K. Bast, M. Behrens, T. Durst, R. Grashey, R. Huisgen, R. Schiffer, R. Temme
81.79, H 5.95. Ϫ Mol. mass. 860, 933 (vapor-phase osmometry, in 10 ml of 90% aqueous dioxane for 15 h; 81 mg (76%) of N,NЈ-
FULL PAPER
benzene, 37°C). Ϫ Reaction with dimethyl fumarate: It proceeded
in CDCl3 in the NMR tube at room temp.; after several h, the H
diphenylurea came from benzene, m.p. 237Ϫ238°C.
1
3-(4-Chlorophenyl)-1,10b-dihydro-1-phenyl-1,2,4-triazolo[5,1-a]-
isoquinoline-2(3H)-one (32a): With salt 13, the above procedure
furnished 99% of colorless crystals from ether, m.p. 176°C (dec.).
NMR spectrum showed only small extra signals beyond those of
adduct 27[28] and the excess of the dipolarophile.
1
Ϫ H NMR (CDCl3): δ ϭ 6.07 (s, 10b-H, coincides with low-field
Cycloadditions to Heterocumulenes
branch of AB), 6.00, 6.25 (AB, J5,6 ϭ 7.6 Hz, 6-H and 5-H),
6.5Ϫ7.6 (m, 9 arom. H), 7.38, 7.83 (2 mc, AAЈMMЈ of C6H4Cl).
Ϫ C22H16ClN3O (373.8): calcd. 70.68, H 4.31, N 11.24; found C
70.89, H 4.48, N 11.06.
3-Phenyl-10bH-1,3,4-thiadiazolo[2,3-a]-isoquinoline-2(3H)-
thione (29): Salt 11 (25.6 g, 99.4 mmol) in 60 ml of water was ba-
sified with 11.7 g (110 mmol) of sodium carbonate in 40 ml of
water. The deep red-brown suspension was extracted with 5 ϫ 100
ml of CS2. The dried organic phase was concentrated up to begin-
ning crystallization; after 2 d at Ϫ10°C, 25.6 g (86%) of coarse
yellow-brown rhombes of 29 were filtered. Due to the cyclorever-
sion, only CS2 is suitable for recrystallization, m.p. 101Ϫ105°C
(dec., red). The crystalline 29 can be stored at room temp. Ϫ IR
(KBr): ν˜ ϭ 690 cmϪ1, 744, 776 (arom. CH out-of-plane def.), 1059
st (CϭS ?), 1282; 1495, 1595 st (arom. ring vibr.), 1636 m (CϭC).
Ϫ UV-Vis (0.35 m in CHCl3): λmax (log ε) ϭ 470 nm (3.76), 405
(3.83), 290 sh (3.93), 260 sh (4.08); the long-wave absorption is that
1,10b-Dihydro-1,3-diphenyl-1,2,4-triazolo[5,1-a]isoquinoline-
2(3H)-thione (31b): The ethereal solution of 19, prepared from 1.51
g (5.00 mmol) of 11, Br instead of Cl, was treated with 810 mg (6.0
mmol) of phenyl isothiocyanate at room temp.; within 15 h the deep
red color turned orange. On recrystallization from acetonitrile, 1.36
g (77%) of crude 31b gave colorless needles, m.p. 130Ϫ131°C (dec.,
red). The red color of hot solutions signals some cycloreversion. Ϫ
1H NMR (CDCl3): δ ϭ 6.11 (s, 10b-H), 5.93, 6.17 (AB, J5,6 ϭ 7.8
Hz, 6-H, 5-H), 6.40Ϫ8.23 (m, 14 arom. CH). Ϫ C22H17N3S (355.5):
calcd. C 74.34, H 4.82, N 11.82; found C 74.73, H 4.80, N 11.66.
1
of 19. Ϫ H NMR (CS2): δ ϭ 5.86, 6.02 (AB, J5,6 ϭ 8.0 Hz, 6-H
3-(4-Chlorophenyl)-1,10b-dihydro-1-phenyl-1,2,4-triazolo[5,1-a]-
isoquinoline-2(3H)-thione (32b) was analogously prepared from 13,
Br instead of Cl, in 84% yield; colorless 32b, m.p. 137Ϫ139°C
(dec.), was obtained from acetonitrile. Ϫ C22H16ClN3S (389.9):
calcd. C 67.77, H 4.14, N 10.78; found C 67.77, H 4.05, N 10.60.
and 5-H), 6.93 (s, 10b-H), 7.0Ϫ8.0 (m, 9 arom. H). Ϫ 13C NMR
(CDCl3): δ ϭ 71.5 (s, 10b-H), 108.1 (d, C-6), 192.1, 192.2 (2 s, C-
2, CS2); the other signals of 19 and 29 cannot be distinguished. Ϫ
C16H12N2S2 (296.4): calcd. C 64.83, H 4.08, N 9.45, S 21.64; found
C 64.76, H 4.10, N 9.47, S 21.28.
1,10b-Dihydro-1,1,3-triphenylpyrazolo[5,1-a]isoquinoline-2(3H)-
one (33): Addition of 1.16 g (5.98 mmol) of diphenylketene in 5 ml
of CH2Cl2 to 1.78 g (6.00 mmol) of 29 in 20 ml of CH2Cl2 led to
immediate decolorization. 2.09 g (84%) of pale-yellow cubes, m.p.
3-(p-Tolyl)-10bH-1,3,4-thiadiazolo[2,3-a]isoquinoline-2(3H)-
thione (30): Analogously, salt 12 was converted to 82% of pale yel-
low, long needles, m.p. 109Ϫ111°C (dec., red above 80°C). Ϫ IR
(KBr): ν ϭ 770 cmϪ1, 775, 830, 838 (arom. CH out-of-plane def.),
˜
104Ϫ105°C, came from petrol ether. Ϫ IR (KBr): ν˜ ϭ 699 cmϪ1
,
1
1057 st (CϭS ?); 1493, 1505 (ring vibr.), 1634 (CϭC). Ϫ H NMR
753, 775 st (arom. CH out-of-plane def.); 1497, 1599 st (ring vibr.);
(CS2): δ ϭ 2.37 (s, CH3), 5.82, 6.00 (AB, J5,6 ϭ 8.0 Hz, 6-H, 5-H),
6.90 (s, 10b-H), 6.98Ϫ7.30, 7.53Ϫ7.83 (2 m, 8 arom. H). Ϫ 13C
NMR (CDCl3): δ ϭ 21.2 (q, CH3), 71.4 (d, C-10b), 108.0 (d, C-6),
192.7 (s, C-2, CS2). For most Car signals the distinction between 20
and 30 was unsuccessful; 20.9 (s, CH3) belongs to 20. Ϫ
C17H14N2S2 (310.4): calcd. C 65.77, H 4.55, N 9.02, S 20.66; found
C 65.45, H 4.51, N 9.11, S 20.75.
1
1636 m (CϭC), 1710 vst (CϭO). Ϫ H NMR (CDCl3): δ ϭ 4.98,
6.16 (AX, J5,6 ϭ 8.0 Hz, 6-H, 5-H), 6.16 (s, 10b-H), 6.57Ϫ8.07 (m,
19 arom. CH). Ϫ C29H22N2O (414.5): calcd. C 84.03, H 5.35, N
6.76; found C 84.02, H 5.45, N 6.54.
Di-tert-butyl 1,2,3,10b-Tetrahydro-3-phenyltetrazolo[5,1-a]iso-
quinoline-1,2-dicarboxylate (34): 1.48 g (5.00 mmol) of 29 in 10 ml
of CH2Cl2 reacted with 1.15 g (5.00 mmol) of di-tert-butyl azodicar-
boxylate[29]; the red color disappeared immediately. Pale yellow
cubes, m.p. 98Ϫ100°C, crystallized from ether/petroleum ether. The
pink solutions of 34 in benzene or CHCl3 reversibly assume the red
color of 19 on heating. Ϫ IR (KBr): ν˜ ϭ 703 cmϪ1, 770, 781, 806
(arom. CH out-of-plane def.); 1161, 1292, 1327 st (CϪO); 1497,
1576, 1598 (arom. ring vibr.), 1647 m (CϭC); 1710, 1751 st
1,10b-Dihydro-1,3-diphenyl-1,2,4-triazolo[5,1-a]isoquinoline-
2(3H)-one (31a): Salt 11, Br instead of Cl (1.51 g, 5.00 mmol), was
dissolved in 75 ml of water and some drops of acetic acid; the 1,3-
dipole 19, set free with Na2CO3, was extracted with ether (125 ml).
The organic phase was briefly clarified with dry Na2SO4, but still
contained water dissolved. After addition of 655 mg (5.5 mmol) of
phenyl isocyanate, the red color faded to pale-yellow in about 2
min; thus, the cycloaddition is faster than the hydrolysis of the
phenyl isocyanate. Colorless crystals (1.47 g, 87%) came from a
small vol. of ether, m.p. 133°C (dec., red) after recrystallization
from ethanol. Ϫ IR (KBr): ν˜ ϭ 688 cmϪ1, 737, 750, 779 (arom.
CH out-of-plane def.), 1594 st (arom. ring vibr.), 1631 m (CϭC),
1704 st (CϭO). Ϫ UV (CHCl3): λmax (log ε) ϭ 308 nm sh (3.56),
261 (4.35). Ϫ C22H17N3O (339.4): calcd. C 77.85, H 5.05, N 12.38;
found C 77.57, H 5.10, N 12.47. Ϫ Hydrogenolysis: 31a (679 mg,
2.00 mmol) in 25 ml of methanol and 10 ml of ethyl acetate was
shaken with Raney nickel and hydrogen; 2.5 mmol of H2 were con-
sumed in 45 min, and N,NЈ-diphenylurea (297 mg, 70%), m.p.
238°C (mixed m.p.) was obtained. The residue of the mother liquor
was distilled at 120°C (bath)/10 Torr and afforded 139 mg (54%)
of isoquinoline (picrate m.p. and mixed m.p. 226°C). Ϫ Reaction
with aniline: 31a (2.00 mmol) in 20 ml of benzene and 1.0 ml of
aniline was refluxed for 15 h; on cooling, 83% of diphenylurea (m.p.
236°C) crystallized. Ϫ Thermolysis: 1.00 mmol of 31a was refluxed
1
(CϭO). Ϫ H NMR (CDCl3): δ ϭ 1.28 (s, 2 tBu), 6.07 (s, 10b-H),
5.56, 6.53 (AX, J5,6 ϭ 7.9 Hz, 6-H, 5-H), 6.7Ϫ7.6 (m, 8 arom. H),
8.04 (mc, 1 arom. H). Ϫ C25H30N4O4 (450.5): calcd. C 66.65, H
6.71, N 12.44; found C 66.94, H 6.72, N 12.56.
Ƞ
This paper is dedicated to George A. Olah, University of Sou-
thern California, on the occasion of his 70th birthday.
[1]
Part 100: R. Huisgen, H. Giera, Liebigs Ann. 1997, 1691Ϫ1696.
R. Huisgen, in “10 Jahre Fonds der Chemischen Industrie”,
[2]
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1961, 14, 63. R. Huisgen, Centenary Lecture, London 1960;
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[3]
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[4]
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Ber. 1977, 110, 522Ϫ539, and ibid. 540Ϫ558. A. Eckell, R.
Huisgen, Chem. Ber. 1977, 110, 559Ϫ570.
[5]
R. Huisgen, R. Grashey, P. Laur, H. Leitermann, Angew. Chem.
1960, 72, 416Ϫ417.
[6]
R. Grashey, Habilitation Thesis, Univ. of Munich, 1965.
384
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