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A.E. Sheshenev et al. / Tetrahedron 65 (2009) 10036–10046
(17), 149 (21), 143 (13), 142 (18), 141 (63), 129 (57), 128 (84), 127
(16), 119 (10), 116 (19), 115 (77).
(30), 206 (26),132 (9),131 (23),115 (6),104 (17),103 (40), 85 (55), 84
(100), 77 (17), 51 (9).
4.12.7. Ethyl 5-phenyl-2,5-dihydropyridazine-3-carboxylate (29). Ethyl
diazoacetate (0.1 mL, 96 mg, 0.84 mmol, 1 mol equiv) in ether
(2 mL) was added dropwise to a stirred ethereal solution of 1
(method 4.12b) at 0 ꢀC. After 20 h at rt solvent was removed under
reduced pressure. The crude product was purified on silica (petrol–
ether, 5:4, Rf 0.41) to give ethyl ester 29 (38 mg, 0.17 mmol, 20%) as
an orange oil (Found Mþ: 230.1085. C13H1414N2O2 requires:
230.1055), which showed dH: 1.33 (3H, t, J¼7.0 Hz, CH3), 4.07 (1H,
dd, J¼4.3, 2.4 Hz, H-5), 4.28 (2H, q, J¼7.0 Hz, OCH2), 5.73 (1H, dd,
J¼4.3, 2.1 Hz, H-4), 6.56 (1H, dd, J¼2.4, 2.1 Hz, H-6), 7.24–7.41 (5H,
m, Ph), 7.83 (1H, br s, NH); dC: 14.1þ, 39.8þ, 61.6–, 105.4þ, 127.4þ,
127.9þ, 129.0þ, 129.8, 135.5þ, 142.1, 162.0; nmax: 3386 br s, 3061 w,
3029 w, 2982 m, 2937 w, 2905 w, 1717 s, 1678 s, 1654 s, 1600 m,
1493 m, 1454 s, 1394 m, 1371 s, 1320 m, 1301 s, 1264 s, 1210 s, 1132 s,
1096 m, 1027 m, 911 m, 864 m, 752 s, 733 s, 700 s cmꢁ1; m/z, %: 231
(Mþþ1, 1), 230 (Mþ, 8), 229 (Mþꢁ1, 15), 211 (6), 201 (9), 184 (12),
183 (6), 157 (13), 156 (95), 155 (31), 153 (21), 131 (8), 130 (22), 129
(40), 128 (21), 115 (18), 102 (100), 77 (27).
4.12.4. anti-3-Phenyltricyclo[3.2.1.02,4]oct-6-ene (22). Freshly dis-
tilled cyclopentadiene (0.35 mL, 280 mg, 4.2 mmol, 5 mol equiv) was
added dropwise to an ethereal solution of 1 prepared from tri-
bromide 13 (300 mg, 0.84 mmol) and methyllithium in ether
(2.0 mL, 1.85 mmol, 0.92 M, 2.2 mol equiv) in dry ether (10 mL)
according to procedure 4.12a. The resulting mixture was stirred for
1 h at rt and quenched with water (2 mL). The organic layer was
separated, the aqueous layer was extracted with ether (3 mL). The
combined organics were washed with water (3 mL), dried and
evaporated to yield an orange oil (140 mg), which contained adduct
22 (purity>90% by 1H NMR spectroscopy). This crude product was
purified on silica (petrol, Rf 0.53) to give compound 22 (98 mg,
0.54 mmol, 64%) as colourless oil (Found: C 92.3, H 7.8%. C14H14 re-
quires: C 92.26, H 7.74%), which showed dH: 1.68 (3H, br s, H-2,3,4),
1.68 (1H, d, J¼6.7 Hz, H-bridge),1.80 (1H, d, J¼6.7 Hz, H-bridge), 2.98
(2H, s, H-1,5), 5.87 (2H, s, H-6,7), 7.00–7.21 (5H, m, Ph); dC: 23.9þ,
34.3þ, 43.6þ, 63.3–, 125.4þ, 126.3þ, 128.0þ, 131.4þ, 142.1; nmax
:
3135 w, 3090 m, 3065 m, 3035 m, 2980 s, 2937 m, 2870 m, 1600 m,
1502 m, 1457 m, 1380 w, 1340 m, 1255 m, 1240 m, 1215 w, 1180 m,
1120 w, 1080 w, 1055 m, 1033 m, 970 w, 919 w, 907 w, 890 m, 830 w,
4.12.8. 1,2-Di-iodo-3-phenylcyclopropene (30). A solution of iodine
(235 mg, 0.92 mmol, 1.1 mol equiv) in CHCl3 (8 mL) was added
dropwise to an ethereal solution of 1 (method 4.12b) at rt. The
mixture was stirred for 30 min at rt and quenched with satd aq
Na2S2O3 solution (5 mL). The organic layer was separated, the
aqueous layer was extracted with chloroform (5 mL). The combined
organic layers were washed with water (5 mL), dried and evapo-
rated. It afforded di-iodide 30 (190 mg, 0.51 mmol, 61%, mixture of
isomers, t:c¼1:1 by 1H NMR spectroscopy) as a brown oil (Found Mþ:
369.8721. C9H8I2 requires: 369.8716). The mixture showed dH: 2.30
(1Hc, t, J¼5.7 Hz, H-3), 2.37 (1Ht, dd, J¼8.7, 5.8 Hz, H-3), 3.07 (2Hc, d,
J¼5.7 Hz, H-1,2), 3.14 (1Ht, dd, J¼5.8, 4.3 Hz), 3.31 (1Ht, dd, J¼8.7,
4.3 Hz), 7.07–7.41 (5H, m, Ph); dC: ꢁ10.3þ, 0.3þ, 2.0þ, 32.8þ, 39.4þ,
800 w, 750 s, 710 s cmꢁ1
.
4.12.5. exo-6-Phenyl-2,3-diazabicyclo[3.1.0]hex-2-ene (26). Diazome-
thane in ether (7 mL, w1.2 mmol, w0.2 M,1.4 mol equiv) was added
dropwise to an ethereal solution of 1 prepared according to pro-
cedure 4.12b at 0 ꢀC over 10 min. The yellow-green reaction mixture
was stirred for 50 min at 0 ꢀC and the solvent was removed under
reduced pressure. The crude product was columned on silica
(pentane–ether, 1:1, Rf 0.36) to afford adduct 26 (82 mg, 0.52 mmol,
62%) as a yellowish powder, mp 59–61 ꢀC (Found Mþ: 158.0851.
C10H1014N2 requires: 158.0844), which showed dH: 1.20 (1H, dd,
J¼1.6, 4.4 Hz, H-6), 2.15 (1H, dddd, J¼1.3, 4.4, 4.7, 6.6 Hz, H-5), 4.54
(1H, dd, J¼1.3, 19.2 Hz, H-4), 4.74 (1H, dd, J¼6.6, 19.2 Hz, H-4), 4.93
(1H, dd, J¼1.6, 4.7 Hz, H-1), 7.07 (2H, m, Ph), 7.25–7.35 (3H, m, Ph);
dC: 23.6þ, 32.5þ, 73.2þ, 80.1–, 126.0þ, 126.8þ, 128.6þ, 138.3; nmax
(CHCl3): 3055 m, 2925 m,1955 w,1835 w,1604 s,1516 s,1496 s,1455
s, 1415 s, 1386 m, 1285 m, 1268 m, 1176 m, 1146 m, 1070 s, 1037 m,
990 m, 931 m, 914 m, 884 m, 751 s, 698 s cm–1; m/z (CI, CH4), %: 158
(Mþ, 8), 157 (MþꢁH, 100), 156 (11), 139 (5), 137 (5), 125 (3), 123 (5),
111 (1), 109 (3), 107 (2), 97 (2), 95 (1).
125.7þ, 127.3þ, 127.5þ, 128.2þ, 128.3þ, 128.8þ, 136.7, 138.2; nmax
:
3059 m, 3025 s, 2893 m,1944 w,1602 s,1492 s,1450 m,1352 w,1215
w, 1155 w, 1113 w, 1072 m, 1029 m, 989 m, 910 w, 839 w, 760 s, 747 s,
696 s, 634 s cmꢁ1; m/z, %: 370 (Mþ, 0.05), 254 (5), 243 (MþꢁI, 56),128
(3), 127 (Iþ, 100), 116 (2), 114 (3), 89 (39), 63 (12).
4.13. Preparation of an ethereal solution of 1-lithio-3-
phenylcyclopropene (18) and its reactions with electrophiles
Methyllithium in ether (1.42 mL, 1.85 mmol, 1.30 M, 2.2 mol
equiv) was added dropwise to tribromide 13 (300 mg, 0.84 mmol)
in dry ether (10 mL) at ꢁ82 to ꢁ80 ꢀC over 3 min. The mixture was
stirred for 5 min at ꢁ80 ꢀC and allowed to reach rt (20 min). After
a further 30 min at rt the prepared solution of 18 was cooled down
to ꢁ60 ꢀC and directly used for reactions with electrophiles (MeI,
BnBr, acetone, PhCHO, ClCO2Me, CO2, ZnCl2).
4.12.6. exo-4,6-Diphenyl-2-oxo-3-azabicyclo[3.1.0]hex-3-ene (27). A
solution of Et3N (78 mg, 0.77 mmol, 0.9 mol equiv) in dry ether
(1 mL) was added dropwise to a stirred ethereal solution of 1
(method 4.12b) and benzohydroximinoyl chloride (120 mg,
0.77 mmol, 0.9 mol equiv) in dry ether (2 mL) at ꢁ15 ꢀC over 1 min.
The mixture was stirred for 30 min at ꢁ15 ꢀC and 7 h at rt, carefully
quenched with 1 M HCl (4 mL), diluted with water (5 mL) and ether
(5 mL). The organic layer was separated and the aqueous layer was
extracted with ether (2ꢂ5 mL). The combined organics were
washed with water (2ꢂ5 mL), dried and evaporated. Chromatog-
raphy of the residue (164 mg) on silica (petrol–ether, 5:1 to CH2Cl2,
Rf 0.42) gave compound 27 (141 mg, 0.60 mmol, 78%) as a white
powder, mp 154–157 ꢀC (dec) (Found Mþ: 235.1006. C16H1314NO
requires: 235.0997), which showed dH: 1.85 (1H, dd, J¼1.9, 3.2 Hz, H-
6), 3.24 (1H, dd, J¼3.2, 5.4 Hz, H-5), 5.11 (1H, dd, J¼1.9, 5.4 Hz, H-1),
7.05 (2H, m, Ph), 7.28–7.48 (6H, m, Ph), 7.84 (2H, m, Ph); dC: 23.7þ,
35.6þ, 70.8þ,125.6þ,126.5þ,127.3þ,128.6,128.7þ,128.8þ,130.5þ,
138.3, 161.6; nmax (CHCl3): 3087 w, 3060 m, 3043 s, 1958 w, 1891 w,
1602 s,1582 w,1544 m,1496 s,1448 s,1382 s,1362 s,1286 w,1156 w,
1076 m, 1052 m, 1031 m, 1006 s, 973 m, 922 m, 898 m, 866 s, 847 m,
696 s cmꢁ1; m/z, %: 236 (Mþþ1, 1), 235 (Mþ, 8), 234 (Mþꢁ1, 10), 219
4.13.1. 1-Methyl-3-phenylcyclopropene (2) and 1,2-dimethyl-3-phenyl-
cyclopropene (31). Methyl iodide (0.5 mL, 1.14 g, 8.0 mmol,
9.5 mol equiv) was added dropwise to an ethereal solution of 18 at
ꢁ60 ꢀC. The mixture was allowed to reach rt, stirred for 9 h, cooled
to ꢁ10 ꢀC and quenched with water (2 mL). The organic layer was
separated, the aqueous layer was extracted with ether (2ꢂ5 mL).
The combined organic layers were washed with brine (3 mL), dried
and evaporated. The crude product (112 mg, ratio, %: 2/31¼87:13 by
1H NMR spectroscopy) was columned on silica (pentane, Rf 0.43) to
give cyclopropene 2 (57 mg, 0.44 mmol, 53%) as colourless oil
(Found Mþ: 130.0787. C10H10 requires: 130.0783), which showed
dH: 2.19 (3H, s, CH3), 2.59 (1H, s, H-3), 6.62 (1H, s, H-2), 7.13–7.15
(2H, m, Ph), 7.18 (1H, m, Ph), 7.29–7.32 (2H, m, Ph); dC: 10.2þ, 22.8þ,
99.4þ, 116.3, 125.1þ, 125.4þ, 128.0þ, 147.3; nmax: 3078 w, 3059 w,