The Journal of Organic Chemistry
Note
3.16 (m, 1H), 3.07−2.92 (m, 1H), 2.45 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ 165.1, 164.5, 150.6, 148.0, 145.3, 143.4, 132.5, 129.7, 129.3,
128.5, 127.5, 125.6, 122.4, 121.7, 112.6, 41.4, 40.2, 35.1, 21.7. Mp
121−123 °C. HRMS (EI-MS): calcd for C25H22O5S1 [M]+ 434.1182;
found 434.1197.
1090 (m) cm−1. H NMR (500 MHz, CDCl3) δ 7.73 (s, 1H), 7.71−
7.67 (m, 1H), 7.43−7.34 (m, 4H), 7.22 (t, J = 7.4 Hz, 1H), 7.16−7.11
(m, 2H), 5.94 (p, J = 2.4 Hz, 1H), 3.79−3.65 (m, 2H), 3.41−3.25 (m,
2H), 3.11 (ddt, J = 18.5, 7.5, 2.6 Hz, 1H), 1.36 (s, 12H). 13C NMR
(125 MHz, CDCl3) δ 166.1, 164.7, 150.7, 143.6, 132.9, 132.7, 129.3,
129.3, 128.0, 125.6, 121.8, 112.3, 83.9, 41.5, 40.4, 35.6, 24.9. HRMS
(EI-MS): calcd for C24H27O4B1 [M]+ 390.1997; found 390.1998.
Phenyl 2-(3-Isopropyl-3-methylcyclobutylidene)acetate [25]. This
compound was prepared according to General Procedure A utilizing
phenyl 2,3-butadienoate 1 and 2,3-dimethylbut-1-ene. Purification by
silica gel column chromatography (2% EtOAc:hexanes, gradient)
provided 39.0 mg (0.16 mmol, 80% yield) of the title compound as a
pale yellow oil. Rf = 0.40 (10% EtOAc:hexanes). IR (neat): 2959 (s),
2873 (m), 1722 (s), 1673 (s), 1595 (s), 1339 (s), 1248 (m), 960(m)
1
Phenyl 2-(3-(o-Tolyl)cyclobutylidene)acetate [20]. This com-
pound was prepared according to General Procedure B utilizing
phenyl 2,3-butadienoate 1 and 2-methylstyrene. Purification by silica
gel column chromatography (2% EtOAc:hexanes) provided 30.1 mg
(0.12 mmol, 62% yield) of the title compound as a pale yellow oil. Rf =
0.40 (10% EtOAc:hexanes). IR (film): 3062 (w), 2956 (w), 2921 (w),
1730 (s), 1676 (s), 1492 (s), 1342 (s), 1198 (s) cm−1. 1H NMR (400
MHz, CDCl3) δ 7.31 (t, J = 7.7 Hz, 2H), 7.22 (d, J = 7.6 Hz, 1H),
7.19−7.12 (m, 2H), 7.11−7.03 (m, 4H), 5.90−5.84 (m, 1H), 3.81−
3.69 (m, 1H), 3.69−3.58 (m, 1H), 3.22 (dddd, J = 19.3, 11.4, 8.3, 3.8
Hz, 2H), 3.06−2.94 (m, 1H), 2.21 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ 165.9, 164.9, 150.8, 141.6, 136.1, 130.4, 129.5, 126.6, 126.2,
125.7, 125.0, 121.9, 112.1, 40.3, 39.1, 33.6, 19.8. HRMS (EI-MS):
calcd for C19H18O2 [M]+ 278.1301; found 278.1298.
cm−1. H NMR (400 MHz, CDCl3) δ 7.42−7.34 (m, 2H), 7.24−7.18
1
(m, 1H), 7.14−7.08 (m, 2H), 5.89 (p, J = 2.3 Hz, 1H), 2.99−2.89 (m,
1H), 2.89−2.78 (m, 1H), 2.74−2.62 (m, 1H), 2.55−2.44 (m, 1H),
1.75 (hept, J = 6.8 Hz, 1H), 1.07 (s, 3H), 0.86 (d, J = 6.8 Hz, 6H). 13C
NMR (100 MHz, CDCl3) δ 166.6, 164.9, 150.9, 129.4, 125.6, 121.9,
113.4, 45.3, 43.9, 39.6, 37.0, 20.2, 17.0. HRMS (EI-MS): calcd for
C16H20O2 [M]+ 244.1458; found 244.1450.
Phenyl 2-(3-(2-Bromophenyl)cyclobutylidene)acetate [21]. This
compound was prepared according to General Procedure B utilizing
phenyl 2,3-butadienoate 1 and 2-bromostyrene 37. Purification by
silica gel column chromatography (2% EtOAc:hexanes) provided 64.3
mg (0.19 mmol, 93% yield) of the title compound as a clear colorless
oil. Rf = 0.42 (10% EtOAc:hexanes). IR (film): 3063 (w), 2970 (w),
2921 (w), 1727 (s), 1676 (s), 1594 (m), 1493 (s), 1164 (s), 1090 (s)
Phenyl 2-(3-Methyl-3-((4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)methyl)cyclobutylidene)acetate (26). This compound was pre-
pared according to General Procedure B utilizing phenyl 2,3-
butadienoate 1 and methallyl boronic acid pinacol ester. Purification
by silica gel column chromatography (2−10% EtOAc:hexanes,
gradient) provided 49.7 mg (0.15 mmol, 73% yield) of the title
compound as a clear colorless oil. Rf = 0.42 (10% EtOAc:hexanes). IR
(film): 3447 (br), 2978 (m), 2950 (m), 1738 (s), 1672 (s), 1493 (m),
1
cm−1. H NMR (400 MHz, CDCl3) δ 7.56 (dd, J = 8.0, 1.2 Hz, 1H),
7.46−7.26 (m, 4H), 7.28−7.16 (m, 1H), 7.17−7.03 (m, 3H), 5.94 (p, J
= 2.3 Hz, 1H), 4.05−3.89 (m, 1H), 3.83−3.67 (m, 1H), 3.47−3.35 (m,
1H), 3.36−3.22 (m, 1H), 3.01 (dddd, J = 17.0, 7.9, 3.4, 2.3 Hz, 1H).
13C NMR (100 MHz, CDCl3) δ 165.1, 164.72, 150.8, 142.6, 133.1,
129.5, 128.1, 127.6, 127.0, 125.7, 124.3, 121.9, 112.5, 39.9, 39.3, 36.1.
HRMS (CI-MS): calcd for C18H16O2Br1 [M + H]+ 343.0328; found
343.0328.
Phenyl 2-(3-(2-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-
phenyl)cyclobutylidene)acetate [22]. This compound was prepared
according to General Procedure B utilizing phenyl 2,3-butadienoate 1
and 2-vinylphenylboronic acid pinacol ester. Purification by silica gel
column chromatography (2−10% EtOAc:hexanes, gradient) provided
28.9 mg (0.07 mmol, 37% yield) of the title compound as a pale yellow
oil. Rf = 0.46 (10% EtOAc:hexanes) IR (film): 3442 (br), 2976 (m),
2930 (w), 1732 (s), 1678 (m), 1487 (m), 1345 (s), 1096 (m) cm−1.
1H NMR (400 MHz, CDCl3) δ 7.82 (dd, J = 7.4, 1.5 Hz, 1H), 7.52−
7.31 (m, 4H), 7.31−7.17 (m, 2H), 7.17−7.07 (m, 2H), 6.04−5.83 (m,
1H), 4.39 (p, J = 8.3 Hz, 1H), 3.80−3.58 (m, 1H), 3.44−3.19 (m,
2H), 3.12−2.92 (m, 1H), 1.35 (s, 12H). 13C NMR (100 MHz, CDCl3)
δ 167.4, 164.9, 150.9, 150.1, 136.4, 131.4, 129.4, 125.7, 125.6, 124.8,
121.9, 112.1, 83.7, 41.3, 40.6, 34.8, 25.0, 25.0. HRMS (CI-MS): calcd
for C24H27O4B1 [M]+ 390.1997; found 390.2000.
Phenyl 2-(3-(3-Bromophenyl)cyclobutylidene)acetate [23]. This
compound was prepared according to General Procedure B utilizing
phenyl 2,3-butadienoate 1 and 3-bromostyrene 38. Purification by
silica gel column chromatography (2% EtOAc:hexanes) provided 53.5
mg (0.16 mmol, 78% yield) of the title compound as a clear colorless
oil. Rf = 0.41 (10% EtOAc:hexanes). IR (film): 3062 (w), 2924 (w),
1728 (s), 1678 (m), 1597 (m), 1492 (m), 1163 (s), 1088 (s) cm−1. 1H
NMR (500 MHz, CDCl3) δ 7.45−7.41 (m, 1H), 7.42−7.34 (m, 3H),
7.25−7.19 (m, 3H), 7.15−7.09 (m, 2H), 5.95 (q, J = 2.2 Hz, 1H),
3.78−3.63 (m, 2H), 3.40−3.21 (m, 2H), 3.08−3.00 (m, 1H). 13C
NMR (125 MHz, CDCl3) δ 165.0, 164.6, 150.8, 146.9, 130.3, 129.7,
129.7, 129.5, 125.8, 125.2, 122.8, 121.8, 112.9, 41.4, 40.3, 35.5. HRMS
(CI-MS): calcd for C18H16O2Br1 [M + H]+ 343.0328; found 343.0325.
Phenyl 2-(3-(3-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-
phenyl)cyclobutylidene)acetate [24]. This compound was prepared
according to General Procedure B utilizing phenyl 2,3-butadienoate 1
and 3-vinylphenylboronic acid pinacol ester 43. Purification by silica
gel column chromatography (2−10% EtOAc:hexanes gradient)
provided 54.6 mg (0.14 mmol, 70% yield) of the title compound as
a clear colorless oil. Rf = 0.33 (10% EtOAc:hexanes) IR (film): 3448
(br), 2978 (m), 2930 (w), 1729 (s), 1675 (m), 1492 (m), 1341 (s),
1359 (s), 1274 (m), 1144 (m) cm−1. H NMR (400 MHz, CDCl3) δ
1
7.40−7.33 (m, 2H), 7.23−7.17 (m, 1H), 7.12−7.07 (m, 2H), 5.87 (p, J
= 2.3 Hz, 1H), 3.07−2.99 (m, 1H), 2.99−2.90 (m, 1H), 2.82−2.74 (m,
1H), 2.68−2.59 (m, 1H), 1.28−1.21 (m, 15H), 1.13 (s, 2H). 13C
NMR (100 MHz, CDCl3) δ 167.2, 164.7, 150.7, 129.2, 125.4, 121.8,
113.0, 83.0, 47.7, 46.4, 34.1, 28.6, 24.8. HRMS (EI-MS): calcd for
C20H27O4B1 [M]+ 342.1997; found 342.1994.
Phenyl 2-(3-Phenyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)cyclobutylidene)acetate [27]. This compound was prepared
according to General Procedure B utilizing phenyl 2,3-butadienoate
1 and 1-phenylvinylboronic acid pinacol ester 45. Purification by silica
gel column chromatography (2−10% EtOAc:hexanes gradient)
provided 62.5 mg (0.16 mmol, 80% yield) of the title compound as
a clear colorless oil. Rf = 0.4 (10% EtOAc:hexanes). IR (film): 3428
(br), 3061 (w), 2978 (m), 2931 (w), 1728 (s), 1674 (s), 1493 (m),
1356 (s), 1319 (s), 1139 (m), 1094 (s) cm−1. H NMR (500 MHz,
1
CDCl3) δ 7.38 (dd, J = 8.5, 7.4 Hz, 2H), 7.34−7.29 (m, 2H), 7.24−
7.19 (m, 3H), 7.19−7.15 (m, 1H), 7.14−7.10 (m, 2H), 5.86 (p, J = 2.3
Hz, 1H), 3.84 (dq, J = 17.6, 2.8 Hz, 1H), 3.55−3.41 (m, 2H), 3.18
(ddd, J = 16.8, 3.6, 2.3 Hz, 1H), 1.18 (s, 12H). 13C NMR (125 MHz,
CDCl3) δ 166.4, 164.7, 150.9, 146.6, 129.4, 128.4, 126.1, 125.6, 125.3,
121.9, 112.2, 84.1, 43.4, 42.1, 24.6. HRMS (CI-MS): calcd for
C26H32O4B1 [M + C2H5]+ 419.2388; found 419.2383.
Phenyl 2-(3-Methyl-3-phenylcyclobutylidene)acetate [28]. This
compound was prepared according to General Procedure A utilizing
phenyl 2,3-butadienoate 1 and α-methylstyrene. Purification by silica
gel column chromatography (2% EtOAc:hexanes) provided 54.5 mg
(0.19 mmol, 98% yield) of the title compound as a pale yellow oil. Rf =
0.44 (10% EtOAc:hexanes). IR (film): 3059 (w), 3024 (w), 2958 (m),
2920 (w), 1729 (s), 1676 (m), 1493 (s), 1340 (s), 1198 (s), 1080 (m)
cm−1. H NMR (600 MHz, CDCl3) δ 7.39−7.31 (m, 3H), 7.26−7.18
1
(m, 5H), 7.12−7.09 (m, 2H), 5.95 (p, J = 2.3 Hz, 1H), 3.53−3.46 (m,
1H), 3.39−3.32 (m, 1H), 3.31−3.25 (m, 1H), 3.00−2.93 (m, 1H),
1.52 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 165.1, 164.8, 150.8,
149.6, 129.5, 128.6, 126.0, 125.7, 125.2, 121.9, 113.6, 46.8, 45.7, 40.2,
31.0 HRMS (EI-MS): calcd for C19H18O2 [M]+ 278.1301; found
278.1310.
Phenyl 2-(3,3-Diphenylcyclobutylidene)acetate [29]. This com-
pound was prepared according to General Procedure B utilizing
phenyl 2,3-butadienoate 1 and 1,1-diphenylethylene 40. Purification by
silica gel column chromatography (2% EtOAc:hexanes) provided 56.8
G
J. Org. Chem. XXXX, XXX, XXX−XXX