REACTION OF GRIGNARD COMPOUNDS WITH 4-CHLORO-2-METHYL-3-BUTYN-2-OL
7
appear as a singlet at 1.50 ppm, and the singlet at
4.31 ppm belongs to the hydroxy proton. In the
1H NMR spectrum of XVI we observed signals from
4.0 g (0.166 mol) of metallic magnesium, 1.5 ml of
THF, and 30 ml of benzene. When a reaction started,
5.5 ml (5.9 g, 0.05 mol) of 4-chloro-2-methyl-3-
butyn-2-ol, 16.9 ml (20.40 g, 0.135 mol) of pentyl
bromide, and 11 ml of THF in 60 ml of benzene were
simultaneously added dropwise at 50 65 C over
a period of 3 h. The mixture was heated for 4 h at that
temperature and decomposed with 3% hydrochloric
acid on cooling. The organic phase was separated
and dried over magnesium sulfate, and volatile com-
pounds were distilled off. Vacuum distillation of
the residue at 93 95 C (12 mm) gave 4.25 g (55.2%)
of 2-methyl-3-nonyn-2-ol, n2D0 1.4465; published data
[4]: bp 94 96 C (10 mm), n2D2 1.4489.
aromatic protons at
6.95 7.20 ppm and hydroxy
group at 4.53 ppm. Protons of the methyl groups
attached to the carbinol moiety appear at 1.59 ppm,
and the aromatic methyl group protons give a singlet
at 2.38 ppm. According to the GLC data, the purity
of XVI was 94.3% after single distillation.
EXPERIMENTAL
The IR spectra were obtained from thin films or
1
KBr discs using a UR-20 spectrometer. The H NMR
spectra were recorded on a Tesla BS-587A instrument
operating at 80 MHz; cyclohexane-d12 was used as
solvent, and TMS, as internal reference. GLC was
performed on a Khrom-5 chromatograph; flame-
ionization detector; 3.5-m glass column; stationary
phase 3% of SP2100 on Chromaton N-AW-DMCS;
carrier gas helium.
Initial 4-chloro-2-methyl-3-butyn-2-ol was syn-
thesized by treatment of 2-methyl-3-butyn-2-ol with
sodium hypochlorite at room temperature. Unlike the
procedure reported in [9] which employs diethyl ether,
we used benzene as solvent. As a result, the process
was simplified, and the target product was isolated
in 90% yield.
2,5-Dimethyl-3-hexyn-2-ol (I). 4-Chloro-2-methyl-
3-butyn-2-ol, 5.9 g (0.05 mol), was added dropwise
with stirring to the Grignard compound obtained from
7.2 g (0.23 mol) of metallic magnesium and 18.5 g
(0.15 mol) of isopropyl bromide in benzene containing
10.8 g (0.15 mol) of THF. The mixture was heated
for 5 h at 60 C and decomposed with 3% hydro-
chloric acid on cooling. The organic phase was dried
over magnesium sulfate and evaporated, and the
residue was distilled at 145 147 C to isolate 3.8 g
(60.3%) of 2,5-dimethyl-3-hexyn-2-ol, n2D0 1.4425;
Compounds III, VII, and X were synthesized in
a similar way. Products III, V, and VII were also
obtained by the same procedure but with a twofold
excess of magnesium. The yields are given in table.
2-Methyl-4-(3-tolyl)-3-butyn-2-ol
(XVI).
3-Bromotoluene, 1.8 ml (2.56 g, 0.015 mol), was
added to a mixture of 4 g (0.16 mol) of metallic
magnesium, 30 ml of anisole, and 1.2 ml of THF.
When a reaction started, 5.5 ml (5.9 g, 0.05 mol) of
4-chloro-2-methyl3-butyn-2-ol, 15.9 ml (23.1 g,
0.135 mol) of 3-bromotoluene, and 11 ml of THF in
40 ml of anisole were simultaneously added in
a dropwise manner at 40 45 C over a period of 3 h.
The mixture was heated for 4 h at that temperature
and decomposed with 3% hydrochloric acid on
cooling. The organic phase was separated and dried
over magnesium sulfate, and volatile fractions were
distilled off. Vacuum distillation of the residue at
105 108 C (3 mm) gave 5.5 g (63.2%) of 2-methyl-4-
(3-tolyl)-3-butyn-2-ol, n2D0 1.5498; published data [4]:
bp 92 93.5 C (1.5 mm), n1D6.5 1.5485.
Compounds XIV, XV, XVII, and XVIII were
synthesized by a similar procedure and with similar
yields. In the reaction of phenylmagnesium bromide
with 4-chloro-2-methyl-3-butyn-2-ol in toluene we
isolated a fraction containing 41.8% (GLC) of the
corresponding arylacetylenic alcohol and 58.2% of
biphenyl (overall yield 83.8%, calculated on the
expected 2-methyl-4-phenyl-3-butyn-2-ol).
1-Decyne (IX). Octyl bromide, 5.2 ml (5.80 g,
0.03 mol), was added to a mixture of 6.0 g (0.25 mol)
of metallic magnesium, 60 ml of benzene, and 1.5 ml
of THF. When a reaction started, 8.3 ml (8.9 g,
0.075 mol) of 4-chloro-2-methyl-3-butyn-2-ol, 34.4 ml
(38.60 g, 0.20 mol) of octyl bromide, and 16 ml of
THF in 80 ml of benzene were simultaneously added
dropwise at 50 65 C over a period of 3 h. The mix-
ture was heated for 4 h at that temperature and was
published data [4]: bp 48 50 (12 mm) n2D0 1.4411.
Compounds II IV were synthesized in a similar way;
their yields are given in table.
2,7-Dimethyl-3-octyn-2-ol (IV). bp 71 73 C
(4 mm), n2D0 1.4460, d240 0.8451. Found, %: C 77.84;
H 11.72. C10H18O. Calculated, %: C 77.92; H 11.69.
Reaction of tert-butylmagnesium chloride with
4-chloro-2-methyl-3-butyn-2-ol. The reaction was
carried out as described above for isopropyl bromide.
As a result, 1.9 g (33.3%) of the initial alcohol was
recovered from the reaction mixture.
2-Methyl-3-nonyn-2-ol (V). Pentyl bromide,
3.8 ml (2.25 g, 0.015 mol), was added to a mixture of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 1 2001