Photosensitized oxygenation of twisted 1,3-dienes: Abnormally higher reactivity of vinyl hydrogen rather than allyl hydrogen toward singlet oxygen

Article abstract of DOI:10.1021/jo980955o

As one of the novel examples to investigate the characteristic reactivity of significantly twisted 1,3-dienes, the photosensitized oxygenation of two types of significantly twisted 1,3-dienes, cis-βionol derivative 2 and acyclic derivative 11, is investigated. Photosensitized oxygenation of 2a-f and 11a-e revealed that the vinyl hydrogen Ha was more reactive than the allyl hydrogen Hb. Thus, phenyl derivative 2e and tert- butyl-substituted compound 11d selectively produced allenes 3e and 13d in 67% and 75% yield resulting from the ene reaction of the vinyl hydrogen Ha rather than allyl alcohols 4e and 14d resulting from the allyl hydrogen abstraction in 24% and 8% yield, respectively. Furthermore, in the case of methyl- substituted compound 11b, the extent of the inherent reactivity of the vinyl hydrogen Ha was similar to that of the allyl hydrogen Hc. On the basis of X- ray analysis and MM and MO calculations, the discovered abnormally higher reactivity of the vinyl hydrogen would be rationalized by considering mainly the large σ*-π orbital interaction between the vinyl C-H bond and another double bond in significantly twisted 1,3-dienes resulting from calculations of HOMO electron densities.

Full text of DOI:10.1021/jo980955o

8704
J . Org. Chem. 1998, 63, 8704-8718
P h otosen sitized Oxygen a tion of Tw isted 1,3-Dien es: Abn or m a lly
High er Rea ctivity of Vin yl Hyd r ogen Ra th er th a n Allyl Hyd r ogen
tow a r d Sin glet Oxygen
Hajime Mori,† Keiichi Ikoma,† Sachihiko Isoe,‡ Kazuo Kitaura,§ and Shigeo Katsumura*,†
School of Science, Kwansei Gakuin University, Uegahara 1-1-155, Nishinomiya 662, J apan,
Faculty of Science, Osaka City University, Sugimoto 3-3-138, Sumiyoshi, Osaka 558, J apan, and
College of Integrated Arts and Sciences, Osaka Prefecture University,
Gakuencho 1-1, Sakai-shi 593, J apan
Received May 19, 1998
As one of the novel examples to investigate the characteristic reactivity of significantly twisted
1,3-dienes, the photosensitized oxygenation of two types of significantly twisted 1,3-dienes, cis-â-
ionol derivative 2 and acyclic derivative 11, is investigated. Photosensitized oxygenation of 2a -f
and 11a -e revealed that the vinyl hydrogen Ha was more reactive than the allyl hydrogen Hb.
Thus, phenyl derivative 2e and tert-butyl-substituted compound 11d selectively produced allenes
3e and 13d in 67% and 75% yield resulting from the ene reaction of the vinyl hydrogen Ha rather
than allyl alcohols 4e and 14d resulting from the allyl hydrogen abstraction in 24% and 8% yield,
respectively. Furthermore, in the case of methyl-substituted compound 11b, the extent of the
inherent reactivity of the vinyl hydrogen Ha was similar to that of the allyl hydrogen Hc. On the
basis of X-ray analysis and MM and MO calculations, the discovered abnormally higher reactivity
of the vinyl hydrogen would be rationalized by considering mainly the large σ*-π orbital interaction
between the vinyl C-H bond and another double bond in significantly twisted 1,3-dienes resulting
from calculations of HOMO electron densities.
In tr od u ction
that the solvolysis of twisted 2-bromo 1,3-diene deriva-
tives was much faster than that of the conjugated ones.7
However, no study on the reactivity of the vinyl hydrogen
in significantly twisted 1,3-dienes has been reported,
probably because these compounds are relatively unusual
and the method of their synthesis has not been well
established.
In 1968, we and another two groups independently
reported the first example of allene formation by an ene
reaction of vinyl hydrogens in trans-â-ionone derivatives
with a singlet oxygen.8 The yields of the allenes, how-
ever, were less than 10% for all the reported compounds,
and a 1,4-addition product and the product resulting from
the ene reaction of the allyl hydrogen were produced as
major products. The reported unique allene formation
should be attributable to the characteristic nature of the
slightly twisted 1,3-diene of â-ionone derivatives because
photosensitized oxygenation of normal conjugated 1,3-
dienes did not produce allene at all.9 In our program of
Conjugated 1,3-dienes are some of the most common
systems in organic synthesis, and their derivatives are
widely used for the construction of numerous six-mem-
bered carbocycles by pericyclic reactions.1 On the other
hand, the chemistry of significantly twisted 1,3-dienes
is relatively limited. Thus, the structural characteristics
of twisted 1,3-dienes have been observed in cycloalkene
derivatives substituted with a vinyl group having bulky
substituents,2 polysubstituted 1,3-butadienes,3 bis-iso-
propylidenebornane derivatives,4 and retinoid com-
pounds.5 Compared with these examples, little study on
the characteristic reactivities of twisted 1,3-dienes can
be found in the literature.6 As a novel example for the
characteristic reactivity, Hanack and co-workers reported
† Kwansei Gakuin University.
‡ Osaka City University.
§ Osaka Prefecture University.
(1) For example: (a) Kloetzel, M. C. The Diels-Alder Reaction with
Maleic Anhydride. In Organic Reactions; Adams, R., et al., Eds.; J ohn
Wiley & Sons: New York, 1948; Vol. 4, pp 1-59. (b) Holmes, H. L. The
Diels-Alder Reaction: Ethylenic and Acetylenic Dienophiles. In Or-
ganic Reactions; Adams, R., et al., Eds.; J ohn Wiley & Sons: New York,
1948; Vol. 6, pp 60-173. (c) Ciganek, E. The Intramolecular Diels-
Alder Reaction. In Organic Reactions; Dauben, W. G., et al., Eds.; J ohn
Wiley & Sons: New York, 1984; Vol. 32, pp 1-374.
(2) (a) Honig, B.; Hudson, B.; Sykes, B. D.; Karplus, M. Proc. Nat.
Acad. Sci. 1971, 68, 1289. (b) Ramamurthy, V.; Bopp, T. T.; Liu, R. S.
H. Tetrahedron Lett. 1972, 3915. (c) Miller, D.; Trammel, M.; Kini, A.;
Liu, R. S. H. Tetrahedron Lett. 1981, 22, 409.
(3) For example: (a) Bo¨decker H.-O.; J onas, V.; Kolb, B.; Mann-
schreck, A.; Ko¨brich, G. Chem. Ber. 1975, 108, 3497. (b) Becher, G.;
Mannschreck, A. Chem. Ber. 1983, 116, 264. (c) Traetteberg, M.; Hopf,
H.; Lipka, H.; Ha¨nel, R. Chem. Ber. 1994, 127, 1459. (d) Werstiuk, N.
H.; Timmins, G.; Ma, J .; Wildman, T. A. Can. J . Chem. 1992, 70, 1971.
(e) Hopf, H.; Ha¨nel, R.; J ones, P. G.; Bubenitschek, P. Angew. Chem.,
Int. Ed. Engl. 1996, 35, 222.
(5) For example: (a) Wada, A.; Sakai, M.; Kinumi, T.; Tsujimoto,
K.; Yamaguchi, M.; Ito, M.J . Org. Chem. 1994, 59, 6922. (b) Doering,
W. E.; Leventis, C. S.; Roth, W. R. J . Am. Chem. Soc. 1995, 117, 2747.
(c) Sakai, N.; Decatur, J .; Nakanishi, K. J . Am. Chem. Soc. 1996, 118,
1559.
(6) (a) Grob, C. A.; Spaar, R. Tetrahedron Lett. 1969, 1439. (b) Grob.
C. A.; Spaar, R. Helv. Chim. Acta 1970, 53, 2119. (c) Grob, C. A.;
Pfaendler, H. R. Helv. Chim. Acta 1970, 53, 2130. (d) Lamparter, E.;
Hanack, M. Chem. Ber. 1973, 106, 3216. (e) Apeloig, Y.; Schleyer, P.
v. R.; Pople, J . A. J . Org. Chem. 1977, 42, 3004. (f) Hopf, H.; Lipka,
H.; Traetteberg, T. Angew. Chem., Int. Ed. Engl. 1994, 33, 204.
(7) (a) Hanack, M.; Benz, H.; Markl, R.; Subramanian, L. R. Liebigs
Ann. Chem. 1978, 1894. (b) Hanack, M.; Sproesser, L. J . Am. Chem.
Soc. 1978, 100, 7066.
(8) (a) Isoe, S.; Hyeon, B. S.; Ichikawa, H.; Katsumura, S.; Sakan,
T. Tetrahedron Lett. 1968, 5561. (b) Isoe, S.; Katsumura, S.; Hyeon,
S. B.; Sakan, T. Tetrahedron Lett. 1971, 1089. (c) Mousseron-Canet,
M.; Dalle, J .-P.; Mani, J .-C. Tetrahedron Lett. 1968, 6037. (d) Foote,
C. S.; Brenner, M. Tetrahedron Lett. 1968, 6041.
(4) Crist, B. V.; Rodgers, S. L.; Gawronski, J . K.; Lightner, D. A.
Spectrosc. Int. J . 1985, 4, 19.
10.1021/jo980955o CCC: $15.00 © 1998 American Chemical Society
Published on Web 11/10/1998

Photosensitized Oxygenation of Twisted 1,3-Dienes
J . Org. Chem., Vol. 63, No. 24, 1998 8705
Sch em e 1
rotational isomers, which were detectable by NMR.
Silylation of the resulting alcohols 1b-f along with cis-
â-ionol (1a )12 with triethylsilyl chloride gave the corre-
sponding silyl ethers 2a -f and that of 1d with trimeth-
ylsilyl chloride gave the trimethylsilyl ether 2d -1 under
the usual conditions, while treatment of 1d with more
bulky tert-butyldimethylsilyl chloride completely recov-
ered the starting material. The prepared silyl ethers
2b-f were used for the next step without purification
because of their instability for column chromatography.
The photosensitized oxygenations were carried out in
dichloromethane by irradiation using a halogen lamp
under an oxygen atmosphere in the presence of a catalytic
amount of tetraphenylporphine and 1 molar equiv of
triethyl phosphite or triphenylphosphine at 0 °C. Metha-
nol as a solvent or methylene blue as a sensitizer was
not suitable for this reaction. In addition, the presence
of the phosphine reducing agents gave the oxygenated
products 3 and 4 in 67-95% combined yield, while in
their absence, the yields of the combined products were
less than 50%.14 Thus, the intermediary peroxides
seemed to be unstable. The results of the photosensitized
oxygenation are shown in Scheme 2 and listed in Table
1. In entries 8 and 10 of Table 1, the allenes 3d ,e, which
resulted from the vinyl hydrogen abstraction at C7, were
obtained in 63 and 67% yield along with exomethylene
4d ,e, which were produced by the allyl hydrogen abstrac-
tion at C11, in 32 and 24% yield from 1d ,e, respectively.
Surprisingly, in these cases the vinyl hydrogens were
clearly more reactive than the allyl hydrogens toward the
singlet oxygen. The obtained products, except for 3b and
4b, were a mixture of diastereoisomers of almost 1:1
ratio, and these would result from the rotational isomers.
In Table 1, we additionally noticed the following three
points relating to the C9 substituents responsible for the
selective allene formation: (1) The C9 carbon atom
should be quaternary. (2) The sterically bulky group for
R2 is essentially important. (3) Unsaturated substituent
for R1 may be concerned in the selective allene formation.
For the first point, in entry 1, compound 2a having a
tertiary carbon at C9 and a triethylsilyl group of R2 gave
the exomethylene 4a in nearly four times greater amount
than the allene 3a , whereas the compounds 2b-f having
a quaternary C9 carbon and a triethylsilyl group of R2
predominantly gave the allenes 3b-f rather than the
exomethylenes 4b -f. Obviously, the fully substituted
carbon atom at C9 clearly affected the allene formation.
For the second point, in every R1 substituent, in particu-
lar entries 6-8, the triethylsilyl group of R2 gave the best
selectivity for the allene formation. Bulkiness of the R2
group clearly affected the selective ene reaction of the
C7 vinyl hydrogen against that of the C11 allyl methyl
hydrogen. For the third point, comparing the results of
entries 3, 5, and 8, where R1 is methyl, ethyl, and vinyl
and R2 is triethylsilyl in 2, we noticed that the unsatur-
ated substituent at the C9 position might participate in
the selective allene formation. The photosensitized
oxygenation of ethynyl derivative 2f was then examined
under the same conditions, and allene 3f was obtained
in 55% yield along with exomethylene 4f in 27% yield as
described in entry 11. Thus, the similar ratio of the
products, 3 and 4, from the photooxygenation of methyl,
the synthetic study of peridinin, which is a norcarotenoid
possessing an allene moiety in one terminal, our attention
had been focused on the novel allene formation with
singlet oxygen. We designed cis-â-ionol derivatives 1 and
2 as significantly twisted 1,3-dienes and examined their
photosensitized oxygenation. We found a regioselective
ene reaction of the vinyl hydrogen rather than the allyl
hydrogen with the singlet oxygen. Furthermore, in newly
designed linear significantly twisted 1,3-dienes, we also
observed the high reactivity of the vinyl hydrogen
compared to the allyl hydrogen in a manner similar to
that previously discussed. These abnormally higher
reactivities of the vinyl hydrogen rather than the allyl
hydrogen toward the singlet oxygen in significantly
twisted 1,3-dienes would be rationalized by considering
large σ*-π orbital interactions between the vinyl C-H
bond and another double bond. In this paper, as one of
the novel examples to study the characteristic reactivity
of significantly twisted 1,3-dienes, we would like to
describe in detail the photosensitized oxygenation of
significantly twisted 1,3-dienes and report the first
examples that the vinyl C-H bond of significantly
twisted 1,3-dienes is remarkably activated due to the
large interaction between the σ* orbital of the vinyl C-H
bond and the π orbital of another double bond.10,11
Resu lts
Syn th esis, P h otooxygen a tion , a n d Con for m a tion -
a l An a lysis of cis-â-Ion ol Der iva tives. As a signifi-
cantly twisted 1,3-diene, we designed cis-â-ionol deriva-
tives possessing a tetrasubstituted carbon atom. The
requisite substrates 1b-f and 2b-f were prepared by
the Grignard reaction of cis-â-ionone12 followed by sily-
lation as shown in Scheme 1. The Grignard reactions
required reflux conditions in THF because cis-â-ionone
is mainly present as R-pyran at room temperature and
as an equilibrium mixture at higher temperature.13 The
alkylated products 1b-f were obtained by the reaction
with methyl, ethyl, vinyl, phenyl, and ethynyl Grignard
reagents in 49-82% yields as a nearly 1:1 mixture of
(9) (a) Hasty, N. M.; Kearns, D. R. J . Am. Chem. Soc. 1973, 95, 3380.
(b) Manring, L. E.; Kanner, R. C.; Foote, C. S. J . Am. Chem. Soc. 1983,
105, 4707. (c) Manring, L. E.; Foote, C. S. J . Am. Chem. Soc. 1983,
105, 4710. (d) Matsumoto, M.; Dobashi, S.; Kuroda, K.; Kondo, K.
Tetrahedron 1985, 41, 2147.
(10) Mori, H.; Ikoma, K.; Masui, Y.; Isoe, S.; Kitaura, K.; Katsumura,
S. Tetrahedron Lett. 1996, 37, 7771.
(11) Mori, H.; Ikoma, K.; Katsumura, S. Chem. Commun. 1997,
2243.
(12) (a) Ramamurthy, V.; Butt, Y.; Yang, C.; Liu, R. S. H. J . Org.
Chem. 1973, 38, 1247. (b) Ramamurthy, V.; Tustin, G.; Yau, C. C.;
Liu, R. S. H. Tetrahedron 1975, 31, 193.
(14) Oxidation of triphenylphosphine and triphenyl phosphite with
singlet oxygen would be slower than that of substrates: (a) Turner, J .
A.; Herz, W. J . Org. Chem. 1977, 42, 1657. (b) Poon, T. H. W.; Pringle,
K.; Foote, C. S. J . Am. Chem. Soc. 1995, 117, 7611.
(13) (a) Mavell, E. N.; Caple, G.; Gosink, T. A.; Zimmer, G. J . Am.
Chem. Soc. 1966, 88, 619. (b) Marvell, E. N.; Chadwick, T.; Caple, G.;
Gosink, T.; Zimmer, G. J . Org. Chem. 1972, 37, 2992.

8706 J . Org. Chem., Vol. 63, No. 24, 1998
Mori et al.
Sch em e 2
Ta ble 1. En e Rea ction of â-Ion ol Der iva tives w ith Sin glet Oxygen
F igu r e 1. ORTEP drawing of 1e.
ethyl, and ethynyl derivatives of R1 (entries 3, 5, and 11)
suggests that some participation of the unsaturated bond
at C9 may contribute to the selective allene formation.
To understand the previous observations, we tried to
determine the conformation of the cis-â-ionol derivatives.
Fortunately, the conformation of one of the rotational
isomers of the phenyl derivative 1e was successfully
determined by X-ray analysis as shown in Figure 1. It
was revealed that this molecule entirely exists in an s-cis
conformer and that the double bond in the cyclohexene
ring makes a torsion angle of about 70° toward the
z-olefin plane. Thus, this molecule is largely twisted
around the C6-C7 single bond. On the basis of the
results obtained by X-ray analysis, the most stable
conformation of another rotational isomer of 1e and two
rotational isomers of the vinyl derivative 2d -2 were
obtained by molecular mechanics and molecular orbital
calculations.15 Their conformations were almost identical
and are represented by that of one isomer of 2d -2 as
shown in Figure 2. In its pictorial representation, the
F igu r e 2. Chem 3D representation of optimized structure of
2d -2 and its pictorial representation.
vinyl hydrogen at C7 is exactly located at the â-face, and
therefore, the attack of the singlet oxygen from the R-face
only abstracts the allyl hydrogen to give the exomethyl-
(15) The geometries were optimized with the CFF91 force field using
software packages Insight II 2.1.0 Program. Biosym, Technol., Inc.,
San Diego, CA, and with semiempirical method (PM3) using the
SPARTAN versions 3.1, 4.0 Wavefunction, Inc., Irvine, CA. The
conformation of the compounds possessing a full substituent carbon
at C9 is represented by that of 2d -2 because their most stable
conformations obtained by calculations are almost same as that of 2d -2
except the substituents R1 and R2.

Photosensitized Oxygenation of Twisted 1,3-Dienes
J . Org. Chem., Vol. 63, No. 24, 1998 8707
Sch em e 3
ene compound 4d . However, the R-face is entirely
covered over by the bulky substituents at the C9 posi-
tion. The results of entries 6-8 in Table 1 clearly
demonstrate the remarkable effect of the bulky sub-
stituents at the C9 position of compound 2 in compari-
son with the results of entry 1. Thus, the singlet oxy-
gen attacks 2d -2 selectively from its â-face and abstracts
the C7 vinyl hydrogen to give the allene 3d or abstracts
the C11 allyl hydrogen to give the exomethylene 4d ,
respectively. In the case of free hydroxy compounds 1b-
e,15 the corresponding allene 3 resulting from â-face
attack of singlet oxygen were produced in moderate yield
along with exomethylene 4. The remarkable hydroxyl
group directing effect, which was recently reported by
Adam’s group in the photosensitized oxygenation of
secondary alcohols,16 was not observed in our tertiary
alcohols 1b-e.
having bulky substituents were synthesized by the
coupling of stannylacetylide 8 with enol triflates 7c,d ,19
which were prepared from the corresponding ketones20
by reaction with lithium diisopropylamide and N-phen-
yltrifluoroimide, in the presence of the same palladium
reagent (THF/rt: 9c, 45% yield; 9d , 52% yield).21 An-
other eneyne compound 9e was also synthesized in 84%
yield by coupling of vinyl bromide 5e prepared from
methyl 3,3-dimethylacrylate with 12 under the same
conditions as those of 5a ,b. Partial reduction of the
acetylene groups of 9a -e to the corresponding cis-olefins
by catalytic hydrogenation in hexane reflected the reac-
tivity of their acetylene groups. Thus, 10a ,b were
obtained with Lindlar catalyst in the presence of a
catalytic amount of quinoline (10a , 47% yield; 10b, 49%
yield). In the absence of quinoline with Lindlar catalyst,
10c was obtained (47% yield). The hydrogenation of 9d
with palladium on barium sulfate gave 10d (60% yield)
and of 9e with palladium charcoal in methanol gave 11e
(90% yield). The cis-alcohols obtained were transformed
into the corresponding triethylsilyl ethers 11a -d by the
usual way in excellent yield, and they were used for
photosensitized oxygenation without purification because
of their instability for column chromatography. It was
noteworthy that the synthesized compounds exhibited
characteristic spectroscopic nature. Thus, the maximum
absorption values of the electronic spectra of compounds
10b-d were less than 210 nm, whereas that of 10a was
238 nm.22 It is evident that 1,3-dienes in the compounds
10b-d are not conjugated, and these molecules are
significantly twisted around the central single bond of
the 1,3-dienes. The most stable conformations of 11b-e
were obtained by molecular mechanics calculations and
molecular orbital calculations similar to those of the cis-
The above conformational analysis for 2d -2 made
possible the comparison of the relative reactivity between
the C7 vinyl hydrogen Ha and the C11 allyl hydrogen
Hb toward the singlet oxygen (See Discussion).
Syn th esis a n d P h otosen sitized Oxygen a tion of
Acyclic Tw isted 1,3-Dien es. Next, acyclic substrates
11a -e were designed for the photosensitized oxygenation
because the substituent R at the one olefin group could
be changed from hydrogen to methyl, isopropyl, and tert-
butyl, and their 1,3-diene structures would be twisted
by the bulky substituent of R. The synthesis of these
1,3-diene derivatives having bulky substituents (R )
isopropyl and tert-butyl) was somewhat unusual.17 After
several unsuccessful attempts by ionic reactions, we
found that their synthesis was achieved by palladium-
catalyzed coupling of the appropriate vinyl halides or enol
triflates with zinc or stannyl acetylides followed by
partial hydrogenation strategy (Scheme 3). Thus, com-
pounds 9a ,b were prepared from commercially available
vinyl bromides 5a ,b, respectively, by reaction with zinc
acetylide 6, which was derived from a lithium derivative
of 3-methyl-1-butyn-3-ol and zinc chloride, in the pres-
ence of tetrakis(triphenylphosphine)palladium (THF/60
°C: 9a , 80% yield; 9b , 45% yield).18 Compounds 9c,d
(18) (a) King, A. O.; Okukado, N.; Negishi, E. J . Chem. Soc., Chem.
Commun. 1977, 683. (b) Hirama, M.; Fujiwara, K.; Shigematu, K.;
Fukazawa, Y. J . Am. Chem. Soc. 1989, 111, 4120. (c) Alami, M.; Ferri,
F.; Linstrumelle, G. Tetrahedron Lett. 1993, 34, 6403.
(19) McMurry, J . E.; Scott, W. J .Tetrahedron Lett. 1983, 24, 979.
(20) Dubois, J . E.; Boussu, M.; Lion, C. Tetrahedron Lett. 1971, 829.
(21) Stille, J . K.; Simpson, J . H. J . Am. Chem. Soc. 1987, 109,
2138.
(22) It has been well-known that the molar absorptivity in electronic
spectra shows the probability of the activation to the excited state of
molecules. Therefore, it has been pointed that there is some relation-
ship between the molar absorptivity and the torsion angle of two
unsaturated bonds in 1,3-dienes. In the present cases, however,
measurement of the exact molar absorptivity of 10b-d was unfortu-
nately very difficult. On the other hand, maximum absorption values
of 10a -d show whether the 1,3-dienes in these molecule are conju-
gated: Hedden, G. D.; Brown, W. G. J . Am. Chem. Soc. 1953, 75, 3744.
(16) (a) Adam, W.; Nestler, B. J . Am. Chem. Soc. 1993, 115, 5041.
(b) Adam, W.; Bru¨nker, H.-G.; Kumar, A. S.; Peters, E.-M.; Peters, K.;
Schneider, U.; Schnering, H. G. J . Am. Chem. Soc. 1996, 118, 1899.
(17) (a) Hopf, H.; Lipka, H. Chem. Ber. 1991, 124, 2075. (b) Hopf,
H.; Ha¨nel, R. Nachr, Chem. Technol. Lab. 1994, 42, 856. (c) Hopf, H.;
Ha¨nel, R.; J ones, P. G.; Bubenitschek, P. Angew. Chem. 1994, 106,
1444.

8708 J . Org. Chem., Vol. 63, No. 24, 1998
Mori et al.
Sch em e 4
Ta ble 2. En e Rea ction of Acyclic Tw isted 1,3-Dien es w ith Sin glet Oxygen
entry
substrates
yield (%) of 13a
yield (%) of 14a
yield (%) of 15a,b
yield (%) of 16a,b
1
2
3
4
5
1a
11b
11c
11d
11e
29b (13a )
32b (13b)
38b (13c)
75b (13d )
74c (13e)
45b (14a )
12b (14b)
27b (14c)
8b (14d )
9c (14e)
42 (15b)
8 (15c)
17 (16)
a
b
Isolated yield. The yields were for three steps; silylation of the corresponding alcohols followed by photosensitized oxygenation and
then desilylation. c The yields were for two steps: photosensitized oxygenation and desilylation.
â-ionol derivatives 2d -2 and 2e. The results of the
calculations also support their significantly twisted struc-
tures.
gen Ha and the allyl hydrogen Hc. This result was the
first example to directly compare the relative inherent
reactivity between the vinyl hydrogen and the allyl
hydrogen in significantly twisted 1,3-dienes toward a
singlet oxygen under the same conditions. It is quite
interesting that the vinyl hydrogen Ha shows an extent
of inherent reactivity similar to that of the allyl hydrogen
Hc toward singlet oxygen in significantly twisted 1,3-
dienes. Next, in the photooxygenation of the compound
11c, allene 13c, isopropenyl compound 14c, diene 15c,
and trihydroxy allene 16 were obtained after desilylation
in 38, 27, 8, and 17% yield, respectively. In this case,
because compound 16 must be produced from 15c, the
allyl hydrogen Hc was totally abstracted in 25% yield,
and hence, the relative reactivity of the vinyl hydrogen
Ha and the allyl hydrogen Hc in 11c is estimated to be
38:25.
The photosensitized oxygenation of 11a -e was carried
out under the same conditions as those of the cis-â-ionol
derivatives. In these compounds, the triethylsilyl group
was also essentially important for comparing the relative
reactivity between the vinyl hydrogen Ha and the allyl
hydrogen Hb of compound 11 in a similar manner as the
case of the cis-â-ionol derivatives. The results are shown
in Scheme 4 and Table 2. In the photosensitized oxy-
genation of compounds 11a -e, the ene reaction of Ha
and Hb gave allene 13 and isopropenyl compound 14,
respectively. In the case of 11b,c, the ene reaction of Hc
gave compound 15b,c, respectively, and 15c would
produce allene 16 by further oxygenation. Because the
silyl ethers of both the 1,3-dienes 11a -d and the oxygen-
ated products were not stable for column chromatogra-
phy, the yields mentioned were for three steps: silylation,
photosensitized oxygenation, and then desilylation. In
compounds 11d ,e having a bulky quaternary carbon atom
in the R group, allenes 13d ,e were produced in 75 and
74% yield along with isopropenyl compounds 14d ,e in 8
and 9% yield, respectively. In these cases, the abstracted
vinyl hydrogen Ha and allyl hydrogen Hb of 11d ,e are
located at the opposite side on the C5-C6 double bond,
and their vinyl hydrogens Ha were abnormally much
more reactive than their allyl hydrogens Hb toward the
singlet oxygen. On the contrary, compound 11a produced
allene 13a and isopropenyl compound 14a in 29 and 45%
yield, respectively. These results are well compatible
with those of the cyclic cis-â-ionol derivatives. In addi-
tion, photosensitized oxygenation of 11b (entry 2 in Table
2) gave allene 13b and allyl alcohol 15b in 32 and 42%
yield, respectively, along with isopropenyl compound 14b
in 12% yield. In this case, the abstracted vinyl hydrogen
Ha and allyl hydrogen Hc are located at the same side
on the C5-C6 double bond in 11b, and the allene 13b
and the allyl alcohol 15b were produced by the ene
reaction of the Ha and Hc in 11b, respectively. There-
fore, the relative yields of 13b and 15b obviously reflect
the relative inherent reactivity between the vinyl hydro-
Discu ssion
The ene reaction of a singlet oxygen with alkenes often
exhibits a remarkable regio-23 and stereoselectivity.24 In
particular, the prominent controlling factor for the regio-
selectivity is classified as the so-called “cis effect”,25 and
(23) (a) Fristad, W. E.; Bailey, T. R.; Paquette, L. A.; Gleiter, R.;
Bo¨hm, M. C. J . Am. Chem. Soc. 1979, 101, 4420. (b) Fristad, W. E.;
Bailey, T. R.; Paquette, L. A. J . Org. Chem. 1980, 45, 3028. (c) Schulte-
Elte, K. H.; Rautenstrauch, V. J . Am. Chem. Soc. 1980, 102, 1738. (d)
Adam, W.; Griesbeck, A. Angew. Chem. 1985, 97, 1071. (e) Orfanopo-
ulos, M.; Foote, C. S. Tetrahedron Lett. 1985, 26, 5991 (f) Adam, W.;
Griesbeck, A. Synthesis 1986, 1050. (g) Akasaka, T.; Takeuchi, K.;
Ando, W. Tetrahedron Lett. 1987, 28, 6633. (h) Clennan, E. L.; Chen.
X. J . Org. Chem. 1988, 53, 3124. (i) Kwon, B.-M.; Kanner, R. C.; Foote,
C. S. Tetrahedron Lett. 1989, 30, 903. (j) Akasaka, T.; Misawa, Y.; Goto,
M.; Ando, W. Tetrahedron 1989, 45, 6657. (k) Orfanopoulos, M.;
Stratakis, M.; Elemes, Y. Tetrahedron Lett. 1989, 30, 4875. (l) Akasaka,
T.; Takeuchi, K.; Misawa, Y.; Ando, W. Heterocycles 1989, 28, 445. (m)
Adam, W.; Nestler, B. Liebigs Ann. Chem. 1990, 1051. (n) Adam, W.;
Bru¨nker, H.-G.; Nestler, B. Tetrahedron Lett. 1991, 32, 1957 (o)
Orfanopoulos, M.; Stratakis, M.; Elemes, Y. J . Am. Chem. Soc. 1991,
113, 3180. (p) Orfanopoulos, M.; Stratakis, M. Tetrahedron Lett. 1991,
32, 7321. (q) Adam, W.; Richter, M. J . Tetrahedron Lett. 1993, 34, 8423.
(r) Adam, W.; Richter, M. J . J . Org. Chem. 1994, 59, 3335. (s) Adam,
W.; Nestler, B. J . Inf. Rec. Mats. 1994, 21, 425. (t) Li, X.; Ramamarthy,
V. J . Am. Chem. Soc. 1996, 118, 10666.
(24) For reviews, see: Prein, M.; Adam, W. Angew. Chem., Int. Ed.
Engl. 1996, 35, 477.

Photosensitized Oxygenation of Twisted 1,3-Dienes
J . Org. Chem., Vol. 63, No. 24, 1998 8709
the cis effect selectivity has attracted the mechanistic
interest in singlet oxygen oxidation of many organic
chemists. Stephenson suggested that the interaction
between the LUMO of oxygen and the “pseudobutadiene-
like” HOMO of the cis-olefin stabilizes the transition state
more than that of the trans-olefin, leading to the forma-
tion of the proper perepoxide intermediate.26,27 Schulte-
Elte and co-workers suggested for cycloalkenes that
regioselectivity of the singlet oxygen ene reaction is
related to the conformation of the allylic hydrogens with
respect to the olefin plane.28 Recently, other predominant
controlling factors for the regioselectivity in the ene
reaction have been classified as the “gem-directing
effect”23q,29 and “nonbonding large group effect”.30 The
former applies to gem-substituted olefins with the electron-
withdrawing group, and abstraction at the geminal
position is predominant. The latter has been recognized
in the transition state for the formation of the perepoxide
intermediates, and the preferred site of abstraction is
geminal to the larger substituent of the double bond.
These various mechanistic studies of the ene reaction of
singlet oxygen with simple olefins, isotope effect mea-
surements of the tetramethylethylene-d6 series,31 2-butene-
d3 series,30a trisubstituted alkene series,32 and the reac-
tion of trans-cyclooctene14b have strongly suggested that
the reaction proceeds through a polarized intermediate
with perepoxide geometry, and the rate-determining step
in the ene photooxygenation is the formation of the
perepoxide intermediate. Thus, the perepoxide interme-
diate has been generally accepted now.
F igu r e 3. Activation of the vinyl hydrogen in twisted 1,3-
dienes by σ*-π orbital interaction.
F igu r e 4. Orbital interaction between singlet oxygen and the
twisted 1,3-diene.
system one of the abstracted hydrogens is allyl and the
other is vinyl. Generally, the reactivities of these hy-
drogens are regarded to be quite different. What is the
reason why the selective ene reaction of the vinyl hy-
drogen Ha rather than the allyl hydrogen Hb remarkably
proceeds in the significantly twisted 1,3-dienes 2d -2, 2e,
and 11d -e?
All the reported systems, however, in the mechanistic
study for ene photooxygenation are relatively simple
olefins, and the abstracted hydrogens possess very simi-
lar character; they are all allylic hydrogens. The regio-
selectivity of the singlet oxygen ene reaction has been
mainly considered in connection with the substituent
effect such as the “cis effect”, the “gem-directing effect”,
and the “nonbonding large group effect”; therefore, the
consideration on the inherent reactivity of each compared
hydrogen has not been required. However, in our present
Focusing our attention on the conformations of the
significantly twisted 1,3-dienes 2d -2, 2e, and 11d -e, we
can easily notice that the vinyl C-Ha bond is close to
perpendicular to another double bond and that its
conformation is favorable for the ene reaction with a
singlet oxygen. Moreover, such a C-H bond would be
parallel to the π orbital of another double bond and may
be activated by orbital interaction in a similar manner
as an allyl C-H bond as shown in Figure 3. We first
considered the relative reactivity between the vinyl
hydrogen Ha and the allyl hydrogen Hb in the ground
state because of their different reactivities, although the
regioselectivity of the singlet oxygen ene reaction should
be discussed in the transition states. We planned to
compare the relative electron density of the frontier
orbitals around the vinyl C-Ha bond and the allyl C-Hb
bond in order to investigate the relative inherent reactiv-
ity of these hydrogens because it has been well-known
that the ene reaction of the singlet oxygen with olefins
starts from interactions of the LUMO of the singlet
oxygen with the HOMO of olefins as shown in Figure 4.33
In Figure 4, the structure A is a plausible transition state
to produce the perepoxide intermediate, which leads to
the allene 3, whereas the transition state B is that for
the exomethylene 4.
(25) Orfanopoulos, M.; Grdina, M. B.; Stephenson, L. M. J . Am.
Chen. Soc. 1979, 101, 275.
(26) (a) Stephenson, L. M. Tetrahedron Lett. 1980, 21, 1005. (b)
Stephenson, L. M.; Grdina, M. B.; Orfanopoulos, M. Acc. Chem. Res.
1980, 13, 419.
(27) Houk and co-workers rationalized the syn selectivity in trialkyl-
substituted alkenes based on STO-3G ab initio calculations. They
reported that the rotational energy barrier of the methyl group cis to
the transition state was lower than that of the trans methyl group:
Houk, K. N.; Williams, J . C.; Mitchell, P. A.; Yamaguchi, K. J . Am.
Chem. Soc. 1981, 103, 449. Schuster and co-workers measured the
activation parameters of the reaction of singlet oxygen with cis-alkenes
and suggested that in the rate-determining step there is some type of
“positive interaction” between the oxygen and two allylic hydrogens
of cis-olefins: (a) Hurst, J . R.; McDonald, J . D.; Schuster, G. B. J . Am.
Chem. Soc. 1982, 104, 206. (b) Hurst, J . R.; Wilson, S. L.; Schuster, G.
B. Tetrahedron 1985, 41, 2191.
(28) Schulte-Elte, K. H.; Rantenstrauch, V. J . Am. Chem. Soc. 1980,
102, 1738.
(29) (a) Ensley, H. E.; Carr, R. V. C.; Martin, R. S.; Pierce, T. E. J .
Am. Chem. Soc. 1980, 102, 2836. (b) Clennan, E. L.; Chen, X.; Koola,
J . J . J . Am. Chem. Soc. 1990, 112, 5193. (c) Stratakis, M.; Orfanopoulos,
M. Tetrahedron Lett. 1997, 38, 1067.
(30) (a) Orfanopoulos, M.; Smonou, I.; Foote, C. S. J . Am. Chem.
Soc. 1990, 112, 3607. (b) Orfanopoulos, M.; Stratakis, M.; Elemes, Y.
J . Am. Chem. Soc. 1990, 112, 6417. (c) Stratakis, M.; Orfanopoulos,
M.; Tetrahedron Lett. 1995, 36, 4291. (d) Elemes, Y.; Stratakis, M.,
Orfanopoulos, M., Tetrahedron Lett. 1997, 38, 6437.
(31) (a) Kopecky, K. R.; Sande, J . H. Can. J . Chem. 1972, 50, 4034.
(b) Grdina, M. B.; Orfanopoulos, M.; Stephenson, L. M. J . Am. Chem.
Soc. 1979, 101, 3111.
The relative electron densities of the frontier orbitals
of 2d -2 were calculated with HF/6-31G* level by the
(32) Stratakis, M.; Orfanopoulos, M.; Chen, J . S.; Foote, C. S.
Tetrahedron Lett. 1996, 37, 4105.
(33) (a) Inagaki, S.; Fukui, K. J . Am. Chem. Soc. 1975, 97, 7480. (b)
Inagaki, S.; Fujimoto, H.; Fukui, K. Chem. Lett. 1976, 749.

8710 J . Org. Chem., Vol. 63, No. 24, 1998
Mori et al.
F igu r e 5. Electron density surface of 2d -2 encoded by the
electron density of HOMO, which was calculated at the HF/
6-31G* level. Scale: 0.000 e/Å3 (red) to 0.012 e/Å3 (blue).
F igu r e 6. Electron density surface of rotational isomers of
2d -2 encoded by the electron density of HOMO, which was
calculated at the HF/6-31G* level. Torsion angles (C5-C6-
C7-C8) of the depicted molecules are 0° (top, left), 30° (top,
right), 60° (bottom, left), and 90° (bottom, right). Scale: 0.000
e/Å3 (red) to 0.012 e/Å3 (blue).
software packages SPARTAN versions 3.1 and 4.0 (Wave-
function, Inc., Irvine CA). The results of the calculations
are shown in Figure 5. The depth of the blue color
indicates the relative frontier electron density, and the
central blue part represents the cyclohexene double bond;
also, the upper and lower right parts with the blue color
represent the C7 vinyl hydrogen and the C11 allyl
hydrogen, respectively. The results show that the fron-
tier electron density around the C7 vinyl hydrogen is
slightly richer than that around the C11 allyl hydrogen,
and these calculation results are well in accord with the
obtained experimental results. Thus, the relative frontier
electron densities around these hydrogens have satisfac-
torily reflected their reactivity toward the singlet oxygen.
F igu r e 7. Nonbonding large group effect in 2d -2, 2e, and
11d -e.
Furthermore, we compared the calculated electron
densities of the frontier orbitals around both the C7 vinyl
hydrogen and the C11 allyl hydrogen of various rotational
isomers around the C6-C7 bond of 2d -2. Those of four
representative rotational isomers (dihedral angle Φ ) 0,
30, 60, and 90°) are shown in Figure 6. In this picture,
the color tone shows the relative frontier electron densi-
ties in a manner similar to that of Figure 5. They
gradually increased with the enlargement of the torsion
angle between the two double bonds, and they were
greatest at 90°. These calculated results can be rational-
ized by considering that the σ* orbital of the C7 vinyl
C-H bond interacts with the π orbital of the C5-C6
double bond in significantly twisted 2d -2, as shown in
Figure 3. Thus, the vinyl hydrogen in a significantly
twisted 1,3-diene would be highly activated by the large
σ*-π orbital interaction between the vinyl C-H bond and
another double bond. To the best of our knowledge, this
is the first example of these interactions in 1,3-dienes.
The previous calculation results revealed that the vinyl
hydrogen in significantly twisted 1,3-dienes bears a close
reactivity to the allyl hydrogen, and the obtained novel
experimental results in 11b of a significantly twisted 1,3-
diene also show that the inherent reactivity of the vinyl
hydrogen Ha is close to that of the allyl hydrogen Hc as
previously described. Now, we can discuss the regiose-
lectivity of the ene reaction of significantly twisted 1,3-
dienes by the “nonbonding large group effect” because
this idea is applicable for such hydrogens that possess
close reactivity to one another. Thus, if the significantly
twisted vinyl group could be regarded as a common alkyl
group, the results obtained from 2d -2, 2e, and 11d -e
are readily understandable by the idea of the “nonbond-
ing large group effect” as shown in Figure 7. Obviously,
the intermediate A′ is more favorable than B′ because of
the smaller nonbonding interactions. In the case of the
compound 11c having a propyl substituent, however, the
amount of the ene reaction product of the vinyl hydrogen
Ha, compound 13c, was only 1.4 times greater than that
of the allyl hydrogen Hb, compound 14c. In this case,
the “nonbonding large group effect” would not be ap-
plicable.
The results of Table 2 also led us to the following
considerations: In compound 11c, the isopropyl hydrogen
Hc should be less reactive to photooxygenation because
its calculated most stable conformation shows that the
isopropyl C-Hc bond is placed on the coplanar with the
C5-C6 double bond and the rotation of Hc toward the
perpendicular position from the coplanar is necessary for
the ene reaction of this hydrogen with the singlet oxygen.
In addition, it had been reported that the photooxygen-
ation of 2,4-dimethyl-2-pentene (17) in Figure 8 gave two
products, which were produced by the abstraction of the
C1 primary hydrogen and the C4 tertiary hydrogen in a
ratio of 93:7.34 Contrary to these results, in the case of

Photosensitized Oxygenation of Twisted 1,3-Dienes
J . Org. Chem., Vol. 63, No. 24, 1998 8711
aqueous NH4Cl solution was added, and the resulting mixture
was extracted with ether. The organic layers were combined,
washed with brine, dried over MgSO4, filtered, and concen-
trated in vacuo to give crude products. Column chromatog-
raphy on silica gel (3% ether in hexane) gave 1b (1.65 g,
1
76%): IR (neat, cm-1) 3544, 1464, 1378, 1362; H NMR (400
MHz, CDCl3) δ 5.73 (1H, brd, J ) 12.4 Hz), 5.49 (1H, d, J )
12.4 Hz), 3.42 (1H, s), 1.98 (2H, m), 1.72 (3H, s), 1.62-1.43
(4H, m), 1.29 (3H, s), 1.26 (3H, s), 1.05 (3H, s), 1.03 (3H, s);
13C NMR (100 MHz, CDCl3) δ 138.22, 136.49, 130.15, 122.45,
73.31, 38.90, 34.43, 31.87, 30.67, 29.28, 28.94, 28.58, 22.34,
19.00; EI HRMS m/e calcd for C14H24O (M+) 208.1821, found
208.1828.
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-1-
p en ten -3-ol (1c). To a THF (115 mL) solution of cis-â-ionone
5.05 g (26.2 mmol) and tetra-n-butylammonium iodide 11.0 g
(34.1 mmol) was added ethylmagnesium bromide (3.0 M in
ether, 18 mL, 52 mmol) at 65 °C. After the reaction mixture
was stirred at 65 °C for 3 min, saturated aqueous NH4Cl
solution was added and the resulting mixture was extracted
with ethyl acetate. The organic layers were combined, washed
with brine, dried over MgSO4, filtered, and concentrated in
vacuo to give crude products. Column chromatography on
silica gel (from 0.7% to 1% ethyl acetate in hexane) gave 1c
(2.86 g, 49%) as a mixture of conformational isomers: IR (neat,
F igu r e 8. Abstracted hydrogens of acyclic systems; the
numbers represent abstracted proportion.
11c, which has the same partial structure as 17, the
isopropyl hydrogen Hc was totally abstracted in 25% yield
(15c plus 16), whose value was nearly the same as that
of the Hb abstraction product (27% yield) as summarized
in the results of the photooxygenation of 11 in Figure 8.
This result may be attributable to the characteristic
nature of the significantly twisted vinyl group. The
characteristic substituent effect of the significantly twisted
vinyl group is also remarkable in the methyl-substituted
twisted 1,3-diene 11b. The ratio between the C5 and the
C6 hydroxy products from this compound was 12:74%
(32% of 13b plus 42% of 15b). Thus, the twisted vinyl
substituent at the double bond may prevent the attack
to the C5 sp2 carbon of the singlet oxygen.
1
cm-1) 3544, 1464, 1376, 1364; H NMR (400 MHz, CDCl3) δ
5.79-5.82 (1H, m), 5.51 (1/2 × 1H, d, J ) 12.7 Hz), 5.46 (1/2 ×
1H, d, J ) 12.7 Hz), 3.37 (1/2 × 1H, s), 3.33 (1/2 × 1H, s), 1.95-
2.00 (2H, m), 1.75 (1/2 × 13H, s), 1.72 (1/2 × 3H, s), 1.43-1.64
(6H, m), 1.25 (1/2 × 3H, s), 1.21 (1/2 × 3H, s), 1.08 (1/2 × 3H, s),
1.06 (1/2 × 3H, s), 1.04 (1/2 × 3H, s), 1.03 (1/2 × 3H, s), 0.94 (1/2
× 3H, t, J ) 7.8 Hz), 0.92 (1/2 × 3H, t, J ) 7.6 Hz); 13C NMR
(100 MHz, CDCl3) δ 137.72, 137.55, 136.59, 136.54, 130.53,
130.26, 123.47, 123.32, 75.57, 75.42, 39.03, 39.00, 36.33, 35.29,
34.58, 31.97, 31.93, 29.18, 29.08, 28.69, 28.67, 27.33, 26.44,
22.65, 19.01, 18.98, 8.58, 8.50; EI HRMS m/e calcd for C15H26O1
(M+) 222.1977, found 222.1992.
In conclusion, the remarkable regioselectivity of the
vinyl hydrogen ene reaction of the significantly twisted
1,3-dienes with a singlet oxygen would be attributed to
the following three factors: (1) large σ*-π orbital interac-
tion between the vinyl C-H bond and another double
bond, (2) the “nonbonding large group effect”, and (3)
some special electronic interactions involving the per-
pendicular π orbital of the significantly twisted double
bond with the singlet oxygen.
(1Z)-3-Meth yl-1-(2′,2′,6′-tr im eth ylcycloh ex-1′-en yl)-1,4-
p en ta d ien -3-ol (1d ). To a THF (80 mL) solution of cis-â-
ionone (3.0 g, 15.8 mmol) was added a 2.0 M solution of
vinylmagnesium bromide in THF prepared from vinyl bromide
(8.70 mL, 123 mmol), magnesium turnings (1.65 g, 67.9 mmol),
and THF (33 mL) at 65 °C until the starting material was
completely consumed (2-4 equiv of Grignard reagent was
required). After the reaction mixture was stirred at 65 °C for
15 min, saturated aqueous NH4Cl solution was added, and the
resulting mixture was extracted with ether. The organic
layers were combined, washed with brine, dried over MgSO4,
filtered, and concentrated in vacuo to give crude products.
Column chromatography on silica gel (2% ether in hexane)
gave 1d (2.69 g, 78%) as a mixture of conformational isomers:
Exp er im en ta l Section
All commercially available reagents were used without
further purification. All solvents were used after distillation.
Tetrahydrofuran, diethyl ether, and hexane were refluxed over
and distilled from sodium. Dichloromethane and diisopropyl-
amine were refluxed over and distilled from CaH2. Dimeth-
ylformamide (DMF) was distilled from CaH2 under reduced
pressure. Methanol was refluxed over and distilled from mag-
nesium. Preparative separation was usually performed by
column chromatography on silica gel (FUJ I Silysia Ltd., BW-
200 and BW-300). 1H NMR and 13C NMR spectra were
recorded at 400 and 100 MHz, respectively, and chemical shifts
were represented as δ values relative to internal standard
TMS. Melting points were uncorrected.
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-1-
bu ten -3-ol (1b). To a THF (50 mL) solution of cis-â-ionone
2.0 g (10.4 mmol), which was prepared by the reported
procedure,12 was added a 2.0 M solution of methylmagnesium
iodide in ether prepared from methyl iodide (6.18 mL, 104
mmol), magnesium turnings (2.52 g, 98.8 mmol), and ether
(44 mL) at 65 °C until the starting material was completely
consumed (2-4 equiv of Grignard reagent was required). After
the reaction mixture was stirred at 65 °C for 15 min, saturated
1
IR (neat, cm-1) 3528, 1655, 1462, 1364; H NMR (400 MHz,
CDCl3) δ 5.91 (5/13 × 1H, dd, J ) 17.0, 10.5 Hz), 5.90 (8/13
×
1H, dd, J ) 17.0, 10.5 Hz), 5.82 (1H, d, J ) 11.5 Hz), 5.52 (8/13
× 1H, d, J ) 11.5 Hz), 5.50 (5/13 × 1H, d, J ) 11.5 Hz), 5.22
(5/13 × 1H, J ) 17.0, 1.2 Hz), 5.21 (8/13 × 1H, dd, J ) 17.0, 1.5
Hz), 4.99 (8/13 × 1H, dd, J ) 10.5, 1.5 Hz), 4.96 (5/13 × 1H, dd,
J ) 10.5, 1.5 Hz), 3.57 (5/13 × 1H, s), 3.46 (8/13 × 1H, s), 1.98
(2H, m), 1.73 (5/13 × 3H, s), 1.52 (8/13 × 3H, s), 1.47-1.73 (4H,
m), 1.35 (5/13 × 3H, s), 1.31 (8/13 × 3H, s), 1.08 (8/13 × 3H, s),
1.05 (8/13 × 3H, s), 1.02 (5/13 × 3H, s), 1.01 (5/13 × 3H, s); 13C
NMR (100 MHz, CDCl3) δ 144.15, 142.79, 136.61, 135.99,
135.64, 135.31, 130.83, 130.30, 123.61, 123.34, 110.85, 110.73,
75.74, 75.62, 38.91, 34.86, 34.42, 31.96, 31.90, 29.38, 29.02,
28.94, 28.64, 28.51, 27.80, 22.40, 22.36, 19.02; EI HRMS m/e
calcd for C15H24O (M+) 220.1821, found 220.1820.
(1Z)-3-P h en yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-1-
bu ten -3-ol (1e). To a THF (4 mL) solution of cis-â-ionone 256
mg (1.33 mmol) was added a 1.8 M solution of phenylmagne-
sium bromide in ether prepared from bromobenzene (1.29 mL,
12.4 mmol), magnesium turnings (328 mg, 13.5 mmol), and
ether (7 mL) at 65 °C until the starting material was
completely consumed (2-4 equiv of Grignard reagent was
required). After the reaction mixture was stirred at 65 °C for
2 h, saturated aqueous NH4Cl solution was added, and the
(34) Wasserman, H. H.; Murray, R. W. Singlet Oxygen; Academic
Press Inc.: New York, 1979; p 342.

8712 J . Org. Chem., Vol. 63, No. 24, 1998
Mori et al.
resulting mixture was extracted with ethyl acetate. The
organic layers were combined, washed with brine, dried over
MgSO4, filtered, and concentrated in vacuo to give crude
products. Column chromatography on silica gel (1% ethyl
acetate in hexane) gave 1e (277 mg, 77%) as a mixture of
reaction mixture was gradually warmed to room temperature.
After the reaction mixture was stirred at the same tempera-
ture for 18.5 h, saturated aqueous NaHCO3 solution was
added, and the resulting mixture was extracted with ethyl
acetate. The organic layers were combined, washed with
brine, dried over MgSO4, filtered, and concentrated in vacuo
to give crude silyl ether 2b, which was used for photosensitized
oxygenation without any purification because of its instability
for column chromatography.
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-3-
tr ieth ylsiloxy-1-p en ten e (2c). To a solution of 1c (303 mg,
1.4 mmol), 4-(dimethylamino)pyridine (50 mg, 0.41 mmol), and
triethylamine (0.78 mL, 5.5 mmol) in DMF (7 mL) was added
triethylsilyl chloride (0.82 mL, 4.9 mmol) at 0 °C, and the
reaction mixture was gradually warmed to room temperature.
After the reaction mixture was stirred at the same tempera-
ture for 66 h, saturated aqueous NaHCO3 solution was added,
and the resulting mixture was extracted with ether. The
organic layers were combined, washed with brine, dried over
MgSO4, filtered, and concentrated in vacuo to give crude silyl
ether 2c, which was used for photosensitized oxygenation
without any purification because of its instability for column
chromatography.
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-3-
tr im eth ylsiloxy-1,4-p en ta d ien e (2d -1). To a solution of 1d
(308 mg, 1.4 mmol), 4-(dimethylamino)pyridine (17 mg, 0.14
mmol), and triethylamine (0.48 mL, 3.5 mmol) in dichlo-
romethane (7 mL) was added trimethylsilyl chloride (0.41 mL,
3.2 mmol) at 0 °C, and the reaction mixture was gradually
warmed to room temperature. After the reaction mixture was
stirred at the same temperature for 4 h, saturated aqueous
NaHCO3 solution was added, and the resulting mixture was
extracted with ether. The organic layers were combined,
washed with brine, dried over MgSO4, filtered, and concen-
trated in vacuo to give crude silyl ether 2d -1, which was used
for photosensitized oxygenation without any purification
because of its instability for column chromatography.
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-3-
tr ieth ylsiloxy-1,4-p en ta d ien e (2d -2). To a solution of 1d
(308 mg, 1.4 mmol), 4-(dimethylamino)pyridine (17 mg, 0.14
mmol), and triethylamine (0.78 mL, 5.6 mmol) in DMF (7 mL)
was added triethylsilyl chloride (0.84 mL, 5.0 mmol) at 0 °C,
and the reaction mixture was gradually warmed to room
temperature. After the reaction mixture was stirred at the
same temperature for 5 days, saturated aqueous NaHCO3
solution was added, and the resulting mixture was extracted
with ether. The organic layers were combined, washed with
brine, dried over MgSO4, filtered, and concentrated in vacuo
to give crude silyl ether 2d -2, which was used for photosen-
sitized oxygenation without any purification because of its
instability for column chromatography.
(1Z)-3-P h en yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-3-
(tr ieth ylsiloxy)-1-bu ten e (2e). To a solution of 1e (299 mg,
1.1 mmol), 4-(dimethylamino)pyridine (14 mg, 0.11 mmol), and
triethylamine (0.61 mL, 4.4 mmol) in DMF (6 mL) was added
triethylsilyl chloride (0.67 mL, 4.0 mmol) at 0 °C, and the
reaction mixture was gradually warmed to room temperature.
After the reaction mixture was stirred at the same tempera-
ture for 19.5 h, saturated aqueous NaHCO3 solution was
added, and the resulting mixture was extracted with ether.
The organic layers were combined, washed with brine, dried
over MgSO4, filtered, and concentrated in vacuo to give crude
silyl ether 2e, which was used for photosensitized oxygenation
without any purification because of their instability for column
chromatography.
conformational isomers: mp 57.0-57.5 °C; IR (KBr disk, cm-1
)
3500, 1958, 1600, 1446, 1334, 1210; 1H NMR (400 MHz, CDCl3)
δ 7.50-7.51 (2H, m), 7.30-7.33 (2H, m), 7.18-7.22 (1H, m),
6.03 (2/3 × 1H, d, J ) 12.4 Hz), 5.87 (2/3 × 1H, d, J ) 12.7 Hz),
5.86 (1/3 × 1H, d, J ) 13.0 Hz), 5.83 (1/3 × 1H, d, J ) 12.9 Hz),
4.09 (1/3 × 1H, s), 3.93 (2/3 × 1H, s), 1.80-2.04 (2H, m), 1.82
(1/3 × 3H, s), 1.30-1.66 (4H, m), 1.64 (1/3 × 3H, s), 1.61 (2/3 ×
3H, s), 1.29 (2/3 × 3H, s), 1.15 (2/3 × 3H, s), 1.08 (2/3 × 3H, s),
0.97 (1/3 × 3H, s), 0.89 (1/3 × 3H, s); 13C NMR (100 MHz,
CDCl3) δ 148.19, 147.77, 137.47, 136.81, 136.68, 136.15, 131.23,
131.03, 128.00, 127.92, 126.26, 126.22, 124.85, 124.72, 123.30,
123.15, 76.37, 38.97, 38.93, 34.97, 34.48, 32.80, 31.98, 30.40,
29.15, 28.90, 28.66, 28.53, 22.52, 22.02, 18.98; EI HRMS m/e
calcd for C19H26O (M+) 270.1977, found 270.1974.
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-1-
p en ten -4-yn -3-ol (1f). To a THF (8 mL) solution of cis-â-
ionone (300 mg, 1.56 mmol) was added a 0.5 M solution of
ethynylmagnesium chloride in THF prepared from acetylene
and n-butylmagnesium chloride (magnesium turnings (2.43 g
100 mmol), n-butyl chloride (10.7 mL, 100 mmol), and THF
(200 mL) at 65 °C until the starting material was completely
consumed (2-4 equiv of Grignard reagent was required). After
the reaction mixture was stirred at 65 °C for 2 h, saturated
aqueous NH4Cl solution was added, and the resulting mixture
was extracted with ethyl acetate. The organic layers were
combined, washed with brine, dried over MgSO4, filtered, and
concentrated in vacuo to give crude products. Column chro-
matography on silica gel (0.7% ethyl acetate in hexane) gave
1f (289 mg, 85%) as a mixture of conformational isomers: IR
(neat, cm-1) 3508, 3312, 2936, 2872, 1464, 1364, 1260, 1154,
1058; 1H NMR (400 MHz, CDCl3) δ 5.88 (1H, d, J ) 12.2 Hz),
5.78 (5/18 × 1H, d, J ) 12.2 Hz), 5.56 (13/18 × 1H, d, J ) 12.0
Hz), 3.93 (13/18 × 1H, s), 3.79 (5/18 × 1H, s), 2.49 (13/18 × 1H, s),
2.46 (5/18 × 1H, s), 2.02-1.94 (2H, m), 1.80 (13/18 × 3H, s), 1.69
(5/18 × 3H, s), 1.57 (5/18 × 3H, s), 1.55 (13/18 × 3H, s), 1.67-1.42
(4H, m), 1.05 (3H, s), 1.02 (3H, s); 13C NMR (100 MHz, CDCl3)
136.31, 134.87, 133.88, 133.79, 131.52, 130.86, 125.32, 124.62,
87.12, 86.19, 71.25, 70.93, 69.19, 68.86, 38.83, 38.76, 34.26,
31.93, 31.83, 31.10, 30.95, 30.60, 30.38, 28.97, 28.67, 28.60,
28.40, 22.30, 22.06, 18.94; EI HRMS m/e calcd for C15H22O (M+)
218.1665, found 218.1682.
(1Z)-3-Tr iet h ylsiloxy-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-
en yl)-1-bu ten e (2a ). To a solution of 1a (3.0 g, 15.4 mmol),
4-(dimethylamino)pyridine (188 mg, 1.54 mmol), and trieth-
ylamine (3.2 mL, 23.0 mmol) in DMF (80 mL) was added
triethylsilyl chloride (3.1 mL, 18.5 mmol) at 0 °C, and the
reaction mixture was gradually warmed to room temperature.
After being stirred at the same temperature for 1 h, the
reaction mixture was poured into H2O, and the resulting
mixture was extracted with ether. The organic layers were
combined, washed with brine, dried over MgSO4, filtered, and
concentrated in vacuo to give crude products. Column chro-
matography on silica gel (3% triethylamine in hexane) gave a
colorless oil. The oil was evacuated in vacuo (1-2 mmHg) at
80 °C for 3 days in order to remove triethylsiloxane to give
pure silyl ether 2a (3.6 g, 73%): IR (neat, cm-1) 1418, 1366,
1238, 1112, 1070; 1H NMR (400 MHz, CDCl3) δ 5.78 (1H, ddtq,
J ) 11.5, 2.4, 1.2, 0.7 Hz), 5.51 (1H, dd, J ) 11.5, 8.7 Hz),
4.37 (1H, ddq, J ) 8.7, 6.4, 0.7 Hz), 1.95 (2H, t, J ) 6.3 Hz),
1.64-1.59 (2H, m), 1.57 (3H, brs), 1.46-1.43 (2H, m), 1.20 (3H,
d, J ) 6.4 Hz), 0.99 (6H, s), 0.94 (9H, t, J ) 7.2 Hz), 0.59 (6H,
q, J ) 7.2 Hz); 13C NMR (100 MHz, CDCl3) δ 136.33, 135.20,
127.98, 126.54, 65.92, 39.15, 34.20, 31.94, 28.78, 28.59, 23.89,
21.96, 19.29, 6.95, 5.49; EI HRMS m/e calcd for C19H36OSi (M+)
308.2526, found 308.2545.
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-3-
tr ieth ylsiloxy-1-p en ten -4-yn e (2f). To a solution of 1f (300
mg, 1.4 mmol), 4-(dimethylamino)pyridine (50 mg, 0.41 mmol),
and triethylamine (0.76 mL, 5.5 mmol) in DMF (7 mL) was
added triethylsilyl chloride (0.83 mL, 5.0 mmol) at 0 °C, and
the reaction mixture was gradually warmed to room temper-
ature. After the reaction mixture was stirred at the same
temperature for 16 h, saturated aqueous NaHCO3 solution was
added, and the resulting mixture was extracted with ether.
The organic layers were combined, washed with brine, dried
(1Z)-3-Met h yl-1-(2′,2′,6′-t r im et h ylcycloh ex-1′-en yl)-3-
tr ieth ylsiloxy-1-bu ten e (2b). To a solution of 1b (244 mg,
1.2 mmol), 4-(dimethylamino)pyridine (14 mg, 0.15 mmol), and
triethylamine (0.49 mL, 3.5 mmol) in DMF (8 mL) was added
triethylsilyl chloride (0.51 mL, 3.0 mmol) at 0 °C, and the

Photosensitized Oxygenation of Twisted 1,3-Dienes
J . Org. Chem., Vol. 63, No. 24, 1998 8713
over MgSO4, filtered, and concentrated in vacuo to give crude
silyl ether 2f, which was used for photosensitized oxygenation
without any purification because of its instability for column
chromatography.
P h otosen sitized Oxygen a tion of 1b. Following the
general procedure of photosensitized oxygenation, 1b (302 mg,
1.45 mmol), a catalytic amount of TPP, and triphenylphos-
phine (380 mg, 1.45 mmol, and after oxidation 760 mg, and
2.90 mmol) in dichloromethane (8 mL) gave, after the usual
workup and column chromatography (from 25% to 75% ether
in hexane), 3b (129 mg, 40%) and 4b (175 mg, 54%).
P h otosen sitized Oxygen a tion of 2b. Following the
general procedure of photosensitized oxygenation, 2b (ca. 1.20
mmol), a catalytic amount of TPP, and triphenylphosphine
(316 mg, 1.20 mmol, and after oxidation 316 mg, 1.20 mmol)
in dichloromethane (7 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (315 mg, 1.20 mmol) in THF (7 mL) gave
3b (138 mg, 51% for three steps) and 4b (79 mg, 29% for three
steps), after the usual workup and column chromatography
(from 25% to 75% ether in hexane).
Gen er a l P r oced u r e for P h otosen sitized Oxygen a tion .
To a solution of cis-â-ionol derivatives 1 or 2 (1-2 mmol) in
dichloromethane (8 mL) were added 1 equiv of triphenylphos-
phine or triethyl phosphite and a catalytic amount of 5,10,-
15,20-tetraphenyl-21H, 23H-porphine (TPP), and the solution
was cooled to 0 °C. The mixture was irradiated with a Riko-
HGA-300A Halogen lamp under oxygen atmosphere, and the
reaction was monitored by TLC. After the starting material
was consumed, the reaction mixture was flushed with argon.
To complete the reduction of the intermediary peroxides,
another 1 equiv of triphenylphosphine or triethyl phosphite
was added, and the mixture was stirred until the peroxides
were completely consumed. It was concentrated in vacuo to
give crude products that were purified by column chromatog-
raphy on silica gel to yield the pure allene 3 and exomethylene
4.
Gen er a l P r oced u r e of Desilyla tion . In the case of silyl
ether, the following procedures were performed in addition to
those above. To a THF solution of the mixture, which was
treated with a reducing agent, was added 1-2 equiv of
n-tetrabutylammonium fluoride (TBAF) at room temperature
at 0 °C, and the mixture was stirred at the same temperature
until the starting material was consumed. It took overnight
for the desilylation of triethylsilyl ether. The reaction mixture
was diluted with saturated aqueous NaHCO3 solution and was
extracted with ether. The organic layers were combined,
washed with brine, dried over MgSO4, filtered, and concen-
trated in vacuo to give crude products. Column chromatog-
raphy on silica gel (from 17% to 75% ether in hexane) gave
pure oxygenated products.
P h otosen sitized Oxygen a tion of 2a . Following the
general procedure of photosensitized oxygenation, 2a (500 mg,
1.56 mmol), TPP (9 mg, 0.015 mmol), and triphenylphosphine
(409 mg, 1.56 mmol, and after oxidation 409 mg, 1.56 mmol)
in dichloromethane (10 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (450 mg, 1.72 mmol) in THF (10 mL) gave
3a (56 mg, 17% for two steps) and 4a (263 mg, 80% for two
steps) as a nearly 1:1 mixture of diastereoisomers, respectively,
after the usual workup and column chromatography (from 17%
to 50% ethyl acetate in hexane). In addition, exomethylene
4a contained about 10% unidentified products that could not
be removed by column chromatography.
1-(2′-Hydr oxy-2′,6′,6′-tr im eth ylcycloh exyliden e)-3-m eth -
yl-1-bu ten -3-ol (3b): mp 94.0-94.5 °C; IR (KBr disk, cm-1
)
3452, 1965, 1655, 1452, 1396, 1374, 1258, 1166, 1100; 1H NMR
(400 MHz, CDCl3) δ 5.45 (1H, s), 1.77-1.98 (3H, m), 1.50-
1.56 (3H, s), 1.36 (3H, s), 1.34 (6H, s), 1.23 (3H, s), 1.07 (3H,
s); 13C NMR (100 MHz, CDCl3) δ 195.51, 120.76, 104.21, 70.66,
69.95, 40.58, 40.49, 34.24, 31.41, 31.06, 29.91, 29.83, 29.44,
18.48. Anal. Calcd for C14H24O2: C, 74.95; H, 10.78. Found:
C, 74.47; H, 10.76.
(1Z)-1-(1′-Hyd r oxy-2′-m eth ylid en e-6′,6′-d im eth ylcyclo-
h exyl)-3-m eth yl-1-bu ten -3-ol (4b): mp 59.0-60.0 °C; IR
(KBr disk, cm-1) 3350, 3220, 1646, 1380, 1172, 1120; 1H NMR
(400 MHz, CDCl3) δ 5.73 (1H, d, J ) 13.4 Hz), 5.53 (1H, d, J
) 13.2 Hz), 4.92 (1H, brd, J ) 2.0 Hz), 4.84 (1H, m), 2.47 (1H,
brdt, J ) 13.1, 6.1 Hz), 2.16 (1H, brdt, J ) 13.1, 6.8 Hz), 1.56-
1.68 (4H, m), 1.40 (3H, s), 1.36 (3H, s), 0.92 (6H, s); 13C NMR
(100 MHz, CDCl3) δ 154.50, 137.29, 130.93, 107.85, 79.42,
71.94, 39.72, 36.84, 32.80, 31.74, 30.06, 24.00, 23.20, 23.09;
EI HRMS m/e calcd for
C
14H24O2 (M+) 224.1770, found
224.1776.
P h ot osen sit ized Oxygen a t ion of 1c. Following the
general procedure of photosensitized oxygenation, 1c (311 mg,
1.40 mmol), a catalytic amount of TPP, and triphenylphos-
phine (367 mg, 1.40 mmol, and after oxidation 417 mg, 1.59
mmol) in dichloromethane (7 mL) gave 3c (64 mg, 19%), its
diastereoisomer (70 mg, 21%), and 4c (147 mg, 44%) as a
nearly 1:1 mixture of diastereoisomers, after the usual workup
and column chromatography (from 17% to 71% ether in
hexane).
P h ot osen sit ized Oxygen a t ion of 2c. Following the
general procedure of photosensitized oxygenation, 2c (ca. 1.36
mmol), a catalytic amount of TPP, and triphenylphosphine
(360 mg, 1.37 mmol, and after oxidation 360 mg, 1.37 mmol)
in dichloromethane (7 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (356 mg, 1.36 mmol) in THF (7 mL) gave
3c (87 mg, 26% for three steps), its diastereoisomer (87 mg,
26% for three steps), and 4c (117 mg, 15% for three steps) as
a nearly 1:1 mixture of diastereoisomers, after workup and
column chromatography (from 17% to 71% ether in hexane).
In addition, 4c contained triethylsilanol, which could not be
removed by column chromatography. The yield of 4c was
calculated on the integral basis of the values of 4c and
triethylsilanol in the NMR spectrum.
1-(2′-Hydr oxy-2′,6′,6′-tr im eth ylcycloh exyliden e)-1-bu ten -
3-ol (3a ) (m ixtu r e of d ia ster eoisom er s): IR (neat, cm-1
)
3368, 1958, 1456, 1374, 1072, 1024; 1H NMR (400 MHz, CDCl3)
δ 5.43 (1/2 × 1H, d, J ) 5.4 Hz), 5.40 (1/2 × 1H, d, J ) 6.1 Hz),
4.34-4.28 (1H, m), 1.94-1.72 (3H, m), 1.58-1.48 (3H, m), 1.37
(1/2 × 1H, s), 1.36 (1/2 × 1H, s), 1.29 (1H, d, J ) 6.3 Hz), 1.29
(1/2 × 3H, s), 1.21 (1/2 × 3H, s), 1.07 (1/2 × 3H, s), 1.06 (1/2 ×
3H, s); 13C NMR (100 MHz, CDCl3) δ 196.98, 196.89, 120.42,
120.16, 100.04, 70.57, 66.56, 66.16, 40.50, 40.42, 40.33, 40.29,
34.05, 34.02, 31.32, 31.27, 31.01, 30.89, 29.53, 29.43, 23.24,
23.16, 18.48, 18.42; EI HRMS m/e calcd for C13H22O2 (M+)
210.1614, found 210.1631.
(1Z)-1-(1′-Hyd r oxy-2′-m eth ylid en e-6′,6′-d im eth ylcyclo-
h exyl)-1-bu ten -3-ol (4a ) (m ixtu r e of d ia ster eoisom er s):
1
IR (neat, cm-1) 3372, 1644, 1456, 1368, 1094, 1046; H NMR
1-(2′-Hydr oxy-2′,6′,6′-tr im eth ylcycloh exyliden e)-3-m eth -
(400 MHz, CDCl3) δ 5.87 (1/2 × 1H, dd, J ) 12.2, 1.5 Hz), 5.82
(1/2 × 1H, dd, J ) 12.4, 1.5 Hz), 5.56 (1/2 × 1H, dd, J ) 12.2,
7.3 Hz), 5.53 (1/2 × 1H, dd, J ) 12.4, 6.6 Hz), 5.00 (1/2 × 1H,
dd, J ) 1.7, 1.0 Hz), 4.98 (1/2 × 1H, dd, J ) 1.7, 0.7 Hz), 4.94-
4.81 (2H, m), 2.45-2.12 (2H, m), 1.62-1.46 (4H, m), 1.27 (1/2
× 3H, d, J ) 6.6 Hz), 1.22 (1/2 × 3H, d, J ) 6.3 Hz), 0.97 (1/2 ×
3H, s), 0.96 (1/2 × 3H, s), 0.93 (1/2 × 3H, s), 0.91 (1/2 × 3H, s);
13C NMR (100 MHz, CDCl3) δ 152.35, 151.23, 136.29, 134.99,
132.87, 132.37, 108.11, 107.36, 81.31, 80.40, 64.10, 63.05,
37.17, 37.10, 33.32, 32.89, 24.15, 23.83, 23.45, 22.77, 22.70,
22.62, 22.41, 22.01; EI HRMS m/e calcd for C13H22O2 (M+)
210.1614, found 210.1631.
yl-1-p en ten -3-ol (3c): mp 113.5-114.5 °C; IR (KBr disk, cm-1
)
3408, 3320, 1964, 1454, 1364, 1120; 1H NMR (400 MHz, CDCl3)
δ 5.39 (1H, s), 1.49-1.92 (8H, m), 1.36 (3H, s), 1.27 (3H, s),
1.24 (3H, s), 1.08 (3H, s), 0.95 (3H, t, J ) 7.6 Hz); 13C NMR
(100 MHz, CDCl3) δ 195.65, 121.05, 103.36, 72.10, 70.63, 40.48,
40.46, 35.55, 34.14, 31.64, 29.39, 27.19, 18.40, 8.61. Anal.
Calcd for C15H26O2: C, 75.58; H, 10.99. Found: C, 75.53; H,
10.87. Dia ster eoisom er : mp 89.0-92.5 °C; IR (KBr disk,
cm-1) 3344, 1964, 1458, 1374, 1136; 1H NMR (400 MHz, CDCl3)
δ 5.40 (1H, s), 1.27-1.87 (8H, m), 1.39 (3H, s), 1.22 (3H, s),
1.21 (3H, s), 1.08 (3H, s), 0.94 (3H, t, J ) 7.6 Hz); 13C NMR
(100 MHz, CDCl3) δ 195.72, 121.12, 103.42, 72.20, 70.64, 40.64,

8714 J . Org. Chem., Vol. 63, No. 24, 1998
Mori et al.
40.37, 35.54, 34.25, 31.07, 30.95, 29.83, 26.83, 18.60, 8.65.
Anal. Calcd for C15H26O2: C, 75.58; H, 10.99. Found: C, 75.63;
H, 11.08.
(1Z)-1-(1′-Hyd r oxy-2′-m eth ylid en e-6′,6′-d im eth ylcyclo-
h exyl)-3-m eth yl-1,4-p en ta d ien -3-ol (4d ): mp 31.5-34.0 °C;
IR (KBr disk, cm-1) 3352, 1640, 1464, 1366, 1120; 1H NMR
(400 MHz, CDCl3) δ 6.03 (1H, dd, J ) 17.3, 10.5 Hz), 5.81 (1H,
d, J ) 13.4 Hz), 5.64 (1H, d, J ) 13.4 Hz), 5.20 (1H, dd, J )
17.3, 1.2 Hz), 5.02 (1H, dd, J ) 10.5, 1.2 Hz), 4.89 (1H, d, J )
1.7 Hz), 4.86 (1H, m), 2.46 (1H, brdt, J ) 13.4, 6.6 Hz), 2.16
(1H, brdt, J ) 12.9, 6.4 Hz), 1.58-1.71 (4H, m), 1.42 (3H, s),
0.97 (3H, s), 0.96 (3H, s); 13C NMR (100 MHz, CDCl3) δ 153.30,
145.69, 135.31, 131.94, 111.67, 108.81, 80.01, 73.26, 39.53,
36.63, 32.58, 29.35, 24.04, 23.54, 22.91; EI HRMS m/e calcd
for C15H24O2 (M+) 236.1770, found 236.1775. Dia ster eoiso-
m er : mp 50.0-51.5 °C; IR (KBr disk, cm-1) 3288, 1642, 1388,
(1Z)-1-(1′-Hyd r oxy-2′-m eth ylid en e-6′,6′-d im eth ylcyclo-
h exyl)-3-m eth yl-1-p en ten -3-ol (4c) (m ixtu r e of d ia ster eo-
isom er s): IR (KBr disk, cm-1) 3340, 1640, 1462, 1382; 1H NMR
(400 MHz, CDCl3) δ 5.81 (1/2 × 1H, d, J ) 13.4 Hz), 5.79 (1/2 ×
1H, d, J ) 13.4 Hz), 5.45 (1/2 × 1H, d, J ) 13.4 Hz), 5.44 (1/2 ×
1H, d, J ) 13.4 Hz), 4.96 (1/2 × 1H, d, J ) 2.2 Hz), 4.93 (1/2 ×
1H, d, J ) 2.2 Hz), 4.84 (1/2 × 1H, m), 4.83 (1/2 × 1H, m), 2.47
(1H, brdt, J ) 12.8, 6.4 Hz), 2.16 (1/2 × 1H, brdt, J ) 13.2, 7.8
Hz), 2.14 (1/2 × 1H, brdt, J ) 13.9, 7.1 Hz), 1.43-1.75 (6H,
m), 1.35 (1/2 × 3H, s), 1.29 (1/2 × 3H, s), 0.93-0.97 (6H, m),
0.92 (1/2 × 3H, t, J ) 7.6 Hz), 0.88 (1/2 × 3H, t, J ) 7.6 Hz);
13C NMR (100 MHz, CDCl3) δ 155.15, 154.54, 136.39, 132.20,
131.48, 107.81, 107.62, 79.09, 74.57, 74.44, 39.72, 39.71,
39.66, 36.84, 36.77, 23.23, 23.15, 23.14, 23.10, 8.46, 8.04, 8.03;
1
1358, 1116, 1098; H NMR (400 MHz, CDCl3) δ 6.10 (1H, dd,
J ) 17.3, 10.5 Hz), 5.84 (1H, d, J ) 13.2 Hz), 5.61 (1H, d, J )
13.2 Hz), 5.26 (1H, dd, J ) 17.3, 1.2 Hz), 5.05 (1H, dd, J )
10.5, 1.2 Hz), 4.97 (1H, brd, J ) 2.0 Hz), 4.88 (1H, m), 4.00
(2H, brs), 2.43 (1H, brdt, J ) 13.6, 6.1 Hz), 2.18 (1H, brdt, J
) 13.6, 6.4 Hz), 1.58-1.62 (4H, m), 1.39 (3H, s), 0.95 (3H, s),
0.93 (3H, s); 13C NMR (100 MHz, CDCl3) δ 153.25, 145.67,
135.28, 131.92, 111.67, 108.81, 80.00, 73.22, 39.52, 36.61,
29.33, 24.04, 23.53, 22.90; EI HRMS m/e calcd for C15H24O2
(M+) 236.1770, found 236.1775.
P h otosen sitized Oxygen a tion of 1e. Following the
general procedure of photosensitized oxygenation, 1e (302 mg,
1.11 mmol), a catalytic amount of TPP, and triphenylphos-
phine (292 mg, 1.11 mmol, and after oxidation 292 mg, 1.11
mmol) in dichloromethane (6 mL) gave 3e (68 mg, 21%), its
diastereoisomer (57 mg, 18%), and 4e (163 mg, 51%) as a
nearly 1:1 mixture of diastereoisomers after the usual workup
and column chromatography (from 17% to 50% ether in
hexane).
P h otosen sitized Oxygen a tion of 2e. Following the gen-
eral procedure of photosensitized oxygenation, 2e (ca. 1.10
mmol), a catalytic amount of TPP, and triphenylphosphine
(285 mg, 1.11 mmol, and after oxidation 285 mg, 1.11 mmol)
in dichloromethane (6 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (568 mg, 2.17 mmol) in THF (6 mL) gave
3e (208 mg, 67% for three steps) and 4e (76 mg, 24% for three
steps) as a nearly 1:1 mixture of diastereoisomers, respectively,
after the usual workup and column chromatography (from 17%
to 60% ether in hexane).
EI HRMS m/e calcd for
C
15H26O2 (M+) 238.1926, found
238.1932.
P h otosen sitized Oxygen a tion of 1d . Following the
general procedure of photosensitized oxygenation, 1d (304 mg,
1.38 mmol), a catalytic amount of TPP, and triethyl phosphite
(0.47 mL, 2.76 mmol) in dichloromethane (7 mL) gave, after
the usual workup and column chromatography (from 17% to
67% ether in hexane), 3d (120 mg, 37%) and 4d (179 mg, 55%)
as a nearly 1:1 mixture of diastereoisomers, respectively.
P h otosen sitized Oxygen a tion of 2d -1. Following the
general procedure of photosensitized oxygenation, 2d (ca. 1.38
mmol), a catalytic amount of TPP, and triethyl phosphite (0.24
mL and after oxidation 0.24 mL, 1.38 and 1.38 mmol) in
dichloromethane (7 mL) gave crude oxygenated products. To
a THF (7 mL) solution of the oxygenated product was added
two drops of 1 N HCl at 0 °C. After the reaction mixture was
stirred at 0 °C for 1 h, saturated aqueous NaHCO3 solution
was added, and the resulting mixture was extracted with
ether. The organic layers were combined, washed with brine,
dried over MgSO4, filtered, and concentrated in vacuo to give
crude products. Column chromatography on silica gel (from
25% to 67% ether in hexane) gave 3d (130 mg, 40% for three
steps) and 4d (129 mg, 40% for three steps) as a mixture of
diastereoisomers, respectively.
P h otosen sitized Oxygen a tion of 2d -2. Following the
general procedure of photosensitized oxygenation, 2d -2 (ca.
1.40 mmol), a catalytic amount of TPP, and triethyl phosphite
(0.49 mL, 2.85 mmol, and after oxidation 0.73 mL, 4.25 mmol)
in dichloromethane (11 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (743 mg, 2.84 mmol) in THF (11 mL) gave
3d (209 mg, 63% for three steps) and 4d (165 mg, 32% for three
steps) as a nearly 1:1 mixture of diastereoisomers, respectively,
after the usual workup and column chromatography (from 25%
to 67% ether in hexane). In addition, 4d contained triethyl-
silanol, which could not be removed by column chromatogra-
phy. The yield of 4d was calculated on the basis of the integral
values of 4d and triethylsilanol in the NMR spectrum.
1-(2′-Hydr oxy-2′,6′,6′-tr im eth ylcycloh exyliden e)-3-m eth -
yl-1,4-p en ta d ien -3-ol (3d ): mp 93.5-95.5 °C; IR (KBr disk,
cm-1) 3424, 1966, 1454, 1364, 1092; 1H NMR (400 MHz, CDCl3)
δ 5.98 (1H, dd, J ) 17.1, 10.5 Hz), 5.42 (1H, s), 5.28 (1H, dd,
J ) 17.1, 1.2 Hz), 5.05 (1H, dd, J ) 10.5, 1.2 Hz), 1.78-1.88
(2H, m), 1.26-1.55 (4H, m), 1.39 (3H, s), 1.34 (3H, s), 1.24 (3H,
s), 1.07 (3H, s); 13C NMR (100 MHz, CDCl3) δ 196.21, 143.94,
120.99, 111.75, 102.35, 72.13, 70.71, 40.52, 40.41, 34.26, 31.32,
30.93, 29.41, 27.87, 18.43; EI HRMS m/e calcd for C15H24O2
(M+) 236.1770, found 236.1770. Dia ster eoisom er : mp 95.5-
100.5 °C; IR (KBr disk, cm-1) 3372, 1962, 1450, 1386, 1148,
1102; 1H NMR (400 MHz, CDCl3) δ 5.97 (1H, dd, J ) 17.3,
10.5 Hz), 5.42 (3H, s), 5.28 (1H, dd, J ) 17.3, 1.2 Hz), 5.06
(1H, dd, J ) 10.5, 1.2 Hz), 1.78-1.88 (2H, m), 1.26-1.55 (4H,
m), 1.39 (3H, s), 1.36 (3H, s), 1.24 (3H, s), 1.05 (3H, s); 13C
NMR (100 MHz, CDCl3) δ 196.17, 144.01, 121.17, 111.81,
102.30, 72.15, 70.71, 40.55, 40.42, 34.32, 31.31, 31.05, 29.38,
27.78, 18.45; EI HRMS m/e calcd for C15H24O2 (M+) 236.1770,
found 236.1770.
1-(2′-Hydr oxy-2′,6′,6′-tr im eth ylcycloh exyliden e)-3-ph en -
yl-1-bu ten -3-ol (3e): mp 103.0-105.0 °C; IR (KBr disk, cm-1
)
3368, 1968, 1452, 1374, 1156, 1140, 1058; 1H NMR (400 MHz,
CDCl3) δ 7.49-7.52 (2H, m), 7.31-7.35 (2H, m), 7.22-7.26 (1H,
m), 5.65 (1H, s), 1.72-1.90 (2H, m), 1.65 (3H, s), 1.43-1.51
(4H, m), 1.31 (3H, s), 1.22 (3H, s), 1.02 (3H, s); 13C NMR (100
MHz, CDCl3) δ 196.16, 147.21, 128.04, 126.84, 125.09, 121.48,
104.09, 73.59, 40.51, 40.38, 34.38, 31.19, 30.90, 30.02, 29.41,
18.44. Anal. Calcd for C19H26O2: C, 79.68; H, 9.15, Found: C,
79.62; H, 9.20. Dia ster eoisom er : mp 152-154.5 °C; IR (KBr
disk, cm-1) 3292, 1954, 1452, 1160, 1096, 1070; 1H NMR (400
MHz, CDCl3) δ 7.51-7.53 (2H, m), 7.32-7.36 (2H, m), 7.23-
7.26 (1H, m), 5.66 (1H, s), 2.49 (1H, s), 1.73-1.90 (2H, m), 1.65
(3H, s), 1.49-1.53 (4H, m), 1.36 (3H, s), 1.23 (3H, s), 1.08 (3H,
s); 13C NMR (100 MHz, CDCl3) δ 196.11, 147.33, 128.09,
126.85, 125.05, 121.74, 104.11, 73.61, 70.84, 40.60, 40.34,
34.57, 31.09, 30.86, 30.04, 29.73, 18.57. Anal. Calcd for
C
19H26O2: C, 79.68; H, 9.15. Found: C, 79.76; H, 9.30.
(1Z)-1-(1′-Hyd r oxy-2′-m eth ylid en e-6′,6′-d im eth ylcyclo-
h exyl)-3-p h en yl-1-bu ten -3-ol (4e) (m ixtu r e of d ia ster eo-
isom er s): IR (KBr disk, cm-1) 3268, 1642, 1450, 1386, 1368,
1
1096, 1062; H NMR (400 MHz, CDCl3) δ 7.20-7.52 (5H, m),
6.05 (3/4 × 1H, d, J ) 13.2 Hz), 6.03 (1/4 × 1H, d, J ) 13.1 Hz),
5.88 (1/4 × 1H, d, J ) 13.2 Hz), 5.82 (1/4 × 1H, d, J ) 13.4 Hz),
4.99 (3/4 × 1H, s), 4.90 (3/4 × 1H, s), 4.70 (1/4 × 1H, s), 4.56 (1/4
× 1H, s), 2.16-2.41 (2H, m), 1.63 (1/4 × 3H, s), 1.59 (3/4 × 3H,
s), 1.43-1.70 (6H, m), 0.98 (1/4 × 1H, s), 0.94 (1/4 × 1H, s),
0.81 (3/4 × 3H, s), 0.75 (3/4 × 3H, s); 13C NMR (100 MHz, CDCl3)
δ 151.25, 150.76, 149.51, 149.35, 138.08, 137.72, 131.19,
131.14, 128.17, 128.14, 126.68, 126.66, 124.94, 108.86, 108.77,
80.78, 80.72, 73.71, 73.63, 40.10, 39.54, 39.90, 36.75, 33.36,

Photosensitized Oxygenation of Twisted 1,3-Dienes
J . Org. Chem., Vol. 63, No. 24, 1998 8715
32.79, 32.71, 32.57, 24.27, 23.93, 22.85, 22.69, 22.64. Anal.
Calcd for C19H26O2: C, 79.68; H, 9.15. Found: C, 79.79; H, 9.31.
P h otosen sitized Oxygen a tion of 2f. Following the gen-
eral procedure of photosensitized oxygenation, 2f (ca. 1.37
mmol), TPP (9 mg, 0.015 mmol), and triphenylphosphine (360
mg, 1.37 mmol, and after oxidation 360 mg, 1.37 mmol) in
dichloromethane (7 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (611 mg, 2.34 mmol) in THF (7 mL) gave
3f (176 mg, 55% for three steps) and 4f (142 mg, 27% for three
steps) as a nearly 1:1 mixture of diastereoisomers, respectively,
after the usual workup and column chromatography (from 9%
to 50% in hexane). In addition, 4f contained triethylsilanol,
which could not be removed by column chromatography. The
yield of 4f was calculated on the basis of the integral values
of 4f and triethylsilanol in the NMR spectrum.
1-(2′-Hydr oxy-2′,6′,6′-tr im eth ylcycloh exyliden e)-3-m eth -
yl-1-p en ten -4-yn -3-ol (3f): mp 103.5-104 °C; IR (KBr disk,
cm-1) 3320, 2932, 2116, 1964, 1460, 1368, 1188, 1114; 1H NMR
(400 MHz, CDCl3) δ 5.48 (1H, s), 2.52 (1H, brs), 2.48 (1H, s),
1.77-1.91 (2H, m), 1.49-1.65 (4H, m), 1.59 (3H, s), 1.36 (3H,
s), 1.24 (3H, s), 1.09 (3H, s); 13C NMR (100 MHz, CDCl3) δ
196.78, 121.95, 101.46, 86.54, 71.61, 70.82, 66.73, 40.55, 40.43,
34.46, 31.26, 30.87, 29.87, 29.14, 18.39. Anal. Calcd for
(4Z)-2,6-Dim eth yl-2,4-h ep ta d ien -6-ol (10a ). To a solu-
tion of 9a (920 mg, 6.66 mmol) in hexane (95 mL) were added
Lindlar catalyst (1.14 g) and quinoline (76 µL), and the mixture
was stirred at room temperature for 10 min under hydrogen
atmosphere. The reaction mixture was filtered and concen-
trated in vacuo to give crude products that were purified by
column chromatography (9% ether in hexane) to afford 10a
(438 mg, 47%): IR (neat, cm-1) 3384, 2972, 1650, 1450, 1380,
1200, 1142; UVmax (MeOH) 238 nm (ꢀ ) 26 900); 1H NMR (400
MHz, CDCl3) δ 6.58 (1H, brd, J ) 12.0 Hz), 6.12 (1H, dd, J )
12.0, 11.7 Hz), 5.40 (1H, brd, J ) 11.7 Hz), 1.82 (3H, brs), 1.74
(3H, brs), 1.64 (1H, s), 1.41 (6H, s); 13C NMR (100 MHz, CDCl3)
δ 137.15, 135.08, 124.74, 120.87, 71.93, 31.33, 26.50, 17.62;
EI HRMS m/e calcd for C9H16O (M+) 140.1197, found 140.1225.
(4Z)-2,6-Dim eth yl-6-(tr ieth ylsiloxy)-2,4-h eptadien e (11a).
To a solution of 10a (290 mg, 2.07 mmol), 4-(dimethylamino)-
pyridine (25 mg, 0.21 mmol), and triethylamine (0.72 mL, 5.17
mmol) in DMF (11 mL) was added triethylsilyl chloride (0.80
mL, 4.76 mmol) at 0 °C, and the reaction mixture was
gradually warmed to room temperature. After the reaction
mixture was stirred at the same temperature for 11 h,
saturated aqueous NH4Cl solution was added, and the result-
ing mixture was extracted with ether. The organic layers were
combined, washed with brine, dried over MgSO4, filtered, and
concentrated in vacuo to give crude silyl ether 11a , which was
used for photosensitized oxygenation without any purification
because of its instability for column chromatography.
C
15H22O2: C, 76.87; H, 9.47. Found: C, 76.60; H, 9.50. Dia s-
ter eoisom er : mp 79.5-81 °C; IR (KBr disk, cm-1) 3316, 2932,
1
1960, 1452, 1366, 1166, 1120; H NMR (400 MHz, CDCl3) δ
5.48 (1H, s), 2.90 (1H, brs), 2.48 (1H, s), 1.73-1.89 (2H, m),
1.60 (3H, s), 1.48-1.58 (4H, m), 1.42 (3H, s), 1.22 (3H, s), 1.09
(3H, s); 13C NMR (100 MHz, CDCl3) δ 196.66, 122.04, 101.73,
86.48, 71.70, 70.95, 66.92, 40.64, 40.37, 34.51, 30.92, 30.78,
30.04, 29.49, 18.56; EI HRMS m/e calcd for C15H26O (M -
H2O+) 216.1509, found 216.1521.
2,3,6-Tr im eth yl-2-h ep ten -4-yn -6-ol (9b). Compound 9b
was prepared according to the procedure for synthesis of 9a
using 2-(bromomethyl)-2-butene (5b) (2.50 mL, 20.7 mmol) in
place of 1-bromo-2-methyl-2-propene (5a ). The product 9b was
isolated by repeating medium-pressure column chromatogra-
phy (4% ether in hexane) (1.42 g, 45%): IR (neat, cm-1) 3368,
2980, 2204, 1374, 1236, 1166, 1136; 1H NMR (400 MHz, CDCl3)
δ 2.04 (1H, s), 1.91 (3H, brs), 1.78 (3H, brs), 1.73 (3H, brs),
1.56 (6H, s); 13C NMR (100 MHz, CDCl3) δ 140.07, 111.02,
95.10, 83.89, 65.70, 31.71, 23.42, 19.81, 18.51.
(4Z)-2,3,6-Tr im eth yl-2,4-h ep ta d ien -6-ol (10b). To a so-
lution of 9b (450 mg, 2.96 mmol) in hexane (50 mL) were added
Lindlar catalyst (600 mg) and quinoline (38 µL), and the
mixture was stirred at room temperature for 20 min under
hydrogen atmosphere. The reaction mixture was filtered and
concentrated in vacuo to give crude products that were purified
by column chromatography (5% ether in hexane) to give 10b
(225 mg, 49%): IR (neat, cm-1) 3452, 2976, 1454, 1374, 1140;
1H NMR (400 MHz, CDCl3) δ 5.79 (1H, brd, J ) 12.4 Hz), 5.40
(1H, d, J ) 12.4 Hz), 2.96 (1H, s), 1.76 (3H, brs), 1.73 (3H,
brs), 1.69 (3H, brs), 1.29 (6H, s); 13C NMR (100 MHz, CDCl3)
δ 136.44, 128.15, 127.88, 126.57, 72.77, 30.16, 22.49, 19.62,
19.56; EI HRMS m/e calcd for C10H18O (M+) 154.1353, found
154.1372.
(4Z)-2,3,6-Tr im e t h yl-6-(t r ie t h ylsiloxy)-2,4-h e p t a d i-
en e (11b). To a solution of 10b (69 mg, 0.45 mmol), 4-(di-
methylamino)pyridine (6 mg, 0.05 mmol), and triethylamine
(0.21 mL, 1.51 mmol) in DMF (3 mL) was added triethylsilyl
chloride (0.27 mL, 1.43 mmol) at 0 °C, and the reaction mixture
was gradually warmed to room temperature. After the reac-
tion mixture was stirred at the same temperature for 17 h,
saturated aqueous NH4Cl solution was added, and the result-
ing mixture was extracted with ether. The organic layers were
combined, washed with brine, dried over MgSO4, filtered, and
concentrated in vacuo to give crude silyl ether 11b, which was
used for photosensitized oxygenation without any purification
because of its instability for column chromatography.
1-(Tr ibu tylsta n n yl)-1-bu tyn -3-ol (8). To a solution of
3-methyl-1-butyn-3-ol (5.0 mL, 51.6 mmol) in THF (20 mL)
was added n-BuLi (1.6 M solution in hexane, 71 mL, 114 mmol)
at -78 °C and HMPA (10 mL) at 0 °C, and the mixture was
stirred for 2 h. Tributyltin chloride (30.1 mL, 114 mmol) was
then added at 0 °C, and the mixture was warmed to room
temperature. After being stirred at room temperature for 38
h, the reaction mixture was diluted with saturated aqueous
NH4Cl solution and extracted with ether. The organic layers
were combined, washed with brine, dried over MgSO4, filtered,
and concentrated in vacuo to give crude products. Column
(1Z)-1-(1′-Hyd r oxy-2′-m eth ylid en e-6′,6′-d im eth ylcyclo-
h exyl)-3-m eth yl-1-p en ten -4-yn -3-ol (4f): IR (neat, cm-1
)
3524, 3312, 2940, 2872, 1716, 1642, 1452, 1122; 1H NMR (400
MHz, CDCl3) δ 5.79 (1H, d, J ) 12.9 Hz), 5.75 (1H, d, J )
12.9 Hz), 4.97 (1H, brs), 4.91 (1H, dd, J ) 2.6, 1.2 Hz), 2.53
(1H, s), 2.46 (1H, dt, J ) 14.2, 7.1 Hz), 2.22 (1H, dt, J ) 13.4,
5.9 Hz), 1.63 (3H, s), 1.56-1.79 (4H, m), 0.97 (3H, s), 0.96 (3H,
s); 13C NMR (100 MHz, CDCl3) δ 150.21, 135.07, 132.92,
109.93, 89.09, 81.30, 71.42, 64.45, 39.34, 36.43, 32.22, 30.89,
24.22, 23.76, 22.54; EI HRMS m/e calcd for C15H20O (M -
H2O+) 216.1509, found 216.1518. Dia ster eoisom er : mp 65-
65.5 °C; IR (KBr disk, cm-1) 3292, 3036, 2936, 2116, 1646,
1452, 1152, 1094; 1H NMR (400 MHz, CDCl3) δ 5.83 (1H, d, J
) 12.9 Hz), 5.76 (1H, d, J ) 12.9 Hz), 5.52 (1H, brs), 4.97 (1H,
d, J ) 1.2 Hz), 4.90 (1H, dd, J ) 2.7, 1.2 Hz), 3.34 (1H, brs),
2.59 (1H, s), 2.41 (1H, dt, J ) 14.0, 6.8 Hz), 2.21 (1H, dt, J )
14.0, 6.8 Hz), 1.61 (3H, s), 1.47-1.69 (4H, m), 1.01 (3H, s),
0.97 (3H, s); 13C NMR (100 MHz, CDCl3) δ 148.83, 135.49,
132.38, 109.68, 89.69, 81.78, 71.14, 64.21, 40.41, 36.96, 32.51,
31.00, 24.03, 22.90, 22.73. Anal. Calcd for C15H22O2: C, 76.87;
H, 9.47. Found: C, 76.91; H, 9.54.
2,6-Dim eth yl-2-h ep ten -4-yn -6-ol (9a ). To a solution of
3-methyl-1-butyn-3-ol (9.0 mL, 93 mmol) in THF (200 mL)
were added n-BuLi (1.6 M solution in hexane, 128 mL, 204
mmol) and HMPA (20 mL) at -78 °C. The reaction mixture
was stirred at -78 °C for 1.5 h, and zinc chloride (29 g, 204
mmol) was added at the same temperature. The mixture was
warmed to 0 °C and stirred for an additional 3 h. To this
solution were added 1-bromo-2-methyl-2-propene (5a ) (2.0 mL,
193 mmol) and tetrakis(triphenylphosphine)palladium (239
mg, 2.07 mmol). After being stirred at 65 °C for 33 h, the
mixture was diluted with saturated aqueous NH4Cl solution
and extracted with ether. The organic layers were washed
with brine, dried over MgSO4, filtered, and concentrated in
vacuo to give crude products. Column chromatography on
silica gel (17% ether in hexane) gave 9a (2.14 g, 80%): IR (neat,
cm-1) 3364, 2980, 2212, 1632, 1380, 1244, 1166; 1H NMR (400
MHz, CDCl3) δ 5.26 (1H, qq, J ) 1.5, 0.5 Hz), 2.08 (1H, brs),
1.88 (3H, d, J ) 0.5 Hz), 1.80 (3H, d, J ) 1.5 Hz), 1.55 (1H,
s);13C NMR (100 MHz, CDCl3) δ 148.67, 104.50, 95.90, 80.09,
65.71, 31.61, 24.68, 20.83; EI HRMS m/e calcd for C9H14O (M+)
138.1041, found 138.1052.

8716 J . Org. Chem., Vol. 63, No. 24, 1998
Mori et al.
chromatography on silica gel (from 11% to 13% ether in
hexane) gave 8 (17.2 g), which was used for the next reaction
without further purification.
the next reaction without any purification because of its
instability for column chromatography.
To a solution of crude 7d in THF (30 mL) were added
stannylacetylide 8 (6.1 g) in THF (20 mL) and tetrakis-
(riphenylphosphine)palladium (900 mg, 0.78 mmol). After the
reaction mixture was stirred at room temperature for 2.5 h,
the reaction was quenched with saturated aqueous NaCl
solution, and the mixture was extracted with ether. The
organic layers were combined, washed with brine, dried over
MgSO4, filtered, and concentrated in vacuo to give crude
products. Column chromatography on silica gel (from 7% to
9% ethyl acetate in hexane) gave 9d (880 mg, 52% for two
steps): IR (neat, cm-1) 3360, 2972, 2208, 1466, 1366, 1212,
3-Isop r op yl-2,6-d im eth yl-2-h ep ten -4-yn -6-ol (9c). To a
solution of lithium diisopropylamide prepared from diisopro-
pylamine (7.35 mL, 52.4 mmol) and n-BuLi (1.6 M solution in
hexane, 32.8 mL, 52.4 mmol) in THF (132 mL) was added 2,4-
dimethyl-3-pentanone (3.7 mL, 26.2 mmol) at -78 °C. After
the reaction mixture was stirred at -78 °C for 1.5 h, a THF
solution of N-trifluoromethanesulfonimide (11.2 g, 31.5 mmol)
was added. The mixture was stirred at room temperature for
38 h, diluted with saturated aqueous NH4Cl solution, and
extracted with ether. The organic layers were combined,
washed with brine, dried over MgSO4, filtered, and concen-
trated in vacuo to give crude products. Column chromatog-
raphy on silica gel (1% ether in hexane) gave enol triflate 7c
as an oil (5.21 g), which was used for the next reaction without
further purification.
To a solution of 7c in THF (105 mL) were added stanyl-
acetylide 8 (9.32 g) and tetrakis(triphenylphosphine)palladium
(1.22 g, 1.06 mmol). After the mixture was stirred at room
temperature for 18 h, the reaction was quenched with aqueous
NH4Cl solution, and the mixture was extracted with ether. The
organic layers were combined, washed with brine, dried over
MgSO4, filtered, and concentrated in vacuo to give crude
products. Column chromatography on silica gel (11% ether
1
1148; H NMR (400 MHz, CDCl3) δ 1.96 (3H, s), 1.92 (3H, s),
1.56 (6H, s), 1.23 (9H, s); 13C NMR (100 MHz, CDCl3) δ 129.27,
123.62, 98.13, 83.22, 65.94, 31.64, 31.00, 29.22, 26.57, 22.14.
(4Z)-3-ter t-Bu tyl-2,6-d im eth yl-2,4-h ep ta d ien -6-ol (10d ).
To a solution of 9d (210 mg, 1.1 mmol) in hexane (10 mL) was
added Pd/BaSO4 (530 mg), and the mixture was stirred at room
temperature for 50 min under hydrogen atmosphere. The
reaction mixture was filtered and concentrated in vacuo to give
crude products that were purified by column chromatography
(17% ethyl acetate in hexane) to give 10d (128 mg, 61%): IR
(neat, cm-1) 3540, 2972, 1470, 1364, 1162; 1H NMR (400 MHz,
CDCl3) δ 5.76 (1H, dqq, J ) 12.5, 1.9, 1.8 Hz), 5.36 (1H, d, J
) 12.5 Hz), 3.32 (1H, s), 1.86 (3H, d, J ) 2.4 Hz), 1.78 (3H, d,
J ) 1.7 Hz), 1.28 (3H, s), 1.27 (3H, s), 1.20 (9H, s); 13C NMR
(100 MHz, CDCl3) δ 138.94, 135.07, 128.95, 126.32, 72.96,
34.94, 31.05, 30.47, 29.47, 25.88, 22.08; EI HRMS m/e calcd
for C13H24O1 196.1821, found 196.1850.
in hexane) gave 9c (2.13 g, 45% for two steps): IR (neat, cm-1
)
3376, 2972, 2872, 2204, 1628, 1456, 1232, 1166; 1H NMR (400
MHz, CDCl3) δ 2.74 (1H, qq, J ) 6.8, 6.8 Hz), 2.01 (1H, s),
1.91 (3H, s), 1.76 (3H, s),1.58 (6H, s), 1.02 (6H, d, J ) 6.8 Hz);
13C NMR (100 MHz, CDCl3) δ 137.81, 123.23, 97.77, 80.32,
65.79, 31.77, 28.83, 23.85, 21.47, 19.38.
(4Z)-3-ter t-Bu tyl-2,6-d im eth yl-6-(tr im eth ylsiloxy)-2,4-
h ep ta d ien e (11d ). To a solution of 10d (300 mg, 1.50 mmol),
4-(dimethylamino)pyridine (56 mg, 0.46 mmol), and triethyl-
amine (0.85 mL, 6.10 mmol) in DMF (8 mL) was added
triethylsilyl chloride (0.92 mL, 5.50 mmol) at 0 °C, and the
reaction mixture was gradually warmed to room temperature.
After the reaction mixture was stirred at the same tempera-
ture overnight, aqueous saturated NaHCO3 solution was
added, and the resulting mixture was extracted with ether.
The organic layers were combined, washed with brine, dried
over MgSO4, filtered, and concentrated in vacuo to give crude
silyl ether 11d , which was used for photosensitized oxygen-
ation without any purification because of its instability for a
column chromatography.
(4Z)-3-Isop r op yl-2,6-d im eth yl-2,4-h ep ta d ien -6-ol (10c).
To a solution of 9c (622 mg, 3.45 mmol) in hexane (18 mL)
was added Lindlar catalyst (1.5 g), and the mixture was stirred
at room temperature for 3 days under hydrogen atmosphere.
The reaction mixture was filtered and concentrated in vacuo
to give crude products that were purified by column chroma-
tography (from 11% to 13% ether in hexane) to give 10c (294
mg, 47%): IR (neat, cm-1) 3540, 2972, 2872, 1468, 1378, 1362,
1
1146; H NMR (400 MHz, CDCl3) δ 5.67 (1H, dqq, J ) 12.7,
2.0, 1.7 Hz), 5.52 (1H, d, J ) 12.7 Hz), 3.41 (1H, s), 2.90 (1H,
qq, J ) 6.8 Hz), 1.78 (3H, d, J ) 1.7 Hz), 1.72 (3H, d, J ) 2.0
Hz), 1.28 (6H, s), 0.99 (6H, d, J ) 6.8 Hz); 13C NMR (100 MHz,
CDCl3) δ 138.50, 136.61, 127.05, 121.71, 73.19, 30.05, 29.72,
23.47, 21.37, 19.20; EI HRMS m/e calcd for C12H22O (M+)
182.1665, found 182.1665.
3-Br om o-2,4-d im eth yl-2-p en ten -4-ol (5e). To a solution
of methyl 3,3-dimethylacryrate (4.1 mL, 30.4 mmol) in dichlo-
romethane (110 mL) was added bromine (2.4 mL, 45.7 mmol)
at 0 °C. After being stirred at 0 °C for 10 h, the reaction
mixture was diluted with aqueous saturated Na2S2O3 solution,
poured into aqueous saturated NaHCO3 solution, and ex-
tracted with dichloromethane. The organic layers were com-
bined, washed with brine, dried over MgSO4, filtered, and
concentrated in vacuo to give crude products. Column chro-
matography on silica gel (2% ethyl acetate in hexane) gave
dibromide (7.41 g, 73%): IR (neat, cm-1) 2984, 1754, 1440,
(4Z)-3-Isopr opyl-2,6-dim eth yl-2-(tr ieth ylsiloxy)-2,4-h ep-
ta d ien e (11c). To a solution of 10c (268 mg, 1.47 mmol),
4-(dimethylamino)pyridine (18 mg, 0.15 mmol), and trieth-
ylamine (0.41 mL, 2.94 mmol) in DMF (8 mL) was added
triethylsilyl chloride (0.41 mL, 2.65 mmol) at 0 °C, and the
reaction mixture was gradually warmed to room temperature.
After the reaction mixture was stirred at the same tempera-
ture for 11 h, aqueous saturated NH4Cl solution was added,
and the resulting mixture was extracted with ether. The
organic layers were combined, washed with brine, dried over
MgSO4, filtered, and concentrated in vacuo to give crude silyl
ether 11c, which was used for photosensitized oxygenation
without any purification because of its instability for column
chromatography.
3-ter t-Bu tyl-2,6-d im eth yl-2-h ep ten -4-yn -6-ol (9d ). To a
solution of lithium diisopropylamide prepared from diisopro-
pylamine (2.2 mL, 16 mmol) and n-BuLi (1.6 M solution in
hexane, 9.8 mL, 16 mmol) in THF (30 mL) was added 2,2,4-
trimethyl-3-pentanone20 (1.0 g, 7.8 mmol) at -78 °C. The
solution was warmed to room temperature and maintained at
the same temperature for an additional 30 min. To this
solution was added N-trifluoromethansulfonimide (3.3 g, 9.2
mmol) in THF at 0 °C. After the reaction mixture was stirred
at room temperature for 1.5 h, the reaction was quenched with
saturated aqueous NH4Cl solution, and the mixture was
extracted with ether. The organic layers were combined,
washed with brine, dried over MgSO4, filtered, and concen-
trated in vacuo to give crude 7d . Obtained 7d was used for
1
1350, 1246, 1146, 1102, 1030; H NMR (400 MHz, CDCl3) δ
4.65 (1H, s), 3.81 (3H, s), 2.05 (3H, s), 1.95 (3H, s); 13C NMR
(100 MHz, CDCl3) δ 168.08, 61.60, 54.15, 52.89, 33.69, 28.44.
To a solution of the obtained dibromide (6.4 g, 23.4 mmol)
in THF (110 mL) was added DBU (3.49 mL, 23.4 mmol) at
-78 °C. After being stirred at -78 °C for 1.5 h, the reaction
mixture was diluted with aqueous saturated NH4Cl solution
and extracted with ether. The organic layers were combined,
washed with brine, dried over MgSO4, filtered, and concen-
trated in vacuo to give crude products. Column chromatog-
raphy on silica gel (1% ethyl acetate in hexane) gave vinyl
bromide (4.0 g, 89%): IR (neat, cm-1) 2956, 1722, 1438, 1252,
1
1218, 1096, 1016; H NMR (400 MHz, CDCl3) δ 3.81 (3H, s),
2.15 (3H, s), 2.06 (3H, s); 13C NMR (100 MHz, CDCl3) δ 164.50,
149.05, 108.15, 52.66, 27.16, 23.18.
To a solution of the obtained vinyl bromide (8.24 g, 42.7
mmol) in THF (150 mL) was added methylmagnesium iodide
prepared from magnesium turnings (6.7 g, 277 mmol) and
methyl iodide (16.5 mL, 264 mmol) in ether (130 mL), until
the starting material disappeared. After being stirred at 0

Photosensitized Oxygenation of Twisted 1,3-Dienes
J . Org. Chem., Vol. 63, No. 24, 1998 8717
°C for 8 h, the reaction mixture was diluted with aqueous
saturated NH4Cl solution and extracted with ethyl acetate.
The organic layers were combined, washed with brine, dried
over MgSO4, filtered, and concentrated in vacuo to give crude
products. Column chromatography on silica gel (11% ethyl
(4Z)-2,6-Dim eth yl-1,4-h eptadien e-3,6-diol (14a): IR (neat,
cm-1) 3324, 2976, 1652, 1454, 1374, 1170, 1064, 1008; 1H NMR
(400 MHz, CDCl3) δ 5.60 (1H, dd, J ) 12.0, 1.5 Hz), 5.39 (1H,
dd, J ) 12.2, 6.8 Hz), 5.15 (1H, d, J ) 6.8 Hz), 5.03 (1H, m),
4.85 (1H, m), 1.78 (3H, s), 1.39 (6H, s); 13C NMR (100 MHz,
CDCl3) δ 147.29, 139.42, 129.44, 110.74, 71.86, 71.68, 31.79,
30.64, 18.44; EI HRMS m/e calcd for C9H14O1 (M - H2O+)
138.1041, found 138.1046.
P h otosen sitized Oxygen a tion of 11b. Following the
general procedure of photosensitized oxygenation, 11b (ca. 0.45
mmol), TPP (2 mg, 0.002 mmol), and triphenylphosphine (117
mg, 0.45 mmol, and after oxidation 117 mg, 0.45 mmol) in
dichloromethane (3 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (175 mg, 0.67 mmol) in THF (3 mL) gave
13b (24 mg, 32% for three steps), 14b (9 mg, 12% for three
steps), and 15b (32 mg, 42% for three steps) after the usual
workup and column chromatography (from 20% to 67% ethyl
acetate in hexane).
2,3,6-Tr im eth yl-3,4-h ep ta d ien e-2,6-d iol (13b): IR (KBr
disk, cm-1) 3496, 3252, 2980, 1978, 1370, 1156; 1H NMR (400
MHz, CDCl3) δ 5.38 (1H, q, J ) 2.9 Hz), 1.79 (3H, d, J ) 2.9
Hz), 1.36 (6H, s), 1.34 (6H, s); 13C NMR (100 MHz, CDCl3) δ
195.68, 115.51, 103.04, 71.02, 69.92, 29.97, 29.86, 28.84, 28.56,
14.90; EI HRMS m/e calcd for C10H17O1 (M - OH+) 153.1275,
found 153.1268.
(4Z)-2,3,6-Tr im eth yl-1,4-h ep ta d ien e-3,6-d iol (14b): IR
(neat, cm-1) 3220, 2980, 1644, 1452, 1366, 1300, 1148; 1H NMR
(400 MHz, CDCl3) δ 5.51 (1H, d, J ) 12.9 Hz), 5.43 (1H, d, J
) 12.9 Hz), 5.08 (1H, dq, J ) 1.7, 0.7 Hz), 4.81 (1H, dq, J )
1.6, 1.5 Hz), 1.85 (3H, dd, J ) 1.7, 1.5 Hz), 1.66 (1H, brs), 1.43
(3H, s), 1.39 (3H, s), 1.36 (3H, s); 13C NMR (100 MHz, CDCl3)
δ 153.27, 136.56, 134.48, 109.33, 74.61, 72.20, 31.50, 30.16,
29.14, 19.18; EI HRMS m/e calcd for C10H16O1 (M - H2O+)
152.1197, found 152.1189.
acetate in hexane) gave 5e (5.81 g, 71%): IR (KBr disk, cm-1
)
1
3304, 2980, 1624, 1380, 1144; H NMR (400 MHz, CDCl3) δ
2.06 (3H, s), 1.98 (1H, s), 1.94 (3H, s), 1.56 (6H, s); 13C NMR
(100 MHz, CDCl3) δ 132.51, 128.35, 75.78, 31.06, 28.99, 22.27.
5-Isopr opylid en e-2,6-dim eth yl-2-(tr ieth ylsiloxy)-3-h ep-
tyn -6-ol (9e). To a solution of 3-methyl-1-butyn-3-ol (12 mL,
124 mmol), 4-(dimethylamino)pyridine (1.51 g, 12.4 mmol), and
triethylamine (25.8 mL, 18.6 mmol) in DMF (240 mL) was
added triethylsilyl chloride (24.9 mL, 149 mmol) at 0 °C, and
the reaction mixture was gradually warmed to room temper-
ature. After being stirred at the same temperature for 2 days,
the reaction mixture was diluted with aqueous saturated NH4-
Cl solution and then extracted with ether. The organic layers
were combined, washed with brine, dried over MgSO4, filtered,
and concentrated in vacuo to give crude products. Column
chromatography on silica gel (3% triethylamine in hexane)
gave silyl ether as an oil (25 g), which was used for the next
reaction without further purification.
To a solution of the silyl ether (4.0 g) in THF (40 mL) was
added n-BuLi (1.6 M solution in hexane, 3.9 mL, 22.2 mmol)
at -78 °C. The reaction mixture was stirred at -78 °C for
1.5 h, and zinc chloride (3.15 g, 22.2 mmol) was added at the
same temperature. The mixture was warmed to room tem-
perature and stirred for an additional 3 h. To this solution
were added the alcohol 5e (1.0 g, 5.18 mmol), and tetrakis-
(triphenylphosphine)palladium (600 mg, 0.518 mmol) was
added. After being stirred at 65 °C for 4 h, the reaction
mixture was diluted with aqueous saturated NH4Cl solution
and extracted with ethyl acetate. The organic layers were
combined, washed with brine, dried over MgSO4, filtered, and
concentrated in vacuo to give crude products. Column chro-
matography on silica gel (3% ethyl acetate and 3% triethyl-
amine in hexane) gave 9e (1.35 g, 84%): IR (neat, cm-1) 3432,
2960, 2204, 1464, 1380, 1160, 1040; 1H NMR (400 MHz, CDCl3)
δ 2.05 (3H, s), 1.98 (3H, s), 1.74 (1H, brs), 1.52 (6H, s),1.47
(6H, s), 0.96 (9H, t, J ) 8.0 Hz), 0.66 (6H, q, J ) 8.0 Hz); 13C
NMR (100 MHz, CDCl3) δ 143.10, 124.36, 99.49, 81.90, 72.56,
66.80, 33.21, 30.77, 25.91, 21.61, 6.97, 5.95.
(3Z)-5-Isop r op ylid en e-2,6-d im eth yl-2-(tr ieth ylsiloxy)-
3-h ep ten -6-ol (11e). To a solution of 9e (300 mg, 0.97 mmol)
in MeOH (6 mL) was added Pd-C (90 mg), and the mixture
was stirred at room temperature for 40 min under hydrogen
atmosphere. The reaction mixture was filtered and concen-
trated in vacuo to give crude products that were purified by
column chromatography on silica gel (2% triethylamine in
hexane) to give 11e (271 mg, 90%): IR (neat, cm-1) 3452, 2964,
1466, 1378, 1150, 1042; 1H NMR (400 MHz, CDCl3) δ 5.76 (1H,
dqq, J ) 12.7, 2.2, 1.5 Hz), 5.54 (1H, d, J ) 12.7 Hz), 2.60
(1H, s), 1.86 (3H, d, J ) 2.2 Hz), 1.68 (3H, d, J ) 1.5 Hz), 1.44
(6H, s), 1.37 (6H, s), 0.95 (9H, t, J ) 7.8 Hz), 0.61 (6H, q, J )
7.8 Hz); 13C NMR (100 MHz, CDCl3) δ 138.45, 137.50, 127.19,
127.14, 74.07, 72.37, 30.67, 30.20, 25.26, 21.37, 7.01, 6.65.; EI
HRMS m/e calcd for C17H31O1Si1 (M - H2O - CH3+) 279.2136,
found 279.2178.
(3Z)-5-Meth yliden e-2,6-dim eth yl-3-h epten e-2,6-diol(15b):
1
IR (neat, cm-1) 3352, 2976, 1626, 1464, 1364, 1254, 1152; H
NMR (400 MHz, CDCl3) δ 5.99 (1H, ddd, J ) 12.4, 1.8, 1.7
Hz), 5.62 (1H, d, J ) 12.4 Hz), 5.21 (1H, dd, J ) 1.7, 1.6 Hz),
4.91 (1H, dd, J ) 1.8, 1.7 Hz), 2.95 (2H, brs), 1.39 (6H, s), 1.35
(6H, s); 13C NMR (100 MHz, CDCl3) δ 155.50, 139.68, 124.78,
110.49, 72.90, 71.94, 31.28, 29.00; EI HRMS m/e calcd for
C
10H16O1 (M - H2O+) 152.1197, found 152.1190.
P h otosen sitized Oxygen a tion of 11c. Following the
general procedure of photosensitized oxygenation, 11c (ca. 1.47
mmol), TPP (5 mg, 0.005 mmol), and triphenylphosphine (386
mg, 1.47 mmol, and after oxidation 386 mg, 1.47 mmol) in
dichloromethane (8 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (769 mg, 2.94 mmol) in THF (8 mL) gave
13c (111 mg, 38% for three steps), 14c (80 mg, 27% for three
steps), 15c (24 mg, 8% for three steps), and 16 (48 mg, 17%
for three steps) after the usual workup and column chroma-
tography (from 25% to 95% ether in hexane).
3-Isop r op yl-2,6-d im eth yl-3,4-h ep ta d ien e-2,6-d iol (13c):
IR (neat, cm-1) 3396, 2972, 2872, 1958, 1464, 1366, 1210, 1148;
1H NMR (400 MHz, CDCl3) δ 5.56 (1H, d, J ) 0.5 Hz), 2.34
(1H, dqq, J ) 6.8, 6.6, 0.5 Hz), 2.17 (2H, brs),1.37 (6H, s), 1.35
(6H, s), 1.09 (3H, d, J ) 6.8 Hz), 1.06 (3H, d, J ) 6.6 Hz); 13
C
P h otosen sitized Oxygen a tion of 11a . Following the
general procedure of photosensitized oxygenation, 11a (ca. 2.07
mmol), TPP (7 mg, 0.01 mmol), and triphenylphosphine (542
mg, 2.07 mmol, and after oxidation 813 mg, 3.10 mmol) in
dichloromethane (11 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (1.22 mg, 4.65 mmol) in THF (11 mL) gave
13a (144 mg, 45% for three steps) and 14a (93 mg, 29% for
three steps), after the usual workup and column chromatog-
raphy (from 2% to 9% hexane in ether).
2,6-Dim eth yl-3,4-h eptadien e-2,6-diol (13a): IR (KBr disk,
cm-1) 3368, 2980, 1968, 1468, 1366, 1152; 1H NMR (400 MHz,
CDCl3) δ 5.51 (1H, s), 2.63 (2H, brs), 1.36 (12H, s); 13C NMR
(100 MHz, CDCl3) δ 197.53, 104.63, 69.65, 30.02, 29.83.; FAB
HRMS m/e calcd for C9H15O1 (M - OH+) 139.1119, found
139.1124.
NMR (100 MHz, CDCl3) δ 194.48, 123.85, 106.76, 71.52, 69.85,
30.12, 29.97, 29.32, 29.12, 27.09, 24.78, 24.08; EI HRMS m/e
calcd for C12H21O1 (M - OH+) 181.1587, found 181.1589.
(4Z)-3-Isop r op yl-2,6-d im et h yl-1,4-h ep t a d ien e-3,6-d iol
(14c): mp 69.0-69.5 °C; IR (KBr disk, cm-1) 3272, 3132, 2972,
1
1640, 1454, 1294, 1154, 1044; H NMR (400 MHz, CDCl3) δ
5.50 (2H, d, J ) 3.4 Hz), 5.07 (1H, m), 4.85 (1H, m), 1.92 (1H,
qq, J ) 6.8 Hz), 1.78 (3H, m), 1.40 (3H, s), 1.35 (3H, s), 0.93
(3H, d, J ) 6.8 Hz), 0.86 (3H, d, J ) 6.8 Hz); 13C NMR (100
MHz, CDCl3) δ 151.55, 136.84, 133.24, 110.43, 79.58, 71.97,
34.45, 31.68, 30.06, 19.49, 17.07, 16.23. Anal. Calcd for
C
12H22O2: C, 72.67; H, 11.19. Found: C, 72.75; H, 11.19.
(3Z)-5-Isop r op ylid en e-2,6-d im et h yl-3-h ep t en e-2,6-d i-
ol (15c): IR (neat, cm-1) 3404, 2976, 1632, 1466, 1250, 1170;
1H NMR (400 MHz, CDCl3) δ 5.79 (1H, dqq, J ) 12.2, 2.2, 1.7
Hz), 5.50 (1H, d, J ) 12.2 Hz), 3.00 (1H, brs), 2.47 (1H, brs),

8718 J . Org. Chem., Vol. 63, No. 24, 1998
Mori et al.
1.94 (3H, d, J ) 2.2 Hz), 1.76 (3H, d, J ) 1.7 Hz), 1.43 (6H,
brs), 1.30 (6H, s); 13C NMR (100 MHz, CDCl3) δ 138.19, 137.52,
129.23, 125.40, 72.83, 72.35, 30.19, 25.11, 21.46; EI HRMS m/e
calcd for C12H20O (M - H2O+) 180.1509, found 180.1514.
3-(1-Hyd r oxy-1-m eth yleth yl)-2,6-d im eth yl-3,4-h ep ta d i-
en e-2,6-d iol (16): mp 76.0-77.0 °C; IR (neat, cm-1) 3344,
P h otosen sitized Oxygen a tion of 11e. Following the
general procedure of photosensitized oxygenation, 11e
(475 mg, 1.62 mmol), TPP (10 mg, 0.016 mmol), and tri-
phenylphosphine (840 mg, 320 mmol, and after oxidation 420
mg, 1.60 mmol) in dichloromethane (8 mL) gave crude oxy-
genated products. Following the general procedure of desily-
lation, the oxygenated products and TBAF (562 mg, 1.92
mmol) in THF (8 mL) gave 13e (240 mg, 74% for two steps)
and 14e (26 mg, 8% for three steps) after the usual workup
and column chromatography (from 33% to 80% ethyl acetate
in hexane).
1
2976, 1956, 1464, 1378, 1124; H NMR (400 MHz, CDCl3) δ
5.43 (1H, s), 4.28, 4.34 (2H, brs), 2.43, 2.48 (1H, brs),1.48 (6H,
s), 1.47 (6H, s), 1.35 (6H, s); 13C NMR (100 MHz, CDCl3) δ
195.36, 120.48, 104.38, 73.50, 70.02, 32.43, 31.69, 29.92; FAB
HRMS m/e calcd for C12H22O3Na (M + Na+) 237.1476, found
237.1455.
13e ) 16.
P h otosen sitized Oxygen a tion of 11d . Following the
general procedure of photosensitized oxygenation, 11d (ca. 1.50
mmol), TPP (9 mg, 0.015 mmol), and triphenylphosphine (400
mg, 1.5 mmol, and after oxidation 600 mg, 2.3 mmol) in
dichloromethane (8 mL) gave crude oxygenated products.
Following the general procedure of desilylation, the oxygenated
products and TBAF (600 mg, 2.3 mmol) in THF (13 mL) gave
13d (244 mg, 75% for three steps) and 14d (28 mg, 8% for
three steps) after the usual workup and column chromatog-
raphy (from 9% to 25% ethyl acetate in hexane). In addition,
14d contained triethylsilanol that could not be removed by
column chromatography. The yield of 14d was calculated on
the basis of the integral values of 14d and triethylsilanol in
the NMR spectrum.
3-ter t-Bu tyl-2,6-d im eth yl-3,4-h ep ta d ien e-2,6-d iol (13d ):
IR (KBr disk, cm-1) 3372, 2972, 1952, 1468, 1362, 1244, 1136;
1H NMR (400 MHz, CDCl3) δ 5.38 (1H, s), 1.83 (2H, brs), 1.48
(3H, s),1.46 (3H, s), 1.35 (6H, s), 1.23 (9H, s); 13C NMR (100
MHz, CDCl3) δ 196.80, 103.48, 72.86, 69.90, 32.95, 32.45, 31.59,
29.92, 29.82; EI HRMS m/e calcd for C13H22O (M - H2O+)
194.1655, found 194.1694.
(3Z)-5-Isopr opyl-2,6-dim eth yl-3-h epten e-2,5,6-tr iol (14e):
IR (KBr disk, cm-1) 3416, 3248, 2980, 1478, 1358, 1166, 1054;
1H NMR (400 MHz, CDCl3) δ 5.84 (1H, d, J ) 13.2 Hz), 5.51
(1H, d, J ) 13.2 Hz), 5.07 (1H, m), 5.03 (1H, dq, J ) 1.6, 1.5
Hz), 2.50 (1H, brs), 1.91 (3H, dd, J ) 1.5, 1.4 Hz), 1.40 (3H, s),
1.35 (3H, s), 1.27 (3H, s), 1.24 (3H, s);13C NMR (100 MHz,
CDCl3) δ 150.60, 136.73, 131.32, 114.01, 80.44, 75.35, 72.10,
31.25, 30.17, 25.38, 24.91, 22.13; FAB HRMS m/e calcd for
C12H23O3 (M + H+) 215.1641, found 215.1651.
Ack n ow led gm en t. We thank Ms. Kanako Yamash-
ita and Mr. Tamotsu Yamamoto of the Institute for Life
Science Research at Asahi Chemical Industry Co., Ltd.,
for their X-ray crystallographic measurements, elemen-
tal analyses, and high-resolution mass spectra mea-
surements. This work was supported by Grant-in-Aid
for Scientific Research on Priority Areas (No. 283,
“Innovative Synthetic Reactions”) from Monbusho.
(4Z)-3-ter t-Bu tyl-2,6-d im eth yl-1,4-h ep ta d ien e-3,6-d iol
(14d ): IR (KBr disk, cm-1) 3196, 2972, 1486, 1364, 1172, 1100;
1H NMR (400 MHz, CDCl3) δ 5.88 (1H, d, J ) 13.4 Hz), 5.44
(1H, d, J ) 13.2 Hz), 5.05 (1H, dq, J ) 1.7, 1.2 Hz), 5.02 (1H,
dq, J ) 1.7, 1.5 Hz), 1.86 (3H, dd, J ) 1.5, 1.2 Hz), 1.40 (3H,
s), 1.35 (3H, s), 1.00 (9H, s); 13C NMR (100 MHz, CDCl3) δ
150.89, 135.87, 133.04, 113.84, 80.34, 72.19, 38.69, 31.59,
30.10, 25.81, 22.78; EI HRMS m/e calcd for C13H22O (M -
H2O+) 194.1655, found 194.1645.
Su p p or tin g In for m a tion Ava ila ble: Full details of the
crystal structure of 1e and 400 MHz 1H NMR and 13C NMR
spectra of 1d , 3d , 4d , 10d , 13d , and 14d (21 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
J O980955O