36o) 55 mg, 21% over 4
steps. Colorless oil. 1H NMR (500 MHz, CDCl3, TMS): δ 8.60 (s, 1H), 7.76 (d, J = 8.0 Hz, 2H), 7.56ꢀ7.52 (m, 3H), 7.37 (d, J = 8.0
Hz, 1H), 7.30 (d, J = 8.0 Hz, 2H), 7.23 (s, 1H), 7.20 (t, J = 7.8 Hz, 1H), 7.15 (d, J = 8.0 Hz, 2H), 7.05 (t, J = 3.0 Hz, 1H), 6.94 (t, J
= 7.5 Hz, 1H), 6.10 (s, 1H), 3.11 (s, 1H), 2.78 (s, 1H), 2.38 (s, 3H), 2.36 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 145.6, 143.8,
136.9, 136.2, 135.9, 131.6, 130.5, 129.9, 129.8, 129.3, 128.4, 127.5, 127.3, 123.3, 122.0, 119.4, 118.9, 112.4, 84.2, 76.5, 71.3, 21.9,
21.8. IR (neat) ν 3280, 2926, 1598, 1338, 1063, 924, 815, 760. HRMS (ESI) m/z calcd for C27H24N2O5S2 (M+Na)+ 543.1018, found
543.1027.
General procedure for the Rhꢀcatalyzed tandem annulation [5+1] cycloaddition in Table 2.
Condition A: To an ovenꢀdried flask was added enyne substrate (0.1 mmol), anhydrous DCE (2 ml) and [Rh(CO)2Cl]2 (2.0 mg,
0.005 mmol). The flask was degassed, filled with CO and attached with a CO balloon. The oil bath was heated to 60 oC. The reacꢀ
tion was monitored by TLC. After the reaction was completed, the solvent was evaporated and the residue was purified by flash
column chromatography.
Condition B: The condition was modified by adding ligand (CF3CH2O)3P (6.6 mg, 0.02 mmol) based on Condition A.
Condition C: The condition was modified by replacing THF with dioxane (2 ml) based on Condition B.
General procedure for the Rhꢀcatalyzed tandem annulation [5+1] cycloaddition in Table 2.
Condition A: To an ovenꢀdried flask was added propargylic alcohol substrate (0.1 mmol), anhydrous DCE (2 ml), [Rh(CO)2Cl]2
(2.0 mg, 0.005 mmol). The flask was degassed, filled with CO and attached with a CO balloon. The reaction was stirred at room
temperature. The reaction was monitored by TLC. After the reaction was completed, the solvent was evaporated and the residue
was purified by flash column chromatography.
Condition B: The condition was modified by adding ligand (CF3CH2O)3P (6.6 mg, 0.02 mmol) based on Condition A.
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9-tosyl-9H-carbazol-2-ol (31a) Condition A. 27.3 mg, 81%. Yellow oil. H NMR (400 MHz, CDCl3, TMS): δ 8.25 (d, J = 8.0
Hz, 1H), 7.84 (d, J = 2.0 Hz, 1H), 7.78 (d, J = 8.0 Hz, 1H), 7.73 (d, J = 8.4 Hz, 1H), 7.69 (d, J = 8.0 Hz, 2H), 7.39 (t, J = 8.4 Hz,
1H), 7.31 (t, J = 7.6 Hz, 1H), 7.09 (d, J = 8.0 Hz, 2H), 6.89 (dd, J = 8.4, 2.4 Hz, 1H), 5.25 (s, 1H), 2.26 (s, 3H). 13C NMR (100
MHz, CDCl3): δ 155.8, 145.2, 139.9, 138.5, 135.2, 129.9, 126.7, 126.7, 126.4, 124.2, 121.1, 120.3, 119.4, 115.2, 112.8, 102.3, 21.8.
IR (neat) ν 2963, 1454, 1362, 1099, 1023, 872, 802. HRMS (ESI) m/z calcd for C19H15NO3S (M+Na)+ 360.0664, found 360.0648.
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9-((4-nitrophenyl)sulfonyl)-9H-carbazol-2-ol (31b) Condition A. 25.8 mg, 70%. Yellow oil. H NMR (500 MHz, CD3OD): δ
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8.22 (d, J = 8.5 Hz, 1H), 8.20 (d, J = 9.0 Hz, 2H), 8.01 (d, J = 9.5 Hz, 2H), 7.81 (d, J = 7.5 Hz, 1H), 7.75 (d, J = 6.0 Hz, 1H), 7.74
(d, J = 4.5 Hz, 1H), 7.41 (t, J = 7.5 Hz, 1H), 7.33 (t, J = 7.5 Hz, 1H), 6.87 (dd, J = 8.5, 2.0 Hz, 1H). 13C NMR (100 MHz, CD3OD):
δ 159.4, 152.4, 143.5, 140.8, 139.2, 129.0, 128.6, 127.1, 125.9, 125.4, 122.1, 120.3, 120.3, 116.2, 114.6, 103.0. IR (neat) ν 2925,
1620, 1531, 1459, 1377, 1179, 991, 854. HRMS (ESI) m/z calcd for C18H12N2O5S (M+Na)+ 391.0359, found 391.0344.
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9-((4-methoxyphenyl)sulfonyl)-9H-carbazol-2-ol (31c) Condition A. 27.5 mg, 78%. White solid, mp = 179ꢀ181 C. H NMR
(500 MHz, CD3OD): δ 8.21 (d, J = 8.0 Hz, 1H), 7.80 (d, J = 7.5 Hz, 1H), 7.75ꢀ7.73 (m, 2H), 7.70 (d, J = 9.0 Hz, 2H), 7.37 (t, J =
8.5 Hz, 1H), 7.29 (t, J = 8.5 Hz, 1H), 6.85 (dd, J = 8.5, 2.5 Hz, 1H), 6.82 (d, J = 9.0 Hz, 2H), 3.69 (s, 3H). 13C NMR (100 MHz,
CD3OD): δ 165.6, 159.0, 141.2, 139.6, 130.3, 129.8, 128.3, 126.7, 125.2, 121.8, 120.2, 120.0, 116.1, 115.3, 113.9, 102.9, 56.1. IR
(neat) ν 2925, 1714, 1593, 1459, 1366, 1264, 1090, 989, 830. HRMS (ESI) m/z calcd for C19H15NO4S (M+Na)+ 376.0614, found
376.0600.
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3-methyl-9-tosyl-9H-carbazol-2-ol (31d) Condition A. 30.1 mg, 86%. White solid, mp = 184ꢀ186 C. H NMR (500 MHz,
CDCl3, TMS): δ 8.23 (d, J = 8.5 Hz, 1H), 7.78 (s, 1H), 7.75 (d, J = 8.0 Hz, 1H), 7.67 (d, J = 8.5 Hz, 2H), 7.61 (s, 1H), 7.37 (t, J =
8.5 Hz, 1H), 7.30 (t, J = 7.5 Hz, 1H), 7.09 (d, J = 8.0 Hz, 2H), 5.15 (s, 1H), 2.36 (s, 3H), 2.26 (s, 3H). 13C NMR (125 MHz,
CDCl3): δ 154.1, 145.0, 138.5, 138.1, 135.2, 129.9, 126.9, 126.7, 126.1, 124.1, 121.8, 121.4, 120.0, 119.3, 115.3, 101.8, 21.7, 16.3.
IR (neat) ν 2923, 1627, 1597, 1451, 1367, 1265, 1029, 954, 812. HRMS (ESI) m/z calcd for C20H17NO3S (M+Na)+ 374.0821, found
374.0811.
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9-((4-methoxyphenyl)sulfonyl)-3-methyl-9H-carbazol-2-ol (31e) Condition A. 30.0 mg, 82%. White solid, mp = 197ꢀ199 C.
1H NMR (500 MHz, CDCl3, TMS): δ 8.23 (d, J = 8.5 Hz, 1H), 7.79 (s, 1H), 7.75 (d, J = 8.0 Hz, 1H), 7.71 (d, J = 9.0 Hz, 2H), 7.61
(s, 1H), 7.36 (t, J = 7.5 Hz, 1H), 7.29 (t, J = 7.5 Hz, 1H), 6.72 (d, J = 9.0 Hz, 2H), 5.24 (s, 1H), 3.69 (s, 3H), 2.36 (s, 3H). 13C NMR
(100 MHz, CDCl3): δ 163.9, 154.1, 138.5, 138.1, 129.7, 128.9, 126.9, 126.1, 124.1, 121.8, 121.4, 120.1, 119.3, 115.3, 114.4, 101.8,
55.7, 16.3. IR (neat) ν 2925, 2341, 1593, 1494, 1340, 1263, 1018, 954, 829. HRMS (ESI) m/z calcd for C20H17NO4S (M+Na)+
390.0770, found 390.0761.
1
3-phenyl-4-tosyl-2,4-dihydrocyclopenta[b]indole (32a, Figure 2): Condition B. 22.0 mg, 57%. Yellow oil. H NMR (500
MHz, CDCl3, TMS): δ 7.71 (d, J = 8.0 Hz, 1H), 7.52 (d, J = 7.5 Hz, 1H), 7.43ꢀ7.41 (m, 2H), 7.36ꢀ7.33 (m, 4H), 7.30ꢀ7.25 (m, 3H),
7.10 (d, J = 8.0 Hz, 2H), 5.93 (t, J = 4.5 Hz, 1H), 4.49 (d, J = 5.0 Hz, 2H), 2.28 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 144.1,
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135.9, 135.1, 131.7, 129.5, 129.1, 129.0, 129.0, 128.8, 128.6, 127.5, 127.3, 127.2, 125.8, 122.9, 120.7, 91.7, 84.8, 45.8, 21.7. IR
(neat) ν 2212, 1598, 1490, 1353, 1265, 1089, 894, 814. HRMS (ESI) m/z calcd for C24H19NO2S (M+Na)+ 408.1028, found
408.1031.
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Figure 2. NOESY Study for 32a
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4-((4-methoxyphenyl)sulfonyl)-3-phenyl-2,4-dihydrocyclopenta[b]indole (32b) Condition B. 23.3 mg, 58%. Yellow oil. H
NMR (400 MHz, CDCl3, TMS): δ 7.70 (d, J = 8.0 Hz, 1H), 7.52 (d, J = 7.6 Hz, 1H), 7.43ꢀ7.41 (m, 2H), 7.36ꢀ7.30 (m, 5H), 7.30ꢀ
7.25 (m, 2H), 6.77 (d, J = 9.2 Hz, 2H), 5.94 (t, J = 4.8 Hz, 1H), 4.48 (d, J = 4.8 Hz, 2H), 3.69 (s, 3H). 13C NMR (100 MHz, CDCl3):
δ 163.5, 135.2, 131.8, 130.4, 129.7, 129.1, 129.0, 128.8, 128.6, 127.5, 127.2, 125.8, 122.9, 120.7, 114.1, 91.8, 84.9, 55.7, 45.8. IR
(neat) ν 2212, 1596, 1497, 1352, 1264, 1160, 1091, 817. HRMS (ESI) m/z calcd for C24H19NO3S (M+Na)+ 424.0977, found
424.0968.
2,3-dimethyl-4-tosyl-2,4-dihydrocyclopenta[b]indole (33) Condition B. 26.2 mg, 78%. Yellow oil. 1H NMR (400 MHz,
CDCl3, TMS): δ 7.70 (d, J = 8.0 Hz, 1H), 7.44 (d, J = 7.6 Hz, 1H), 7.32 (t, J = 8.0 Hz, 1H), 7.26ꢀ7.21 (m, 3H), 7.08 (d, J = 8.4 Hz,
2H), 5.83 (d, J = 6.0 Hz, 1H), 4.93 (dq, J = 6.6, 6.4 Hz, 1H), 2.34 (s, 3H), 1.96 (s, 3H), 1.13 (d, J = 6.8 Hz, 3H). 13C NMR (100
MHz, CDCl3): δ 143.7, 135.9, 133.4, 132.5, 129.4, 128.8, 128.0, 127.3, 126.7, 125.6, 118.9, 110.0, 88.2, 75.4, 51.1, 21.7, 19.6, 4.4.
IR (neat) ν 2361, 1600, 1484, 1344, 1166, 1088, 813. HRMS (ESI) m/z calcd for C20H19NO2S (M+Na)+ 360.1028, found 360.1024.
General procedure for the Rhꢀcatalyzed tandem annulation [5+1] cycloaddition in Table 4.
Condition A: To an ovenꢀdried flask was added propargylic alcohol substrate (0.1 mmol), anhydrous DCE (2 ml) and
[Rh(CO)2Cl]2 (2.0 mg, 0.005 mmol). The flask was degassed, filled with CO and attached with a CO balloon. The mixture was
stirred at room temperature. The reaction was monitored by TLC. After the reaction was completed, the solvent was evaporated and
the residue was purified by flash column chromatography.
Condition B: The reaction was carried out at 60oC instead of room temperature.
Condition C: The reaction was carried out at 60oC under 10 atm of CO instead of room temperature and a CO balloon.
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6-tosyl-6H-furo[3,2-c]carbazol-4-ol (37a) Condition A. 27.5 mg, 73%. Brown solid, mp = 149ꢀ151 C. H NMR (500 MHz,
CDCl3, TMS): δ 8.31 (d, J = 10.0 Hz, 1H), 8.10 (d, J = 9.5 Hz, 1H), 7.81 (s, 1H), 7.68ꢀ7.66 (m, 3H), 7.42ꢀ7.37 (m, 2H), 7.05 (d, J =
10.0 Hz, 2H), 6.98ꢀ6.97 (m, 1H), 5.89 (s, broad, 1H), 2.22 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 150.0, 149.3, 145.2, 144.0,
138.1, 137.6, 135.0, 129.9, 126.7, 125.9, 124.6, 124.6, 121.5, 115.3, 114.2, 106.5, 104.2, 96.5, 21.7. IR (neat) ν 2924, 1650, 1597,
1458, 1362, 1171, 1090, 1053, 752. HRMS (ESI) m/z calcd for C21H15NO4S (M+Na)+ 400.0614, found 400.0606.
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6-((4-nitrophenyl)sulfonyl)-6H-furo[3,2-c]carbazol-4-ol (37b) Condition A. 17 mg, 42%. Brown solid, mp = 83ꢀ85 C. H
NMR (500 MHz, CDCl3, TMS): δ 8.29ꢀ8.27 (m, 1H), 8.13ꢀ8.10 (m, 3H), 7.93 (d, J = 9.0 Hz, 2H), 7.73 (s, 1H), 7.70 (d, J = 2.5 Hz,
1H), 7.47ꢀ7.42 (m, 2H), 6.98 (d, J = 2.0 Hz, 1H), 5.51 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 149.5, 147.3, 144.5, 142.8, 137.7,
137.1, 127.9, 126.3, 125.5, 125.1, 124.5, 121.9, 115.4, 115.0, 110.0, 104.2, 96.6. IR (neat) ν 2925, 2854, 1531, 1348, 1175, 1138,
1054, 738. HRMS (ESI) m/z calcd for C20H12N2O6S (M+Na)+ 431.0308, found 431.0304.
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6-((4-methoxyphenyl)sulfonyl)-6H-furo[3,2-c]carbazol-4-ol (37c) Condition A. 29.8 mg, 76%. Colorless oil. H NMR (500
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MHz, (CD3)2CO): δ 8.32 (d, J = 9.0 Hz, 1H), 8.07 (d, J = 8.5 Hz, 1H), 7.90 (d, J = 3.0 Hz, 1H), 7.83 (s, 1H), 7.80 (d, J = 11.5 Hz,
2H), 7.48ꢀ7.43 (m, 2H), 7.11 (d, J = 3.0 Hz, 1H), 6.91 (d, J = 11.0 Hz, 2H), 3.74 (s, 3H). 13C NMR (100 MHz, (CD3)2CO): δ 165.1,
152.1, 150.5, 145.0, 138.7, 138.6, 129.9, 129.6, 126.3, 125.3, 125.3, 121.6, 115.9, 115.3, 115.2, 105.3, 96.7, 56.1. IR (neat) ν 3055,
1652, 1594, 1496, 1365, 1264, 1144, 1055, 835. HRMS (ESI) m/z calcd for C21H15NO5S (M+H)+ 394.0743, found 394.0746.
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2-methyl-6-tosyl-6H-furo[3,2-c]carbazol-4-ol (37d) Condition B. 25.0 mg, 64%. Yellow solid, mp = 196ꢀ198 C. H NMR
(500 MHz, (CD3)2CO): δ 9.22 (s, 1H), 8.33 (d, J = 7.0 Hz, 1H), 8.07 (d, J = 7.0 Hz, 1H), 7.79 (s, 1H), 7.74 (d, J = 9.0 Hz, 2H),
7.50ꢀ7.43 (m, 2H), 7.25 (d, J = 8.0 Hz, 2H), 6.73 (s, 1H), 2.55 (s, 3H), 2.28 (s, 3H). 13C NMR (100 MHz, (CD3)2CO): δ 155.1,
151.3, 150.0, 146.3, 138.7, 137.9, 135.5, 130.7, 127.3, 126.2, 125.5, 125.3, 121.7, 116.6, 115.9, 105.5, 101.1, 96.7, 21.3, 14.0. IR
(neat) ν 2923, 1597, 1459, 1368, 1176, 1091, 812, 740. HRMS (ESI) m/z calcd for C22H17NO4S (M+Na)+ 414.0770, found
414.0772.
2,3-dimethyl-6-tosyl-6H-furo[3,2-c]carbazol-4-ol (37e) Condition B. 22.3 mg, 55%. Yellow solid, mp = 210ꢀ212 oC. 1H NMR
(500 MHz, CDCl3, TMS): δ 8.27 (d, J = 7.0 Hz, 1H), 8.08 (d, J = 7.0 Hz, 1H), 7.65ꢀ7.62 (m, 3H), 7.39ꢀ7.36 (m, 2H), 7.05 (d, J =
8.0 Hz, 2H), 5.45 (s, 1H), 2.42 (s, 3H), 2.38 (s, 3H), 2.24 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 150.0, 149.5, 148.9, 145.0, 138.1,
136.6, 135.0, 129.8, 126.7, 125.6, 125.0, 124.4, 121.5, 116.0, 115.3, 109.8, 106.1, 96.2, 21.7, 11.9, 10.0. IR (neat) ν 2926, 2342,
1648, 1435, 1368, 1190, 1098, 746. HRMS (ESI) m/z calcd for C23H19NO4S (M+Na)+ 428.0927, found 428.0928.
2-(((tert-butyldimethylsilyl)oxy)methyl)-6-tosyl-6H-furo[3,2-c]carbazol-4-ol (37f) Condition B. 31.7 mg, 61%. Yellow solid,
mp = 161ꢀ163 oC. 1H NMR (500 MHz, CDCl3, TMS): δ 8.29 (d, J = 7.5 Hz, 1H), 8.09 (d, J = 7.5 Hz, 1H), 7.74 (s, 1H), 7.66 (d, J =
8.5 Hz, 2H), 7.42ꢀ7.38 (m, 2H), 7.07 (d, J = 8.5 Hz, 2H), 6.80 (s, 1H), 5.61 (s, 1H), 4.86 (s, 2H), 2.25 (s, 3H), 0.96 (s, 9H), 0.17 (s,
6H). 13C NMR (100 MHz, CDCl3): δ 156.3, 149.8, 149.1, 145.1, 138.1, 137.4, 135.0, 129.9, 126.7, 125.8, 124.6, 124.5, 121.5,
115.3, 115.0, 106.4, 101.4, 96.5, 58.9, 26.2, 21.7, 18.8, ꢀ4.8. IR (neat) ν 2929, 2857, 1651, 1612, 1460, 1370, 1189, 1090, 837, 799.
HRMS (ESI) m/z calcd for C28H31NO5SSi (M+Na)+ 544.1584, found 544.1584.
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N-(2-(4-bromofuran-2-carbonyl)phenyl)-4-methylbenzenesulfonamide (37g) Condition A. 21.3 mg, 51%. Yellow oil. H
NMR (500 MHz, CDCl3, TMS): δ 9.66 (s, 1H), 7.74ꢀ7.72 (m, 2H), 7.57 (d, J = 8.0 Hz, 2H), 7.53ꢀ7.48 (m, 2H), 7.16 (t, J = 7.5 Hz,
1H), 7.07 (d, J = 8.0 Hz, 2H), 6.67 (d, J = 1.5 Hz, 1H), 2.25 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 183.4, 147.6, 146.0, 143.7,
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138.7, 136.2, 134.1, 132.0, 129.7, 127.5, 126.0, 124.0, 123.7, 118.0, 110.7, 21.7. IR (neat) ν 2924, 1626, 1543, 1378, 1261, 1161,
1090, 924, 864. HRMS (ESI) m/z calcd for C18H14BrNO4S (M+Na)+ 441.9719, found 441.9724.
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7-methyl-6-tosyl-6H-furo[3,2-c]carbazol-4-ol (37h) Condition A. 21.1 mg, 54%. Yellow solid, mp = 162ꢀ165 C. H NMR
(500 MHz, CDCl3, TMS): δ 7.77 (d, J = 9.0 Hz, 1H), 7.63ꢀ7.61 (m, 2H), 7.30 (t, J = 9.5 Hz, 1H), 7.23 (d, J = 9.5 Hz, 1H), 7.06 (d,
J = 10.5 Hz, 2H), 6.92 (d, J = 3.0 Hz, 1H), 6.84 (d, J = 10.5 Hz, 2H), 5.55 (s, 1H), 2.84 (s, 3H), 2.17 (s, 3H). 13C NMR (125 MHz,
CDCl3): δ 149.5, 148.7, 144.5, 144.2, 140.4, 140.0, 132.6, 130.9, 129.6, 129.0, 127.1, 126.3, 118.8, 115.4, 109.5, 104.3, 100.7,
22.2, 21.7. IR (neat) ν 2952, 1701, 1613, 1495, 1364, 1175, 1038, 736. HRMS (ESI) m/z calcd for C22H17NO4S (M+H)+ 392.0951,
found 392.0963.
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6-tosyl-9-(trifluoromethyl)-6H-furo[3,2-c]carbazol-4-ol (37i) Condition A. 25.8 mg, 58%. White solid, mp = 193ꢀ195 C. H
NMR (500 MHz, (CD3)2CO): δ 8.48 (s, 1H), 8.12 (d, J = 8.0 Hz, 1H), 7.82 (d, J = 2.0 Hz, 1H), 7.69 (s, 1H), 7.66ꢀ7.63 (m, 3H),
7.15 (d, J = 8.0 Hz, 2H), 7.01 (d, J = 2.0 Hz, 1H), 2.14 (s, 3H). 13C NMR (100 MHz, (CD3)2CO): δ 153.6, 150.6, 147.0, 145.4,
139.8, 138.0, 135.2, 131.0, 128.3, 127.4, 127.2 (q, J = 32.1 Hz), 125.7 (q, J = 270 Hz), 122.25 (q, J = 3.6 Hz), 122.16, 115.7, 112.6
(q, J = 4.3 Hz), 105.4, 104.6, 96.5, 21.4. IR (neat) ν 2926, 1651, 1597, 1323, 1169, 1130, 1052, 738. HRMS (ESI) m/z calcd for
C22H14F3NO4S (M+Na)+ 468.0487, found 468.0480.
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8,9-dimethoxy-6-tosyl-6H-furo[3,2-c]carbazol-4-ol (37j) Condition A. 19.2 mg, 44%. Yellow solid, mp = 189ꢀ191 C. H
NMR (400 MHz, CDCl3, TMS): δ 7.92 (s, 1H), 7.72 (s, 1H), 7.66 (s, 1H), 7.60 (d, J = 8.4 Hz, 2H), 7.54 (s, 1H), 7.06 (d, J = 8.0 Hz,
2H), 6.96 (d, J = 2.4 Hz, 1H), 5.44 (s, 1H), 4.05 (s, 3H), 4.02 (s, 3H), 2.25 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 148.5, 148.0,
147.7, 145.1, 143.8, 137.3, 134.8, 132.3, 129.9, 126.6, 117.5, 114.2, 107.1, 104.3, 103.2, 99.8, 97.0, 56.7, 56.5, 21.7. IR (neat) ν
2925, 1650, 1484, 1363, 1165, 1054, 849, 811. HRMS (ESI) m/z calcd for C23H19NO6S (M+Na)+ 460.0825, found 460.0832.
9-bromo-6-tosyl-6H-furo[3,2-c]carbazol-4-ol (37k) Condition A. 27.2 mg, 60%. Yellow solid, mp = 156ꢀ158 oC. 1H NMR (500
MHz, (CD3)2CO): δ 8.14 (d, J = 9.0 Hz, 1H), 8.02 (d, J = 2.0 Hz, 1H), 7.80 (d, J = 2.0 Hz, 1H), 7.66 (s, 1H), 7.62 (d, J = 9.0 Hz,
2H), 7.49 (dd, J = 9.0, 2.5 Hz, 1H), 7.14 (d, J = 8.0 Hz, 2H), 6.99 (d, J = 2.0 Hz, 1H), 2.14 (s, 3H). 13C NMR (125 MHz,
(CD3)2CO): δ 152.9, 150.4, 146.8, 145.3, 139.1, 137.5, 135.2, 130.9, 128.9, 127.4, 127.2, 124.0, 118.0, 117.6, 115.5, 105.4, 104.5,
96.6, 21.4. IR (neat) ν 2922, 2357, 1585, 1251, 1185, 1154, 810, 761. HRMS (ESI) m/z calcd for C21H14BrNO4S (M+Na)+
477.9719, found 477.9711.
6-tosyl-6H-thieno[3,2-c]carbazol-4-ol (37l) Condition A. 24.7 mg, 63%. Yellow solid, mp = 194ꢀ196 oC. H NMR (400 MHz,
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(CD3)2CO): δ 8.35ꢀ8.32 (m, 1H), 7.95 (s, 1H), 7.90ꢀ7.87 (m, 1H), 7.73 (d, J = 8.4 Hz, 2H), 7.68ꢀ7.63 (m, 2H), 7.49ꢀ7.46 (m, 2H),
7.21 (d, J = 8.0 Hz, 2H), 2.22 (s, 3H). 13C NMR (125 MHz, CD3OD): δ 154.2, 146.8, 139.3, 138.8, 135.9, 134.5, 130.7, 129.4,
127.5, 127.4, 125.5, 124.5, 122.0, 121.0, 116.3, 113.9, 98.1, 21.4. IR (neat) ν 2925, 1582, 1407, 1170, 1147, 1090, 1026, 977, 748.
HRMS (ESI) m/z calcd for C21H15NO3S2 (M+Na)+ 416.0385, found 416.0386.
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7-methyl-6-tosyl-6H-thieno[3,2-c]carbazol-4-ol (37m) Condition A. 21.6 mg, 53%. Yellow oil. H NMR (400 MHz, CDCl3,
TMS): δ 7.77 (s, 1H), 7.60ꢀ7.57 (m, 2H), 7.41 (d, J = 5.6 Hz, 1H), 7.35 (t, J = 7.6 Hz, 1H), 7.26ꢀ7.24 (m, 1H), 7.08 (d, J = 8.4 Hz,
2H), 6.83 (d, J = 8.0 Hz, 2H), 5.89 (s, 1H), 2.86 (s, 3H), 2.15 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 150.5, 144.6, 140.1, 133.2,
132.6, 130.9, 130.6, 129.7, 129.1, 128.6, 127.0, 126.2, 124.6, 120.7, 117.9, 117.6, 101.9, 22.2, 21.7. IR (neat) ν 3055, 2952, 1597,
1452, 1366, 1166, 1089, 936, 812. HRMS (ESI) m/z calcd for C22H17NO3S2 (M+Na)+ 430.0542, found 430.0530.
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3,6-ditosyl-3,6-dihydropyrrolo[2,3-c]carbazol-4-ol (37o) Condition B. 28.6 mg, 55%. White solid, mp = 214ꢀ216 oC. 1H NMR
(500 MHz, CDCl3, TMS): δ 9.00 (s, 1H), 8.32 (d, J = 8.5 Hz, 1H), 7.96 (s, 1H), 7.84 (d, J = 7.5 Hz, 1H), 7.71ꢀ7.68 (m, 4H), 7.64
(d, J = 4.0 Hz, 1H), 7.39 (t, J = 7.5 Hz, 1H), 7.34 (t, J = 7.5 Hz, 1H), 7.21 (d, J = 8.5 Hz, 2H), 7.14 (d, J = 3.5 Hz, 1H), 7.09 (d, J =
8.0 Hz, 2H), 2.32 (s, 3H), 2.26 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 146.0, 145.1, 144.9, 138.5, 137.2, 135.2, 134.0, 130.4,
129.9, 129.8, 127.3, 127.2, 126.8, 126.4, 125.9, 124.2, 121.2, 120.1, 115.4, 111.7, 110.0, 100.9, 21.9, 21.8. IR (neat) ν 2923, 2360,
1588, 1454, 1367, 1170, 947, 812, 735. HRMS (ESI) m/z calcd for C28H22N2O5S2 (M+Na)+ 553.0862, found 553.0867.
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12-(phenylsulfonyl)-5-tosyl-5,12-dihydroindolo[3,2-a]carbazol-7-ol (37p) Condition A. 40.1 mg, 71%. Yellow solid, mp =
141ꢀ143 oC. 1H NMR (500 MHz, CDCl3, TMS): δ 8.63 (d, J = 7.0 Hz, 1H), 8.31 (d, J = 7.5 Hz, 1H), 8.18 (d, J = 8.0 Hz, 1H), 7.98
(s, 1H), 7.87 (d, J = 7.5 Hz, 1H), 7.69 (d, J = 8.0 Hz, 2H), 7.46ꢀ7.41 (m, 2H), 7.39ꢀ7.36 (m, 1H), 7.30ꢀ7.23 (m, 2H), 7.12 (d, J = 8.5
Hz, 2H), 6.91 (dd, J = 7.5, 8.5 Hz, 2H), 6.75 (d, J = 8.0 Hz, 2H), 6.15 (s, 1H), 2.26 (s, 3H). 13C NMR (125 MHz, CDCl3): δ 150.8,
145.4, 141.1, 140.0, 138.8, 136.3, 134.8, 133.7, 133.4, 129.9, 129.6, 129.5, 127.9, 127.3, 126.8, 126.7, 126.5, 126.3, 126.1, 125.3,
123.9, 122.7, 119.6, 117.3, 114.9, 100.9, 21.8. IR (neat) ν 2920, 2851, 1693, 1448, 1412, 1369, 1265, 1174, 1072, 836. HRMS
(ESI) m/z calcd for C31H22N2O5S2 (M+Na)+ 589.0862, found 589.0860.
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7-tosyl-7H-benzo[c]carbazol-5-ol (35) Condition C. 25.5 mg, 66%. White solid, mp = 205ꢀ207 C. H NMR (500 MHz,
(CD3)2CO): δ 8.61 (d, J = 8.5 Hz, 1H), 8.34ꢀ8.28 (m, 3H), 8.02 (s, 1H), 7.63ꢀ7.59 (m, 3H), 7.43 (t, J = 8.5 Hz, 1H), 7.35ꢀ7.33 (m,
2H), 7.09 (d, J = 8.5 Hz, 2H), 2.10 (s, 3H). 13C NMR (125 MHz, (CD3)2CO): δ 154.9, 146.5, 138.524, 138.456, 135.7, 130.8, 130.2,
129.0, 128.3, 127.3, 125.6, 125.4, 125.0, 124.343, 124.317, 124.1, 121.9, 115.9, 113.2, 98.2, 21.3. IR (neat) ν 2964, 2927, 1587,
1450, 1170, 1089, 936, 812, 759. HRMS (ESI) m/z calcd for C23H17NO3S (M+Na)+ 410.0821, found 410.0815.
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Supporting Information. Copies of H NMR and 13C NMR spectra. This material is available free of charge via the Internet at
http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
wtang@pharmacy.wisc.edu; xbm08@aliyun.com.
ACKNOWLEDGMENT
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We thank the NSF (CHEꢀ1464754) and the University of WisconsinꢀMadison for financial support. B.ꢀm. X. thanks Southern Medical
University for financial support of the visiting professorship at UWꢀMadison. X.ꢀl. Z. thanks Chinese Scholarship Council and National
Natural Science Foundation of China (No. 21302168) for the financial support of visiting scholarship at UWꢀMadison. This study made
use of the Medicinal Chemistry Center at UWꢀMadison instrumentation, funded by the Wisconsin Alumni Research Foundation (WARF)
and the UW School of Pharmacy.
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