SPECIAL TOPIC
Rhodium-Catalyzed Dimerization of Arylacetylenes
2091
1,1′-(3-Methyleneprop-1-yne-1,3-diyl)bis(4-methoxybenzene)
(dd, J = 8.8, 8.6 Hz, 2 H), 7.05 (dd, J = 8.8, 8.8 Hz, 2 H), 7.18 (dd,
J = 8.8, 5.4 Hz, 2 H), 7.46 (dd, J = 8.8, 5.4 Hz, 2 H).
(3b)
Yield: 66 mg (50%); white solid; mp 77 °C.
13C NMR (CDCl3): δ = 40.8, 52.1, 53.1, 56.4, 64.9, 114.9 (d,
JC,F = 20.7 Hz), 115.4 (d, J = 21.6 Hz), 125.6, 127.5 (d, J = 8.5 Hz),
130.6 (d, JC,F = 7.5 Hz), 131.0 (d, JC,F = 3.8 Hz), 134.7 (d, JC,F = 2.8
Hz), 139.4, 162.1 (d, JC,F = 246.2 Hz), 162.5 (d, JC,F = 248.0 Hz),
169.6, 172.2.
HRMS (ESI): m/z [M + Na]+ calcd for C21H18F2O4 + Na:
395.10709; found: 395.10702.
IR (KBr): 2961w, 2939w, 2908w, 2840w, 1654m, 1604m, 1559w,
1507s, 1289m, 1248s, 1180m, 1030s, 899m, 837s cm–1.
1H NMR (CDCl3): δ = 3.829 (s, 3 H), 3.833 (s, 3 H), 5.62 (s, 1 H),
5.84 (s, 1 H), 6.88 (d, J = 8.8 Hz, 2 H), 6.90 (d, J = 8.8 Hz, 2 H),
7.47 (d, J = 8.8 Hz, 2 H), 7.66 (d, J = 8.8 Hz, 2 H).
13C NMR (CDCl3): δ = 55.30, 55.33, 87.5, 90.5, 113.7, 114.0, 115.3,
118.1, 127.3, 130.0, 130.1, 133.1, 159.7, 159.7.
HRMS (ESI): m/z [M + H]+ calcd for C18H17O2: 265.12285; found:
265.12236.
Dimethyl 2,4-Bis(4-trifluoromethylphenyl)cyclopent-3-ene-1,1-
dicarboxylate (6e)
Yield: 40 mg (15%); white solid; mp 126 °C.
IR (KBr): 2955w, 1732s, 1617m, 1434w, 1418w, 1327s, 1271m,
1251m, 1229w, 1167s, 1109s, 1068s, 1017m, 967w, 908w, 857w,
842m, 828m cm–1.
1H NMR (CDCl3): δ = 3.15 (s, 3 H), 3.21 (d, J = 16.8 Hz, 1 H), 3.81
(s, 3 H), 3.92 (d, J = 16.8 Hz, 1 H), 5.16 (s, 1 H), 6.21 (s, 1 H), 7.35
(d, J = 8.3 Hz, 2 H), 7.54 (d, J = 8.3 Hz, 2 H), 7.60 (d, J = 8.3 Hz, 2
H), 7.63 (d, J = 8.3 Hz, 2 H).
13C NMR (CDCl3): δ = 41.0, 52.4, 53.5, 57.1, 65.2, 124.3 (q,
J = 272.5 Hz), 124.3 (q, J = 272.5 Hz), 125.3 (q, J = 3.8 Hz), 125.8
(q, J = 3.8 Hz), 126.3, 128.0, 129.6, 130.0 (q, J = 32.6 Hz), 130.1
(q, J = 32.9 Hz), 138.2, 140.4, 143.2, 169.5, 172.1.
Dimethyl 2,4-Diphenylcyclopent-3-ene-1,1-dicarboxylate (6a)
Yield: 59 mg (35%); colorless oil.
IR (KBr): 3032w, 2953m, 2849w, 1733s, 1601w, 1495m, 1436m,
1250s, 1077w, 756w, 699w cm–1.
1H NMR (CDCl3): δ = 3.15 (s, 3 H), 3.17 (d, J = 16.9 Hz, 1 H), 3.78
(s, 3 H), 3.92 (d, J = 16.9 Hz, 1 H), 5.05 (s, 1 H), 6.14 (s, 1 H), 7.20–
7.52 (m, 10 H).
13C NMR (CDCl3): δ = 40.6, 52.0, 53.0, 57.2, 65.0, 125.8, 126.2,
127.4, 127.9, 128.0, 128.5, 129.0, 134.9, 139.0, 140.2, 169.7, 172.4.
HRMS (ESI): m/z [M + Na]+ calcd for C21H20O4 + Na: 359.12593;
HRMS (ESI): m/z [M + Na]+ calcd for C23H18F6O4 + Na:
found: 359.12570.
495.10070; found: 495.09946.
Dimethyl 2,4-Bis(4-methoxyphenyl)cyclopent-3-ene-1,1-dicar-
boxylate (6b)
Dimethyl 2,4-Bis(3-methylphenyl)cyclopent-3-ene-1,1-dicar-
boxylate (6f)
Yield: 58 mg (32%); yellow oil.
Yield: 21 mg (21%); yellow solid; mp 36 °C.
IR (KBr): 2952w, 2837w, 1734s, 1609m, 1513s, 1436m, 1251s,
1178s, 1031s, 829m cm–1.
1H NMR (CDCl3): δ = 3.12 (d, J = 16.8 Hz, 1 H), 3.21 (s, 3 H), 3.76
(s, 3 H), 3.77 (s, 3 H), 3.83 (s, 3 H), 3.85 (d, J = 16.8 Hz, 1 H), 4.97
(s, 1 H), 5.97 (s, 1 H), 6.79 (d, J = 8.6 Hz, 2 H), 6.89 (d, J = 9.0 Hz,
2 H), 7.12 (d, J = 8.6 Hz, 2 H), 7.44 (d, J = 9.0 Hz, 2 H).
13C NMR (CDCl3): δ = 40.5, 52.0, 53.0, 55.2, 55.3, 56.4, 65.0,
113.4, 113.8, 124.4, 127.0, 127.8, 130.1, 131.1, 139.3, 158.8, 159.3,
169.9, 172.6.
IR (neat): 3032m, 2953m, 1735s, 1700m, 1652w, 1604w, 1437m,
1253s, 1156w, 1057w, 784m, 703m cm–1.
1H NMR (CDCl3): δ = 2.29 (s, 3 H), 2.37 (s, 3 H), 3.5 (d, J = 16.8
Hz, 1 H), 3.17 (s, 3 H), 3.77 (s, 3 H), 3.90 (d, J = 16.8 Hz, 1 H), 5.00
(s, 1 H), 6.10 (s, 1 H), 6.99–7.33 (m, 8 H).
13C NMR (CDCl3): δ = 21.3, 21.4, 40.6, 51.9, 52.9, 57.0, 65.0,
122.9, 126.1, 126.2, 126.5, 127.9, 128.0, 128.4, 128.5, 129.7, 134.9,
137.5, 138.0, 138.9, 140.1, 169.7, 172.4.
HRMS (ESI): m/z [M + Na]+ calcd for C23H24O6 + Na: 419.14706;
found: 419.14757.
HRMS (ESI): m/z [M + Na]+ calcd for C23H24O4 + Na: 387.15723;
found: 387.15724.
Dimethyl 2,4-Bis(4-methylphenyl)cyclopent-3-ene-1,1-dicar-
boxylate (6c)
Yield: 50 mg (27%); colorless oil.
One-Pot Rhodium- and Palladium-Catalyzed Reaction between
Phenylacetylene (1a) and Malonate 5b; Dimethyl 2-(2,4-Diphe-
nylbuta-2,3-dienyl)-2-methylmalonate (7)
In a glovebox, Pd(OAc)2 (1.1 mg, 0.005 mmol, 1 mol%), TDMPP
(2.2 mg, 0.005 mmol, 1 mol%), toluene (0.5 mL), and phenylacety-
lene (1a; 51 mg, 0.5 mmol, 1 equiv) were added into a 10 mL
Schlenk tube in this order. The solution was stirred for 1 h, after
which a solution of 2 (8.9 mg, 0.025 mmol, 5 mol%) and P(p-anis)3
(17.8 mg, 0.05 mmol, 20 mol%) in toluene (0.5 mL), CsF (76.0 mg,
0.5 mmol, 1 equiv), and 5b (365 mg, 2.5 mmol, 5 equiv) were add-
ed. The tube was sealed, taken out of the glovebox, and then heated
at 90 °C for 3 h. The mixture was cooled to r.t., and hexane (10 mL)
was added, which gave a white precipitate. The precipitate was re-
moved by filtration, and the solution was concentrated under re-
duced pressure. The crude residue was purified by flash
chromatography (hexane–EtOAc, 25:1) to afford allene 7 mixed
with 5b. Bulb-to-bulb distillation of the mixture gave pure 7; yield:
54 mg (60%); colorless oil.
IR (neat): 3026w, 2952m, 2922w, 2864w, 1734s, 1514m, 1436m,
1249s, 1062w, 813m cm–1.
1H NMR (CDCl3): δ = 2.29 (s, 3 H), 2.36 (s, 3 H), 3.14 (d, J = 16.8
Hz, 1 H), 3.18 (s, 3 H), 3.76 (s, 3 H), 3.88 (d, J = 16.8 Hz, 1 H), 4.98
(s, 1 H), 6.05 (s, 1 H), 7.05 (d, J = 8.1 Hz, 2 H), 7.09 (d, J = 8.1 Hz,
2 H), 7.17 (d, J = 8.1 Hz, 2 H), 7.40 (d, J = 8.1 Hz, 2 H).
13C NMR (CDCl3): δ = 21.0, 21.2, 40.5, 51.9, 52.9, 56.7, 65.0,
125.5, 125.7, 128.7, 128.9, 129.1, 132.1, 135.9, 136.9, 137.6, 139.8,
169.8, 172.5.
HRMS (ESI): m/z [M + Na]+ calcd for C23H24O4 + Na: 387.15723;
found: 387.15790.
Dimethyl 2,4-Bis(4-fluorophenyl)cyclopent-3-ene-1,1-dicarbox-
ylate (6d)
Yield: 12 mg (34%); white solid; mp 138 °C.
IR (neat): 2998s, 2953w, 2844w, 1936w, 1735s, 1597w, 1494w,
1458w, 1447w, 1435w, 1378w, 1300w, 1247m, 1202m, 1161m,
1101m, 1029w, 986w, 914w, 873w, 828w, 762w, 746s, 718w,
693m cm–1.
IR (KBr): 3059w, 3000w, 2951w, 2843w, 1728s, 1602w, 1510s,
1507s, 1437m, 1302w, 1280s, 1257m, 1217w, 1201m, 1181m,
1165s, 1104m, 1060m, 964w, 951w, 939w, 826m, 788w cm–1.
1H NMR (CDCl3): δ = 3.13 (d, J = 16.8 Hz, 1 H), 3.20 (s, 3 H), 3.79
(s, 3 H), 3.85 (d, J = 16.8 Hz, 1 H), 5.04 (s, 1 H), 6.02 (s, 1 H), 6.95
1H NMR (CDCl3): δ = 1.50 (s, 3 H), 3.19 (dd, J = 15.1, 2.7 Hz, 1 H),
3.30 (dd, J = 15.1, 2.7 Hz, 1 H), 3.46 (s, 3 H), 3.57 (s, 3 H), 6.49 (t,
J = 2.7 Hz, 1 H), 7.20–7.45 (m, 10 H).
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, 2088–2092