Thallium trinitrate mediated oxidation of 3-alkenols: Ring contraction vs cyclization

Article abstract of DOI:10.1021/jo011178m

The reaction of a series of six-membered ring 3-alkenols with thallium trinitrate (TTN) in three different experimental conditions was studied. Either cyclization products or ring contraction products were obtained, depending on the structure of the substrate as well as the nature of the solvent. The reaction of a seven-membered ring 3-alkenol with TTN led to the ring contraction product exclusively.

Full text of DOI:10.1021/jo011178m

3518
J . Org. Chem. 2002, 67, 3518-3521
Sch em e 1
Th a lliu m Tr in itr a te Med ia ted Oxid a tion of
3-Alk en ols: Rin g Con tr a ction vs
Cycliza tion
Helena M. C. Ferraz* and Luiz S. Longo J r.
Instituto de Quı´mica, Universidade de Sa˜o Paulo,
CEP 05508-900, Sa˜o Paulo SP, Brazil
J ulio Zukerman-Schpector
Departamento de Quı´mica, Universidade Federal de
Sa˜o Carlos, CEP 13565-905, Sa˜o Carlos SP, Brazil
hmferraz@iq.usp.br
TTN, using aqueous AcOH as solvent. This reaction
furnished the cyclization products in very good yields.
Recently,9 we observed that homoallylic alcohols bearing
an endocyclic double bond react with TTN to afford ring
contraction products, instead of the expected cyclic ethers.
In Scheme 1 are shown two representative examples of
these reactions.
On the basis of these results, it is possible to suppose
that 3-alkenols containing an endocyclic double bond
would undergo ring contraction preferentially to cycliza-
tion. However, Kocovsky et al.10,11 reported a different
behavior for some steroidal 3-alkenols, which underwent
a fragmentation reaction, instead of ring contraction and/
or cyclization, when treated with TTN in dioxane.
Taking into account the different results mentioned
above, we decided to investigate the behavior of other
cyclic 3-alkenols toward TTN, under different experi-
mental conditions, to better understand the influence of
the substrate structure, as well as of the solvent, in the
course of the reaction.
Received December 26, 2001
Abstr a ct: The reaction of a series of six-membered ring
3-alkenols with thallium trinitrate (TTN) in three different
experimental conditions was studied. Either cyclization
products or ring contraction products were obtained, de-
pending on the structure of the substrate as well as the
nature of the solvent. The reaction of a seven-membered ring
3-alkenol with TTN led to the ring contraction product
exclusively.
In tr od u ction
Thallium(III) salts can promote a number of different
reactions in organic substrates.1 Among the most useful
transformations mediated by these salts are the ring
contraction of cyclic olefins and the cyclofunctionalization
of unsaturated alcohols.
Although the ring contraction of simple substrates,
such as cyclohexene2,3 and cycloheptene,4 is a well-known
reaction, its application to more complex olefins is less
common than might be expected.5
Resu lts a n d Discu ssion
Concerning the thallium(III)-promoted cyclization of
unsaturated alcohols, the works developed by Mihailovic
et al.6 and Bartlett et al.7 should be mentioned. The
former studied the cyclization of some 4-, 5-, and 6-alk-
enols, using thallium triacetate (TTA), and carefully
discussed the influence of different solvents in the course
of the reaction. Bartlett et al. reported a number of
examples of TTN- and TTA-mediated cyclization of
4-alkenols and elucidated several aspects of this reaction.
Nevertheless, the only 3-alkenol studied by them gave
rise to a complex mixture of products.
The 3-alkenols 4a -f were prepared from the corre-
sponding cyclohexanones, using classical methodologies,12
as outlined in Scheme 2.
The first set of reactions with TTN was carried out
using 50% aqueous AcOH as solvent. Under these condi-
tions, the alkenols 4a and 4b had furnished the corre-
sponding cyclopentane derivatives 5a and 5b, respec-
tively, as previously communicated by us13 (Table 1,
entries 1 and 3). However, the reaction of 4c under the
same conditions led to a mixture of the ring contraction
product 5c and the cyclic ether 6c, isolated in poor yields,
while 4d afforded the cyclic ether 6d as the only identi-
fied product (Table 1, entries 5 and 7). The alkenols 4e
and 4f led to an untractable mixture of products.
NMR and GC analysis of the crude products of the TTN
oxidation performed in aqueous AcOH indicated the
formation of diastereomeric glycol derivatives as the main
products of the reaction. It is noteworthy that the
substrates 4a and 4b, which afforded the ring contraction
products in reasonable yields, differ from 4c-f only by
In a previous paper,8 we described the reaction of the
monoterpenes isopulegol and neoisopulegol with TTA and
(1) For reviews, see: (a) McKillop, A.; Taylor, E. C. In Comprehensive
Organometallic Chemistry; Pergamon Press: New York, 1982; Vol. 7,
p 465. (b) Ferraz, H. M. C.; Silva, L. F., J r.; Vieira, T. de O. Synthesis
1999, 2001.
(2) Kabbe, H.-J . Ann. 1962, 656, 204.
(3) McKillop, A.; Hunt, J . D.; Kienzle, F.; Bigham, E.; Taylor, E. C.
J . Am. Chem. Soc. 1973, 95, 3635.
(4) Abley, P.; Byrd, J . E.; Halpern, J . J . Am. Chem. Soc. 1973, 95,
2591.
(5) For a review concerning thallium(III) salt mediated ring contrac-
tion, see: Ferraz, H. M. C.; Silva, L. F., J r. Quı´m. Nova 2000, 23, 216.
(6) Mihailovic, M. Lj.; Vukicevic, R.; Konstantinovic, S.; Milosavl-
jevic, S.; Schroth, G. Liebigs Ann. Chem. 1992, 305.
(7) Michael, J . P.; Ting, P. C.; Bartlett, P. A. J . Org. Chem. 1985,
50, 2416.
(9) Ferraz, H. M. C.; Silva, L. F., J r. Tetrahedron 2001, 57, 9939.
(10) Kocovsky, P.; Pour, M. J . Org. Chem. 1990, 55, 5580.
(11) Kocovsky, P.; Baines, R. S. J . Org. Chem. 1994, 59, 5439.
(12) For references concerning the preparation of compounds out-
lined in Scheme 2, see the Supporting Information.
(13) Ferraz, H. M. C.; Santos, A. P.; Silva, L. F., J r.; Vieira, T. de
O. Synth. Commun. 2000, 30, 751.
(8) Ferraz, H. M. C., Ribeiro, C. M. R.; Grazini, M. V. A.; Brocksom,
T. J .; Brocksom, U. Tetrahedron Lett. 1994, 35, 1497.
10.1021/jo011178m CCC: $22.00 © 2002 American Chemical Society
Published on Web 04/11/2002

Notes
J . Org. Chem., Vol. 67, No. 10, 2002 3519
Sch em e 2a
The next set of reactions was performed in methanol,
since this solvent has proved to be efficient for the ring
contraction of a series of 1,2-dihydronaphthalenes.16 The
consumption of the starting materials occurred almost
instantaneously, at 0 °C, but the results were very similar
to those observed when the solvent was aqueous AcOH.
Thus, the alkenols 4a and 4b afforded the ring contrac-
tion products in moderate yields, while 4c led to the
cyclopentane derivative 5c in poor yield, along with a
mixture of glycolic products (Table 1, entries 2, 4, and
6). The substrates 4d -f furnished complex mixtures of
products, mainly glycolic derivatives. In the mixture
obtained from 4f were detected the â-methoxy cyclic
ethers 7f and 7f ′, which could be isolated in 6% yield
(4:1 ratio, respectively).
a
These results indicate that the formation of glycolic
derivatives is the preferential process when the reaction
is carried out in MeOH. Moreover, only the substrates
4a and 4b, without substituents in the ring, were able
to undergo selectively the ring contraction reaction.
The alkenols 4a and 4b were then treated with TTN
in 35% aqueous HClO4 at room temperature.17 In contrast
to the favorable results obtained using aqueous AcOH
and MeOH, both reactions led to a complex mixture of
products, from which no identifiable material could be
isolated. Somewhat surprisingly, the substrates 4c-f
underwent a smooth cyclization reaction with a high
degree of stereocontrol (Table 2). The â-hydroxy cyclic
ethers 6c-f thus obtained exhibit cis-fused rings and cis-
relationships between the hydroxyl group and the alkyl
substituent at the carbocyclic moiety.
Reagents and Conditions: (a) Zn, benzene, reflux then 10%
aqueous H2SO4; (b) SOCl2, Py, Et2O, rt; (c) 10% aqueous NaOH,
EtOH, 30 °C; (d) LiAlH4, THF, rt.
Ta ble 1. Rea ction of 3-a lk en ols 4a -d w ith TTN
The diastereoisomers 6e/6e′ and 6f/6f ′ were obtained
in 5:1 and 7:3 ratios, respectively, as deduced by GC and
NMR analysis of the crude products. These isomers were
separated by flash chromatography and duly character-
ized. A suitable crystal of the minor isomer 6e′ could be
obtained and was submitted to crystallographic analysis,
which corroborated the previously assigned structure.
The relative configurations of 6f and 6f ′ was proposed
1
by comparison of the H and 13C NMR data with those of
6e and 6e′, respectively.
We also investigated the behavior of the seven-
membered ring alkenol 818 toward TTN oxidation, under
the three experimental conditions already mentioned.
Using 35% aqueous HClO4, a complex mixture of prod-
ucts was obtained, similar to 4a and 4b. When the
reaction was run in aqueous AcOH or MeOH, the
expected six-membered ring contraction product 9 was
(14) Ferraz, H. M. C.; Silva, L. F., J r. Tetrahedron Lett.1997, 38,
1899.
(15) Hoberg, H.; Ballesteros, A.; Sigan, A.; J egat, C.; Milchereit, A.
Synthesis 1991, 395.
(16) Ferraz, H. M. C.; Silva, L. F., J r.; Vieira, T. O. Tetrahedron
2001, 57, 1709.
a
Reference 13.
(17) For examples of TTN-promoted oxidations performed in aqueous
HClO4, see: (a) Wiberg, K. B.; Koch, W. Tetrahedron Lett. 1966, 1779.
(b) Byrd, J . E.; Halpern, J . J . Am. Chem. Soc. 1973, 95, 2586. (c) Corey,
E. J .; Snider, B. S. J . Org. Chem. 1974, 39, 256.
(18) The alkenol 8 was prepared from cycloheptanone, according to
the sequence of reactions shown in Scheme 2.
the absence of the alkyl group at the ring. The 1,3-trans
relationship of the substituents of 5c was tentatively
assigned by NMR analysis and comparison with data of
similar structures.14,15

3520 J . Org. Chem., Vol. 67, No. 10, 2002
Notes
Ta ble 2. Rea ction of 3-a lk en ols 4c-f w ith TTN in 35%
Sch em e 4
Aqu eou s HClO4
a
b
Isolated yields. A small amount of 5c (ca. 5%) was detected
in the NMR spectra. c Ratio determined by GC and 1H NMR.
Sch em e 3a
corresponding cyclopentane derivatives. For these sub-
strates, the alternative cyclization reaction becomes the
preferable pathway, providing the solvent is non-nucleo-
philic. Otherwise, a conventional electrophilic addition
to the double bond takes place, and the glycolic deriva-
tives are the major components of the reactional mixture.
a
Reagents and conditions: (a) 1.2TTN, 50% aqueous AcOH, rt,
Exp er im en ta l Section
8 min; (b) 1.0 TTN, MeOH, 0 °C, 2 min.
Gen er a l Meth od s. Thallium trinitrate20 was used as re-
ceived. Other known compounds used in this research were also
purchased from standard chemical suppliers and were dried and/
or purified by usual methods. Column chromatography was
performed using silica gel (230-400 mesh). TLC analyses were
performed with silica gel plates using vanilline or p-anisaldehyde
solution for visualization.
Gen er a l P r oced u r e A. Rea ction of 3-Alk en ols w ith TTN
in 50% Aqu eou s AcOH. To a stirred solution of the 3-alkenol
(1.00 mmol) in 50% aqueous AcOH (3 mL) was added TTN‚3H2O
(1.20 mmol), which promptly dissolved. The mixture was stirred
at room temperature for the time indicated in Table 1, and
saturated aqueous NaHCO3 was added dropwise. The aqueous
phase was extracted with ethyl acetate (three times), the
combined organic phases were washed with brine (twice) and
dried over anhydrous MgSO4, and the solvent was removed
under reduced pressure.
3-Hyd r oxy-1-(tr a n s-3-m eth ylcyclop en tyl)p r op a n -1-on e
(5c) an d 6r-Meth yl-7arH-h exah ydr oben zofu r an -3ar-ol (6c).
The crude product was purified by flash chromatography (CH2-
Cl2/AcOEt 9:1 as eluent) to afford 5c and 6c in 20% and 9% yield,
respectively. 5c: colorless oil; IR (film) 3425 and 1705 cm-1; 1H
NMR (300 MHz, CDCl3) δ 0.98 (d, J ) 6.4 Hz, 3H), 1.10-1.50
(m, 2H), 1.75-2.03 (m, 5H), 2.70 (t, J ) 5.4 Hz, 2H), 2.90-3.10
(m, 1H), 3.85 (t, J ) 5.4 Hz, 2H); 13C NMR (75 MHz, CDCl3) δ
20.2, 28.5, 34.2, 34.9, 36.5, 43.2, 51.1, 58.0, 214.0; MS m/z 156
obtained in 62% and 46% isolated yield, respectively
(Scheme 3).
A possible explanation for the different behavior of the
3-alkenols 4a ,b and 4c-f toward TTN-promoted oxida-
tion is depicted in Scheme 4. Due to the required anti-
periplanarity between the C1-C6 bond and the C2-Tl
bond for the contraction to occur, the oxythallated adduct
I must equilibrate to its conformer II before the rear-
rangement step. Such an equilibration (pathway a) is
easily achieved when R is hydrogen, but is not favored
when R is a bulky group. Thus, for these latter groups,
the glycolic derivatives (using aqueous AcOH or MeOH
as solvent) or the cyclic ethers (using aqueous HClO4)
become the main products of the reaction. To explain the
stereochemistry observed for the cyclic ethers, the cy-
clization of I must involve the participation of the
oxonium ion III (pathway b). Such a kind of intermediate
was already postulated by McKillop et al. for the ring
contraction of cyclohexanone.19
Con clu sion
From the results herein discussed, it can be concluded
that the presence of substituents (tert-butyl or, at a least
extension, methyl) in the cyclohexene ring of the 3-alk-
enols precludes the oxidative rearrangement to the
(19) McKillop, A.; Hunt, J . D.; Taylor, E. C. J . Org. Chem. 1972,
37, 3381.
(20) WARNING! Thallium salts are toxic and must be handled with
care.

Notes
J . Org. Chem., Vol. 67, No. 10, 2002 3521
(11, M+). 6c: colorless oil; IR (film) 3410 cm-1
;
1H NMR (500
3â,6r-Dim eth yl-7a rH-h exa h yd r oben zofu r a n -3a r-ol (6e)
a n d 3r,6r-Dim et h yl-7a rH -h exa h yd r ob en zofu r a n -3a r-ol
(6e′). The crude product was purified by flash chromatography
(gradient elution 0-40% AcOEt in hexanes) to afford a 5:1
MHz, CDCl3) δ 0.91 (d, J ) 6.7 Hz, 3H), 1.14-1.20 (m, 1H), 1.31
(ddd, J ) 3.6, 11.5, 14.8 Hz, 1H), 1.49-1.71 (m, 4H, OH), 1.85-
2.04 (m, 3H), 3.63 (t, J ) 3.3, 3.3 Hz, 1H), 3.87 (dd, J ) 8.8, 17
Hz, 1H), 3.98 (ddd, J ) 4.0, 8.8, 10 Hz, 1H); 13C NMR (75 MHz,
CDCl3) δ 21.7, 26.2, 29.8, 34.0, 34.4, 39.9, 64.9, 75.1, 80.2; MS
m/z 156 (20, M+); HRMS calcd for C9H16O2 156.1150, found
156.0699.
1
mixture (by GC and H NMR) of 6e and 6e′, respectively, in 75%
yield. Analytical samples of diastereoisomers 6e and 6e′ were
obtained performing a second flash chromatography (gradient
elution, 0-35% AcOEt in hexanes) followed by recrystallization
in dry hexanes. 6e: white solid; mp ) 57.1-57.2 °C; IR (KBr)
6r-ter t-Bu t yl-7a rH-h exa h yd r ob en zofu r a n -3a r-ol (6d ).
The crude product was purified by flash chromatography (CH2-
Cl2/AcOEt 9:1 as eluent) to afford 6d in 22% yield. 6d : white
solid; mp ) 81.2-82.0 °C. Analytical samples of 6d were
obtained by recrystallization in dry hexanes: IR (KBr) 3320
3394 cm-1 1H NMR (500 MHz, CDCl3) δ 0.90 (d, J ) 6.6 Hz,
;
3H), 0.93 (d, J ) 6.9 Hz, 3H), 1.15 (ddd, J ) 4.2, 12.3, 24.7 Hz,
1H), 1.27 (ddd, J ) 3.3, 12.0, 14.7 Hz, 1H), 1.44-1.64 (m, 4H,
OH), 1.87 (dq, J ) 2.3, 14.7 Hz, 1H), 2.27-2.32 (m, 1H), 3.40
(dd, J ) 8.5, 10.2 Hz, 1H), 3.69 (br s, 1H), 4.08 (t, J ) 8.8 Hz,
1H); 13C NMR (125 MHz, CDCl3) δ 9.4, 22.0, 26.4, 28.4, 29.4,
34.7, 44.2, 71.9, 75.0, 81.3; MS m/z 170 (4.1, M+). Anal. Calcd
for C10H18O2: C, 70.55; H, 10.66. Found: C, 70.39; H, 10.33.
1
cm-1; H NMR (300 MHz, CDCl3) δ 0.86 (s, 9H), 1.18-1.43 (m,
3H), 1.55-1.82 (m, 4H), 1.87-2.07 (m, 3H), 3.68 (br s, 1H), 3.83-
4.02 (m, 2H); 13C NMR (75 MHz, CDCl3) δ 22.3, 26.8, 27.4, 32.0,
34.8, 40.2, 40.9, 65.0, 75.0, 80.7; MS m/z 198 (6.0, M+). Anal.
Calcd for C12H22O2: C, 72.68; H, 11.18. Found: C, 72.28; H,-
10.88.
6e′: white solid; mp ) 54.8-55.6 °C; IR (KBr) 3394 cm-1 1H
;
NMR (500 MHz, CDCl3) δ 0.91 (d, J ) 6.7 Hz, 3H), 1.00 (d, J )
7.2 Hz, 3H), 1.17-1.35 (m, 2H), 1.46-1.51 (m, 1H), 1.59-1.73
(m, 3H, OH), 1.83-1.88 (m, 1H), 1.99-2.06 (m, 1H), 3.50 (dd, J
) 4.5, 8.8 Hz, 1H), 3.67 (t, J ) 3.6 Hz, 1H), 4.14 (dd, J ) 7.7,
8.8 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ 14.2, 21.5, 26.3, 29.7,
34.5, 34.8, 41.2, 76.1, 76.7, 78.2; MS m/z 170 (3.9, M+). Anal.
Calcd for C10H18O2: C, 70.55; H, 10.66. Found: C, 70.36; H,
10.33.
1-Cycloh exyl-3-h yd r oxyp r op a n -1-on e (9). The crude prod-
uct was purified by flash chromatography (gradient elution, 10-
60% AcOEt in hexanes) affording 9 in 62% yield. 9: colorless
oil; IR (film) 3410 and 1703 cm-1; 1H NMR (300 MHz, CDCl3) δ
1.18-1.41 (m, 5H), 1.65-1.89 (m, 5H), 2.30-2.38 (m, 1H), 2.58
(br s, OH), 2.69 (t, J ) 5.4 Hz, 2H), 3.84 (br s, 2H); 13C NMR (75
MHz, CDCl3) δ 25.6, 25.9, 28.4, 42.2, 51.2, 58.0, 214.9; MS m/z
156 (11, M+); HRMS calcd for C9H16O2 156.1150, found 156.1152.
Gen er a l P r oced u r e B. Rea ction of 3-Alk en ols w ith TTN
in MeOH. To a stirred solution of the 3-alkenol (1.00 mmol) in
MeOH (6 mL) at 0 °C was added TTN‚3H2O (1.00 mmol), which
promptly dissolved. The mixture was stirred for the time
indicated in Table 1, and an abundant precipitation was
observed. The resulting suspension was filtered through a silica
gel pad (70-230 mesh, ca. 10 cm), using CH2Cl2 as eluent. The
filtrate was then washed with water followed by brine (twice)
and dried over anhydrous MgSO4, and the solvent was removed
under reduced pressure.
1-Cyclop en tyl-3-h yd r oxyp r op a n -1-on e (5a ).13 The crude
product was purified by flash chromatography (gradient elution,
10-50% AcOEt in hexanes) to afford 5a in 62% yield. (5a ):
colorless oil; 1H NMR (300 MHz, CDCl3) δ 1.52-1.89 (m, 8H),
2.46 (br s, OH), 2.72 (t, J ) 5.4 Hz, 2H), 2.88 (quintet, J ) 7.5
Hz, 1H), 3.85 (t, J ) 5.4 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ
26.0, 28.8, 43.4, 51.9, 58.0, 214.0.
3â-Meth yl-6r-ter t-bu tyl-7arH-h exah ydr oben zofu r an -3ar-
ol (6f) a n d 3r-Meth yl-6r-ter t-bu tyl-7a rH-h exa h yd r oben -
zofu r a n -3a r-ol (6f′). The crude product was purified by flash
chromatography (gradient elution 0-50% AcOEt in hexanes) to
afford a 7:3 mixture (by GC and 1H NMR) of 6f and 6f ′,
respectively, in 75% yield. Analytical samples of diastereoiso-
mers 6f and 6f ′ were obtained by performing a second flash
chromatography (gradient elution, 0-40% AcOEt in hexanes)
followed by recrystallization in dry hexanes. 6f: white solid; mp
) 102.5-103.2 °C; IR (KBr) 3378 cm-1 1H NMR (500 MHz,
;
CDCl3) δ 0.87 (s, 9H), 0.93 (d, J ) 6.9 Hz, 3H), 1.17-1.66 (m,
6H, OH), 1.94 (dq, J ) 2.6, 14.1 Hz, 1H), 2.26-2.33 (m, 1H),
3.41 (dd, J ) 8.5 and 10.1 Hz, 1H), 3.76 (br s, 1H), 4.09 (t, J )
8.8 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ 9.5, 21.8, 27.3, 27.4,
29.1, 32.0, 41.3, 44.2, 71.9, 75.1, 81.8; MS m/z 212 (13, M+). Anal.
Calcd for C13H24O2: C, 73.54; H, 11.39. Found: C, 73.35; H,
11.05. 6f ′: white solid; mp ) 93.8-94.2 °C; IR (KBr) 3378 cm-1
;
1H NMR (500 MHz, CDCl3) δ 0.86 (s, 9H), 1.01 (d, J ) 7.2 Hz,
3H), 1.24-1.37 (m, 3H, OH), 1.54-1.70 (m, 3H), 1.95-2.00 (m,
2H), 3.49 (dd, J ) 4.1, 8.9 Hz, 1H), 3.70 (br s, 1H), 4.15 (dd, J )
7.5, 8.9 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ 14.7, 22.3, 26.9,
27.3, 32.1, 36.2, 40.8, 41.8, 73.8, 75.9, 78.5; MS m/z 212 (17, M+).
Anal. Calcd for C13H24O2: C, 73.54; H, 11.39. Found: C, 73.44;
H, 11.09.
1-Cyclop en t yl-3-h yd r oxy-2-m et h ylp r op a n -1-on e (5b ).13
The crude product was purified by flash chromatography (gradi-
ent elution, 20-50% AcOEt in hexanes) to afford 5b in 77% yield.
1
5b: colorless oil; H NMR (200 MHz, CDCl3) δ 1.13 (d, J ) 7.2
Hz, 3H), 1.56-1.90 (m, 8H), 2.35 (br s, OH), 2.79-3.07 (m, 2H),
3.64 (dd, J ) 4.5 e 11.0 Hz, 1H), 3.76 (dd, J ) 7.2 e 11.0 Hz,
1H); 13C NMR (50 MHz, CDCl3) δ 13.4, 26.0, 26.1, 28.5, 29.7,
47.3, 50.2, 64.5, 217.7.
Ack n ow led gm en t. We thank FAPESP, CNPq, and
CAPES for financial support. We also thank Prof. Luiz
C. Dias for his help in carrying out the HRMS.
Gen er a l P r oced u r e C. Rea ction of 3-Alk en ols w ith TTN
in 35% Aqu eou s HClO4. To a stirred solution of the 3-alkenol
(1.00 mmol) in 35% aqueous HClO4 (3 mL) was added TTN‚3H2O
(1.20 mmol), which promptly dissolved. The mixture was stirred
for 15 min at room temperature, and water was added. The
aqueous phase was extracted with CH2Cl2 (three times), the
combined organic phases were washed with brine (twice) and
dried over anhydrous MgSO4, and the solvent was removed
under reduced pressure.
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures and structural data for all compounds not described
within the text. Representative NMR spectra of 5b, 9, and 6e,
6e′ (including X-ray crystallographic data of 6e′). This material
is available free of charge via the Internet at http://pubs.acs.org.
J O011178M