G
J. Tao et al.
Paper
Synthesis
Phenyliodonium of Methyl (2-Toluoyl)acetate (4g)
HRMS (ESI): m/z [M + H]+ calcd for C10H10O3Cl: 213.0313; found:
213.0313.
General Procedure A was followed using 2′-acetophenone (5.36 g, 40
mmol) to afford methyl (2-toluoyl)acetate as a yellow liquid (6.60 g,
86%) as a 4:1 mixture of keto/enol tautomers. Rf 0.42 (EtOAc–hexanes,
20%).
Ylide formation using (2-chlorobenzoyl)acetate (1.28 g, 6 mmol) gave
the title compound (1.81 g, 73%) as an eggshell-white amorphous sol-
id after precipitation from CH2Cl2 and Et2O. The product decomposed
slightly during NMR analysis.
IR (ATR): 2953, 1743, 1698, 1626, 1434, 1245, 1201, 1037 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 7.87 (d, J = 7.7 Hz, 2 H), 7.53 (t, J =
7.5 Hz, 1 H), 7.40 (t, J = 7.8 Hz, 2 H), 7.35–7.31 (m, 1 H), 7.25–7.21 (m,
3 H), 3.46 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 182.9, 164.7, 140.2, 137.6, 133.0,
131.7, 131.5, 130.4, 129.14, 129.08, 127.9, 126.5, 112.9, 52.1 (C=I not
observed).
1H NMR (500 MHz, CDCl3): δ = 12.46 (s, 0.2 H, enol form), 7.73 (d, J =
7.7 Hz, 0.8 H, keto form), 7.49–7.46 (m, 1 H), 7.40–7.32 (m, 2 H), 7.29
(d, J = 8.4 Hz, 0.4 H, enol form), 5.36 (s, 0.2 H, enol form), 4.04 (s,
1.6 H, keto form), 3.87 (s, 0.6 H, enol form), 3.81 (s, 2.4 H, keto form),
2.62 (s, 2.3 H, keto form), 2.53 (s, 0.6 H, enol form).
13C NMR (125 MHz, CDCl3): δ = 195.2, 174.8, 172.9, 167.9, 139.2,
136.3, 135.8, 134.2, 132.07, 132.01, 130.8, 129.9, 129.1, 128.2, 125.66,
125.57, 91.1, 52.0, 51.1, 47.6, 21.4, 20.3.
Phenyliodonium of Methyl (4-Anisoyl)acetate (4j)
HMRS (ESI): m/z [M + H]+ calcd for C11H13O3: 193.0859; found:
193.0860.
General Procedure A was followed using 4′-methoxyacetophenone
(6.01 g, 60 mmol), to afford methyl (4-anisoyl)acetate (8.14 g, 98%) as
a white solid.
1H NMR (500 MHz, CDCl3): δ = 7.93 (d, J = 9.0 Hz, 2 H), 6.95 (d, J =
8.9 Hz, 2 H), 3.96 (s, 2 H), 3.88 (s, 3 H), 3.75 (s, 3 H). This data is con-
sistent with previously reported data.30
Ylide formation using methyl (2-toluoyl)acetate (1.15 g, 6 mmol) gave
the title compound (1.58 g, 67%) as an amorphous white solid.
1H NMR (500 MHz, CDCl3): δ = 7.82 (d, J = 7.8 Hz, 2 H), 7.49 (t, J =
7.5 Hz, 1 H), 7.35 (t, J = 7.7 Hz, 2 H), 7.19–7.12 (m, 4 H).
Ylide formation using methyl (4-anisoyl)acetate (1.25 g, 6 mmol).
Precipitation from a mixture of CH2Cl2 and Et2O using hexanes and
cooling to –78 °C afforded the title compound (2.15 g, 87%) as yellow
solid. NOTE: All manipulations with this compound after its precipi-
tation were performed using labware cooled by dry-ice. The product
decomposed slightly during NMR analysis.
1H NMR (500 MHz, CDCl3): δ = 7.76 (d, J = 8.1 Hz, 2 H), 7.54 (d, J =
8.6 Hz, 2 H), 7.43 (t, J = 7.4 Hz, 1 H), 7.30 (t, J = 7.6 Hz, 2 H), 6.81 (d, J =
8.6 Hz, 2 H), 3.76 (s, 3 H), 3.45 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 186.3, 164.7, 140.8, 134.0, 133.0,
131.4, 131.2, 129.7, 127.9, 126.3, 125.1, 113.2, 51.8, 19.2. (C=I carbon
not observed).
Phenyliodonium of Methyl (4-Chlorobenzoyl)acetate (4h)
General Procedure A was followed using 4′-chloroacetophenone (6.19
g, 40 mmol) to afford methyl (4-chlorobenzoyl)acetate as a red liquid
(7.03 g, 82.7%) in a 5:1 ratio of keto/enol tautomers.
1H NMR (500 MHz, CDCl3): δ = 12.49 (s, 0.3 H, enol form), 7.89 (d, J =
8.6 Hz, 1.5 H, keto form), 7.71 (d, J = 8.6 Hz, 0.5 H, enol form), 7.46 (d,
J = 8.5 Hz, 1.5 H, keto form), 7.39 (d, J = 8.4 Hz, 0.5 H, enol form), 5.64
(s, 0.3 H, enol form), 3.98 (s, 1.5 H, keto form), 3.80 (s, 0.8 H, enol
form), 3.75 (s, 2.2 H, keto form). This data is consistent with previous-
ly reported data.30
13C NMR (125 MHz, CDCl3): δ = 185.2, 165.1, 160.9, 137.3, 132.9,
131.2, 131.0, 130.6, 113.2, 112.5, 82.8, 55.2, 51.6.
Phenyliodonium Ylide of Methyl (2-Anisoyl)acetate (4k)
General Procedure A was followed using 2′-methoxyacetophenone
(6.01 g, 40 mmol) to afford methyl (2-anisoyl)acetate (8.16 g, 98%) as
a red liquid. Rf 0.18 (EtOAc–hexanes, 20%; UV active).
Ylide formation using methyl (4-chlorobenzoyl)acetate (2.56 g, 12
mmol) gave the title compound (2.39 g, 48%) as a white amorphous
solid. This compound decomposed slightly during NMR analysis.
1H NMR (500 MHz, CDCl3): δ = 7.84 (d, J = 7.9 Hz, 2 H), 7.53 (t, J =
7.4 Hz, 1 H), 7.45 (s, 2 H), 7.38 (t, J = 7.8 Hz, 2 H), 7.29 (d, J = 8.3 Hz,
2 H), 3.49 (s, 3 H).
IR (ATR): 2950, 2842, 1738, 1669, 1597, 1485, 1463, 1485, 1242, 1161,
1019 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 7.88 (d, J = 7.8 Hz, 1 H), 7.51 (app. t, J =
7.5 Hz, 1 H), 7.03 (app. t, J = 7.3 Hz, 1 H), 6.97 (d, J = 8.4 Hz, 1 H), 3.98
(s, 2 H), 3.90 (s, 3 H), 3.72 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 184.8, 165.0, 137.9, 135.5, 133.4,
131.6, 131.5, 129.8, 127.6, 113.0, 100.1, 83.0, 51.9.
13C NMR (125 MHz, CDCl3): δ = 192.9, 168.6, 152.9, 134.8, 131.0,
130.9, 126.1, 120.8, 111.7, 111.4, 55.4, 52.0, 50.4.
Phenyliodonium of Methyl (2-Chlorobenzoyl)acetate (4i)
HRMS (ESI): m/z [M + H]+ calcd for C11H13O4: 209.0808; found:
209.0808.
General Procedure A was followed using 2′-chloroacetophenone (3.09
g, 20 mmol) to afford methyl (2-chlorobenzoyl)acetate (2.02 g, 48%)
as a red liquid in a 2:1 ratio of keto/enol tautomers. Rf 0.45 (EtOAc–
hexanes, 20%).
Ylide formation from methyl (2-anisoyl)acetate (2.50 g, 12 mmol).
The title compound (1.39 g, 28%) was isolated as a light-orange solid.
The product decomposed slightly during NMR analysis.
1H NMR (500 MHz, CDCl3): δ = 7.79 (d, J = 7.7 Hz, 2 H), 7.45 (t, J =
7.4 Hz, 1 H), 7.33 (t, J = 7.7 Hz, 2 H), 7.26 (t, J = 7.8 Hz, 1 H), 7.17 (dd,
J = 7.4, 1.4 Hz, 1 H), 6.93 (t, J = 7.4 Hz, 1 H), 6.87 (d, J = 8.3 Hz, 1 H),
3.77 (s, 3 H), 3.41 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 183.8, 165.0, 156.0, 137.6, 132.2,
131.6, 131.1, 129.5, 127.9, 120.4, 113.0, 110.8, 55.8, 51.9.
IR (ATR): 2953, 1743, 1698, 1626, 1589, 1471, 1434, 1245, 1201, 1038
cm–1
.
1H NMR (500 MHz, CDCl3): δ = 12.41 (s, 0.3 H, enol form), 7.64 (d, J =
7.7 Hz, 0.7 H, keto form), 7.60 (dd, J = 7.4, 1.7 Hz, 0.3 H, enol form),
7.48–7.46 (m, 1.7 H), 7.41–7.33 (m, 1.4 H), 5.60 (s, 0.3 H enol form),
4.09 (s, 1.4 H, keto form), 3.84 (s, 1.0 H, enol form), 3.77 (s, 2.1 H).
13C NMR (125 MHz, CDCl3): δ = 194.5, 173.0, 170.5, 167.4, 137.6,
133.5, 132.7, 132.1, 131.6, 131.2, 130.79, 130.63, 130.15, 130.05,
127.1, 126.9, 93.0, 77.4, 77.2, 76.9, 52.4, 51.6, 48.9.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–K