Reaction of Highly Methylated 2-Methylenecycloalkyl Hydroperoxides with FeSO4/CuCl2. Remarkably Efficient 5-endo-trig or 6-endo-trig Cyclization of the Intermediate Carbon Radicals

Article abstract of DOI:10.1021/jo990127a

Treatment of 1,3,3,4,4,5,5-heptamethyl-2-methylenecyclopentyl hydroperoxide, derived from a singlet oxygen ene reaction of 1,2,3,3,4,4,5,5-octamethylcyclopentene, with FeSO₄/CuCl₂ gave 1-chloro-2,2,3,3,4,4-hexamethylcyclopentyl methy

Full text of DOI:10.1021/jo990127a

4060
J . Org. Chem. 1999, 64, 4060-4063
Rea ction of High ly Meth yla ted 2-Meth ylen ecycloa lk yl
Hyd r op er oxid es w ith F eSO4/Cu Cl2. Rem a r k a bly Efficien t
5-en d o-tr ig or 6-en d o-tr ig Cycliza tion of th e In ter m ed ia te Ca r bon
Ra d ica ls
Yuji Nonami,† J anusz Baran,*,‡ J acek Sosnicki,‡ Herbert Mayr,§ Araki Masuyama,† and
Masatomo Nojima*,†
Department of Materials Chemistry, Faculty of Engineering, Osaka University, Suita,
Osaka 565-0871, J apan, Institute of Fundamental Chemistry, Technical University of Szczecin,
Al. Piasto´w 42, PL-71065 Szczecin, Poland, and Institut fu¨r Organische Chemie,
der Ludwig-Maximilians-Universita¨t, Mu¨nchen, Karlstrasse 23, D-80333 Mu¨nchen, Germany
Received J anuary 25, 1999
Treatment of 1,3,3,4,4,5,5-heptamethyl-2-methylenecyclopentyl hydroperoxide, derived from a
singlet oxygen ene reaction of 1,2,3,3,4,4,5,5-octamethylcyclopentene, with FeSO4/CuCl2 gave
1-chloro-2,2,3,3,4,4-hexamethylcyclopentyl methyl ketone in high yield, suggesting that the
consecutive O-O and C-C bond fission is followed by a novel 5-endo-trig cyclization of the
intermediate carbon radical to the activated C-C double bond. In the case of 1,3,3,6,6-pentamethyl-
2-methylene-1-cyclohexyl hydroperoxide also, an efficient 6-endo-trig cyclization of the corresponding
carbon radical was realized giving 1-chloro-2,2,5,5-tetramethylcyclohexyl methyl ketone in high
yield.
A variety of allylic hydroperoxides have conveniently
Resu lts a n d Discu ssion
been prepared by the singlet oxygen ene reaction of
unactivated olefins with allylic hydrogen atoms.1 The
allylic hydroperoxides thus prepared have proven to be
synthetically useful intermediates.2 While reduction leads
to allylic alcohols, the reaction with TiIV complexes has
been utilized to prepare epoxy alcohols.3 Finally, dehy-
dration provides convenient access to enones.4 We report
here that (1) the reaction of highly methylated cycloalk-
enes with singlet oxygen proceeds very rapidly providing
the corresponding 2-methylenecycloalkyl hydroperoxides
in high yield and (2) the subsequent treatment of the
Sin glet Oxygen En e Rea ction of High ly Meth yl-
a ted Cycloa lk en es. Octamethylcyclopentene (1a ) was
irradiated in CH2Cl2 in the presence of a small amount
of tetraphenylporphine and NaHCO3 under a slow stream
of oxygen. By subsequent column chromatography on
basic alumina, 1,3,3,4,4,5,5-heptamethyl-2-methylene-1-
cyclopentyl hydroperoxide (2a ) was isolated in 87% yield
(Scheme 1).8 However, the hydroperoxide 2a was very
labile even in a refrigerator. In the absence of any
initiator, 2a dissolved in CDCl3 (pretreated with NaH-
CO3) completely rearranged to the regioisomeric hydro-
peroxide 5a within 2 days. However, the presence of a
small amount of methylhydroquinone, a radical scaven-
ger, was found to retard the rearrangement completely,
suggesting that the rearrangement of 2a to 5a proceeds
via the corresponding peroxyl radical intermediates, 8a
and 9a (Scheme 1).9
5
allylic hydroperoxides with FeSO4/CuCl2 affords 1-
chlorocycloalkyl methyl ketones, indicating that the
homolytic O-O and C-C bond fission is followed by
efficient 5-endo-trig6 or 6-endo-trig7 cyclization of the
intermediate carbon radicals.
† Faculty of Engineering.
‡ Technical University of Szczecin.
The reaction of 1,2,3,3,4,4-hexamethylcyclopentene
(1b) with singlet oxygen may produce three different
allylic hydroperoxides 2b-4b (Scheme 1). When the
reaction of 1b was conducted under the reaction condi-
tions described above, all three isomers 2b-4b were
§ Institut fu¨r Organische Chemie der Ludwig-Maximilians-Univer-
sita¨t.
(1) (a) Singlet Oxygen; Wasserman, H. H., Murray, R. W., Eds.;
Academic Press: New York, 1979. (b) Foote, C. S.; Clennan, E. L. In
Active Oxygen in Chemistry; Foote, C. S., Valentine, J . S., A. Greenberg,
A., Liebman, J . F., Eds.; Blackie Academic & Professional: London,
1995; Vol. 2.
(2) Prein, M.; Adam, W. Angew. Chem., Int. Ed. Engl. 1996, 35, 477.
(3) Adam, W.; Richter, M. J . Acc. Chem. Res. 1994, 27, 57 and
references therein.
(7) The appropriate placement of activating groups can also be used
to accelerate 6-endo cyclizations. (a) Beckwith, A. L.; Gream, G. E.;
Struble, D. L. Aust. J . Chem. 1972, 25, 1081. (b) Wehle, D.; Schormann,
N.; Fitjer, L. Chem. Ber. 1988, 121, 2171. (c) Satoh, T.; Itoh, M.;
Yamakawa, K. Chem. Lett. 1987, 1949. See also: Handa, S.; Pattenden,
G.; Li, W.-S. Chem. Commun. 1998, 311.
(8) The photolysis in the absence of NaHCO3, followed by column
chromatography on silica gel, afforded (2,3,3,4,4,5,5-heptamethyl-1-
cyclopentenyl)methyl hydroperoxide (5a ) in 25% yield, together with
unidentified decomposition products. In this connection, allylic hydro-
peroxides are known to be labile toward acid catalysts. Schenck, G.
O.; Schulte-Elte, K.-H. Liebigs Ann. Chem. 1958, 618, 185.
(9) (a) Lowe, J . R.; Porter, N. A. J . Am. Chem. Soc. 1997, 119, 11534.
(b) Dussault, P. H.; Woller, K. R. J . Am. Chem. Soc. 1997, 119, 3824.
(c) Dang, H.-S.; Davies, A. G.; Davison, I. G. E.; Schiesser, C. H. J .
Org. Chem. 1990, 55, 1432. (d) Schenck, G. O.; Neumu¨ller, O.-A.;
Eisfeld, W. Liebigs Ann. Chem. 1958, 618, 202.
(4) Adam, W.; Klug, P. Synthesis 1994, 557 and references therein.
(5) (a) Dussault, P. H. In Active Oxygen in Chemistry; Foote, C. S.,
Valentine, J . S., Greenberg, A., Liebman, J . F., Eds.; Blackie Academic
& Professional: London, 1995; Vol. 2. (b) Curran, D. P. In Compre-
hensive Organic Chemistry; Trost, B. M., Ed.; Pergamon: Oxford, 1991;
Vol 4, p 823. (c) McCullough, K. J .; Motomura, Y.; Masuyama, A.;
Nojima, M. Chem. Commun. 1998, 1173 and references therein.
(6) Bona fide examples of 5-endo cyclizations are even rarer than
their 4-exo counterparts. (a) Curran, D. P.; Porter, N. A.; Giese, B.
Stereochemistry of Radical Reactions; VCH: Weinheim; 1996. (b)
Mendenhall, G. D.; Protasiewicz, J . D.; Brown, C. E.; Ingold, K. U.;
Lusztyk, J . J . Am. Chem. Soc. 1994, 116, 1718. (c) Ponaras, A. A.; Zaim,
O¨ . Tetrahedron Lett. 1993, 34, 2879. (d) Sato, T.; Machigashira, N.;
Ishibashi, H.; Ikeda, M. Heterocycles 1992, 33, 139. (e) Cassayre, J .;
Quiclet-Sire, B.; Saunier, J .-B.; Zard, S. Z. Tetrahedron 1998, 54, 1029.
10.1021/jo990127a CCC: $18.00 © 1999 American Chemical Society
Published on Web 05/11/1999

Highly Methylated 2-Methylenecycloalkyl Hydroperoxides
J . Org. Chem., Vol. 64, No. 11, 1999 4061
Sch em e 1
Sch em e 3
Sch em e 2
This result indicates that oxy radical 10, generated by
fragmentation of the O-O bond, undergoes selective
â-scission of one of the C-C bonds to give the acyclic
radical 11. Successive intramolecular cyclization gives 12,
which in turn reacts with copper(II) chloride to provide
the chlorinated cyclohexane 13. This efficient 6-endo-trig
cyclization is explained by the directing effect of the R,â-
unsaturated carbonyl group in the intermediate 11.7
It was of interest to see that the highly methylated
acyclic carbon radical 15 undergoes the novel 5-endo-trig
cyclization. Treatment of the allylic hydroperoxide 2a
with FeSO4/CuCl2 in aqueous CH3CN gave acetyl-
substituted cyclopentyl chloride 17 (50%), together with
cyclopentenylmethanol 19 (10%) and aldehyde 20 (14%)
(Scheme 3). It is reasonable to assume that an analogous
mechanism as suggested for the compound 7 accounts
for the formation of 17 (Scheme 3). In this reaction
sequence the tertiary carbon radical 15 undergoes an
efficient 5-endo-trig cyclization.
The reaction sequence proposed for the production of
19 and 20 from 2a is based on the former observation
that the allylic hydroperoxide 2a is very labile. Under
the above reaction conditions in which the oxy radical
14 is produced, it is reasonable to expect that isomer-
ization of 2a to 5a competes with the reduction leading
to 17. Consistent with this, treatment of the pure allylic
hydroperoxide 5a with FeSO4/CuCl2 gave the expected
mixture of 19 (38%) and 20 (46%).
isolated. The ratio 2b:3b:4b was determined by 1H NMR
spectroscopy of the crude reaction mixture to be ca. 78:
9:13. The preferential formation of 1,3,3,4,4-pentamethyl-
2-methylene-1-cyclopentyl hydroperoxide (2b) is consis-
tent with the proposal by Orfanopoulos and co-workers10
that a “large group nonbonding effect” plays an important
role in determining the regioselectivity of Schenck ene
reaction, thereby affording predominantly the corres-
ponding allylic hydroperoxide 2b derived from abstrac-
tion of hydrogen from the more shielded 2-methyl group.
Compared with 2a , the sterically less-congested allylic
hydroperoxide 2b was very stable and could be kept in a
refrigerator for at least 1 month without notable rear-
rangement.
From 1,2,3,3,6,6-hexamethylcyclohexene (6) also, the
ene product 7 was obtained in 76% yield (Scheme 2).
Tr ea tm en t of Allylic Hyd r op er oxid es w ith F eSO4/
Cu Cl2. With the highly methylated allylic hydroperoxides
2a ,b and 7 in hand, we then conducted the Fe(II)-
catalyzed decomposition.5 Treatment of a solution of the
hydroperoxide 7 in MeCN with a solution of iron(II)
sulfate (1 equiv) and copper(II) chloride (3 equiv) in water
at room temperature gave the acetyl-substituted cyclo-
hexyl chloride 13 selectively (78%) (Scheme 2).
In marked contrast to the efficient formation of the
cyclopentyl chloride 17 from 2a , the reaction of 1,3,3,4,4-
pentamethyl-2-methylene-1-cyclopentyl hydroperoxide (2b)
under the same conditions yielded the corresponding
alcohol 22 (76%) (Scheme 4). Obviously, the â-scission
in the intermediate 21 leading to the primary carbon
radical 23 does not occur.11
The following observation would suggest that 5-endo-
trig cyclization is a difficult process. Treatment of the
allylic hydroperoxide 24, derived from singlet oxygen ene
(10) Orfanopoulos, M.; Stratakis, M.; Elemes, Y. J ensen, F. J . Am.
Chem. Soc. 1991, 113, 3180. See also: (a) Linker, T.; Fro¨hlich, L. J .
Am. Chem. Soc. 1995, 117, 2694. (b) Davis, K. M.; Carpenter, B. K. J .
Org. Chem. 1996, 61, 4617. (c) Clennan, E. L.; Chen, X.; Koola, J . J . J .
Am. Chem. Soc. 1990, 112, 5193.
(11) â-Scission is a well-established reaction of many alkoxyl
radicals. The extent to which â-scission occurs is determined by a
number of factors, one of which is the stability of the organic radical
generated: Labeque, R.; Marnett, L. J . J . Am. Chem. Soc. 1987, 109,
2828.

4062 J . Org. Chem., Vol. 64, No. 11, 1999
Nonami et al.
methods. NMR spectra were measured in CDCl3 pretreated
with NaHCO3.
Sch em e 4
Ca u tion . Since organic peroxides are potentially hazardous
compounds, they must be handled with due care; avoid
exposure to strong heat or light, mechanical shock, oxidizable
organic materials, or transition metal ions. No particular
difficulties were experienced in handling any of the new
peroxides synthesized in this work using the reaction scales
and procedures described below together with the safeguard
mentioned above.
P h otooxygen a tion . A tube containing 20 mL of a CH2Cl2
solution of a cyclopentene 1 (1-2 mmol), tetraphenylporphine
(1 mg), and NaHCO3 (5 mg) was irradiated at 0 °C for 1.5 h
(the reaction was followed by TLC) with a 300 W high-pressure
mercury lamp through an aqueous CuSO4 filter solution (>400
nm) under an oxygen stream. After ether (50 mL) was added,
the organic layer was washed with aqueous NaHCO3 and then
with saturated brine and the solvent was evaporated (room
temperature, 15 mmHg). The residue was separated by column
chromatography (column 2.0 × 60 cm; 40 g of basic alumina;
elution with ether-hexane).
Sch em e 5
P h otooxygen a tion of 1,2,3,3,4,4,5,5-Octa m eth ylcyclo-
p en ten e (1a ). The photooxygenation of 1a (180 mg, 1 mmol)
1
was conducted as described above. The H NMR spectrum of
the crude product showed the presence of only 2a . Column
chromatography of the residue (elution with ether-hexane,
5:95) gave 2a (184 mg, 87%).
1,3,3,4,4,5,5-Heptam eth yl-2-m eth ylen e-1-cyclopen tyl h y-
d r op er oxid e (2a ): mp 58-62 °C; 1H NMR δ 0.82 (s, 3 H),
0.85 (s, 3 H), 0.89 (s, 3 H), 1.03 (s, 3 H), 1.08 (s, 3 H), 1.13 (s,
3 H), 1.32 (s, 3 H), 5.20 (s, 1 H), 5.23 (s, 1 H), 6.96 (s, 1 H); 13
C
NMR δ 15.58, 16.89, 22.41, 24.64, 26.27, 29.89, 30.68, 44.96,
46.11, 49.89, 94.52, 110.51, 162.57. Anal. Calcd for C13H24O2:
C, 73.54; H, 11.39. Found: C, 73.58; H, 11.49.
1
Rea r r a n gem en t of 2a . The H NMR spectra of a solution
reaction of 2,3-dimethylindene,12 with FeSO4/CuCl2 gave
exclusively the benzyl chloride 27 (Scheme 5). This
implies that â-scission in the oxy radical 25 occurs.
However, chlorine atom transfer from CuCl2 is much
faster than 5-endo-trig cyclization, thereby providing
exclusively the acyclic product 27.13
of 2a (22 mg, 0.1 mmol) in CDCl3 was periodically measured,
which demonstrated that in 2 days 2a rearranged to 5a
completely. Column chromatography on silica gel (elution with
ether-hexane, 5:95) gave the rearranged allylic hydroperoxide
5a quantitatively. When the same reaction was repeated in
the presence of 0.05 equiv of methylhydroquinone, the rear-
rangement was completely suppressed.
Con clu sion . The singlet oxygen ene reaction of highly
methylated cycloalkenes proceeds well providing the
corresponding 2-methylenecycloalkyl hydroperoxides in
good yield. In the case of the unsymmetrically substituted
1b, the regioselectivity is notable, affording predomi-
nantly the corresponding allylic hydroperoxide derived
from abstraction of hydrogen from the more shielded
2-methyl group. As a new and attractive transformation
of allylic hydroperoxide, treatment of 2a and 7 with
FeSO4/CuCl2 gives the corresponding 1-chlorocycloalkyl
methyl ketones in high yield.
(2,3,3,4,4,5,5-Hep ta m eth yl-1-cyclop en ten yl)m eth yl h y-
1
d r op er oxid e (5a ): an oil; H NMR δ 0.78 (s, 6 H), 0.92 (s, 6
H), 0.96 (s, 6 H), 1.66 (s, 3 H), 4.55 (s, 2 H), 8.09 (s, 1 H); 13C
NMR δ 10.44, 21.44, 23.99, 24.91, 46.08, 49.04, 52.21, 71.40,
133.15, 147.60. Anal. Calcd for C13H24O2: C, 73.54; H, 11.39.
Found: C, 73.58; H, 11.59.
P h otooxygen a tion of 1,2,3,3,4,4-Hexa m eth ylcyclop en -
ten e (1b). The photooxygenation of 1b (280 mg, 1.84 mmol)
1
was conducted as described above. The H NMR spectrum of
the crude product showed the presence of three allylic hydro-
peroxides, 2b-4b. By comparing the peak areas of the
characteristic signals of 2b (δ 2.04), 3b (δ 2.37), and 4b (δ 5.40),
the product ratio was determined to be 78:9:13. Column
chromatography of the residue (elution with ether-hexane.
5:95) gave first 4b (34 mg, 10%). From the second fraction, 3b
was obtained (27 mg, 8%). Elution with ether-hexane (8:92)
gave 2b (226 mg, 67%).
Exp er im en ta l Section
Ma t er ia ls. 1,2,3,3,4,4,5,5-Octamethylcyclopentene (1a ),14
1,2,3,3,4,4-hexamethylcyclopentene (1b ),14 1,2,3,3,6,6-hexa-
methylcyclohexene (6),15 and 2-methyl-1-methylene-2-indenyl
hydroperoxide (24) (63% yield; an oil; 1H NMR δ 1.14 (s, 3 H),
2.88 (d, J ) 17.2 Hz, 1 H), 3.38 (d, J ) 17.2 Hz, 1 H), 5.21 (s,
1 H), 5.62 (s, 1 H), 7.1-7.4 (m, 4 H), 7.65 (s, 1 H); 13C NMR δ
23.76, 41.58, 90.26, 105.39, 121.01, 125.25, 126.85, 129.22,
138.56, 142.16, 151.52)12 were prepared by the reported
1,3,3,4,4-P en ta m eth yl-2-m eth ylen e-1-cyclop en tyl h y-
1
d r op er oxid e (2b): an oil; H NMR δ 0.84 (s, 3 H), 0.92 (s, 3
H), 0.94 (s, 3 H), 1.00 (s, 3 H), 1.49 (s, 3 H), 1.64 (d, J ) 14.2
Hz, 1 H), 2.04 (d, J ) 14.2 Hz, 1 H), 5.05 (s, 1 H), 5.18 (s, 1 H),
7.81 (s, 1 H); 13C NMR δ 23.87, 23.92, 24.42, 24.93, 25.11,
41.02, 47.71, 49.20 (CH2), 88.92, 108.88 (CH2), 162.81. Anal.
Calcd for C11H20O2: C, 71.70; H, 10.94. Found: C, 71.54; H,
10.56.
(12) Fenical, W.; Kearns, D. R.; Radlick, P. J . Am. Chem. Soc. 1969,
91, 3396.
(13) Compared with 5-endo cyclization, 6-endo cyclization is a more
facile process. Consistent with this, the reaction of 2-methylene-1-
methylcyclohexyl hydroperoxide with FeSO4/CuCl2 gives 1-chlorocy-
clohexyl methyl ketone in 55% yield. Masuyama, A.; Sugawara, T.;
Nojima, M. Unpublished result.
1,4,4,5,5-P en ta m eth yl-2-m eth ylen e-1-cyclop en tyl h y-
1
d r op er oxid e (3b): an oil; H NMR δ 0.81 (s, 3 H), 0.88 (s, 3
H), 0.91 (s, 3 H), 1.08 (s, 3 H), 1.33 (s, 3 H), 2.36 (m, 2 H), 5.15
(br s, 2 H), 7.14 (s, 1 H); 13C NMR δ 15.65, 16.3, 23.51, 25.77,
28.21, 41.01, 45.77 (CH2), 49.92, 94.39, 111.34 (CH2), 151.14.
Anal. Calcd for C11H20O2: C, 71.70; H, 10.94. Found: C, 71.64;
H, 10.58.
(14) Klein, H.; Mayr, H. Angew. Chem., Int. Ed. Engl. 1981, 20, 1027.
(15) Mayr, H.; Klein, H.; Sippel, E. Chem. Ber. 1983, 116, 3624.

Highly Methylated 2-Methylenecycloalkyl Hydroperoxides
J . Org. Chem., Vol. 64, No. 11, 1999 4063
1,2,4,4,5,5-Hexa m et h yl-2-cyclop en t en -1-yl h yd r op er -
oxid e (4b): an oil; 1H NMR δ 0.82 (s, 3 H), 0.86 (s, 3 H), 0.96
(s, 3 H), 1.05 (s, 3 H), 1.58 (s, 3 H), 1.70 (s, 3H), 5.40 (s, 1 H),
7.16 (s, 1 H); 13C NMR δ 13.87, 16.37, 17.97, 23.38, 23.84,
27.44, 46.88, 49.49, 98.08, 137.07, 141.26 (CH). Anal. Calcd
for C11H20O2: C, 71.70; H, 10.94. Found: C, 71.66; H, 10.49.
P h otooxygen a tion of 1,2,3,3,6,6-Hexa m eth ylcycloh ex-
en e (6). The photooxygenation of 6 (120 mg, 0.73 mmol) was
conducted as described above. Column chromatography of the
residue (elution with ether-hexane, 5:95) gave 7 (109 mg,
76%).
1,3,3,6,6-P en t a m et h yl-2-m et h ylen e-1-cycloh exyl h y-
d r op er oxid e (7): mp 60-61 °C; 1H NMR δ 0.83 (s, 3 H), 1.01
(s, 3 H), 1.0-1.1 (m, 1 H), 1.14 (s, 3 H), 1.2-1.3 (m, 1 H), 1.29
(s, 3 H), 1.38 (s, 3 H), 1.53 (td, J ) 13.9 and 4.3 Hz, 1 H), 2.06
(td, J ) 13.9 and 4.3 Hz, 1 H), 5.20 (s, 1 H), 5.30 (s, 1 H), 6.80
(s, 1 H); 13C NMR δ 16.32, 24.44, 24.71, 28.36, 28.65, 32.01,
32.69, 36.07, 38.62, 88.90, 114.43, 153.17. Anal. Calcd for
C12H22O2: C, 72.67; H, 11.18. Found: C, 73.18; H, 11.47.
Rea ction of Allylic Hyd r op er oxid e w ith F eSO4/Cu Cl2.
To a solution of FeSO4 (1 equiv) and CuCl2 (3 equiv) in H2O
(15 mL) was added dropwise a solution of an allylic hydro-
peroxide (0.7-1.2 mmol) in CH3CN (15 mL) during 30 min,
and the mixture was stirred at room temperature for an
additional 15 min. Then, the mixture was extracted with ether
and the extract was dried over anhydrous MgSO4 and evapo-
rated. The residue was separated by column chromatography
(column 2.0 × 60 cm; 40 g of silica gel; elution with ether-
hexane, 1:99).
NMR δ 22.64 (CH3), 23.78 (CH3), 24.69 (CH3), 25.09 (CH3),
27.61 (CH3), 29.02 (CH3), 30.48 (CH3), 40.69, 49.23, 51.35,
52.69 (CH2), 88.12, 202.91; HRMS (EI) calcd for C13H23ClO
(M+) 230.1437, found 230.1452.
(2,3,3,4,4,5,5-H ep t a m et h yl-1-cyclop en t en yl)m et h a n ol
1
(19): an oil; H NMR δ 0.80 (s, 6 H), 0.92 (s, 6 H), 0.98 (s, 6
H), 1.64 (s, 3 H), 1.6-1.7 (br s, 1 H), 4.12 (s, 2 H); 13C NMR δ
10.10, 21.46 (2 C), 24.01 (2 C), 25.08 (2 C), 45.99, 49.31, 49.92,
56.96, 138.90, 142.91. Anal. Calcd for C13H24O: C, 79.53; H,
12.32. Found: C, 79.24; H, 12.29.
1-F or m yl-2,3,3,4,4,5,5-h ep ta m eth ylcyclop en ten e (20):
an oil; 1H NMR δ 0.81 (s, 6 H), 1.01 (s, 6 H), 1.14 (s, 6 H), 2.01
(s, 3 H), 10.04 (s, 1 H); 13C NMR δ 10.42, 20.99 (2 C), 23.65 (2
C), 24.20 (2 C), 46.31, 48.43, 52.13, 132.54, 141.13, 190.22.
Anal. Calcd for C13H22O: C, 80.35; H, 11.41. Found: C, 80.48;
H, 11.65.
Rea ction of (2,3,3,4,4,5,5-Hep ta m eth yl-1-cyclop en te-
n yl)m eth yl Hyd r op er oxid e (5a ) w ith F eSO4/Cu Cl2. The
reaction of 5a (180 mg, 0.85 mmol) was conducted as described
above. By column chromatography on silica gel (elution with
ether-hexane, 1:99), aldehyde 20 was isolated (76 mg, 46%).
Subsequent elution with ether-hexane (2:8) gave alcohol 19
(63 mg, 38%).
Rea ction of 1,3,3,4,4-P en ta m eth yl-2-m eth ylen e-1-cy-
clop en tyl Hyd r op er oxid e (2b) w ith F eSO4/Cu Cl2. The
reaction of 2b (150 mg, 0.81 mmol) was conducted as described
above. By column chromatography on silica gel, alcohol 22 was
isolated (104 mg, 76%). The physical properties of 22 were the
same as those obtained by the reaction of the allyl hydroper-
oxide 2b with 1 equiv of triphenylphosphine in CDCl3.
2-Me t h y le n e -1,3,3,4,4-p e n t a m e t h y lc y c lo p e n t a n o l
Rea ction of 1,3,3,6,6-P en ta m eth yl-2-m eth ylen e-1-cy-
cloh exyl Hyd r op er oxid e (7) w ith F eSO4/Cu Cl2. The reac-
tion of 7 (142 mg, 0.71 mmol) was conducted as described
above. The 1H NMR spectrum of the crude product showed
the presence of only 13. Column chromatography of the residue
gave 13 (121 mg, 78%).
1
(22): an oil; H NMR δ 0.85 (s, 3 H), 0.92 (s, 3 H), 0.95 (s, 3
H), 1.02 (s, 3 H), 1.42 (s, 3 H), 1.6-1.8 (br s, 1H), 1.83 (s, 2 H),
4.92 (s, 1 H), 5.13 (s, 1 H); 13C NMR δ 23.25, 23.70, 24.80,
25.31, 31.25, 41.53, 47.96, 53.84, 76.87, 105.28, 170.08. Anal.
Calcd for C11H20O: C, 78.51; H, 11.98. Found: C, 78.41; H,
12.06.
1-Ch lor o-2,2,5,5-tetr a m eth ylcycloh exyl m eth yl k eton e
1
(13): an oil; H NMR δ 0.92 (s, 3 H), 1.02 (s, 3 H), 1.10 (s, 3
H), 1.19 (s, 3 H), 1.3-1.5 (m, 3 H), 1.74 (d, J ) 15.2 Hz, 1 H),
1.83 (ddd, J ) 13.8, 9.5, and 4.6 Hz, 1 H), 2.27 (d, J ) 15.2
Hz, 1 H), 2.39 (s, 3 H); 13C NMR δ 23.92 (CH3), 27.68 (CH3),
28.12 (CH3), 29.80 (CH3), 31.36, 32.05 (CH3), 34.09 (CH2), 34.15
(CH2), 37.87, 45.09 (CH2), 83.62, 205.53; HRMS calcd for
R ea ct ion of 2-Met h yl-1-m et h ylen e-2-in d en yl H yd r o-
p er oxid e (24) w ith F eSO4/Cu Cl2. The reaction of 24 (202
mg, 1.15 mmol) was conducted as described above. By column
chromatography on silica gel (elution with ether-hexane,
8:92), chloride 27 was isolated (149 mg, 67%).
C
12H21ClO (M+) 216.1281, found 216.1274.
3-(2-Ch lor om eth ylp h en yl)-3-bu ten -2-on e (27): an oil; 1H
NMR δ 2.33 (s, 3 H), 4.37 (s, 2 H), 5.89 (s, 1 H), 6.37 (s, 1 H),
7.0-7.4 (m, 4 H); 13C NMR δ 26.70, 46.37, 128.39, 128.52,
128.79, 129.92, 130.01, 135.24, 137.39, 147.78, 198.47. Anal.
Calcd for C11H11ClO: C, 67.87; H, 5.70. Found: C, 67.62; H,
5.86.
Rea ction of 1,3,3,4,4,5,5-Hep ta m eth yl-2-m eth ylen e-1-
cyclop en tyl Hyd r op er oxid e (2a ) w ith F eSO4/Cu Cl2. The
reaction of 2a (207 mg, 0.98 mmol) was conducted as described
above. Column chromatography of the residue (elution with
ether-hexane, the ratio was changed gradually from 1:99 to
1:9) gave first 17 (113 mg, 50%). From the second fraction,
aldehyde 20 was isolated (27 mg, 14%). The final fraction
contained alcohol 19 (19 mg, 10%).
Ack n ow led gm en t. This work was supported in part
by a Grant-in-Aid for Scientific Research on Priority
Areas (10153238 and 10166211) from the Ministry of
Education, Science, Culture and Sports of J apan.
1-Ch lor o-2,2,3,3,4,4,-h exa m eth yl-1-cyclop en tyl m eth yl
k eton e (17): an oil; 1H NMR δ 0.79 (s, 3 H), 0.89 (s, 3 H),
1.04 (s, 3 H), 1.12 (s, 3 H), 1.13 (s, 3 H), 1.25 (s, 3 H), 1.99 (d,
J ) 15.8 Hz, 1 H), 2.35 (s, 3 H), 3.00 (d, J ) 15.8 Hz, 1 H); 13
C
J O990127A