Organoalanes interactions in CH2Cl2 media
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 4, April, 2003
1007
3ꢀ(3ꢀMethylꢀ1ꢀphenylbutoxy)butanꢀ1ꢀol (13) was separated
by chromatography on a column with silica gel (40/100 µm),
hexane—AcOEt (4 : 1) as the eluent. B.p. 125 °C (1 Torr),
nD 1.4551. Found (%): C, 76.28; H, 10.25. Calculated (%):
C, 76.23; H, 10.24.
formates by trialkylalanes under mild conditions in high
yields. The 1H NMR spectroscopic data provide evidence
for the formation of associates of Bui3Al with CH2Cl2 and
ClCH2CH2Cl.
20
3ꢀ(3ꢀMethylꢀ1ꢀphenylbutoxy)butanꢀ1ꢀol (13a). 1H NMR
(CDCl3), δ: 0.85 (d, 6 H, CH3CH, J = 6.5 Hz); 1.00 (d, 3 H,
CH3CHO, J = 6.2 Hz); 1.53 (m, 1 H, CH3CH); 1.48—1.80 (m,
4 H, CHCH2); 3.00 (br.s, 1 H, OH); 3.70 (m, 1 H, CH3CHO);
3.75 (m, 2 H, CH2OH); 4.39 (t, 1 H, CH—Ar, J = 6.2 Hz, J =
7.6 Hz); 7.22 (m, 5 H, Ar). 13C NMR (CDCl3), δ: 20.8
(CH3CH); 22.5 and 22.9 (CH3CH); 24.4 (CH3CH); 38.0
(CHCH2CH2); 47.5 (CHCH2CH); 60.0 (CH2OH); 73.2
(CH3CHO); 79.0 (CH—Ar); 126.6 (CH, Ar); 128.2 (CH, Ar);
127.3 (CH, Ar); 144.1 (C, Ar).
3ꢀ(3ꢀMethylꢀ1ꢀphenylbutoxy)butanꢀ1ꢀol (13b). 1H NMR
(CDCl3), δ: 0.85 (d, 6 H, CH3CH, J = 6.5 Hz); 1.15 (d, 3 H,
CH3CHO, J = 6.2 Hz); 1.53 (m, 1 H, CH3CH); 1.48—1.80 (m,
4 H, CHCH2); 3.00 (br.s, 1 H, OH); 3.56 (m, 1 H, CH3CHO);
3.60 (m, 2 H, CH2OH); 4.45 (t, 1 H, CH—Ar, J = 6.2 Hz, J =
7.6 Hz); 7.22 (m, 5 H, Ar). 13C NMR (CDCl3), δ: 18.0
(CH3CH); 22.2 and 23.1 (CH3CH); 24.5 (CH3CH); 38.5
(CHCH2CH2); 47.0 (CHCH2CH); 61.0 (CH2OH); 70.1
(CH3CHO); 76.5 (CH—Ar); 126.9 (CH, Ar); 128.5 (CH, Ar);
127.7 (CH, Ar); 142.7 (C, Ar).
Reactions of orthoformates with trialkylalanes (general proꢀ
cedure). A solution of Bui3Al or Et3Al (20 mmol) was added
dropwise to a solution of orthoester (20 mmol) in a chlorineꢀ
containing solvent (80 mmol) at –20 °C. The reaction mixture
was warmed to 20 °C and stirred at this temperature for 2 h.
Then the reaction mixture was cooled to –20 °C and decomꢀ
posed with a 10% aqueous solution of NaOH (20 mL). The
organic layer was separated, dried with MgSO4, and analyzed by
GLC using heptane as the internal standard. The yields of the
reaction products are given in Table 1.
Experimental
The 1H and 13C NMR spectra were recorded on a Bruker
AMꢀ300 spectrometer in CDCl3, C6D12, and C6D6 with Me4Si
as the internal standard. The GLCꢀmass spectra were obtained
on a Hewlett Packard 5890 instrument (evaporator temperature
was 280 °C, linear programming of the thermostat temperature
from 50 to 280 °C with a rate of 5 °C min–1, 50 m×0.25 mm
Ultra capillary column, helium as the carrier gas, energy of
ionizing electrons was 70 eV). The GLC analysis was carried out
on a Chromꢀ5 chromatograph (flame ionization detector,
1200×5 mm stainless steel column, 5% SEꢀ30 on Inerton
NꢀAW DMCS (0.125—0.160), helium as the carrier gas).
The experiments were carried out under dry argon. The
solvents CH2Cl2 and ClCH2CH2Cl were distilled from P2O5
under argon immediately before use. Triethylꢀ and triisoꢀ
butylaluminum were purchased from the Redkinskii pilotꢀproꢀ
duction plant (Russia). The starting acetals 1—3 and orthoꢀ
formates 4 and 5 were synthesized according to known proceꢀ
dures,13,19,20 distilled under a stream of argon over NaOH, and
stored under an inert atmosphere.
1
cisꢀ4ꢀMethylꢀ2ꢀphenylꢀ1,3ꢀdioxane (3). H NMR (CDCl3),
δ: 1.35 (d, 3 H, CH3, J = 6.2 Hz); 1.56 (dq, 1 H, CH2, J =
–14.5 Hz, J = 1.3 Hz); 1.84 (ddt, 1 H, CH2, J = –14.5 Hz, J =
12.9 Hz, J = 5.1 Hz); 4.00 (m, 2 H, CHO and CH2O); 4.28 (dd,
1 H, CH2O, J = –11.5 Hz, J = 5.1 Hz, J = 1.3 Hz); 5.54 (s, 1 H,
OCHO); 7.30—7.60 (m, 5 H, Ar). 13C NMR (CDCl3), δ:
23.0 (CH3); 32.5 (CH2); 66.3 (CH2O); 73.0 (CHO); 101.4
(O—CH—O); 124.0—140.0 (CH and C, Ar).
Propionaldehyde diethylacetal (14), propionaldehyde diꢀ
butylacetal (15), isovaleraldehyde diethylacetal (16), and
isovaleraldehyde dibutylacetal (17) were identified by comparꢀ
ing with samples synthesized according to a procedure described
earlier.25
The vicinal spinꢀspin coupling constant between the H(4)
and H(5a) protons (12.9 Hz) is indicative of the axial orientaꢀ
tion of the H(4) proton and, consequently, of the equatorial
orientation of the Me substituent at the C(4) atom. The fact that
the equatorial orientation of the Ph substituent in the second
position is preferential one was established based on the direct
spinꢀspin coupling constant JC(2),H(2) = 159.3 Hz and taking
into account that this constant increased by 1 Hz as the temꢀ
perature of the sample was increased by 55 °C.21
Reactions of cyclic acetals with trialkylalanes (general proceꢀ
dure). Trialkylalane (20 or 40 mmol) was added dropwise to a
solution of cyclic acetal (20 mmol) in a chlorineꢀcontaining
solvent (80 mmol) stirred at 0 °C. The temperature of the reacꢀ
tion mixture was increased to 20 °C. The reaction mixture was
stirred at this temperature for 2 h, diluted with Et2O (20 mL),
cooled to –10 °C, and decomposed with a 5% aqueous solution
of NaOH (40 mL). The organic layer was separated, dried with
MgSO4, and analyzed by GLC. The yields of the reaction prodꢀ
ucts are given in Table 1.
This study was financially supported by the by the
Russian Foundation for Basic Research, the Program
"Government Support of Integration of the Higher School
and Basic Research" (Project No. 425).
References
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3. A. A. Volkov, S. S. Zlotskii, E. Kh. Kravets, and D. L.
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USSR, 1986, 22 (Engl. Transl.)].
4. O. S. Vostrikova, Yu. T. Gafarova, V. A. Dokichev, and S. S.
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2ꢀMethoxyethanol (6), 2ꢀbenzyloxyethanol (7), 3ꢀbenzylꢀ
oxybutanꢀ1ꢀol (8), 2ꢀ(3ꢀmethylbutoxy)ethanol (9), 2ꢀ(1ꢀphenylꢀ
propoxy)ethanol (10), 3ꢀ(1ꢀphenylpropoxy)butanꢀ1ꢀol (11), and
2ꢀ(3ꢀmethylꢀ1ꢀphenylbutoxy)ethanol (12) were identified by
comparing their physicochemical constants with the published
data.3,4,22—24