Iodine(III)-mediated ring contraction reactions: Synthesis of oxygen-And nitrogen-substituted indanes

Article abstract of DOI:10.5935/0103-5053.20160065

The synthesis of oxygen-And nitrogen-substituted indanes was successfully performed by iodine(III)-mediated ring contraction of 1,2-dihydronaphthalenes. Acetoxy and benzoyloxy alkenes afforded indanes in 60-71percent yield, irrespective of their position on aromatic ring. Similarly, the nitrogen containing substrates protected with 9-fluorenylmethyloxycarbonyl (Fmoc) and benzoyl (Bz) groups smoothly undergoes ring contraction giving indanes in 64-77percent yield. The tosyl-protected substrate resulted only in addition products.

Full text of DOI:10.5935/0103-5053.20160065

http://dx.doi.org/10.5935/0103-5053.20160065
J. Braz. Chem. Soc., Vol. 27, No. 10, 1820-1831, 2016.
Printed in Brazil - ©2016 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
Article
Iodine(III)-Mediated Ring Contraction Reactions: Synthesis of Oxygen- and
Nitrogen-Substituted Indanes
Anees Ahmad and Luiz F. Silva Júnior*
Instituto de Química, Universidade de São Paulo, CP 26077, 05513-970 São Paulo-SP, Brazil
The synthesis of oxygen- and nitrogen-substituted indanes was successfully performed by
iodine(III)-mediated ring contraction of 1,2-dihydronaphthalenes. Acetoxy and benzoyloxy
alkenes afforded indanes in 60-71% yield, irrespective of their position on aromatic ring. Similarly,
the nitrogen containing substrates protected with 9-fluorenylmethyloxycarbonyl (Fmoc) and
benzoyl (Bz) groups smoothly undergoes ring contraction giving indanes in 64-77% yield. The
tosyl-protected substrate resulted only in addition products.
Keywords: indane, hypervalent iodine, ring contraction, 1,2-dihydronaphthalenes
Introduction
Results and Discussion
Indane skeleton occurs in many biologically active
natural products1,2 and pharmaceuticals, constituting
an important target in organic synthesis and in drug
discovery.3 Numerous synthetic methodologies have been
developed to construct indane core including cyclization,4-6
cycloaddition,7-9 and rearrangements.10-13 Indanes substituted
in the aromatic ring by nitrogen14-18 or by oxygen2,19-22 are
present in compounds with promising biological activities.
Hypervalent iodine reagents play a substantial role in
chemical synthesis, promoting efficiently carbon-carbon
bond formations, rearrangements and functional group
interconversions, including asymmetric versions for many
reactions.23-28 The iodine(III)-mediated ring contraction
of 1,2-dihydronaphthalenes gives functionalized indanes
(Scheme 1, 1a).13,29 This transformation was successfully
employed in total syntheses, such as (+)-mutisianthol,30
( )-indatraline,29 and (+)-trans-trikentrinA.31 Although the
reactivity of several substrates was investigated under many
conditions, the tolerance for substitution at aromatic ring
was not high. For example, methoxy-substituted substrates
furnished the desired indanes in low yield and additionally
the main product were those related to the addition of
solvent, as exemplified by the behavior of compound 1b.
Motivated by the importance of oxygen- and nitrogen-
substituted indanes, we herein show the ring contraction
of additional 1,2-dihydronaphthalenes with iodine(III).
The preparation of the required substrates was
performed as described in the following paragraphs. The
protected amine tetralones (7c-f) were prepared by classical
transformations (Table 1).Amine tetralone 5 in the presence
of benzoyl chloride (BzCl), triethylamine (Et3N) and
dichloromethane (DCM) as solvent gave benzoyl protected
amine 7c in 89% yield (entry 1).32 The tosyl protected amine
tetralone 7d was obtained in 96% yield in pyridine with
tosyl chloride (p-TsCl) (entry 2).33 In a similar manner, base
labile Fmoc protected amine 7e was formed in 98% yield
with 9-fluorenylmethyloxycarbonyl chloride (Fmoc-Cl) and
pyridine in DCM (entry 3).34 The acetylation of tetralone 6
was achieved using 4-dimethylaminopyridine (DMAP),
acetic anhydride (Ac2O) in Et3N giving acetyl protected
ketone 7f in 97% yield (entry 4).13,35
Several cyclic olefinic substrates were synthesized
via reduction/dehydration protocol. The commercially
available hydroxy ketone 8g was reduced with NaBH4
in MeOH to the corresponding alcohol as a white solid.
o
Dehydration of alcohol at 130 C in the presence of
phosphoric acid (H3PO4) gave alkene product 1g in 76%
yield (Table 2, entry 1).35 The methoxy functionalized
ketones 8h and 8b were also transformed into cyclic
alkenes 1h and 1b in 93 and 76% yields, respectively
(entries 2 and 3).13,36,37 The benzoyl, tosyl, Fmoc and
acetyl protected amino ketones (7c-f) were smoothly
converted into desired olefinic substrates (1c-f) in good
yields (entries 4-7).13,38
*e-mail: luizfsjr@iq.usp.br

Vol. 27, No. 10, 2016
Ahmad and Silva Júnior
1821
Scheme 1. Oxidation of 1,2-dihydronaphthalenes 1a-b with iodine(III).
Table 1. Synthesis of protected amines tetralones 7c-f
entry
Substrate
Condition
Product (Yield)
BzCl, Et3N
DCM, rt, 3 h
1
pTsCl pyridine
reflux, 16 h, rt
2
3
4
Fmoc-Cl pyridine
DCM, 0 oC to rt, 1 h
Ac2O
DMAP Et3N, rt, 1 h
DCM: dichloromethane; rt: room temperature; DMAP: 4-dimethylaminopyridine.
The acetylation of phenol 1g was accomplished with
DMAP, Ac2O in Et3N as solvent,13 leading to protected
alkene 9g in 96% yields (Table 3, entry 1). Similarly,
phenol 1g was also protected with benzoyl group in 94%
yield using BzCl and Et3N as a base (entry 2).32 Methyl
ethers (1h and 1b) were first demethylated using sodium
ethanethiolate (generated in situ) in dimethylformamide
Iodine(III) is known to act as single-electron-transfer
(SET) for methoxy-substituted aromatic compounds
forming reactive cation radical intermediates.41,42 The
generation of these cation radicals could be a possible
reason of rearrangement failure in substrates like 1b, due
to their susceptibility towards nucleophilic attack and other
side reactions. Thus, we consider that the ring contraction
could take place with an acetyl group instead of a methoxy
making it useful in the synthesis of oxygen-substituted
indanes. Several reaction conditions were tested for the
o
(DMF) at 140 C giving the corresponding phenol,39,40
which were acetylated under standard conditions
(entries 3 and 4).

1822
Iodine(III)-Mediated Ring Contraction Reactions
J. Braz. Chem. Soc.
Table 2. Preparation of dihydronaphthalenes 1b-h via reduction/dehydration
entry
Substrate
Product (Yield)
1
2
3
4
5
6
7
a(i) NaBH4, MeOH, 0 oC to rt, 1 h; (ii) H3PO4, THF, 80 oC, 2 h; b(i) NaBH4, MeOH, 0 oC to rt, 1 h; (ii) cat. TsOH.H2O, toluene, 130 oC, 2 h.
oxidation of alkene 9g with PhI(OH)OTs (HTIB) (Table 4).
The desired ring contraction product 2g was successfully
obtained in 47% yield using trifluoroethanol (TFE)/DCM
(1:4) as solvent (entry 1). Using pure TFE, the yield of
acetal 2g increased to 66% (entry 2). The deprotection of
substrate 9g into phenol 1g was observed when MeOH was
used as solvent (entry 3).
(Table 5). Benzoyl protected alkene 9gg gave acetal 2gg in
71% yield (entry 1). Acetyl protected alkene 9h smoothly
afforded product 2h in 60% yield (entry 2). Acetyl alkene
9b gave acetal 2b in 65% yield (entry 3).
Oxidation with HTIB was also studied in amine
protected alkenes (Table 6). Benzoyl protected alkene
1c experienced ring contraction giving acetal product 3c
in 77% yield in MeOH/DCM (8:1) as solvent (entry 1).
DCM was added to solubilize substrate 1c and to increase
With the optimized conditions, ring contraction was
successfully carried out in other oxygenated substrates

Vol. 27, No. 10, 2016
Ahmad and Silva Júnior
1823
Table 3. Preparation of O-substituted dihydronaphthalenes
entry
1
Substrate
Condition
Product (Yield)
Ac2O, DMAP, Et3N
2
BzCl, Et3N, DCM
(i) NaH, EtSH, DMF
(ii) Ac2O, DMAP, Et3N
3
4
(i) NaH, EtSH, DMF
(ii) Ac2O, DMAP, Et3N
DMAP: 4-dimethylaminopyridine; DCM: dichloromethane; DMF: dimethylformamide.
Table 4. Reactions of acetyl protected alkene 9g with HTIB
entry
Solvent
TFE/DCM (1:4)
TFE
time
5 min
5 min
5 h
Product
2g
Yield / %
1
2
3
47
66
55
2g
MeOH
1g
TFE: trifluoroethanol; DCM: dichloromethane.
the rate of reaction. When the reaction was tried in pure
MeOH, indane 3c was obtained in 51% yield and took 1 h
to consume all starting material (entry 2). The protecting
group tolerance was further investigated with Fmoc
protected alkene 1e and the anticipated ring contraction
product 3e was isolated in 64% yield (entry 3).
The reaction of tosyl protected 7-amine alkene 1d
with HTIB was also investigated under different reaction
conditions (Table 7). Tosyl amide could have a facilitating
effect on ring contraction by increasing electronic density
on migrating carbon 4a.13 However, only the formation of
addition products trans-4d and cis-4d were observed in
MeOH and in DCM/MeOH as solvents (entries 1 and 2).
Fluorinated solvents like TFE and hexafluoroisopropanol
(HFIP) proved to be ineffective under the conditions tested
(entries 3 and 4).
Oxidation in acetyl protected 6-amine alkene 1f
was explored. In this case, amide substituent meta to
migrating carbon would decrease the electronic density
by inductive effect of nitrogen atom and does not increase
directly the electronic density at migrating carbon by
mesomeric effect.13 Several conditions were tested for
ring contraction of alkene 1f (Table 8). Slow reaction and
complex mixtures were observed for substrate 1f using
HTIB either in MeOH or in DCM/MeOH at different
temperatures (entries 1-3). Fluorinated solvents, such as
TFE and HFIP/DCM, also did not provide ring contraction
product (entries 4 and 5).

1824
Iodine(III)-Mediated Ring Contraction Reactions
J. Braz. Chem. Soc.
Table 5. Reactions of oxygenated alkenes 9b, 9gg and 9h with 1.2 equiv of HTIB
entry Substrate
Product (Yield)a
1
2
3
aTrifluoroethanol, 0 oC, 5 min.
Table 6. Reaction of 7-amine alkenes with 1.2 equiv HTIB at 0 oC
entry
Substrate
Condition
Product (Yield)
1
MeOH/DCM (8:1), 10 min
2
3
MeOH, 1 h
MeOH/DCM (4:1), 10 min
DCM: dichloromethane.
Conclusions
in oxygenated substrates independent on their position on
aromatic ring. Acetoxy and benzoyloxy alkenes afforded
indanes in 60-71% yield. The N-protecting groups Fmoc
and Bz are stable under the reaction conditions giving
indanes in 64-77% yield. The Ts-protected substrate gave
only addition products. The results showed the tolerance
In conclusion, the ring contraction of 1,2-dihydro-
naphthalenes using HTIB was expanded to substrates
bearing oxygen and nitrogen substituents in the aromatic
ring. Oxidative rearrangement was successfully carried out

Vol. 27, No. 10, 2016
Ahmad and Silva Júnior
1825
Table 7. Reaction of tosylamide 1d with HTIB
entry
Condition
MeOH, 30 min
Result
1
2
3
4
trans-4d (10%), cis-4d (37%), 1d (14%)a
mixture of cis, trans addition productsb
complex mixture
DCM/50 equiv MeOH, 30 min
TFE, 10 min
H2O, HFIP/DCM (1:4), 10 min
complex mixture
aIsolated yield; bGC monitored; DCM: dichloromethane; HFIP: hexafluoroisopropanol.
Table 8. Reaction of 6-acetamide 1f with HTIB
entry
Solvent
MeOH
Temperature / ºC
Resulta
1
2
3
4
5
0 to rtb
complex mixture
complex mixture
complex mixture
complex mixture
complex mixture
DCMc/50 equiv MeOH
MeOH
0 to rtb
40
0
TFEd
H2O, HFIPe/DCM (1:4)
0
aBy TLC and GC; brt: room temperature; cDCM: dichloromethane; dTFE: trifluoroethanol; eHFIP: hexafluoroisopropanol.
of protecting groups in ring contraction reaction mediated
by HTIB.
Preparation of substrates
N-(7,8-Dihydronaphthalen-2-yl)benzamide (1c)
Experimental
To a stirred solution of ketone 5 (0.677 g, 4.20 mmol)
and Et3N (0.65 mL, 0.467 g, 4.62 mmol) in DCM (35 mL)
was added BzCl (0.683 mL, 0.826 g, 5.88 mmol). After
3 h, the reaction mixture was washed with 10% HCl,
saturated solution of NaHCO3 and dried over anhydrous
MgSO4. Purification by flash column chromatography
(40-60% EtOAc in hexane) gave benzoyl protected
ketone 7c.44 Yield: 0.995 g (89%); light yellow solid; mp:
193.5-195.2 oC; 1H NMR (300 MHz, CDCl3) d 2.13 (quin,
2H, J 6.3 Hz), 2.64 (t, 2H, J 6.3 Hz), 2.97 (t, 2H, J 6 Hz),
7.37 (dd, 1H, J 8.4, 1.8 Hz), 7.45-7.52 (m, 2H), 7.55-7.61
(m, 1H), 7.86-7.89 (m, 3H), 8.04 (d, 1H, J 8.7 Hz), 8.11
(d, 1H, J 6.9 Hz); 13C NMR (75 MHz, CDCl3) d 23.2, 30.0,
117.8, 118.8, 127.1, 128.6, 128.8, 130.1, 132.2, 134.4,
142.3, 146.3, 165.8, 197.4. To a two neck round bottom
flask with magnetic stirrer under nitrogen atmosphere
was added NaBH4 (0.170 g, 4.50 mmol) to the solution of
All commercially available reagents were used
without further purification unless otherwise noted. All
solvents used for reactions and chromatography were
dried and purified by standard methods.43 Thin-layer
chromatography (TLC) analyses were performed using
silica gel 60F 254 precoated plates, with detection
by UV-absorption (254 nm) and by spraying with
p-anisaldehyde and phosphomolybdic acid solutions
followed by charring at ca. 150 °C for visualization. Flash
column chromatography was performed using silica gel
200-400 Mesh. All nuclear magnetic resonance (NMR)
analyses were recorded using CDCl3 as solvent and
tetramethylsilane (TMS) as internal standard. Chemical
shifts are reported in ppm downfield from TMS with
reference to internal solvent.

1826
Iodine(III)-Mediated Ring Contraction Reactions
J. Braz. Chem. Soc.
ketone 7c (0.995 g, 3.75 mmol) in MeOH (40 mL). The
mixture was stirred for 30 minutes at 0 oC. The temperature
was raised to room temperature (rt) for another 1 h. The
reaction was quenched by addition of distilled H2O (10 mL)
and the mixture was extracted with EtOAc (3 × 30 mL).
The combined organic extracts were washed with brine
(2 × 10 mL) and dried over anhydrous MgSO4. The solvent
was removed under reduced pressure and N-(5-hydroxy-
5,6,7,8-tetrahydronaphthalen-2-yl)benzamide was obtained
as white solid (0.980 g, 3.67 mmol, 98.0%) and used in
the next step without purification. The N-(5-hydroxy-
5,6,7,8-tetrahydronaphthalen-2-yl)benzamide (0.980 g,
3.67 mmol) was dissolved in toluene (30 mL) with the
addition of few crystals of TsOH.H2O in round bottom
flask, fitted with Dean-Stark apparatus. The system was
removed under reduced pressure and N-(5-hydroxy-5,6,7,8-
tetrahydronaphthalen-2-yl)-4-methylbenzenesulfonamide
(0.761 g, 2.39 mmol, 96.0%) was obtained as yellowish
white solid and used in the next step without purification.
The reaction was performed using N-(5-hydroxy-5,6,7,8-
tetrahydronaphthalen-2-yl)-4-methylbenzenesulfonamide
(0.761 g, 2.39 mmol), toluene (30 mL) and TsOH.H2O (cat.
few crystals) at 130 oC. The crude product was purified by
flash column chromatography (15-20% EtOAc in hexane)
giving alkene 1d. Yield: 0.542 g (76%); white solid; mp:
o
126.7-127.8 C; IR (film) vmax / cm-1 3524, 3257, 3033,
2930, 2883, 2830, 1916, 1735, 1609, 1599, 1575, 1497,
1465, 1397, 1341, 1329, 1314, 1291, 1241, 1209, 1185,
1163, 1124; 1H NMR (300 MHz, CDCl3) d 2.21-2.29 (m,
2H), 2.37 (s, 3H), 2.69 (t, 2H, J 8.4 Hz), 5.96 (dt, 1H,
J 9.6, 4.4 Hz), 6.36 (dt, 1H, J 9.6 Hz), 6.78-6.86 (m, 4H),
7.22 (d, 2H, J 8.1 Hz), 7.67 (d, 2H, J 8.4 Hz); 13C NMR
(75 MHz, CDCl3) d 21.5 (CH3), 22.8 (CH2), 27.4 (CH2),
119.3 (CH), 121.0 (CH), 126.4 (CH), 126.8 (CH), 127.2
(CH), 128.3 (CH), 129.6 (CH), 131.5 (C), 134.7 (C), 136.1
(C), 136.7 (C), 143.7 (C); HRMS [ESI(+)-TOF] calcd. for
[C17H17NO2S + H]+:300.1053; found: 300.1060.
o
maintained at 130 C and the reaction was monitored
by TLC. The reaction was quenched by addition of
saturated solution of NaHCO3 and extracted with hexane
(3 × 30 mL). The combined organic extracts were washed
with brine (2 × 10 mL) and dried over anhydrous MgSO4.
The solvent was removed at reduced pressure and the
residue was purified by flash chromatography (15-20%
EtOAc in hexane) giving compound 1c.38 Yield: 0.735 g
(80%); white solid; mp: 170.2-172 oC; 1H NMR (300 MHz,
CDCl3) d 2.30-2.36 (m, 2H), 2.83 (t, 2H, J 8.2 Hz), 5.99
(dt, 1H, J 9.2, 4.5 Hz), 6.45 (dt, 1H, J 9.6, 1.8 Hz), 7.02 (d,
1H, J 8.1 Hz), 7.35 (dd, 1H, J 8.1, 2.4 Hz), 7.46-7.58 (m,
4H), 7.75 (bs, 1H), 7.84-7.88 (m, 2H); 13C NMR (75 MHz,
CDCl3) d 23.0, 27.7, 117.8, 119.4, 126.3, 126.9, 127.1,
127.9, 128.8, 130.8, 131.8, 135.1, 136.4, 136.6, 165.4.
(9H-Fluoren-9-yl)methyl (7,8-dihydronaphthalen-2-yl)
carbamate (1e)
To a stirred solution of amino ketone 5 (0.484 g,
3.00 mmol) and pyridine (0.29 mL, 3.60 mmol) in
o
anhydrous DCM (25 mL) at 0 C was added solution of
Fmoc-Cl (0.854 g, 3.30 mmol) in anhydrous DCM and
the resulting reaction mixture was allowed to stir at rt.
After 1 h the solution was acidified with 1 mol L-1 HCl.
The product was extracted with DCM (3 × 10 mL) and
dried over anhydrous Mg2SO4. After workup solvent was
removed under reduced pressure. The crude product was
purified by flash column chromatography (15-25% EtOAc
in hexane) giving Fmoc protected amino ketone 7e.Yield:
1.13 g (98%); white solid; mp: 160.6-161.5 ºC; IR (film)
vmax / cm-1 3305, 3065, 2946, 2890, 1737, 1665, 1602, 1585,
1537, 1495, 1478, 1450, 1427, 1412, 1350, 1336, 1323,
1287, 1219, 1185, 1164, 1129, 1105; 1H NMR (300 MHz,
CDCl3) d 2.06-2.15 (m, 2H), 2.62 (t, 2H, J 6.3 Hz), 2.91
(t, 2H, J 6.0 Hz), 4.27 (t, 1H, J 6.4 Hz, 1H), 4.57 (d, 2H,
J 6.6 Hz), 6.95 (bs, 1H), 7.14 (dd, 1H, J 8.4, 1.5 Hz), 7.32
(td, 1H, J 7.6, 1.2 Hz, 1H), 7.37-7.44 (m, 3H), 7.56-7.62
(m, 2H), 7.78 (dt, 2H, J 7.5, 0.9 Hz), 7.98 (d, 1H, J 8.7 Hz);
13C NMR (75 MHz, CDCl3) d 23.2 (CH2), 30.0 (CH2), 38.9
(CH2), 47.0 (CH), 67.0 (CH2), 116.4 (CH), 117.0 (CH),
120.1 (CH), 124.8 (CH), 127.1 (CH), 127.8 (CH), 128.1
(C), 128.7 (CH), 141.3 (C), 142.2 (C), 143.5 (C), 146.3
(C), 152.9 (C), 197.3 (C); HRMS [ESI(+)-TOF] calcd. for
[C25H21NO3 + H]+:384.1600; found: 384.1600. The reaction
N-(7,8-Dihydronaphthalen-2-yl)-4-methylbenzene-
sulfonamide (1d)
To a stirred solution of ketone 5 (0.161 g, 1.00 mmol) in
pyridine (5 mL) was added TsCl (0.191 g, 1.35 mmol). The
reaction mixture was heated at reflux for 16 h. The solvent
was removed under reduced pressure and the crude residue
was extracted with EtOAc (3 × 10 mL) and washed with
1 mol L-1 HCl (10 mL), water (10 mL) and brine (10 mL)
and dried over anhydrous MgSO4. Purification by flash
column chromatography (40-50% EtOAc in hexane) gave
tosyl protected ketone 7d.45 Yield: 0.304 g (96%); white
o
1
solid; mp: 214.2-215.6 C; H NMR (300 MHz, CDCl3)
d 2.03 (m, 2H), 2.39 (s, 3H), 2.59 (t, 2H, J 6.4 Hz), 2.87 (t,
2H, J 6 Hz), 6.94 (dd, 1H, J 8.7, 2.4 Hz), 6.98-6.99 (m, 1H),
7.15 (bs, 1H), 7.25-7.33 (m, 2H), 7.74 (d, 1H, J 8.1 Hz), 7.90
(d, 1H, J 8.4 Hz); 13C NMR (75 MHz, CDCl3) d 21.6, 23.1,
29.8, 38.8, 117.2, 118.1, 124.8, 127.2, 129.1, 129.9, 135.9,
141.1, 144.4, 146.3, 197.1. The reaction was performed
using ketone 7d (0.788 g, 2.50 mmol), MeOH (30 mL) and
NaBH4 (0.283 g, 7.50 mmol). After workup, solvent was

Vol. 27, No. 10, 2016
Ahmad and Silva Júnior
1827
was performed using ketone 7e (1.15 g, 3.00 mmol), MeOH
(50 mL) and NaBH4 (0.227 g, 6.00 mmol). After workup,
solvent was removed under reduced pressure and crude
alcohol (1.12 g, 2.91 mmol, 97.0%) was obtained as white
solid and used in the next step without purification. The
reaction was performed using (9H-fluoren-9-yl)methyl
(5-hydroxy-5,6,7,8-tetrahydronaphthalen-2-yl)carbamate
(1.12 g, 2.91 mmol), toluene (50 mL) and TsOH.H2O (cat.
few crystals) at 130 oC. The crude product was purified by
flash column chromatography (10-30% EtOAc in hexane)
giving alkene 1e. Yield: 0.890 g (83%); white solid; mp:
141-142 oC; IR (film) vmax / cm-1 3307, 3030, 2931, 2882,
2826, 1703, 1612, 1585, 1527, 1478, 1465, 1450, 1425,
1326, 1308, 1278, 1219, 1170, 1104; 1H NMR (300 MHz,
CDCl3) d 2.25-2.33 (m 2H), 2.77 (t, 2H, J 8.2 Hz), 4.27 (t,
2H, J 6.6 Hz), 4.53 (d, 2H, J 6.9 Hz), 5.95 (dt, 1H, J 9.6,
4.4 Hz), 6.41 (dt, 1H, J 9.6, 1.6 Hz), 6.57 (bs, 1H), 6.94
(d, 1H, J 8.1 Hz), 7.08-7.18 (m, 2H), 7.32 (td, 2H, J 7.4,
1.2 Hz), 7.38-7.44 (m, 2H), 7.61 (d, 2H, J 7.2 Hz), 7.61 (d,
2H, J 7.2 Hz), 7.78 (d, 2H, J 7.5 Hz); 13C NMR (75 MHz,
CDCl3) d 23.0 (CH2), 27.7 (CH2), 47.1 (CH), 66.8 (CH2),
116.5 (CH), 118.2 (CH), 120.0 (CH), 124.9 (CH), 126.4
(CH), 127.0 (CH), 127.1 (CH), 127.5 (CH), 127.7 (CH),
130.0 (C), 136.1 (C), 136.6 (C), 141.3 (C), 143.7 (C),
153.3 (C); HRMS [ESI(+)] calcd. for [C25H21NO2 + H]+:
368.1651; found: 368.1648.
To a stirred solution of alkene 1g (0.614 g, 4.20 mmol) and
DMAP (0.015 g, 0.12 mmol) in Et3N (16 mL) was added
Ac2O (1.50 mL, 15.90 mmol) at rt. After 1 h, the reaction
was quenched with MeOH (5 mL) and H2O (8 mL). The
reaction was extracted with EtOAc (3 × 10 mL), washed
with brine (2 × 10 mL) and dried over anhydrous MgSO4.
Purification by flash column chromatography (3-5% EtOAc
in hexane) gave acetyl protected alkene 9g.47 Yield: 0.760 g
(96%); colorless liquid.
7,8-Dihydronaphthalen-1-yl benzoate (9gg)
The reaction was performed using phenol 1g (0.248 g,
1.70 mmol), BzCl (0.22 mL, 0.267 g, 1.90 mmol) and
Et3N (0.51 mL, 0.374 g, 3.70 mmol) in DCM (10 mL).
Purification by flash column chromatography (3-4% EtOAc
in hexane) gave benzoyl protected alkene 9gg. Yield:
o
0.398 g (94%); white solid; mp: 58.1-58.7 C; IR (film)
vmax / cm-1 3035, 2935, 2887, 2834, 2127, 1735, 1651, 1601,
1583, 1569, 1491, 1451, 1395, 1342, 1314, 1296, 1266,
1247, 1229, 1212; 1H NMR (300 MHz, CDCl3) d 2.24-2.32
(m, 2H), 2.71 (t, 2H, J 8.4 Hz), 6.04 (dt, 1H, J 9.6, 4.5 Hz),
6.49 (dt, 1H, J 9.6, 1.8 Hz), 6.96 (d, 1H, J 7.5 Hz), 7.00
(dd, 1H, J 8.1, 1.2 Hz), 7.17-7.22 (m, 1H), 7.48-7.54 (m,
2H), 7.61-7.66 (m, 1H), 8.21-8.25 (m, 2H); 13C NMR
(75 MHz, CDCl3) d 20.6 (CH2), 22.3 (CH2), 120.8 (CH),
123.8 (CH), 126.8 (CH), 127.2 (C), 127.3 (CH), 128.6
(CH), 129.0 (CH), 129.4 (C), 130.1 (CH), 133.5 (CH),
135.7 (C), 148.0 (C), 164.8 (C); LRMS m/z (rel. int.): 250
(M+●, 9), 144 (3), 128(11), 115 (10), 105 (100), 91 (2), 77
(36), 63 (3), 51 (10), 39 (2); HRMS [ESI(+)-TOF] calcd.
for [C17H14O2 + Na]+:273.0891; found: 273.0890.
N-(5,6-Dihydronaphthalen-2-yl)acetamide (1f)
Compound 1f was prepared according to reported
protocol in literature.35 Yield: 0.184 g (98%); white solid;
mp: 52.1-53.9 °C (lit. 51.2-54.6 oC).
7,8-Dihydronaphthalen-1-yl acetate (9g)
7,8-Dihydronaphthalen-2-yl acetate (9h)
The reaction was performed using ketone 8g (0.892 g,
5.50 mmol), MeOH (40 mL) and NaBH4 (0.208 g,
5.50 mmol). After workup, solvent was removed under
reduced pressure and 1,2,3,4-tetrahydronaphthalene-1,5-
diol (0.885 g, 5.39 mmol, 98.0%) was obtained as white
solid and used in the next step without purification. The
crude 1,2,3,4-tetrahydronaphthalene-1,5-diol (0.885 g,
5.39 mmol), dissolved in anhydrous tetrahydrofuran (THF)
(10 mL) was added with H3PO4 (6 mL). The system was
maintained at 80 oC and the reaction was monitored by TLC.
The reaction was quenched by addition of saturated solution
of NaHCO3 and the mixture was extracted with EtOAc
(3 × 10 mL). The combined organic extracts were washed
with brine and dried over anhydrous MgSO4. The solvent
was removed at reduced pressure and the residue was
purified by flash chromatography (10-15% ethyl acetate
in hexane) giving alkene 1g.35 Yield: 0.614 g (78%); white
solid; mp: 66-67 oC (lit. 53.3-54.6 oC46 and 73.5-74.5 oC).35
The reaction was performed using ketone 8h (2.000 g,
11.35 mmol), MeOH (80 mL) and NaBH4 (0.4290 g,
11.35 mmol). After workup, solvent was removed under
reduced pressure and crude alcohol (1.986 g, 11.14 mmol,
98.0%) was obtained as white solid and used in the next
step without purification. The reaction was performed
following using 6-methoxy-1,2,3,4-tetrahydronaphthalen-1-
ol (1.986 g, 11.14 mmol), toluene (60 mL) and TsOH.H2O
(cat. few crystals) at 130 oC. The crude product was purified
by flash column chromatography (20-40% EtOAc in hexane)
giving alkene 1h.36Yield: 1.702 g (95%); colorless oil. Under
inert atmosphere N2, NaH (6.24 g, 260 mmol, 60% in mineral
oil) was washed with anhydrous hexanes (3 × 20 mL). After
a few minutes, anhydrous DMF (75 mL) was added. To this
mixture was slowly added a solution of EtSH (13.0 mL,
180 mmol, 30 equiv based on olefin 1h) in anhydrous DMF
(14 mL) at 0 °C and the resulting yellow solution was stirred
for 20 min at rt. A solution of alkene 1h (0.961 g, 6.0 mmol)

1828
Iodine(III)-Mediated Ring Contraction Reactions
J. Braz. Chem. Soc.
in DMF (15 mL) was then added dropwise and the resulting
mixture was stirred for 5 h at 140 °C. When the reaction was
becoming slightly brown, the mixture was cooled to the rt
and a saturated solution of NH4Cl was added. The mixture
was extracted with Et2O. The organic phase was washed with
water, brine and dried over anhydrous MgSO4. The solvent
was removed under reduced pressure. The crude product was
purified by flash column chromatography (20-40% EtOAc in
hexane) giving 7,8-dihydronaphthalen-2-ol.39 Yield: 0.851 g
(97%); viscous colorlessliquid. The reaction was performed
using 7,8-dihydronaphthalen-2-ol (0.365 g, 2.50 mmol),
DMAP (0.09 g, 0.07 mmol) andAc2O (0.9 mL, 9.5 mmol) in
Et3N (10 mL). Purification by flash column chromatography
(3-5% EtOAc in hexane) gave acetyl protected alkene 9h.48
Yield: 0.398 g (85%); colorless liquid.
in Et3N (10 mL). Purification by flash column
chromatography (3-5% EtOAc in hexane) gave acetyl
protected alkene 9b.Yield: 0.359 g (85%); colorless liquid;
IR (film) vmax / cm-1 3034, 2935, 2885, 2831, 1761, 1609,
1
1575, 1491, 1432, 1369, 1328, 1271, 1210; H NMR
(300 MHz, CDCl3) d 2.27-2.36 (m, 2H), 2.28 (s, 3H), 2.77
(t, 2H, J 8.0 Hz), 6.06 (m, 1H), 6.41 (dt, 1H, J 9.6, 1.8 Hz),
6.74 (d, 1H, J 2.4 Hz), 6.81 (dd, 1H, J 8.1, 2.4 Hz), 7.08 (d,
1H, J 8.1 Hz); 13C NMR (75 MHz, CDCl3) d 21.1 (CH3),
23.2 (CH2), 26.8 (CH2), 118.8 (CH), 119.4 (CH), 127.3
(CH), 128.2 (CH), 129.6 (CH), 132.9 (C), 135.3 (C), 149.2
(C), 169.7 (C); LRMS m/z (rel. int.): 188 (M+●, 20), 146
(100), 145 (52), 131 (30), 127 (19), 117 (24), 115 (42),
91 (15), 77 (5), 63 (9), 43 (30), 39 (10); HRMS [ESI(+)]
calcd. for [C12H12O2 + Na]+: 211.0735; found: 211.0724.
5,6-Dihydronaphthalen-2-yl acetate (9b)
Ring contraction reactions mediated by HTIB: general
The reaction was performed using ketone 8b (0.705 g,
4.00 mmol), MeOH (40 mL) and NaBH4 (0.152 g,
4.00 mmol). After workup, solvent was removed under
reduced pressure and crude alcohol (0.691 g, 3.88 mmol,
97%) was obtained as white solid and used in the next
step without purification. The reaction was performed
using 7-methoxy-1,2,3,4-tetrahydronaphthalen-1-ol
(0.691 g, 3.88 mmol), toluene (40 mL) and TsOH.H2O
procedure for 2b, 2g, 2gg and 2h
1-(Bis(2,2,2-trifluoroethoxy)methyl)-2,3-dihydro-1H-inden-
4-yl acetate (2g)
To a solution of alkene 9g (0.094 g, 0.50 mmol) in TFE
(10 mL) was added HTIB (0.235 g, 0.60 mmol) at 0 oC. The
reaction mixture was stirred at 0 °C for 5 min. The reaction
was quenched with a saturated solution of NaHCO3. The
reaction mixture was extracted with EtOAc (3 × 15 mL),
washed with brine (2 × 10 mL) and dried over anhydrous
MgSO4. The solvent was evaporated under reduced
pressure. The crude product was purified by flash column
chromatography (4-5% EtOAc in hexanes) giving acetal
o
(cat. few crystals) at 130 C. After workup solvent was
removed under reduced pressure. The crude product was
purified by flash column chromatography (1-2% EtOAc
in hexane) giving alkene 1b.13,37 Yield: 0.488 g (78%);
colorless liquid.The reaction was performed using alkene
1b (0.481 g, 3.00 mmol), NaH (3.12 g, 130 mmol, 60% in
mineral oil), EtSH (6.5 mL, 90 mmol, 30 equiv. based on
olefin 1b) in DMF (35 mL) at 140 oC. The crude product
was purified by flash column chromatography (10-15%
ethyl acetate in hexane) giving 5,6-dihydronaphthalen-
o
2g. Yield: 0.128 g (66%); white solid; mp: 61.6-63.4 C;
IR (film) vmax / cm-1 2947, 1764, 1615, 1587, 1468, 1433,
1372, 1281, 1213; 1H NMR (300 MHz, CDCl3) d 1.98-2.10
(m, 1H), 2.22-2.32 (m, 1H), 2.30 (s, 3H), 2.70-2.91 (m,
2H), 3.47-3.55 (m, 1H), 3.84-4.07 (m, 4H), 4.71 (d, 1H,
J 8.1 Hz), 6.94 (dt, 1H, J 7.8 Hz), 7.21 (t, 1H, J 7.8 Hz), 7.28
(d, 1H, J 7.5 Hz); 13C NMR (75 MHz, CDCl3) d 20.8 (CH3),
26.8 (CH2), 28.1 (CH2), 47.5 (CH), 61.8 (q, J 34.8 Hz)
(CH2), 63.3 (q, J 34.8 Hz) (CH2), 105.0 (CH), 120.6 (CH),
123.2 (CH), 123.6 (q, J 276 Hz) (CF3), 123.7 (q, J 276 Hz)
(CF3), 128.0 (CH), 136.6 (C), 143.3 (C), 147.1 (C), 168.9
(C); HRMS [ESI(+)-TOF] calcd. for [C16H16F6O4 + Na]+:
409.0850; found: 409.0851.
o
2-ol. Yield: 0.351 g (80%); white solid; mp: 98-99 C;
IR (film) vmax / cm-1 3247, 3027, 2936, 2880, 2851, 2818,
1629, 1614, 1574, 1492, 1477, 1465, 1435, 1426, 1395,
1349, 1327, 1282, 1265, 1215; 1H NMR (300 MHz, CDCl3)
d 2.25-2.32 (m, 2H), 2.71 (t, 2H, J 8.1 Hz), 4.59 (s, 1H),
6.04 (dt, 1H, J 9.6, 4.4 Hz), 6.38 (dt, 1H, J 9.6, 1.8 Hz),
6.52 (d, 1H, J 2.7 Hz), 6.59 (dd, 1H, J 7.8, 2.7 Hz), 6.96 (d,
1H, J 8.1, Hz); 13C NMR (75 MHz, CDCl3) d 23.5 (CH2),
26.6 (CH2), 112.9 (CH), 113.1 (CH), 127.5 (CH), 127.7 (C),
128.3 (CH), 129.5 (CH), 135.3 (C), 154.0 (C); LRMS m/z
(rel. int.): 146 (M+●, 100), 145 (71), 131 (45), 127 (43), 117
(36), 115 (55), 103 (5), 91 (12), 77 (7), 63 (14), 51 (13),
39 (10); HRMS [ESI(+)-TOF] calcd. for [C10H10O + K]+:
185.0369; found: 185.0361. The reaction was performed
using 5,6-dihydronaphthalen-2-ol (0.351 g, 2.40 mmol),
DMAP (0.08 g, 0.065 mmol) andAc2O (0.9 mL, 9.0 mmol)
1-(Bis(2,2,2-trifluoroethoxy)methyl)-2,3-dihydro-1H-inden-
4-yl benzoate (2gg)
Yield: 0.159 g (71%); white solid; mp: 79-79.8 oC; IR
(film) vmax / cm-1 3067, 2948, 1738, 1602, 1585, 1469, 1453,
1423, 1383, 1279, 1230, 1168, 1134; 1H NMR (300 MHz,
CDCl3) d 1.99-2.11 (m, 1H), 2.20-2.32 (m, 1H), 2.76-2.97
(m, 2H), 3.54 (q, 1H, J 8.1 Hz), 3.85-4.09 (m, 4H), 4.74

Vol. 27, No. 10, 2016
Ahmad and Silva Júnior
1829
(d, 1H, J 8.1 Hz), 7.10 (dt, 1H, J 7.8, 1.2 Hz), 7.26 (t,
1H, J 7.8 Hz), 7.33 (d, 1H, J 7.8 Hz), 7.48-7.54 (m, 2H),
7.64 (tt, 1H, J 7.5, 1.5 Hz), 8.18-8.22 (m, 2H); 13C NMR
(75 MHz, CDCl3) d 26.8 (CH2), 28.2 (CH2), 47.6 (CH),
61.9 (q, J 34.8 Hz) (CH2), 63.4 (q, J 34.8 Hz) (CH2),
105.1 (CH), 120.7 (CH), 123.2 (CH), 123.69 (q, J 276 Hz)
(CF3), 123.74 (q, J 276 Hz) (CF3), 128.1 (CH), 128.6 (CH),
129.4 (C), 130.2 (CH), 133.6 (CH), 136.8 (C), 143.4 (C),
147.4 (C), 164.5 (C); HRMS [ESI(+)-TOF]: calcd. for
[C21H18F6O4 + Na]+:471.1007; found: 471.1010.
0.60 mmol) at 0 °C for 10 min. The reaction was quenched
with a saturated solution of NaHCO3. The reaction mixture
was extracted with EtOAc (3 × 15 mL), washed with brine
(2 × 10 mL) and dried over anhydrous MgSO4. The solvent
was evaporated under reduced pressure. The crude product
was purified by flash column chromatography (40-50%
EtOAc in hexane), giving acetal 3c. Yield: 0.12 g (77%);
yellowish white solid; mp: 96-97.5 oC; IR (film) vmax / cm-1
3307, 3060, 2937, 2830, 1737, 1650, 1601, 1580, 1532, 1493,
1447, 1424, 1374, 1328, 1283, 1248, 1210, 1187, 1154, 1116;
1H NMR (300 MHz, CDCl3) d 1.92-2.04 (m, 1H), 2.15-2.27
(m, 1H), 2.78-2.99 (m, 2H), 3.37-3.47 (m, 1H), 3.38 (s, 3H),
3.42 (s, 3H), 4.29 (d, 1H, J 7.5 Hz), 7.29 (dd, 1H, J 8.1,
2.1 Hz), 7.38 (d, 1H, J 8.4 Hz), 7.42-7.55 (m, 3H), 7.61 (s,
1H), 7.83-7.86 (m, 2H), 7.93 (bs, 1H); 13C NMR (75 MHz,
CDCl3) d27.5 (CH2), 31.4 (CH2), 46.9 (CH), 52.8 (CH3), 54.2
(CH3), 107.1 (CH), 116.6 (CH), 118.5 (CH), 125.6 (CH),
126.9 (CH), 128.5 (CH), 131.5 (CH), 134.9 (C), 136.8 (C),
139.1 (C), 145.7 (C), 165.8 (C); HRMS [ESI(+)]: calcd. for
[C19H21NO3 + H]+:312.1600; found: 312.1600.
1-(Bis(2,2,2-trifluoroethoxy)methyl)-2,3-dihydro-1H-inden-
5-yl acetate (2h)
Yield: 0.117 g (60%); viscous colorless liquid; IR (film)
vmax / cm-1 2953, 1761, 1610, 1592, 1485, 1460, 1431, 1372,
1282, 1216, 1163, 1134, 1103; 1H NMR (300 MHz, CDCl3)
d 1.97-2.09 (m, 1H), 2.21-2.33 (m, 1H), 2.28 (s, 3H), 2.82-
3.01 (m, 2H), 3.43 (q, 1H, J 7.8 Hz), 3.86-4.08 (m, 4H),
4.68 (d, 1H, J 8.4 Hz), 6.87 (dd, 1H, J 8.4, 2.2 Hz), 6.94
(s, 1H), 7.38 (d, 1H, J 8.1 Hz); 13C NMR (75 MHz, CDCl3)
d 21.0 (CH3), 27.4 (CH2), 31.1 (CH2), 46.4 (CH), 61.6 (q,
J 34.8 Hz) (CH2), 63.3 (q, J 34.8 Hz) (CH2), 105.1 (CH),
117.8 (CH), 119.7 (CH), 123.6 (q, J 276 Hz) (CF3), 123.7
(q, J 276 Hz) (CF3), 126.1 (CH), 138.3 (C), 146.1 (C), 150.3
(C), 169.7 (C); LRMS m/z (rel. int.): 386 (M+●, 4), 344 (7),
245 (7), 211 (14), 175 (8), 145 (6), 133 (100), 115 (7), 105
(11), 83 (11), 77 (6), 43 (19); HRMS [ESI(+)-TOF]: calcd.
for [C16H16F6O4 + Na]+:409.0850; found: 409.0851.
(9H-Fluoren-9-yl)methyl (1-(dimethoxymethyl)-2,3-dihydro-
1H-inden-5-yl)carbamate (3e)
The reaction was performed using alkene 1e (0.183 g,
0.50 mmol), HTIB (0.235 g, 0.60 mmol) and MeOH/DCM
(4:1) (10 mL) at 0 °C for 10 min.13 The crude product was
purified by flash column chromatography (15-25% EtOAc in
hexane) giving acetal 3e.Yield: 0.138 g (64%); white solid;
mp: 115-117 oC; IR (film) vmax / cm-1 3307, 3066, 2942, 2849,
2830, 1730, 1708, 1598, 1538, 1493, 1478, 1450, 1431, 1375,
1326, 1297, 1220; 1H NMR (300 MHz, CDCl3) d 1.89-2.01
(m, 1H), 2.12-2.24 (m, 1H), 2.73-2.94 (m, 2H), 3.34-3.43 (m,
1H), 3.35 (s, 3H), 3.40 (s, 3H), 4.22-4.26 (m, 1H), 4.26 (d,
1H, J 7.5 Hz), 4.51 (d, 2H, J 6.6 Hz), 6.71 (bs, 1H), 7.04 (d,
1H, J 7.2 Hz), 7.27-7.32 (m, 4H), 7.36-7.41 (m, 2H), 7.59
(d, 2H, J 7.5 Hz), 7.76 (d, 2H, J 7.5 Hz); 13C NMR (75 MHz,
CDCl3) d 27.5 (CH2), 31.4 (CH2), 46.8 (CH), 47.0 (CH), 52.8
(CH3), 54.1 (CH3), 66.6 (CH2), 107.1 (CH), 115.0 (CH),
117.0 (CH), 119.9 (CH), 124.8 (CH), 125.6 (CH), 127.0
(CH), 127.6 (CH), 136.6 (C), 138.0 (C), 141.2 (C), 143.7
(C), 145.7 (C), 153.5 (C); HRMS [ESI(+)-TOF]: calcd. for
[C27H27NO4 + Na]+: 452.1832; found: 452.1836.
3-(Bis(2,2,2-trifluoroethoxy)methyl)-2,3-dihydro-1H-inden-
5-yl acetate (2b)
Yield: 0.126 g (65%); white solid; mp: 63.6-65.2 oC; IR
(film) vmax / cm-1 2919, 2850, 1760, 1610, 1591, 1540, 1484,
1459, 1429, 1372, 1281, 1214; 1H NMR (300 MHz, CDCl3)
d 1.98-2.09 (m, 1H), 2.21-2.33 (m, 1H), 2.28 (s, 3H), 2.79-
2.99 (m, 2H), 3.46 (q, 1H, J 7.8 Hz), 3.85-4.06 (m, 2H),
4.69 (d, 1H, J 8.4 Hz), 6.91 (ddd, 1H, J 8.1, 2.1, 0.3 Hz),
7.10 (d, 1H, J 1.8 Hz), 7.20 (d, 1H, J 8.1 Hz); 13C NMR
(75 MHz, CDCl3) d 21.1 (CH3), 27.5 (CH2), 30.6 (CH2), 61.7
(q, J 34.8 Hz) (CH2), 63.5 (q, J 34.8 Hz) (CH2), 105.1 (CH),
118.9 (CH), 120.9 (CH), 123.6 (q, J 276 Hz) (CF3), 123.7
(q, J 276 Hz) (CF3), 125.1 (CH), 142.0 (C), 142.2 (C), 149.5
(C), 169.8 (C); LRMS m/z (rel. int.): 386 (M+●, 2), 344 (25),
287 (7), 244 (8), 211 (100), 145 (17), 133 (92), 115 (15),
105 (17), 83 (29), 77 (12), 43 (43); HRMS [ESI(+)-TOF]
calcd. for [C16H16F6O4 + Na]+:409.0850; found: 409.0851.
N-((5R,6R)-5,6-Dimethoxy-5,6,7,8-tetrahydronaphthalen-2-
yl)-4-methylbenzenesulfonamide (trans-4d) and N-((5R,6S)-
5,6-dimethoxy-5,6,7,8-tetrahydronaphthalen-2-yl)-4-
methylbenzenesulfonamide (cis-4d)
N-(1-(Dimethoxymethyl)-2,3-dihydro-1H-inden-5-yl)
benzamide (3c)
To a solution of alkene 1l (0.125 g, 0.500 mmol) in
MeOH/DCM (8:1) (10 mL) was added HTIB (0.235 g,
The reaction was performed using alkene 1d (0.150 g,
0.50 mmol), HTIB (0.235 g, 0.60 mmol) and MeOH
(10 mL) at 0 °C.13 The crude product was purified by flash
column chromatography (20-50% EtOAc in hexane) giving

1830
Iodine(III)-Mediated Ring Contraction Reactions
J. Braz. Chem. Soc.
trans-4d, cis-4d and starting material 1d (0.021 g, 0.070
mmol, 14%) was recovered.
2. Kim, S.-H.; Kwon, S. H.; Park, S.-H.; Lee, J. K.; Bang, H.-S.;
Nam, S.-J.; Kwon, H. C.; Shin, J.; Oh, D.-C.; Org. Lett. 2013,
15, 1834.
N-((5R,6R)-5,6-Dimethoxy-5,6,7,8-tetrahydronaphthalen-
2-yl)-4-methylbenzenesulfonamide (trans-4d)
3. Ferraz, H. M. C.;Aguilar,A. M.; Silva Jr., L. F.; Craveiro, M.V.;
Quim. Nova 2005, 28, 703.
Yield: 0.019 g (10%); viscous colorless oil; IR (film)
vmax / cm-1 3257, 2932, 2825, 1919, 1614, 1599, 1502,
1463, 1399, 1341, 1320, 1292, 1270, 1185, 1162; 1H NMR
(300 MHz, CDCl3) d 1.82-1.92 (m, 1H), 1.99-2.09 (m, 1H),
2.37 (s, 3H), 2.57-2.80 (m, 2H), 3.42 (s, 3H), 3.48 (s, 3H),
3.65-3.70 (m, 1H), 4.14 (d, 1H, J 4.8 Hz), 6.82-6.88 (m,
3H), 7.17-7.23 (m, 3H), 7.67 (d, 2H, J 8.7 Hz); 13C NMR
(75 MHz, CDCl3) d 21.5 (CH3), 22.9 (CH2), 25.1 (CH2),
56.5 (CH3), 57.6 (CH3), 77.5 (CH), 79.1 (CH), 118.5 (CH),
120.5 (CH), 127.2 (CH), 129.6 (CH), 130.9 (CH), 131.4
(C), 135.9 (C), 136.2 (C), 138.2 (C), 143.7 (C); HRMS
[ESI(+)-TOF]: calcd. for [C19H23NO4S + K]+: 400.0985;
found: 400.0988.
4. Loh, C. C. J.; Atodiresei, I.; Enders, D.; Chem. Eur. J. 2013,
19, 10822.
5. Qian, H.; Zhao, W.; Sung, H. H. Y.; Williams, I. D.; Sun, J.;
Chem. Commun. 2013, 49, 4361.
6. Hu, J.; Hirao, H.; Li,Y.; Zhou, J.; Angew. Chem., Int. Ed. 2013,
52, 8676.
7. Li, H.-H.; Zhang, X.; Jin,Y.-H.; Tian, S.-K.; Asian J. Org. Chem.
2013, 2, 290.
8. Nishimura, T.; Nagamoto, M.; Ebe,Y.; Hayashi, T.; Chem. Sci.
2013, 4, 4499.
9. Yamamoto,Y.; Saigoku, T.; Ohgai, T.; Nishiyama, H.; Itoh, K.;
Chem. Commun. 2004, 2702.
10. Fananas, F. J.; Alvarez-Perez, M.; Rodriguez, F.; Chem. Eur. J.
2005, 11, 5938.
N-((5R,6S)-5,6-Dimethoxy-5,6,7,8-tetrahydronaphthalen-2-
yl)-4-methylbenzenesulfonamide (cis-4d)
11. Urdabayev, N. K.; Popik, V. V.; J. Am. Chem. Soc. 2004, 126,
4058.
Yield: 0.068 g (37%); viscous colorless oil; IR (film)
vmax / cm-1 3249, 3065, 2932, 2827, 1919, 1674, 1647,
1612, 1500, 1463, 1399, 1340, 1320, 1292, 1230; 1H NMR
(300 MHz, CDCl3) d 1.82-1.90 (m, 1H), 2.08-2.18 (m, 1H),
2.36 (s, 1H), 2.60-2.71 (m, 1H), 2.84-2.91 (m, 1H), 3.42 (s,
3H), 3.44 (s, 3H), 3.59 (dt, 1H, J 9.9, 3.0 Hz), 4.26 (d, 1H,
J 2.7 Hz), 6.86 (d, 1H, J 2.1 Hz), 6.90 (dd, 1H, J 8.1, 2.4 Hz),
7.15 (d, 1H, J 8.4 Hz), 7.21 (dd, 2H, J 8.7, 0.6 Hz), 7.50
(bs, 1H), 7.69 (dt, 2H, J 8.4, 1.8 Hz); 13C NMR (75 MHz,
CDCl3) d 21.4 (CH3), 22.1 (CH2), 26.8 (CH2), 56.3 (CH3),
57.0 (CH3), 77.3 (CH), 77.5 (CH), 117.9 (CH), 120.6 (CH),
127.1 (CH), 129.5 (CH), 130.5 (CH), 131.1 (C), 136.1 (C),
136.4 (C), 137.7 (C), 143.7 (C); HRMS [ESI(+)-TOF]:
calcd. for [C19H23NO4S + Na]+:384.1245; found: 384.1248.
12. Kammath, V. B.; Solomek, T.; Ngoy, B. P.; Heger, D.;
Klan, P.; Rubina, M.; Givens, R. S.; J. Org. Chem. 2013, 78,
1718.
13. Siqueira, F. A.; Ishikawa, E. E.; Fogaca, A.; Faccio, A. T.;
Carneiro,V. M. T.; Soares, R. R. S.; Utaka,A.; Tebeka, I. R. M.;
Bielawski, M.; Olofsson, B.; Silva Jr., L. F.; J. Braz. Chem. Soc.
2011, 22, 1795.
14. Gross, M. F.; Beaudoin, S.; McNaughton-Smith, G.; Amato,
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Supplementary Information
Supplementary Information (1H NMR and 13C NMR
spectra) is available free of charge at http://jbcs.sbq.org.br
as PDF file.
19. Jin, Q.; Han, X. H.; Hong, S. S.; Lee, C.; Choe, S.; Lee, D.;
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Acknowledgments
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The authors thank CAPES, FAPESP and CNPq for
financial support.
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FAPESP has sponsored the publication of this article.