4992
J. W. Herndon et al. / Tetrahedron 56 (2000) 4985±4993
1
as dialkylidenecyclopentenone 35-Z. H NMR (CDCl3): d
7.27 (m, 5H), 6.32 (t, 1H, J7.6 Hz), 6.24 (dt, 1H, J4.6-t,
1.4-d Hz), 5.55 (br s, 1H), 4.33 (t, 2H, J6.0 Hz), 4.25 (d,
2H, J7.6 Hz), 2.54 (td, 2H, J6.0-t, 4.6-d Hz); 13C NMR
(CDCl3): d 192.8, 174.2, 139.8, 132.4, 131.1, 128.5, 126.2,
116.1, 108.5, 66.6, 33.2, 23.5; IR (neat): 1648 (s), 1572 (s);
MS (El): m/e 238 (m, 100), 167 (10), 165 (13); HRMS:
Calcd for C16H14O2: 238.0994, Found: 238.1014. The stereo-
chemistry of the 5-exo double bond was assigned as Z by
comparing with alkylidenecyclopentenones in literature,
which feature higher chemical shifts for the vinylic proton
of the E-isomer, and lower chemical shifts for the exocyclic
allylic protons.14 The two compounds (40.2 mg, 43%) in the
second fraction were presumed to be a mixture of the E
isomer of dialkylidenecyclopentenone 35 and alkylidene-
cyclopentenone 36. A nearly pure sample of the Z isomer
of 35 was isolated using prep TLC and partial band cutting.
1H NMR (CDCl3): d 6.79 (t, 1H, J7.6 Hz), 6.52 (br t, 1H,
J6.0 Hz), 5.56 (br s, 1H), 4.40 (t, 2H, J6.0 Hz), 3.80 (d,
2H, J7.6 Hz), 2.65 (q, 2H, J6.0 Hz). A doublet at d 6.70
and doublet of doublets at d 6.10 are suggestive of the styryl
group of compound 36, however a pure sample of this
compound was never successfully isolated.
0.48 mmol) and 5-phenyl-4-penten-2-yn-1-yl acetate20
(37) (95 mg, 0.48 mmol). Toluene was used as the solvent
with the addition of 1% water. The puri®cation was done by
preparative thin layer chromatography (hexane±ethyl
acetate5:1). Two fractions were collected. The compound
in the ®rst fraction (37.2 mg, 34%) was identi®ed as dialkyl-
1
idenecyclopentenone 38-Z. H NMR (CDCI3): d 7.30 (m,
5H), 6.41 (t, 1H, J7.6 Hz), 5.59 (s, 1H); 5.47 (s, 1H), 5.41
(s, 1H), 4.26 (d, 2H, J7.6 Hz), 3.90 (s, 3H), 13C NMR
(CDCl3): d 192.8, 177.5, 139.7, 133.2, 129.8, 128.4,
127.4, 126.0, 106.7 104.2, 57.9, 33.2; IR (neat): 1700 (s),
1601 (vs) cm21; MS (El): m/e 226 (m, 72), 70 (100); HRMS:
Calcd for C15H1402226.0993, Found: 226.0990.The stereo-
chemistry of the 5-exo double bond was determined to be Z
by comparison with Z-alkylidenecyclopentenones in litera-
ture as before.14 The product in the second fraction
(27.1 mg, 25%) was tentatively identi®ed as alkylidene-
1
cyclopentenone 39. H NMR (CDCl3): d 7.40 (m, 5H),
6.64 (d, 1H, J16.0 Hz), 6.02 (dd, 1H, J16.0, 8.0 Hz),
5.73 (s, 1H), 5.50 (s, 1H), 5.27 (s, 1H), 3.74 (d, 1H,
J8.0 Hz), 3.92 (s, 3H); 13C NMR (CDCl3): d 201.2,
180.2, 138.8, 126.4, 133.8, 128.2, 128.0, 126.2, 124.0,
111.6, 105.8, 58.2, 53.0; IR (neat): 1696 (s), 1571 (vs).
Coupling of cyclopropylcarbene complex 1 with 3-
phenylpropargyl alcohol (31A). General procedure III
was followed using carbene complex 12 (182 mg,
0.65 mmol) and 3-phenylpropargyl alcohol19 (31A)
(86 mg, 0.65 mmol). Toluene was used as the solvent with
the addition of 1% water. The puri®cation was done by
preparative thin layer chromatography (hexane±ethyl
acetate2:1). A single fraction (65.2 mg, 46%) identi®ed
Coupling of cyclopropylcarbne complex 1 with 3-
hexyne-2,4-diacetate (42) in the presence of tri-o-tolyl-
phosphine. General procedure III was followed using
carbene complex 12 (134 mg, 0.48 mmol), 3-hexyne-2,4-
diacetate21 (42) (95 mg, 0.48 mmol), and tris-o-tolyl-
phosphine (169 mg, 0.48 mmol). Dioxane was used as the
solvent without the addition of any proton source. The puri-
®cation was done by preparative thin layer chromatography
(hexane±ethyl acetate4:1). Three fractions were collected.
The compound in the ®rst fraction (4.4 mg, 5%) was cyclo-
butenone 44. Isomers of dialkylidenecyclopentenone 43
were obtained in the second (14.2 mg, 18%) and third
(29.1, 37%) fractions. One isomer from the third fraction
(Isomer C) could be successfully isolated free of the other
isomers. 1H NMR (CDCI3): d 6.54 (q, 1H, J7.4 Hz), 6.18
(q, 1H, J7.6 Hz), 5.37 (s, 1H), 3.88 (s, 3H), 2.33 (d, 3H,
J7.4 Hz), 2.00 (d, 3H, J7.6 Hz); 13C NMR (CDCl3): d
194.0, 178.4, 134.5, 132.7, 131.0, 120.7, 103.7, 57.7, 14.2;
IR (neat): 1694 (s), 1599 (s) cm21; MS (m/e): 164 (M, 63),
150 (100), HRMS: Calcd for C10H12O2: 164.0837, Found:
164.0832. The 3:2 mixture of compounds in the second
fraction (major isomer is isomer A, minor isomer is isomer
B) display the following 1H NMR spectrum: d 6.66 (q, 1H,
J7.7 Hz, minor isomer), 6.55 (q, 1H, J7.7 Hz, major
isomer) 6.32 (q, 1H, J7.7 Hz, minor isomer), 6.14 (q, 1H,
J7.7 Hz, major isomer), 5.48 (s, 1H, minor isomer), 5.32
(s, 1H, major isomer), 3.88 (s, 3H, overlapping for both
isomers), 2.13 (d, 3H, J7.7 Hz, minor isomer), 2.00(d,
3H, J7.7 Hz, minor isomer), 1.99 (d, 3H, J7.7 Hz,
major isomer), 1.98 (d, 3H, J7.7 Hz, major isomer). The
remaining isomer in the third fraction (isomer D) displays
1
as cyclopentenone 33A was obtained as a colorless oil. H
NMR (CDCl3); d 7.35 (m, 5H), 5.38 (s, 1H), 3.98 (dd, 1H,
J12.0, 3.6 Hz), 3.95 (s, 3H), 3.86 (dd, 1H, J12.0,
3.0 Hz), 3.62 (d, 1H, J3.2 Hz), 3.08 (br q, 1H,
J3.3 Hz), 1.80 (br s, 1H); 13C NMR (CDCl3): d 203.5,
188.7, 138.4, 128.5, 127.9, 126.6, 104.5, 61.2, 59.1, 54.5,
52.1; IR (neat): 3350 (s), 1677 (s), 1588 (vs); MS (El): m/e
218 (37), 199 (19) 187 (100); HRMS: Calcd for C13H1403:
218.0943, Found 218.0935.
Coupling of cyclopropylcarbene complex 1 with 3-
phenylpropargyl acetate (31B). General procedure III
was followed using carbene complex 12 (136 mg,
0.49 mmol) and 3-phenylpropargyl acetate (31B) (85 mg,
0.49 mmol). Toluene was used as the solvent with the addi-
tion of 1% water. The puri®cation was done by preparative
thin layer chromatography (hexane±ethyl acetate4:1). A
single fraction (63.9 mg, 65%) identi®ed as alkylidene-
cyclopentenone 32 was obtained as a colorless oil. 1H
NMR (CDCl3): d 7.28 (m, 5H), 5.77 (d, 1H, J1.6 Hz),
5.57 (d, 1H, J1.6 Hz), 5.13 (t, 1H, J1.6 Hz), 4.13 (t,
1H, J1.6 Hz), 3.96 (s, 3H); 13C NMR (CDCl3): d 200.9,
181.2, 143.3, 137.4, 128.5, 128.2, 127.0, 111.5, 105.4, 58.4,
55.4; IR (neat): 1695 (s), 1574 (vs); MS (El): m/e 200 (m,
100), 199 (31); HRMS: Calcd for C13H1202: 200.0839,
Found 200.0837. Anal. Calcd for C13H12O2: C 78.02%, H
6.04%, Found: C 77.85%, 6.02%.
1
the following H NMR spectrum. 6.23 (q, 1H, J7.6 Hz),
6.01 (q, 1H, J7.6 Hz), 5.54 (s, 1H), 3.85 (s, 3H), 2.26 (d,
3H, J7.6 Hz), 2.08 (d, 3H, J7.6 Hz). The crude 1H NMR
spectrum shows the four isomers were formed in a
35:22:30:13 A:B:C:D ratio. Since the crude 1H NMR spec-
trum and the 1H NMR spectra for isolated compounds
suggest different isomer ratios, isomerization during puri®-
cation is likely.
Coupling of cyclopropylcarbene complex 1 with -5-phen-
yl--4-penten-2-yn-1-yl acetate (37). General procedure III
was followed using carbene complex 12 (182 mg,