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Organic & Biomolecular Chemistry
(CDCl3, 400 MHz) δ (ppm): 4.94–4.84 (m, 1H), 4.21 (t, J =
4,4,6-Trimethyl-1,3-dioxan-2-one. The product (8a) was puri-
6.3 Hz, 2H), 3.78 (s + s, 6H), 2.05–1.87 (m, 2H), 1.32 (d, J = fied by sublimation at reduced pressure (∼100 °C@200 Pa)
6.3 Hz, 3H). 13C NMR (CDCl3, 400 MHz) δ (ppm): 150.6, after the reaction carried out under the conditions of entry 6
150.1, 67.0, 59.2, 49.6, 49.4, 30.0, 14.9.
in Table 3. The isolated yield was 95%. GC-purity was >99%
2-Methyl propane-1,3-diyl dimethyl dicarbonate. The (white solid). Mass spectrum (70 eV), m/z: 144 (M+ < 1%), 87
product (5c) was purified by distillation at reduced pressure (2), 86 (2), 85 (37), 83 (4), 69 (3), 67 (6), 59 (35), 58 (9), 57 (28),
1
isolated (70 °C@100 Pa) after the reaction carried out under 56 (100), 55 (12), 53 (4). H NMR (CDCl3, 400 MHz) δ (ppm):
the conditions of Fig. 4 (bottom). The isolated yield was 75%. 4.63 (dqd, J1 = 12.4, J2 = 6.2, J3 = 3.2 Hz, 1H), 1.85 (ddd, J1 =
GC-purity was >99% (colourless liquid). Mass spectrum (70 26.1, J2 = 14.2, J3 = 7.6 Hz, 2H); 1.46 (s, 6H); 1.41 (d, J = 6.2 Hz,
eV), m/z: 206 (M+ < 1%), 135 (3), 130 (8), 117 (5), 102 (1), 98 (4), 3H). 13C NMR (CDCl3, 100 MHz) δ (ppm): 149.5, 80.9, 72.3,
91 (23), 87 (5), 86 (4), 85 (3), 77 (19), 73 (3), 72 (6), 71 (100), 59 40.5, 29.9, 26.5, 21.1. Anal. Calcd for C7H12O3: C, 58.32; H,
(60), 57 (4), 56 (4), 55 (35), 54 (14), 47 (11), 45 (47), 43 (11), 42 8.39. Found: C, 58.38; H, 8.44.
(20), 41 (29), 39 (13). 1H NMR (CDCl3, 400 MHz) δ (ppm):
4-Hydroxy-4-methylpentan-2-yl
methyl
carbonate. The
4.11–4.08 (m, 4H), 3.78 (s, 6H), 2.31–2.16 (m, 1H), 1.02 (d, J = product (8b) was obtained by the following procedure. A
7.0 Hz, 3H). 13C NMR (CDCl3, 100 MHz) δ (ppm): 155.5, 68.8, mixture of 8 (11 mmol), DMC (18.5 mL), and [P8,8,8,1][OCO2Me]
54.5, 32.4, 13.2. Anal. Calcd for C8H14O6: C, 46.60; H, 6.84. in a 1 : 20 : 0.005 molar ratio, respectively, was set to react at
Found: C, 46.55; H, 6.87.
90 °C, for 10 min. Then, aq. HCl (5%, 1 mL) was added. DMC
3-Hydroxy-2-methylpropyl methyl carbonate. The product and methanol were removed at reduced pressure. The resulting
(5b) was obtained by the following procedure. A mixture of 5 oily mixture was subjected to FCC on silica gel (eluant: diethyl
(991 mg, 11 mmol), DMC (18.5 mL), and [P8,8,8,1][OCO2Me] in ether). The title compound (8b) was so isolated as a colorless
a 1 : 20 : 0.005 molar ratio, respectively, was set to react at liquid (10%). Mass spectrum (70 eV), m/z: 176 (M+ < 1%), 119
90 °C, for 10 min. Then, aq. HCl (5%, 1 mL) was added. DMC (4), 85 (23), 83 (5), 77 (25), 67 (4), 59 (100), 58 (5), 57 (6), 55 (5),
and methanol were removed at reduced pressure. The resulting 45 (8), 43 (69), 42 (12), 41 (15). 1H NMR (CDCl3, 400 MHz)
oily mixture was subjected to FCC on silica gel (eluant: diethyl δ (ppm): 5.07–4.98 (m, 1H), 3.77 (s, 3H), 1.92 (dd, J = 15.0,
ether). The title compound (5b) was so isolated as a colorless 8.6 Hz, 1H), 1.65 (dd, J = 15.0, 3.4 Hz, 1H), 1.32 (d, J = 6.3 Hz,
liquid (12%). Mass spectrum (70 eV), m/z: 148 (M+ < 1%) 77 3H), 1.25 (s, 3H), 1.24 (s, 3H). 13C NMR (CDCl3, 100 MHz)
(100%), 73 (4), 72 (8), 71 (13), 59 (21), 57 (24), 55 (17), 45 (19), δ (ppm): 155.3, 73.0, 69.8, 54.5, 48.8, 29.8, 29.7, 21.6. Anal.
43 (19), 42 (35), 41 (31), 40 (4), 39 (16). 1H NMR (CDCl3, Calcd for C8H16O4: C, 54.53; H, 9.15. Found: C, 54.58; H, 9.19.
400 MHz) δ (ppm): 4.22–4.06 (m, 2H), 3.78 (s, 3H), 3.63–3.48
Butane-1,4-diyl dimethyl dicarbonate.19 The product (9c)
(m, 2H), 2.10–1.97 (m, 1H), 0.97 (d, J = 7.0 Hz, 1H). 13C NMR was isolated at the end of a reaction carried out by using a
(CDCl3, 100 MHz) δ (ppm): 156.1, 69.8, 64.1, 54.7, 35.4, 13.4. mixture of 9 (11 mmol, 1.00 g), DMC (220 mmol, 18.5 mL),
Anal. Calcd for C6H12O4: C, 48.64; H, 8.16. Found: C, 48.59; and 1a (0.05 mmol, 0.027 g). Once the transesterification was
H, 8.20.
complete (90 °C, 4 hours), the excess of DMC and the co-
Propane-1,3-diyl dimethyl dicarbonate.22 The product (6c) product methanol removed by rotary evaporation. The final
was purified by distillation at reduced pressure (80 °C@200 Pa) product was then distilled at reduced pressure (65 °C@80 Pa).
after the reaction carried out under the conditions of entry 2 To avoid the solidification of the distillate, the condenser was
in Table 3. The isolated yield was 85%. GC-purity was >99% kept at 50 °C throughout the distillation. The title compound
(colourless liquid). Mass spectrum (70 eV), m/z: 192 (M+ < 1%) 9c quickly solidified on standing at rt. (72%, white solid; mp:
135 (3), 117 (11), 116 (14), 103 (6), 91 (51), 77 (21), 73 (16), 59–60 °C). GC-purity was >99%. Mass spectrum (70 eV), m/z:
72 (50), 71 (34), 59 (100), 58 (4), 57 (46),55 (3), 47 (15), 45 (86), 206 (M+ < 1%), 135 (14), 131 (5), 130 (8), 117 (19), 103 (4), 102
44 (4), 43 (12), 42 (21), 41 (47), 39 (10). 1H NMR (CDCl3, (66), 91 (42), 77 (41), 71 (31), 59 (73), 58 (28), 57 (4), 59 (73), 58
400 MHz) δ (ppm): 4.24 (t, J = 6.2 Hz, 4H), 3.78 (s, 6H), 2.04 (p, (28), 57 (4), 56 (4), 55 (63), 54 (100). 1H NMR (CDCl3, 400 MHz)
J = 6.2 Hz, 2H). 13C NMR (CDCl3, 100 MHz) δ (ppm): 155.4, δ (ppm): 4.20–4.13 (m, 4H), 3.77 (s, 6H), 1.79–1.74 (m, 4H). 13
C
64.0, 54.5, 27.8.
2,2-Dimethyl propane-1,3-diyl dimethyldicarbonate. The
NMR (CDCl3, 100 MHz) δ (ppm): 155.7, 67.3, 54.7, 25.1.
Hexane-1,6-diyl dimethyl dicarbonate. The product (10c)
product (7c) was purified by distillation at reduced pressure was isolated at the end of a reaction carried out by using a
(68 °C@200 Pa) after the reaction carried out under the con- mixture of 10 (11 mmol, 1.30 g), DMC (220 mmol, 18.5 mL)
ditions of entry 4 in Table 3. The isolated yield was 70%. GC- and 1a (0.05 mmol, 0.027 g). Once the transesterification was
purity was >99% (colourless liquid). Mass spectrum (70 eV), complete (90 °C, 4 hours), the excess of DMC and the co-
m/z: 220 (M+ < 1%), 135 (3), 132 (6), 131 (84), 91 (9), 87 (44), 85 product methanol removed by rotary evaporation. The final
(25), 77 (14), 74 (4), 71 (11), 69 (51), 68 (64), 67 (6), 59 (68), 57 product was then distilled at reduced pressure (66 °C@80 Pa).
(6), 56 (22), 55 (100), 53 (5), 45 (38), 43 (10), 41 (35), 39 (12). 1H To avoid the solidification of the distillate, the condenser was
NMR (CDCl3, 400 MHz) δ (ppm): 3.97 (s, 4H), 3.78 (s, 6H), 1.00 kept at 50 °C throughout the distillation. The title compound
(s, 6H). 13C NMR (CDCl3, 100 MHz) δ (ppm): 155.5, 72.3, 54.6, 10c quickly solidified on standing at rt. (78%, white solid; mp:
34.8, 21.2. Anal. Calcd for C9H16O6: C, 49.09; H, 7.32. Found: 50–51 °C). GC-purity was >99%. Mass spectrum (70 eV), m/z:
C, 49.15; H, 7.27.
234 (M+ < 1%) 130 (2), 117 (5), 99 (4), 91 (9), 83 (35), 82 (100),
4154 | Org. Biomol. Chem., 2014, 12, 4143–4155
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