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High Diastereoselectivity in Yang Photocyclization
KOREAN CHEMICAL SOCIETY
128.47, 128.4, 127.7, 127.6, 126.6, 121.0, 112.1, 69.8,
32.1, 17.4; IR (CCl4) 1680 (C O) cm−1; EI MS 328 (M+),
237, 105, 91, 77.
120.3, 116.8, 83.1, 72.2, 40.6; IR (CCl4) 3590 cm−1
(O H); EI MS 302 (M+), 133, 105, 91, 77, 57.
E-1,2-Diphenyl-2-dihydrobenzopyranol:
1H
NMR
(CDCl3, 500 MHz) δ 7.27–7.19 (m, 6H), 7.13–7.10 (m,
4H), 7.04–6.99 (m, 2H), 6.83 (d, 2H, J = 7.5 Hz), 5.21 (s,
1H), 3.49, 3.16 (AB quartet, 2H, J = 16.0 Hz), 2.51 (s, 1H,
OH); 13C NMR (CDCl3, 125 MHz) δ 153.9, 141.7, 137.0,
130.0, 128.1, 127.9, 127.8, 127.7, 127.5, 127.4, 126.4,
121.3, 120.7, 116.6, 84.8, 72.2, 36.8; IR (CCl4) 3589
(O H) cm−1; EI MS 302 (M+), 133, 105, 91, 77, 57.
Photolysis
General Procedure. The ketones (typically 0.01–0.02 M)
in benzene were irradiated with Hanovia 450 W medium
pressure lamp with a Pyrex filter. The photoproducts were
separated by either preparative TLC or column chromatog-
raphy with hexane/ethyl acetate as eluent.
For the initial observation of the photochemical changes,
NMR tube scale irradiation was used: an NMR tube con-
taining sample solution (0.01–0.02 M in 0.75 mL of deu-
terated solution) was degassed by bubbling argon through
for 10 min. The NMR tube was attached to an immersion
well by wire and irradiated.
Preparative scale irradiation was done in two different
ways: a large test tube containing sample solution
(0.01–0.02 M in 70–100 mL) was fitted with a 24/40 rub-
ber septum and the sample was degassed by bubbling argon
through for 10 min or throughout the irradiation. The test
tube was attached to an immersion well by wire and irra-
diated. For the larger scale reaction (0.01–0.02 M in
250 mL), photolysis was done in an immersion well
equipped with a quartz cooling jacket, a water cooling
condenser.
Products from α-(o-Isopropoxyphenyl)acetophenone (3).
1,1-Dimethyl-2-phenyl-2-dihydrobenzopyranol: 1H NMR
(CDCl3, 300 MHz) δ 7.65 (distorted d, 2H), 7.41–7.31 (m,
3H), 7.19 (t, 1H, J = 7.7 Hz), 7.13 (d, 1H, J = 7.4 Hz),
6.95 (t, 1H, J = 7.7 Hz), 6.94 (d, 1H, J = 7.4 Hz), 3.73,
2.84 (AB quartet, 2H, J = 17.0 Hz), 2.67 (broad s, 1H,
OH), 1.26 (s, 6H); 13C NMR (CDCl3, 75 MHz) δ 152.2,
141.8, 130.2, 127.8, 127.7, 127.3, 126.8, 121.1, 120.5,
117.5, 80.3, 73.9, 36.6, 22.6, 22.5.
1,2-Di(2-isopropoxyphenyl)ethane: 1H NMR (CDCl3,
300 MHz) δ 7.20–7.11 (m, 4H), 6.90–6.82 (m, 4H), 4.58
(septet, 2H, J = 6.2 Hz), 2.89 (s, 4H), 1.37 (d, 12H,
J = 6.2 Hz).
Products from 1-Benzoyl-1-(o-ethoxyphenyl)cyclopro-
pane (4). Z-2-Methyl-3-hydroxy-3-phenyl-4-spirocyclo-
1
propylbenzo-dihydropyran: H NMR (CDCl3, 300 MHz) δ
Products from α-(o-Ethoxyphenyl)acetophenone (1). Z-
1-Methyl-2-phenyl-2-dihydrobenzopyranol:
1H
NMR
7.46–7.28 (m, 5H), 7.15 (distorted t, 1H), 6.98–6.95 (m,
2H), 6.73 (distorted d, 1H), 4.68 (q, 1H, J = 6.3 Hz), 2.46
(broad s, 1H, OH), 1.23 (d, 3H, J = 6.3 Hz), 0.96 (m,
4H); 13C NMR (CDCl3, 75 MHz) δ 153.7, 139.6, 127.6,
127.3, 127.2, 127.0, 126.5, 123.3, 121.6, 116.7, 74.8, 26.5,
19.1, 15.6, 12.1; IR (CCl4) 3594 (O H) cm−1; EI MS
266 (M+), 251, 133, 115, 105, 91, 77.
(CDCl3, 300 MHz) δ 7.54 (distorted d, 2H), 7.41–7.30 (m,
3H), 7.21–7.12 (m, 2H), 6.95 (t, 1H), 6.92 (d, 1H), 4.34 (q,
1H, J = 6.6 Hz), 3.01, 3.58 (AB quartet, 2H, J = 16.5 Hz),
2.37 (broad s, 1H, OH), 1.07 (d, 3H, J = 6.6 Hz); 13C
NMR (CDCl3, 75 MHz) δ 151.9, 142.1, 130.2, 128.4,
127.8 (two carbons overlapping), 126.1, 121.1, 120.1,
117.2, 78.3, 71.9, 34.7, 15.5; IR (CCl4) 3590 (O H) cm−1;
EI MS 240 (M+), 151, 133, 105, 77.
Products from 1-Benzoyl-1-(o-benzyloxyphenyl)cyclo-
propane (5). Z-2,3-Diphenyl-3-hydroxy-4-spirocyclopro-
pylbenzodihydro-pyran: 1H NMR (CDCl3, 300 MHz) δ
7.26–7.14 (m, 8H), 7.01–6.96 (m, 2H), 6.78 (d, 1H,
J = 7.0 Hz), 5.53 (s, 1H), 2.52 (broad s, 1H, OH), 1.06
(m, 2H), 0.94 (m, 2H); 13C NMR (CDCl3, 75 MHz) δ
154.4, 139.4, 137.1, 129.0, 128.0, 127.7, 127.5, 127.4,
127.2, 127.0, 126.7, 123.3, 121.8, 116.8, 83.2, 75.6, 27.0,
18.7, 12.8; IR (CCl4) 3598 (O H) cm−1; EI MS 328 (M+),
249, 220, 196, 181, 165.
E-1-Methyl-2-phenyl-2-dihydrobenzopyranol: 1H NMR
(CDCl3, 300 MHz) δ 7.47 (distorted d, 2H), 7.39 (distorted
t, 2H), 7.29 (m, 1H), 7.17 (t, 1H), 7.08 (d, 1H), 6.96–6.90
(m, 2H), 4.31 (q, 1H, J = 6.4 Hz), 3.41, 2.90 (AB quartet,
2H, J = 17.0 Hz), 2.05 (broad s, 1H, OH), 1.06 (d, 3H,
J = 6.4 Hz); 13C NMR (CDCl3, 75 MHz) δ 153.7, 143.3,
132.5, 128.4, 127.6, 127.1, 125.0, 121.3, 116.7, 77.3, 71.2,
41.6, 14.7; IR (CCl4) 3584 (O H).cm−1; EI MS 240 (M+),
151, 133, 105, 77.
1,2-Di(2-ethoxyphenyl)ethane: 1H NMR (CDCl3,
300 MHz) δ 7.22–7.10 (m, 4H), 6.90–6.80 (m, 4H), 4.01
(q, 4H, J = 6.9 Hz), 2.88 (s, 4H), 1.40 (t, 6H, J = 6.9 Hz);
IR (CCl4) 1240 (C O) cm−1.
References
1. (a) G. Kuzmanich, C. S. Vogelsberg, E. F. Maverick,
J. C. Netto-Ferreira, J. C. Scaiano, M. A. Garcia-Garibay,
J. Am. Chem. Soc. 2012, 134, 1115; (b) V. Ramamurthy,
K. Venkatesan, Chem. Rev. 1987, 87, 433; (c) M. Garcia-
Garibay, Acc. Chem. Res. 2003, 36, 491; (d) J. R. Scheffer,
M. Garcia-Garibay, O. Nalamasu, In Organic Photochemistry,
Vol. 8, A. Padwa Ed., Marcel Dekker, New York, NY; Basel,
1987, p. 249; (e) M. Sakamoto, In Chiral Photochemistry,
Y. Inoue, V. Ramamurthy Eds., Marcel Dekker, New York,
NY, 2004, p. 415.
Products from α-(o-Benzyloxyphenyl)acetophenone (2).
Z-1,2-Diphenyl-2-dihydrobenzopyranol: H NMR (CDCl3,
1
500 MHz) δ 7.28–7.08 (m, 12H), 7.05 (dd, 1H J = 8.0,
1.0 Hz), 6.99 (td, 1H, J = 7.5, 1.5 Hz), 5.24 (s, 1H), 3.72,
3.04 (AB quartet, 2H, J = 16.8 Hz), 2.46 (s, 1H, OH); 13C
NMR (CDCl3, 125 MHz) δ 153.9, 142.8, 136.0, 130.2,
128.1, 128.0, 127.9, 127.8, 127.6, 127.2, 125.5, 121.4,
Bull. Korean Chem. Soc. 2016, Vol. 37, 1509–1514
© 2016 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim