Checked by Rodolphe Tamion and Leon Ghosez.
1. Procedure
2. Notes
1. All glassware was flame-dried and allowed to cool in a desiccator before use.
2.
Potassium hydride (35% in mineral oil) and (−)-menthol (99%) were purchased from the Aldrich Chemical Company, Inc., and
butyllithium (2.5 M in hexanes) was obtained from Janssen Chimica.
4. Quenching the reaction at this stage with
methanol, followed by the work-up described below and bulb-to-bulb distillation (0.02 mm, oven temperature 60–80°C), gave
12.5 g (
90%) of
menthoxyacetylene as a colorless oil:
[α]25D −74° (
cyclohexane,
c 0.76); IR (film) cm
−1: 3340, 2960, 2940, 2870, 2150, 1450, 1370, 1100, 940, 890, 840;
1H NMR (200 MHz, CDCl
3) δ: 0.68–1.54 (m, 5 H; CH and CH
2), 0.81 (d, 3 H, J = 6.9, CH
3), 0.90 (d, 3 H, J = 7.0, CH
3), 0.94 (d, 3 H, J = 6.4, CH
3), 1.49 (s, 1 H, C

CH), 1.57–1.74 (m, 2 H), 2.00–2.33 (m, 2 H), 3.83 (app td, 1 H, J = 10.9, 4.5, CH-O-);
13C NMR (50.3 MHz, CDCl
3) δ: 16.3 (CH
3), 20.5 (CH
3), 22.0 (CH
3), 23.3 (CH
2), 25.9 (CH), 27.1 (C), 31.6 (CH), 33.9 (CH
2), 39.4 (CH
2), 46.7 (CH), 88.2 (CH), 89.7 (CH); mass spectrum (chemical ionization), m/e 181 (M
+ + 1, 5%), 156 (100%), 139 (58%); analytical TLC (
pentane): Rf 0.54 (single spot). Proton NMR confirmed the complete absence (<1%) of
menthol. Anal. Calcd for C
12H
20O: C, 79.94; H, 11.18. Found: 79.72; H, 10.98.
7. Data for
1-menthoxy-1-butyne are as follows:
[α]25D −78° (
cyclohexane,
c 0.69); IR (film) cm
−1: 2950, 2925, 2870, 2280, 1460, 1390, 1370, 1250, 1230, 1210, 980, 950, 910, 840;
1H NMR (200 MHz, CDCl
3) δ: 0.75–1.20 (m, 3 H, CH and CH
2), 0.80 (d, 3 H, J = 6.9, CH
3), 0.89 (d, 3 H, J = 7.1, CH
3), 0.93 (d, 3 H, J = 6.4, CH
3), 1.08 (t, 3 H, J = 7.5, CH
2CH
3), 1.27–1.51 (m, 2 H), 1.64 (br d, 2 H), 2.11 (q, 2 H, J = 7.5, CH
2CH
3), 2.12–2.25 (m, 2 H), 3.69 (app td, 1 H, J = 10.9, 4.5, CHO);
13C NMR (50.3 MHz, CDCl
3) δ: 11.0 (CH
2), 15.1 (CH
3), 16.2 (CH
3), 20.5 (CH
3), 21.9 (CH
3), 23.2 (CH
2), 25.7 (CH), 31.5 (CH), 34.0 (CH
2), 39.6 (2C: C and CH
2), 46.8 (CH), 86.9 (CH), 87.4 (C); mass spectrum (chemical ionization), m/e 209 (M
+ + 1, 4%), 156 (100%), 139 (26%); analytical TLC (
pentane): R
f 0.54 (single spot). Proton NMR indicated a complete absence (<1%) of both
menthol and
menthoxyacetylene. Anal. Calcd for C
14H
24O: C, 80.71; H, 11.61. Found: C, 80.70; H, 11.55.
9. The reaction was followed by IR analysis of worked-up aliquots (disappearance of band at 2280 cm
−1).
10. Data for
(Z)-1-menthoxy-1-butene are as follows:
[α]25D −18° (
cyclohexane,
c 0.11); IR (film) cm
−1: 3030, 2970, 2920, 2870, 1660, 1460, 1380, 1350, 1250, 1140, 1110, 1090, 1070, 1050;
1H NMR (200 MHz, CDCl
3) δ: 0.72–1.08 (m, 3 H, CH and CH
2), 0.80 (d, 3 H, J = 7.0, CH
3), 0.92 (d, 3 H, J = 7.1, CH
3), 0.93 (d, 3 H, J = 6.5, CH
3), 0.97 (t, 3 H, J = 7.5, CH
2CH
3), 1.22–1.46 (m, 2 H), 1.56–1.70 (m, 2 H), 1.85–2.21 (m, 4 H), 3.35 (app td, 1 H, J = 10.7, 4.3, CHOCH=CH), 4.32 (app q, 1 H, J = 7.1, OCH=CH), 5.97 (d, 1 H, J = 6.2, -OCH=CH);
13C NMR (50.3 MHz, CDCl
3) δ: 14.6 (CH
3), 16.5 (CH
3), 17.5 (CH
2), 20.7 (CH
3), 22.2 (CH
3), 23.6 (CH
2), 25.8 (CH), 31.5 (CH), 34.5 (CH
2), 41.6 (CH
2), 47.9 (CH), 81.3 (CH), 108.2 (CH), 143.6 (CH); mass spectrum (electron impact) m/e 210 (M
+, 14%), 138 (32%), 83 (100%); analytical TLC (
pentane): R
f 0.59 (major spot). Proton NMR indicated a complete absence (<1%) of
menthol,
menthoxybutyne, and
menthoxybutane, but the presence of ca. 3% of the E -isomer. Anal. Calcd for C
14H
26O: C, 79.94; H, 12.46. Found: C, 79.84; H, 12.55.
11.
Lithium aluminum hydride (95+%) was purchased from Janssen Chimica. Lesser amounts led to incomplete reaction under the stated conditions.
12.
CAUTION! Quenching should be performed very carefully as a rapid, exothermic evolution of hydrogen occurs during the initial phase. Flushing with argon throughout the quenching is recommended. Toward completion of the
sodium hydroxide addition, a thick slurry is produced, which makes stirring difficult. This difficulty is alleviated, however, upon the addition of water.
13.
Silica gel (70-230 mesh) was treated with
triethylamine (2.5% v/v) and then shaken to achieve homogeneity.
14. Data for
(E)-1-menthoxy-1-butene are as follows:
[α]25D −37° (
cyclohexane,
c 0.80); IR (neat) cm
−1: 2960, 2910, 2860, 1670, 1650, 1450, 1180, 1140, 920;
1H NMR (200 MHz, CDCl
3) δ: 0.71–1.08 (m, 3 H, CH and CH
2), 0.75 (d, 3 H, J = 7.0, CH
3), 0.87 (d, 3 H, J = 7.1, CH
3), 0.89 (d, 3 H, J = 6.5, CH
3), 0.94 (t, 3 H, J = 7.4, CH
2CH
3), 1.19–1.46 (m, 2 H), 1.54–1.70 (m, 2 H), 1.90 (app quint d, 2 H, J = 7.3, 1.3), 1.96–2.21 (m, 2 H), 3.36 (app td, 1 H, J = 10.6, 4.3, CHOCH=CH), 4.88 (dt, 1 H, J = 12.3, 7.0, OCH=CH), 6.06 (dt, 1 H, J = 12.3, 1.3, OCH=CH);
13C NMR (50.3 MHz, CDCl
3) δ: 15.2 (CH
3), 16.3 (CH
3), 20.8 (CH
3), 21.0 (CH
2), 22.2 (CH
3), 23.4 (CH
2), 25.7 (CH), 31.5 (CH), 34.4 (CH
2), 41.1 (CH
2), 47.8 (CH), 80.0 (CH), 107.5 (CH), 144.8 (CH); mass spectrum (electron impact), m/e 210 (M
+, 4%), 83 (100%), 69 (40%); analytical TLC (
pentane): R
f 0.53 (single spot). Proton NMR confirmed the complete absence (<1%) of
menthol,
menthoxybutyne,
menthoxybutane, and the Z-isomer. Anal. Calcd for C
14H
26O: C, 79.94; H, 12.46. Found: C, 79.91; H, 12.41.
All toxic materials were disposed of in accordance with "Prudent Practices in the Laboratory"; National Academy Press; Washington, DC, 1995.
3. Discussion
Appendix
Compounds Referenced (Chemical Abstracts Registry Number)
silica gel
sodium ketyl of benzophenone
(−)-Menthol
(Z)- AND (E)-1-MENTHOXY-1-BUTENE
[Cyclohexane, 2-(1-butynyloxy)-4-methyl-1-(1-methylethyl)-[1S-(1α,2β,4β)]-]
[[[Cyclohexane, 2-(1-butenyloxy)-4-methyl-1-(1-methylethyl)-, [1S-[1α,2β(Z),4β]]- and [1S-[1α,2β(E),4β]]-
calcium chloride (10043-52-4)
methanol (67-56-1)
diethyl ether (60-29-7)
ammonium chloride (12125-02-9)
hydrogen (1333-74-0)
sodium hydroxide (1310-73-2)
sodium sulfate (7757-82-6)
sodium thiosulfate (7772-98-7)
copper sulfate (7758-98-7)
cyclohexane (110-82-7)
barium sulfate (7727-43-7)
pyridine (110-86-1)
sodium (13966-32-0)
palladium (7440-05-3)
Pentane (109-66-0)
menthol (15356-60-2)
Ethyl iodide (75-03-6)
butyllithium (109-72-8)
Tetrahydrofuran (109-99-9)
lithium aluminum hydride (16853-85-3)
hexane (110-54-3)
trichloroethylene (79-01-6)
triethylamine (121-44-8)
calcium hydride (7789-78-8)
1-Adamantanol (768-95-6)
hexamethylphosphoric triamide,
hexamethylphosphoramide (680-31-9)
argon (7440-37-1)
2-cyclohexylethanol (4442-79-9)
decanol (112-30-1)
potassium hydride (7693-26-7)
dimethylpropyleneurea (7226-23-5)
1-Menthoxy-1-butyne (108266-28-0)
(E)-1-MENTHOXY-1-BUTENE,
(Z)-1-Menthoxy-1-butene (107941-62-8)
menthoxyacetylene
menthoxybutyne
menthoxybutane
adamantyloxyacetylene
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