Diastereoselective protonation on radical anions of electron-deficient alkenes via photoinduced electron transfer

Article abstract of DOI:10.1021/jo0496953

Diastereoselective protonations in the photoinduced electron transfer (PET) reactions of 1,1-dicyanoethene derivatives (1a-e) by use of organosilicon compounds such as allyltrimethylsilane (2) and benzyltrimethylsilane (5) are described. Irradiation of an acetonitrile-acetic acid solution containing 4-tert-butylcyclohexylidenepropanedinitrile (1a) and an excess of 2 in the presence of phenanthrene (Phen) as a sensitizer afforded reduction and allylated products (3a, 4a) in 63:37 and 57:43 ratios in a less regioselective manner. Photoreactions of 3,3,5-trimethylcyclohexylidenepropanedinitrile (1b), 2-methylcyclohexylidenepropanedinitrile (1c), bicyclo[2.2.1]-2- heptylidenepropanedinitrile (1d), and 1,7,7-trimethylbicyclo[2.2.1]-2- heptylidenepropanedinitrile (1e) with 2 showed higher diastereoselectivity via the PET process. Similar diastereoselectivities were obtained in the Phen-sensitized photoreaction of 1a-e with 5. When 2,4,6-trimethylpyridinium tosylate (7) was used as a proton source in place of acetic acid, the product ratios were substantially changed in several cases. From these results, steric and torsional effects have been postulated as important factors for the control of the diastereoselectivity in these PET reactions.

Full text of DOI:10.1021/jo0496953

Dia ster eoselective P r oton a tion on Ra d ica l An ion s of
Electr on -Deficien t Alk en es via P h otoin d u ced Electr on Tr a n sfer
Tomoo Hayamizu, Hajime Maeda, and Kazuhiko Mizuno*
Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University,
1-1 Gakuen-cho, Sakai, Osaka 599-8531, J apan
mizuno@chem.osakafu-u.ac.jp
Received February 23, 2004
Diastereoselective protonations in the photoinduced electron transfer (PET) reactions of 1,1-
dicyanoethene derivatives (1a -e) by use of organosilicon compounds such as allyltrimethylsilane
(2) and benzyltrimethylsilane (5) are described. Irradiation of an acetonitrile-acetic acid solution
containing 4-tert-butylcyclohexylidenepropanedinitrile (1a ) and an excess of 2 in the presence of
phenanthrene (Phen) as a sensitizer afforded reduction and allylated products (3a , 4a ) in 63:37
and 57:43 ratios in a less regioselective manner. Photoreactions of 3,3,5-trimethylcyclohexy-
lidenepropanedinitrile (1b), 2-methylcyclohexylidenepropanedinitrile (1c), bicyclo[2.2.1]-2-heptyl-
idenepropanedinitrile (1d ), and 1,7,7-trimethylbicyclo[2.2.1]-2-heptylidenepropanedinitrile (1e) with
2 showed higher diastereoselectivity via the PET process. Similar diastereoselectivities were
obtained in the Phen-sensitized photoreaction of 1a -e with 5. When 2,4,6-trimethylpyridinium
tosylate (7) was used as a proton source in place of acetic acid, the product ratios were substantially
changed in several cases. From these results, steric and torsional effects have been postulated as
important factors for the control of the diastereoselectivity in these PET reactions.
In tr od u ction
mediates. Because of detailed studies of the syntheticand
mechanistic aspects of these photoinduced carbon-func-
tionalization reactions, many useful photoreactions have
The photochemistry of organosilicon compounds has
been extensively investigated not only from synthetic and
mechanistic perspectives but also in terms of their
chemical and physical properties.1 In the area of synthetic
organic photochemistry, silyl substituents are developed
as the direct protection of functional groups, their indirect
protection by steric bulkiness, and the activation of
organic molecules.2 One most characteristic property of
some organosilicon compounds such as allylic silanes is
that they have lower oxidation potentials compared to
those of the corresponding carbon compounds. Therefore,
some selected organosilicon compounds can be used as
excellent electron donors in PET reactions. For example,
the photoallylation, benzylation, alkylation, and silylation
of a variety of electron-deficient compounds such as
iminium salts, cyanoaromatic compounds, cyanoalkenes,
and carbonyl compounds by use of organosilicon com-
pounds were developed.3-13 In these photoreactions,
radical anions or free radicals generated from the electron-
deficient molecules and carbon radicals such as allylic
radicals generated from radical cations of the organo-
silicon compounds were postulated as the reactive inter-
appeared in the past
2 decades, but the stereo-
chemical control of PET reactions via radical ions has
(3) Review articles for PET reactions by use of organosilicon
compounds: (a) Tamai, T.; Hayamizu, T.; Mizuno, K. In Handbook of
Photochemistry and Photobiology; Nalwa, H. S., Ed.; American Scien-
tific Publishers: Stevenson Ranch, CA, 2003; Vol. 1, pp 125-156. (b)
Mizuno, K.; Tamai, T.; Sugimoto, A.; Maeda, H. In Advances in
Electron-Transfer Chemistry; Mariano, P. S., Ed.; J AI Press: New York,
1999; Vol. 6, pp 131-165. (c) Kako, M.; Nakadaira, Y. Coord. Chem.
Rev. 1998, 176, 87. (d) Yoon, U. C.; Mariano, P. S. Acc. Chem. Res.
1992, 25, 233.
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3594. (c) Lu, H.; Mariano, P. S.; Lam, Y. Tetrahedron Lett. 2001, 42,
4755. (d) Yoon, U. C.; J in, Y. X.; Oh, S. W.; Park, C. H.; Park, J . H.;
Campana, C. F.; Cai, X.; Duesler, E. N.; Mariano, P. S. J . Am. Chem.
Soc. 2003, 125, 10664.
(5) (a) Mizuno, K.; Ikeda, M.; Otsuji, Y. Tetrahedron Lett. 1985, 26,
461. (b) Mizuno, K.; Ikeda, M.; Otsuji, Y. Chem. Lett. 1988, 1507. (c)
Mizuno, K.; Nashiyama, T.; Terasaka, T.; Yasuda, M.; Shima, K.;
Otsuji, Y. Tetrahedron 1992, 48, 9673. (d) Mizuno, K.; Nakanishi, K.;
Tachibana, A.; Otsuji, Y. J . Chem. Soc., Chem. Commun. 1991, 344.
(e) Mizuno, K.; Nakanishi, K.; Chosa, J .; Otsuji, Y. J . Organomet.
Chem. 1994, 473, 35. (f) Hayamizu, T.; Ikeda, M.; Maeda, H.; Mizuno,
K. Tetrahedron Lett. 2001, 42, 2361. (g) Hayamizu, T.; Maeda, H.;
Ikeda, M.; Mizuno, K. Org. Lett. 2001, 3, 1277.
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Mattes, S. L.; Todd, W. P. J . Am. Chem. Soc. 1989, 111, 8973. (b)
Dockery, K. P.; Dinnocenzo, J . P.; Farid, S.; Goodman, J . L.; Gould, I.
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Weber, W. P., Ed.; Springer-Verlag: Berlin, 1983. (c) The Chemistry
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Wiley & Sons: New York, 1989; Parts 1-2.
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1995, 34, 2669. (b) Pandey, G.; Rao, K. S. S. P.; Rao, K. V. N. J . Org.
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10.1021/jo0496953 CCC: $27.50 © 2004 American Chemical Society
Published on Web 06/30/2004
J . Org. Chem. 2004, 69, 4997-5004
4997

Hayamizu et al.
TABLE 1. Dia ster eoselective P h otor ed u ction a n d
not been satisfactory, except for some intramolecular
reactions.14,15
P h otoa llyla tion of 1 in th e P r esen ce of 2 a n d Acetic
Acid a
We have previously reported a highly stereoselective
carbon functionalization of 2-substituted 1-dicyanometh-
ylene-1,2,3,4-tetrahydronaphthalenes to give allylated
and benzylated products having a quaternary carbon
atom via the PET process.5f In this photoreaction, the
bulkiness of substituents at the 2 position is critical for
the stereoselectivity of the products, and the key step is
the attack of the allyl radical to the free radical anions
of 1-dicyanomethylene-1,2,3,4-tetrahydronaphthalenes.
We have also reported the photoallylation of cyclohexy-
lidenepropanedinitrile depending on the pKa values of
additives.5g However, there is no description of the
stereochemical control in the photoallylation of cyclo-
hexylidenepropanedinitrile.
We now report a novel diastereoselective protonation
of alkylidenepropanedinitriles 1a -e followed by allyla-
tion by the use of allyltrimethylsilane (2) via the PET
process. We have succeeded in highly diasteroselective
photoreduction and photoallylation depending on the
proton source and the alkylidenepropanedinitriles. Plau-
sible mechanisms for the regio- and diastereoselective
photoreactions are also described.
Resu lts a n d Discu ssion
P h otoallylation an d Ben zylation of Alkyliden epr o-
p a n ed in itr iles in th e P r esen ce of Acetic Acid . Ir-
radiation of an acetonitrile-acetic acid solution contain-
ing 4-tert-butylcyclohexylidenepropanedinitrile (1a ) and
an excess of 2 in the presence of phenanthrene (Phen)
as a sensitizer with a 300 W high-pressure mercury lamp
through a Pyrex filter (>280 nm light) afforded two kinds
of products, reduction products 3a and allylated products
4a in cis-3a :tr a n s-3a ) 63:37 and cis-4a :tr a n s-4a ) 57:
43 ratios in 15 and 51% yields, respectively (Scheme 1,
reaction 1 and Table 1, run 1). The photoreactions of
1b-e under the same reaction conditions also gave the
corresponding reduction products 3b-e and allylated
a
Irradiation was carried out at room temperature for 8 h. [1]
) 0.085 M, [2] ) 0.255 M, [Phen] ) 0.018 M, [MeCO2H] ) 0.170
M. b Isolated yields of two isomers. c Determined by GC-MS. cis/
d
trans ratio. e Determined by 1H NMR. f endo/exo ratio.
products 4b-e (Scheme 1, reactions 2-5 and Table 1,
runs 2-5). Yields and product ratios are summarized in
Table 1. Higher diastereoselectivity was observed in the
cases of 1b, 1d , and 1e. Similar photoreactions of 1a -e
with benzyltrimethylsilane (5) in the presence of Phen
afforded the reduction and benzylated products 3a -e and
6a -e in almost the same ratios compared to the photo-
reaction of 1a -e with 2 (Table 2). All of these products
were isolated by column chromatography on silica gel and
preparative HPLC. In these photoreactions, Phen was
recovered almost quantitatively. The structures of these
photoproducts were determined by their spectral proper-
ties, and some of them were determined by X-ray crystal-
lographic analyses.
(9) (a) Oku, A.; Takahashi, H.; Asmus, S. M. J . Am. Chem. Soc. 2000,
122, 7388. (b) Oku, A.; Yamauchi, Y.; Schroeder, M. Chem. Lett. 2001,
1194.
(10) Fukuzumi, S.; Satoh, N.; Okamoto, T.; Yasui, K.; Suenobu, T.;
Seko, Y.; Fujitsuka, M.; Ito, O. J . Am. Chem. Soc. 2001, 123, 7756.
(11) Kusukawa, T.; Ando, W. Organometallics 1997, 16, 4027.
(12) (a) Wakahara, T.; Kondo, T.; Okamura, M.; Akasaka, T.;
Hamada, Y.; Suzuki, T.; Kako, M.; Nakadaira, Y. J . Organomet. Chem.
2000, 611, 78. (b) Maeda, Y.; Sato, R.; Wakahara, T.; Okamura, M.;
Akasaka, T.; Fujitsuka, M.; Ito, O.; Kobayashi, K.; Nagase, S.; Kako,
M.; Nakadaira, Y.; Horn, E. J . Organomet. Chem. 2000, 611, 414. (c)
Kako, M.; Nakadaira, Y. Bull. Chem. Soc. J pn. 2000, 73, 2403.
(13) (a) Kobayashi, T.; Shimura, H.; Mitani, S.; Mashimo, S.; Amano,
A.; Takano, T.; Abe, M.; Watanabe, H.; Kijima, M.; Shirakawa, H.;
Yamaguchi, H. Angew. Chem., Int. Ed. 2000, 39, 3110. (b) Wakahara,
T.; Matsunaga, Y.; Katayama, A.; Maeda, Y.; Kako, M.; Akasaka, T.;
Okamura, M.; Kato, T.; Choe, Y.-K.; Kobayashi, K.; Nagase, S.; Huang,
H. J .; Ata, M. Chem. Commun. 2003, 2940.
(14) (a) Cossy, J .; Pete, J . P. In Advances in Electron-Transfer
Chemistry; Mariano, P. S., Ed.; J AI Press: New York, 1996; Vol. 5, pp
141-195. (b) Xu, W.; Zhang, X.-M.; Mariano, P. S. J . Am. Chem. Soc.
1991, 113, 8863. (c) Pandey, G.; Reddy, G. D.; Chakrabarti, D. J . Chem.
Soc., Perkin Trans. 1 1996, 219. (d) Hintz, S.; Fro¨hlich, R.; Mattay, J .
Tetrahedron Lett. 1996, 37, 7349. (e) Ackermann, L.; Heidbreder, A.;
Wurche, F.; Kla¨rner, F. G.; Mattay, J . J . Chem. Soc., Perkin Trans. 2
1999, 863. (f) Heinemann, C.; Demuth, M. J . Am. Chem. Soc. 1999,
121, 4894.
Ster eoch em istr y of P h otop r od u cts 4, 5, a n d 6. The
stereochemistry of some selected photoproducts has been
determined by X-ray crystallographic analyses. Single
crystals of tr a n s-6a , tr a n s-6b, cis-6c, exo-6d , and exo-
6e were obtained by slow evaporation of the methanol
solutions. ORTEP drawings and crystallographic data are
shown in Supporting Information. We decided the cis/
trans and endo/exo ratios of products on the basis of the
results, which are summarized in Table 2. The stereo-
chemistry of the reduction products 3a -e was deter-
mined by comparison with the authentic samples after
conversion into the benzylated products 6. Treatment of
3a -e with NaH followed by the reaction with benzyl
bromide in THF afforded 6a -e in high yields. The
stereochemistry of 4a -e as shown in Table 1 was
determined in a similar manner.
(15) (a) Abe, M.; Ikeda, M.; Shirodai, Y.; Nojima, M. Tetrahedron
Lett. 1996, 37, 5901. (b) Griesbeck, A. G.; Hundertmark, T.; Steinw-
ascher, J . Tetrahedron Lett. 1996, 37, 8367. (c) Bertrand, S.; Hoffmann,
N.; Humbel, S.; Pete, J . P. J . Org. Chem. 2000, 65, 8690.
4998 J . Org. Chem., Vol. 69, No. 15, 2004

Diastereoselective Protonation in PET Reactions
SCHEME 1
P h otoa llyla tion in th e P r esen ce of 2,4,6-Tr im eth -
ylp yr id in iu m Tosyla te 7. 2,4,6-Trimethylpyridinium
tosylate (7) can be used as an excellent proton source for
diastereoselective photoallylation. The results of these
photoreactions are summarized in Table 3.16 Compared
with the results in Tables 1 and 2, the diastereomeric
ratios were substantially changed. In the cases of 1a and
1b, the photoallylation in the presence of 7 proceeded
more stereoselectively (runs 1 and 2), but the photore-
action of 1c afforded the reverse selectivity (run 3). In
the photoreaction of 1e (run 5), not only did the diaste-
reoselectivity of 3e and 4e decrease from 78:22 to 60:40
and 82:18 to 60:40, respectively, but also the chemical
yield of this photoreaction was decreased.
Mech a n ism . Recently, we have reported a simple
mechanism for the photoallylation of alkylidenepropane-
dinitriles depending on pKa values of additives.5g The
photoreaction proceeded via the Phen-sensitized electron
transfer (redox photosensitization) as shown in Scheme
2.5,17 The primary step is generation of the radical cation
(16) The product ratios of these photoreactions were dependent on
the pKa values of the additives. Lower acidity of 2,4,6-trimethylpyri-
dinium tosylate (7) compared with that of acetic acid increased the
ratio of 3/4. A pathway in which 1-• abstracts allylic hydrogen of 1
may be included when 7 was used as a proton source. See ref 5g.
J . Org. Chem, Vol. 69, No. 15, 2004 4999

Hayamizu et al.
SCHEME 2
TABLE 2. Dia ster eoselective P h otor ed u ction a n d
P h otoben zyla tion of 1 in th e P r esen ce of 5 a n d Acetic
Acid a
TABLE 3. Dia ster eoselective P h otoa llyla tion a n d
P h otor ed u ction of 1 in th e P r esen ce of 2 a n d 7a
run
substrate
products
yieldsb/% (ratios)c,d
1
2
3
4
5
1a
1b
1c
1d
1e
3a 4a
3b 4b
3c 4c
3d 4d
3e 4e
55 (83:17)
22 (79:21)
18 (5:95)
16 (40:60)
16 (86:14)f
3 (60:40)f
57 (5:95)
58 (42:58)e
58 (84:16)f
18 (60:40)e,f
a
Irradiation was carried out at room temperature for 8 h. [1]
) 0.085 M, [2] ) 0.255 M, [Phen] ) 0.018 M, [7] ) 0.170 M.
b
d
Isolated yields of two isomers. c Determined by GC-MS. cis/
trans ratio. e Determined by 1H NMR. f endo/exo ratio.
This is evidently supported by the formation of 3(d1) and
4(d1) when acetic acid-d1 is used as the proton source.5g
Diastereoselectivity in the photoreaction should appear
in this step; then the major pathway is the radical
coupling of 8 with the allyl radical to give 4. The minor
pathway is the hydrogen abstraction of 8 or an electron
transfer from 1-• to 8 followed by the protonation to give
3.
The diastereoselectivity in the PET reactions of alky-
lidenepropanedinitriles summarized in Tables 1-3 can
be reasonably explained by steric and torsional effects.
The mechanisms of the protonation on the radical anions
of cyclohexylidenepropanedinitriles and bicyclo[2.2.1]-
heptylidenepropanedinitriles are shown in Schemes 3-7.
In the case of 1a , both the steric and torsional effects
were not critical for the diastereoselective protonation
of the radical anion of 1a when acetic acid was used as
the proton source. However, the use of sterically hindered
proton source 7 resulted in higher diastereoselectivity as
a result of the stereoselective equatorial attack of the
a
Irradiation was carried out at room temperature for 8 h. [1]
) 0.085 M, [5] ) 0.255 M, [Phen] ) 0.018 M, [MeCO2H] ) 0.170
M. b Isolated yields of two isomers. c Determined by GC-MS. cis/
d
trans ratio. e Determined by 1H NMR. f endo/exo ratio.
of Phen (Phen+•) and the radical anion of 1 (1-•) through
a one-electron transfer from the excited singlet state of
Phen (1Phen*) to 1. The secondary electron transfer from
2 to Phen+• produces the radical cation of 2 (2+•), which
gives the allyl radical via the nucleophile-assisted cleav-
age of the C-Si bond.7 In the presence of a proton source,
the protonation at the â position to the cyano group of
(17) (a) Majima, T.; Pac, C.; Sakurai, H. J . Am. Chem. Soc. 1980,
102, 5265. (b) Majima, T.; Pac, C.; Nakasone, A.; Sakurai, H. J . Am.
Chem. Soc. 1981, 103, 4499.
1
-• predominantly takes place to generate the radical 8.16
5000 J . Org. Chem., Vol. 69, No. 15, 2004

Diastereoselective Protonation in PET Reactions
SCHEME 3
a small proton source. In the photoreaction of 1d , the
diastereomeric ratios in the presence of acetic acid were
almost the same as those in the presence of 7. However,
the exo attack of the protons to the methylated norbornyl
derivative 1e was slightly suppressed because of steric
repulsion between the methyl group and the proton
source. This repulsion also caused the lowering of the
yield.
Con clu sion
The stereoselective photoallylation and benzylation of
alkylidenepropanedinitriles (1a -e) effectively took place
by use of 2 and 5 in the presence of Phen via the PET
process. Highly diastereoselective protonation on the
radical anions was achieved in some cases. The diaster-
eomeric ratios of these photoreactions were changed
depending on the proton source. In this type of PET
reactions we have suggested that the diastereoselectivity
can be controlled by two factors, the steric and torsinal
effects.
SCHEME 4
Exp er im en ta l Section
P r ep a r a tion of 1a -e. A mixture of a corresponding ketone,
malononitrile, and â-alanine in H2O was refluxed for 8-12 h.
The reaction was monitered by TLC. The cooled reaction
mixture was extracted with Et2O. The organic layer was dried
over MgSO4 and concentrated in a vacuum. The organic
residue was purified by column chromatography or Kugelrohr
distillation. The product was recrystallized or redistillated
before use for the photoreaction. Substrate 1e was synthesized
according to a literature procedure.18
4-ter t-Bu tylcycloh exyliden epr opan edin itr ile (1a).19 This
compound was prepared from 4-tert-butylcyclohexanone (8.00
g, 52 mmol), malononitrile (3.44 g, 52 mmol), â-alanine (0.01
g), and H2O (10 mL) in a 82% yield (8.70 g) according to the
general procedure: mp 87-88 °C; IR (KBr) 2955, 2228, 1592,
1479, 1465, 1437, 1424, 1393, 1366, 1177, 1152, 1091, 1016,
998, 928, 911, 825, 770, 706 cm-1; 1H NMR (300 MHz, CDCl3)
δ 0.89 (s, 9H), 1.25-1.38 (m, 3H), 2.11-2.16 (m, 2H), 2.25-
2.35 (m, 2H), 3.07-3.13 (m, 2H); 13C NMR (75 MHz, CDCl3) δ
27.5, 28.9, 32.7, 34.7, 46.9, 82.3, 111.6, 184.9; GC-MS (EI)
m/z ) 57, 79, 91, 104, 131, 145, 159, 187, 202 (M+).
3,3,5-Tr im eth ylcycloh exyliden epr opan edin itr ile (1b).20
This compound was prepared from 3,3,5-trimethylcyclohex-
anone (3.50 g, 25 mmol), malononitrile (1.65 g, 25 mmol),
â-alanine (0.01 g), and H2O (5 mL) in a 72% yield (3.39 g)
according to the general procedure: oil; IR (KBr) 2958, 28867,
2230, 1709, 1597, 1458, 1390, 1369, 1334, 1259, 1227, 1169,
1012, 979 cm-1; 1H NMR (300 MHz, CDCl3) δ 0.87 (s, 3H), 1.06
(d, 3H, J ) 6.0 Hz), 1.11 (s, 3H), 1.18 (d, 1H, J ) 11.9 Hz),
1.54-1.59 (m, 1H), 1.77-1.88 (m, 2H), 2.080 (d, 1H, J ) 13.0
Hz), 2.71-2.73 (m, 1H), 2.97-3.02 (m, 1H); 13C NMR (75 MHz,
CDCl3) δ 22.2, 25.0, 31.2, 31.9, 36.8, 42.4, 47.1, 47.3, 83.2,
111.66, 111.73, 183.3; GC-MS (EI) m/z ) 41, 55, 65, 77, 83,
91, 104, 119, 131, 145, 159, 173, 188 (M+).
proton based on the steric repulsion between 7 and two
axial hydrogens at the 3 and 5 positions. Consequently,
the cis/trans ratios of 3a and 4a increased to 83:17 and
79:21, respectively (Scheme 3).
In the case of 1b having an axial methyl group at the
3 position, the effect of the steric repulsion was much
larger than that of 1a , even if acetic acid was used. The
higher diastereoselective photoreaction was achieved
when 7 was used (Scheme 4).
A methyl group at the 2 position of cyclohexylidenepro-
panedinitrile in the case of 1c plays a different role in
the determination of the diastereomeric ratio in this
photoreaction. When a small proton source was used, a
torsional effect as shown in Scheme 5 predominantly
controlled the stereochemistry of the photoproducts 3c,
4c, and 6c. However, the torsional effect was not impor-
tant when a larger proton source such as 7 was used.
The protonation on the radical anions of norbornyl
derivatives 1d ,e is mainly controlled by torsional effects
as shown in Schemes 6 and 7. High diastereoselectivity
was achieved in both of the substrates in the presence of
2-Meth ylcycloh exylid en ep r op a n ed in itr ile (1c).19 This
compound was prepared from 2-methylcyclohexanone (5.05 g,
45 mmol), malononitrile (2.97 g, 45 mmol), â-alanine (0.01 g),
and H2O (5 mL) in a 73% yield (5.24 g) according to the general
procedure: oil; IR (KBr) 2942, 2866, 2230, 1590, 1461, 1360,
1028, 982, 957 cm-1 1H NMR (300 MHz, CDCl3) δ 1.26 (d,
;
(18) Lalk, M.; Peseke, K.; Reinke, H. J . Prakt. Chem. 1999, 341,
552.
(19) Leitich, J .; Ritter-Thomas, U.; Heise, I.; Tsay, Y. H.; Rust, J .
J . Photochem. Photobiol. A 2002, 147, 157 and references therein.
(20) Clarke, N. C.; Runciman, P. J . I.; Utley, J . H. P.; Landquist, J .
K. J . Chem. Soc., Perkin Trans. 2 1987, 435.
J . Org. Chem, Vol. 69, No. 15, 2004 5001

Hayamizu et al.
SCHEME 5
SCHEME 6
SCHEME 7
3H, J ) 7.1 Hz), 1.38-1.83 (m, 5H), 2.03-2.11 (m, 1H), 2.39-
2.50 (m, 1H), 2.87-2.95 (m, 1H), 3.27-3.30 (m, 1H); 13C NMR
(75 MHz, CDCl3) δ 18.6, 19.5, 27.8, 30.6, 33.2, 36.9, 82.1, 111.4,
111.7, 189.1; GC-MS (EI) m/z ) 41, 55, 69, 91, 105, 118, 132,
145, 159, 160 (M+).
2 or 5 (1.75 mmol) in the presence of phenanthrene (25 mg,
0.14 mmol) was irradiated at ambient temperature with a 300
W high-pressure mercury arc lamp in
a merry-go-round
apparatus through a Pyrex filter under argon atmosphere. The
progress of the photoreaction was followed by estimating the
amounts of 1 with GC. After 8 h (>90% consumption of 1,
except for the photoreaction of 1e with 7) the solvent was
removed under reduced pressure, and the residue was ana-
lyzed by GC-MS and 1H NMR. The photoproducts were
isolated by column chromatography on silica gel and HPLC.
cis-3a : mp 84-85 °C; IR (KBr) 2947, 2912, 2867, 2259, 1475,
Bicyclo[2.2.1]h ept-2-yliden epr opan edin itr ile (1d).19 This
compound was prepared from bicyclo[2.2.1]heptan-2-one (3.30
g, 30 mmol), malononitrile (2.00 g, 30 mmol), â-alanine (0.01
g), and H2O (5 mL) in a 75% yield (3.56 g) according to the
general procedure: oil; IR (KBr) 2977, 2882, 2233, 1618, 1452,
1413, 1310, 1288, 1078, 960, 915, 844 cm-1; 1H NMR (300 MHz,
CDCl3) δ 1.30-1.44 (m, 2H), 1.56-1.64 (m, 2H), 1.71-1.85 (m,
1H), 1.92-2.05 (m, 1H), 2.36-2.47 (m, 1H), 2.52-2.60 (m, 1H),
2.65-2.67 (m, 1H), 3.46 (br d, 1H J ) 4.6 Hz); 13C NMR (75
MHz, CDCl3) δ 26.8, 27.8, 36.5, 39.8, 41.6, 47.5, 78.5, 111.6,
192.9; GC-MS (EI) m/z ) 44, 67, 80, 92, 104, 119, 130, 143,
157, 158 (M+).
1458, 1368, 1239, 1178 cm-1 1H NMR (300 MHz, CDCl3) δ
;
0.86 (s, 9H), 0.89-1.14 (m, 3H), 1.61-1.78 (m, 4H), 2.04-2.09
(m, 2H), 2.42-2.47 (m, 1H), 3.82 (d, 1H, J ) 11.5 Hz); 13C NMR
(75 MHz, CDCl3) δ 21.1, 24.4, 27.3, 27.9, 35.7, 39.5, 47.5, 112.5;
GC-MS (EI) m/z ) 57, 81, 95, 123, 148, 189; HRMS (EI) calcd
for C13H20N2 (M+) 204.1626, found 204.1629.
P h otor ea ction of 1. An acetonitrile solution (8 mL)
containing the proton source (1.36 mmol), the alkylidenepro-
panedinitriles 1 (0.68 mmol), and the organosilicon compound
tr a n s-3a : mp 86-87 °C; IR (KBr) 2950, 2909, 2866, 2255,
1447, 1364, 1238, 1184 cm-1 1H NMR (300 MHz, CDCl3) δ
;
0.86 (s, 9H), 0.89-1.16 (m, 3H), 1.24-1.35 (m, 2H), 1.88-1.96
5002 J . Org. Chem., Vol. 69, No. 15, 2004

Diastereoselective Protonation in PET Reactions
(m, 3H), 2.03-2.08 (m, 2H), 3.56 (d, 1H, J ) 5.9 Hz); 13C NMR
(75 MHz, CDCl3) δ 26.4, 27.5, 29.3, 30.5, 32.4, 39.6, 47.0, 111.9;
GC-MS (EI) m/z ) 57, 81, 95, 123, 148, 189; HRMS (EI) calcd
for C13H20N2 (M+) 204.1626, found 204.1623.
cis-4a : oil; IR (KBr) 2245 cm-1; 1H NMR (300 MHz, CDCl3)
δ 0.89 (s, 9H), 1.15-1.25 (m, 1H), 1.56-1.70 (m, 4H), 1.72-
1.93 (m, 4H), 1.97-2.06 (m, 1H), 2.70 (d, 2H, J ) 7.1 Hz),
5.36-5.43 (m, 2H), 5.84-5.98(m, 1H); 13C NMR (75 MHz,
CDCl3) δ 22.2, 25.8, 27.7, 33.0, 39.1, 40.2, 41.7, 43.9, 115.5,
122.7, 128.8; GC-MS (EI): m/z ) 41, 57, 81, 97, 121, 148, 160,
178, 201, 229, 244 (M+); HRMS (EI) calcd for C16H24N2 (M+)
244.1941, found 244.1939.
tr a n s-4a : IR (KBr) 2246 cm-1; 1H NMR (300 MHz, CDCl3)
δ 0.86 (s, 9H), 0.97-1.13 (m, 3H), 1.29-1.42 (m, 2H), 1.76 (tt,
1H, J ) 3.5, 12.1 Hz), 1.92-2.01 (m, 2H), 2.05-2.17 (m, 2H),
2.68 (d, 2H, J ) 7.1 Hz), 5.34-5.43 (m, 2H), 5.83-5.97(m, 1H);
13C NMR (75 MHz, CDCl3) δ 26.5, 27.5, 28.7, 32.4, 39.0, 43.0,
43.2, 47.2, 114.7, 122.6, 128.8; GC-MS (EI): m/z ) 41, 57,
81, 97, 121, 148, 160, 178, 201, 229, 244 (M+).
cis-3c: oil; IR (KBr) 2936, 2862, 2253, 1716, 1469, 1448,
1
1388 cm-1; H NMR (300 MHz, CDCl3) δ 0.96 (d, 3H, J ) 7.1
Hz), 1.25-1.62 (m, 5H), 1.66-1.73 (m, 1H), 1.84 (br d, 2H, J
) 12.5 Hz), 2.14-2.22 (m, 1H), 2.26-2.32 (m, 1H), 3.45 (d,
1H, J ) 10.3 Hz); 13C NMR (75 MHz, CDCl3) δ 12.0, 19.5, 24.8,
25.7, 27.3, 29.8, 32.7, 42.4, 111.9, 112.4; GC-MS (EI) m/z )
41, 55, 70, 81, 97, 108, 120, 134, 147, 161, 162 (M+); HRMS
(CI) calcd for C10H15N2 (M+H) 163.1217, found 163.1226.
tr a n s-3c: oil; IR (KBr) 2930, 2859, 2253, 1717, 1465, 1448,
1
1385 cm-1; H NMR (300 MHz, CDCl3) δ 0.99 (d, 3H, J ) 6.2
Hz), 1.03-1.19 (m, 1H), 1.25-1.68 (m, 5H), 1.72-1.91 (m, 3H),
2.05-2.11 (m, 1H), 3.99 (d, 1H, J ) 3.5 Hz); 13C NMR (75 MHz,
CDCl3) δ 19.7, 25.6, 25.6, 26.8, 29.1, 34.6, 34.8, 45.8, 111.2,
112.5; GC-MS (EI) m/z ) 41, 55, 69, 81, 97, 108, 120, 134,
147, 161, 162 (M+).
cis-4c: oil; IR (KBr) 3086, 2940, 2858, 2245, 1644, 1447,
1389, 1313, 1265, 1161, 991, 933, 860, 735 cm-1; 1H NMR (300
MHz, CDCl3) δ 1.16 (d, 3H, J ) 7.1 Hz), 1.20-1.40 (m, 1H),
1.42-1.57 (m, 3H), 1.59-1.78 (m, 3H), 1.87-1.97 (m, 2H),
2.30-2.38 (m, 1H), 2.64 (dd, 1H, J ) 7.0, 13.9 Hz), 2.76 (dd,
1H, J ) 7.0, 13.9 Hz), 5.29-5.70(m, 2H), 5.86-6.20 (m, 1H);
13C NMR (75 MHz, CDCl3) δ 13.0, 19.6, 22.9, 26.3, 30.5, 34.0,
40.3, 41.3, 46.0, 114.6, 115.3, 122.8, 128.9; GC-MS (EI) m/z
) 41, 55, 69, 97, 120, 134, 145, 160, 173, 187, 202 (M+); HRMS
(CI) calcd for C13H19N2 (M + H) 203.1549, found 203.1551.
cis-6c: mp 120-121.5 °C; IR (KBr) 3031, 2943, 2902, 2866,
2245, 1453, 1388, 863, 777, 704, 669 cm-1; 1H NMR (300 MHz,
CDCl3) δ 1.19 (d, 3H, J ) 7.1 Hz), 1.23-1.40 (m, 1H), 1.44-
1.58 (m, 3H), 1.62-2.00 (m, 5H), 2.37-2.41 (m, 1H), 3.15 (d,
1H, J ) 13.6 Hz), 3.26 (d, 1H, J ) 13.6 Hz), 7.33-7.46 (m,
5H); 13C NMR (75 MHz, CDCl3) δ 13.1, 19.7, 23.0, 26.3, 30.8,
34.1, 42.0, 43.3, 46.5, 114.5, 115.3, 128.6, 128.8, 130.2, 132.3;
GC-MS (EI) m/z ) 41, 55, 65, 77, 91, 97, 115, 128, 140, 154,
167, 182, 196, 210, 224, 252 (M+); HRMS (CI) calcd for
cis-6a : oil; IR (KBr) 3033, 2954, 2246, 1604, 1458, 1365,
1240, 1178, 1086, 1031, 765, 700 cm-1 1H NMR (300 MHz,
;
CDCl3) δ 0.89 (s, 9H), 1.19-1.25 (m, 3H), 1.56-1.75 (m, 4H),
1.79-2.09 (m, 4H), 3.20 (s, 2H), 7.37-7.42 (m, 5H); 13C NMR
(75 MHz, CDCl3) δ 21.1, 22.1, 25.8, 27.6, 32.9, 39.5, 41.5, 43.6,
115.4, 128.4, 128.7, 130.0, 132.2; GC-MS (EI) m/z ) 57, 78,
91, 108, 130, 147, 161, 183, 196, 210, 238, 279, 294 (M+);
HRMS (EI) calcd for C20H26N2 (M+) 294.2096, found 294.2089.
tr a n s-6a : mp 121.5-122.5 °C; IR (KBr) 3029, 2962, 2941,
2862, 2251, 1478, 1451, 1365, 1258, 1236, 1086, 768, 707 cm-1
;
1H NMR (300 MHz, CDCl3) δ 0.87 (s, 9H), 0.99-1.11 (m, 3H),
1.39-1.50 (m, 2H), 1.74-1.87 (m, 1H), 1.95-1.98 (m, 2H),
2.16-2.21 (m, 2H), 3.18 (s, 2H), 7.37-7.42 (m, 5H); 13C NMR
(75 MHz, CDCl3) δ 26.5, 27.4, 28.9, 32.3, 40.5, 43.7, 45.0, 47.1,
114.6, 128.4, 128.7, 129.9, 132.3; GC-MS (EI) m/z ) 57, 78,
91, 108, 130, 147, 161, 183, 196, 210, 238, 279, 294 (M+);
HRMS (EI) calcd for C20H26N2 (M+) 294.2096, found 294.2099.
C
17H21N2 (M + H) 253.1705, found 253.1709.
1
en d o-3d : IR (KBr) 2253 cm-1; H NMR (300 MHz, CDCl3)
δ 0.92 (ddd, 1H, J ) 2.1, 4.7, 10.9 Hz), 1.16-1.25 (m, 1H),
1.33-1.71 (m, 5H), 1.97-2.07 (m, 1H), 2.35 (br t, 1H, J ) 4.2
Hz), 2.47-2.58 (m, 2H), 3.49 (d, 1H, J ) 10.9 Hz); 13C NMR
(75 MHz, CDCl3) δ 22.4, 25.3, 29.5, 35.3, 37.1, 39.4, 39.5, 42.1,
112.2, 112.9; GC-MS (EI) m/z ) 41, 67, 95, 106, 119, 132, 145,
159; HRMS (EI) calcd for C10H12N2 (M+) 160.1006, found
160.1000.
tr a n s-3b: oil; IR (KBr) 2954, 2909, 2254, 1460, 1384, 1367,
1314, 1253, 1184, 1145, 999, 863 cm-1 1H NMR (300 MHz,
;
CDCl3) δ 0.97 (s, 3H), 1.01 (s, 3H), 1.04 (d, 3H, J ) 7.1 Hz),
1.17 (dd, 1H, J ) 6.4, 13.8 Hz), 1.34-1.45 (m, 2H), 1.51-1.66
(m, 3H), 1.81-2.01 (m, 1H), 2.31-2.42 (m, 1H), 3.69 (d, 1H, J
) 7.7 Hz); 13C NMR (75 MHz, CDCl3) δ 21.5, 26.0, 28.8, 30.3,
31.0, 31.8, 33.7, 35.4, 41.4, 44.8, 112.1, 112.2; GC-MS (EI)
m/z ) 41, 55, 69, 83, 109, 119, 133, 148, 175, 189; HRMS (EI)
calcd for C12H18N2 (M+) 190.1470, found 190.1472.
en d o-4d : oil; IR (KBr) 2245, 1643 cm-1; 1H NMR (300 MHz,
CDCl3) δ 1.25 (dd, 1H, J ) 5.6, 12.8 Hz), 1.41 (br s, 2H), 1.42-
1.71 (m, 3H), 1.83-1.97 (m, 1H), 1.99-2.04 (m, 1H), 2.21-
2.29 (m, 1H), 2.37 (br t, 1H, J ) 4.4 Hz), 2.54 (br s, 1H), 2.56-
2.72 (m, 2H), 5.35-5.43 (m, 2H), 5.84-5.98 (m, 1H); 13C NMR
(75 MHz, CDCl3) δ 23.3, 28.8, 32.9, 37.3, 39.6, 40.4, 40.6, 42.5,
46.4, 114.9, 115.1, 122.7, 128.8; GC-MS (EI) m/z ) 41, 67,
95, 107, 118, 132, 146, 159, 172, 185, 199, 200 (M+); HRMS
(EI) calcd for C13H16N2 (M+) 200.1317, found 200.1313.
en d o-6d : mp 118.5-119.5 °C; IR (KBr) 3035, 2966, 2914,
2873, 2244, 1457 cm-1; 1H NMR (300 MHz, CDCl3) δ 1.30 (dd,
1H, J ) 5.5, 12.8 Hz), 1.41 (br s, 2H), 1.43-1.69 (m, 3H), 1.84-
1.95 (m, 1H), 1.99-2.08 (m, 1H), 2.26-2.34 (m, 1H), 2.39 (br
t, 1H, J ) 4.0 Hz), 2.57 (br s 1H), 3.13 (d, 1H, J ) 13.7 Hz),
3.19 (d, 1H, J ) 13.6 Hz), 7.32-7.43 (m, 5H); 13C NMR (75
MHz, CDCl3) δ 23.4, 28.8, 33.0, 37.4, 40.4, 40.9, 41.4, 44.1,
46.7, 115.0, 115.2, 128.6, 128.8, 130.1, 132.1; GC-MS (EI) m/z
) 41, 51, 65, 71, 91, 115, 128, 140, 154, 180, 195, 222, 250
(M+); HRMS (EI) calcd for C17H18N2 (M+) 250.1470, found
250.1464.
tr a n s-4b: oil; IR (KBr) 3087, 2954, 2929, 2247, 1645, 1461,
1384, 1367, 1295, 991, 934, 862, 732 cm-1; 1H NMR (300 MHz,
CDCl3) δ 0.98 (s, 3H), 1.01 (s, 3H), 1.05 (d, 3H, J ) 7.3 Hz),
1.20-1.29 (m, 2H), 1.34-1.43 (m, 1H), 1.44-1.71 (m, 3H),
2.06-2.17 (m, 2H), 2.70 (d, 1H, J ) 7.3 Hz), 5.37-5.45 (m,
2H), 5.83-5.97 (m, 1H); 13C NMR (75 MHz, CDCl3) δ 21.4,
27.0, 28.7, 31.1, 33.6, 33.8, 36.0, 39.0, 40.5, 43.1, 43.8, 114.7,
114.8, 122.7, 128.7; GC-MS (EI) m/z ) 41, 55, 69, 83, 109,
123, 125, 148, 159, 173, 189, 215, 229, 230 (M+); HRMS (EI)
calcd for C15H22N2 (M+) 230.1783, found 230.1776.
1
cis-6b: H NMR (300 MHz, CDCl3) δ 0.92 (s, 3H), 0.96 (d,
3H, J ) 6.4 Hz), 1.02 (s, 3H), 1.22-1.28 (m, 2H), 1.41-1.46
(m, 1H), 1.72-2.78 (m, 2H), 2.02-2.10 (m, 2H), 3.19 (s, 2H),
7.37-7.40 (m, 5H); 13C NMR (75 MHz, CDCl3) δ 22.4, 25.3,
27.8, 31.7, 32.9, 36.9, 40.4, 40.7, 40.5, 43.7, 47.3, 114.7, 128.5,
128.7, 130.0, 132.3; GC-MS (EI) m/z ) 55, 69, 91, 109, 128,
148, 167, 265, 280 (M+).
tr a n s-6b: mp 115-116 °C; IR (KBr) 3033, 2953, 2902, 2248,
1497, 1457, 1383, 1087, 766, 702, 669 cm-1; 1H NMR (300 MHz,
CDCl3) δ 1.00 (s, 3H), 1.01 (s, 3H), 1.06 (d, 3H, J ) 7.3 Hz),
1.231-1.55 (m, 3H), 1.57-1.68 (m, 1H), 1.72-1.80 (m, 2H),
2.09-2.20 (m, 2H), 3.20 (s, 2H), 7.38-7.42 (m, 5H); 13C NMR
(75 MHz, CDCl3) δ 21.4, 27.0, 28.7, 31.1, 33.5, 33.9, 36.7, 40.5,
40.6, 43.7, 45.2, 114.6, 114.7, 128.5, 128.7, 130.0, 132.2; GC-
MS (EI) m/z ) 55, 69, 91, 109, 128, 148, 167, 265, 280 (M+);
HRMS (EI) calcd for C19H24N2 (M+) 280.1939, found 280.1936.
exo-6d : mp 139.0-140.0 °C; IR (KBr) 3034, 2961, 2919,
1
2873, 2244, 1458 cm-1; H NMR (300 MHz, CDCl3) δ 1.19-
1.29 (m, 3H), 1.59-1.66 (m, 3H), 1.69-1.77 (m, 1H), 1.87-
1.95 (m, 2H), 2.43 (br s, 1H), 2.54 (br s, 1H), 3.14 (s, 2H), 7.34-
7.42 (m, 5H); 13C NMR (75 MHz, CDCl3) δ 27.6, 31.3, 35.8,
35.9, 36.5, 39.7, 42.2, 43.6, 48.4, 115.0, 115.5, 128.5, 128.8,
130.1, 132.0; GC-MS (EI) m/z ) 41, 51, 65, 77, 91, 115, 128,
140, 155, 168, 195, 250 (M+); HRMS (EI) calcd for C17H18N2
(M+) 250.1470, found 250.1480.
J . Org. Chem, Vol. 69, No. 15, 2004 5003

Hayamizu et al.
1
en d o-3e: mp 77.5-78.5 °C; IR (KBr) 2251 cm-1; H NMR
For tr a n s-6a , a sweep of data was done using ω scans from
130.0 to 190.0° in 5.0° steps, at ø ) 45.0° and φ ) 0.0°. The
exposure rate was 300.0 s/deg. A second sweep was performed
using ω scans from 0.0 to 160.0° in 5.0° steps, at ø ) 45.0°
and φ ) 180.0°. The exposure rate was 300.0 s/deg. The
maximum and minimum peaks on the final difference Fourier
map corresponded to 0.95 and -0.47 e-/Å3, respectively. The
structure was solved by direct methods (SIR92)24 and expanded
using Fourier techniques.21 The crystal structure was refined
by full-matrix least-squares on F.
(300 MHz, CDCl3) δ 0.91 (s, 3H), 0.92 (s, 3H), 1.02-1.11 (m,
1H), 1.05 (s, 3H), 1.14-1.25 (m, 1H), 1.35-1.44 (m, 1H), 1.50-
1.61 (m, 1H), 1.73-1.89 (m, 2H), 2.17-2.35 (m, 1H), 2.38-
2.47 (m, 1H), 3.60 (d, 1H, J ) 9.5 Hz); 13C NMR (75 MHz,
CDCl3) δ 14.5, 18.4, 19.5, 24.5, 28.1, 28.6, 35.5, 44.1, 45.4, 48.8,
50.3, 113.0, 113.2; GC-MS (EI) m/z ) 41, 55, 69, 81, 95, 110,
121, 137, 145, 159, 187, 202 (M+); HRMS (EI) calcd for
C
13H18N2 (M+) 202.1470, found 202.1466.
exo-3e: IR (KBr) 2255 cm-1; H NMR (300 MHz, CDCl3) δ
1
For tr a n s-6b, a sweep of data was done using ω scans from
130.0 to 190.0° in 5.0° steps, at ø ) 45.0° and φ ) 0.0°. The
exposure rate was 600.0 s/deg. A second sweep was performed
using ω scans from 0.0 to 160.0° in 5.0° steps, at ø ) 45.0°
and φ ) 180.0°. The exposure rate was 600.0 s/deg. The
maximum and minimum peaks on the final difference Fourier
map corresponded to 0.84 and -0.43 e-/Å3, respectively. The
structure was solved by direct methods (SIR92)24 and expanded
using Fourier techniques.21 The crystal structure was refined
by full-matrix least-squares on F2.
For cis-6c, a sweep of data was done using ω scans from
130.0 to 190.0° in 5.0° steps, at ø ) 45.0° and φ ) 0.0°. The
exposure rate was 100.2 s/deg. A second sweep was performed
using ω scans from 0.0 to 160.0° in 5.0° steps, at ø ) 45.0°
and φ ) 180.0°. The exposure rate was 100.2 s/deg. The
maximum and minimum peaks on the final difference Fourier
map corresponded to 0.36 and -0.32 e-/Å3, respectively. The
structure was solved by direct methods (SIR92)24 and expanded
using Fourier techniques.21 The crystal structure was refined
by full-matrix least-squares on F2.
For exo-6d , a sweep of data was done using ω scans from
130.0 to 190.0° in 5.0° steps, at ø ) 45.0° and φ ) 0.0°. The
exposure rate was 150.0 s/deg. A second sweep was performed
using ω scans from 0.0 to 160.0° in 5.0° steps, at ø ) 45.0°
and φ ) 180.0°. The exposure rate was 150.0 s/deg. The
maximum and minimum peaks on the final difference Fourier
map corresponded to 0.43 and -0.46 e-/Å3, respectively. The
structure was solved by direct methods (SHELX97)25 and
expanded using Fourier techniques.21 The crystal structure
was refined by full-matrix least-squares on F2.
For exo-6e, a sweep of data was done using ω scans from
130.0 to 190.0° in 5.0° steps, at ø ) 45.0° and φ ) 0.0°. The
exposure rate was 289.8 s/deg. A second sweep was performed
using ω scans from 0.0 to 160.0° in 5.0° steps, at ø ) 45.0°
and φ ) 180.0°. The exposure rate was 289.8 s/deg. The
maximum and minimum peaks on the final difference Fourier
map corresponded to 0.56 and -0.44 e-/Å3, respectively. The
structure was solved by direct methods (SIR92)24 and expanded
using Fourier techniques.21 The crystal structure was refined
by full-matrix least-squares on F2.
0.87 (s, 3H), 0.88 (s, 3H), 1.07 (s, 3H), 1.19-1.31 (m, 2H), 1.62-
1.70 (m, 1H), 1.75-1.84 (m, 4H), 2.17-2.26 (m, 1H), 3.67 (d,
1H, J ) 11.2 Hz); 13C NMR (75 MHz, CDCl3) δ 13.0, 20.1, 20.5,
26.3, 26.8, 35.5, 38.7, 44.5, 47.7, 48.10, 48.12, 112.2, 113.8;
GC-MS (EI) m/z ) 41, 55, 69, 81, 95, 110, 121, 137, 145, 159,
187, 202 (M+).
en d o-4e: oil; IR (KBr) 2245 cm-1 1H NMR (300 MHz,
;
CDCl3) δ 0.87 (s, 3H), 0.90 (s, 3H), 1.12 (s, 3H), 1.23-1.36 (m,
1H), 1.40-1.49 (m, 1H), 1.53-1.61 (m, 1H), 1.72-1.89 (m, 2H),
1.99-2.19 (m, 3H), 2.55-2.62 (m, 1H), 2.71-2.79 (m, 1H),
5.35-5.44 (m, 2H), 5.86-6.00 (m, 1H); 13C NMR (75 MHz,
CDCl3) δ 15.2, 18.2, 19.1, 27.5, 29.0, 33.3, 38.7, 43.7, 43.9, 49.3,
49.6, 51.2, 115.3, 115.8, 122.9, 128.7; GC-MS (EI) m/z ) 41,
55, 69, 81, 95, 110, 137, 159, 171, 199, 213, 227, 242 (M+);
HRMS (EI) calcd for C16H22N2 (M+) 242.1783, found 242.1787.
en d o-6e: mp 79.5-81 °C; IR (KBr) 2244 cm-1; 1H NMR (300
MHz, CDCl3) δ 0.86 (s, 3H), 0.91 (s, 3H), 1.10 (s, 3H), 1.41 (d,
1H, J ) 7.9 Hz), 1.48-1.62 (m, 2H), 1.75-1.89 (m, 2H), 2.02-
2.26 (m, 3H), 3.12 (d, 1H, J ) 13.6 Hz), 3.26 (d, 1H, J ) 13.6
Hz), 7.33-7.42 (m, 5H); 13C NMR (75 MHz, CDCl3) δ 15.2, 18.2,
19.1, 27.5, 29.0, 33.6, 40.4, 43.8, 45.3, 49.4, 49.8, 51.2, 115.3,
115.9, 128.6, 128.7, 130.3, 131.9; GC-MS (EI) m/z ) 41, 55,
81, 91, 95, 110, 137, 155, 185, 250, 277, 292 (M+); HRMS (EI)
calcd for C20H24N2 (M+) 292.1939, found 292.1941.
exo-6e: mp 94-95.5 °C; IR (KBr) 2243 cm-1; 1H NMR (300
MHz, CDCl3) δ 0.92 (s, 3H), 1.14 (s, 3H), 1.22 (d, 1H, J ) 8.4
Hz), 1.30 (s, 3H), 1.65-1.78 (m, 3H), 1.79-1.89 (m, 2H), 1.94-
2.036 (m, 1H), 2.16 (t, 1H, J ) 9.0 Hz), 3.07 (d, 1H, J ) 13.5
Hz), 3.22 (d, 1H, J ) 13.5 Hz), 7.30-7.44 (m, 5H); 13C NMR
(75 MHz, CDCl3) δ 13.0, 21.4, 22.0, 26.4, 34.8, 41.0, 41.5, 43.9,
44.6, 48.2, 49.6, 55.0, 115.8, 116.5, 128.59, 128.63, 130.5, 132.0;
GC-MS (EI) m/z ) 41, 55, 81, 91, 95, 110, 137, 155, 185, 250,
277, 292 (M+); HRMS (EI) calcd for C20H24N2 (M+) 292.1939,
found 292.1946.
X-r a y Cr ysta llogr a p h ic An a lysis. A single crystal was
mounted on a glass fiber. All measurements were made on a
Rigaku RAXIS RAPID imaging plate area detector with
graphite monochromated Mo KR radiation. A total of 44
oscillation images were collected. The crystal-to-detector dis-
tance was 127.40 mm. Readout was performed in the 0.100
mm pixel mode. The data were corrected for Lorentz and
polarization effects. The structure was solved by direct meth-
ods and expanded using Fourier techniques.21 The non-
hydrogen atoms were refined anisotropically. Hydrogen atoms
were refined using the riding model. The crystal structure was
refined by full-matrix least-squares. All calculations were
performed using the CrystalStructure22,23 crystallographic
software package. Crystal data and details of the data collec-
tion are provided in Supporting Information.
Ack n ow led gm en t. We are grateful to Dr. A. Sug-
imoto (Osaka University) for the X-ray crystallographic
analyses. This work was supported by a Grant-in-Aid
for Scientific Research (B) (15350026) from the Ministry
of Education, Culture, Sports, Science and Technology
(MEXT) of J apan.
Su p p or tin g In for m a tion Ava ila ble: Copies of 1H and 13C
NMR spectra for 1a -d and the selected photoproducts and
crystallographic data for cis-3a , tr a n s-6a , tr a n s-6b, cis-6c,
exo-6d , and exo-6e in PDF and CIF format. This material is
available free of charge via the Internet at http://pubs.acs.org.
(21) DIRDIF99; Beurskens, P. T.; Admiraal, G.; Beurskens, G.;
Bosman, W. P.; de Gelder, R.; Israel, R.; Smits, J . M. M. The DIRDIF-
99 program system, Technical Report of the Crystallography Labora-
tory, University of Nijmegen, The Netherlands, 1999.
(22) CrystalStructure 3.5.1; Crystal Structure Analysis Package,
Rigaku and Rigaku/MSC; 9009 New Trails Dr., The Woodlands TX
77381, 2000-2003.
(23) CRYSTALS Issue 10; Watkin, D. J .; Prout, C. K.; Carruthers,
J . R.; Betteridge, P. W. Chemical Crystallography Laboratory, Oxford,
UK, 1996.
J O0496953
(24) SIR92: Altomare, A., Cascarano, M., Giacovazzo, C., Gua-
gliardi, A. J . Appl. Crystallogr. 1994, 26, 343.
(25) SHELX97; Sheldrick, G. M. Universita¨t Go¨ttingen, Germany,
1997.
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