gemꢀDifluoroꢀsubstituted organozinc reagent
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 11, November, 2016 2761
Scheme 3
(CH3); 80.5 (=СH2); 90.4 (t, CH, J = 33.1 Hz); 119.7 (t, CF2,
J = 240.9 Hz); 129.4 (C—CO2Me); 129.6 (CAr); 130.8 (CAr);
138.1 (t, CAr, J = 3.6 Hz); 167.0 (CO); 208.4 (t, =C=, J = 9.5 Hz).
19F NMR (282 MHz, CDCl3), δ: –88.7 (tdt, CF2, J = 15.3 Hz,
J = 8.7 Hz, J = 6.5 Hz). HRMS (ESI), found m/z: 239.0885.
C13H13F2O2. Calculated, m/z: 239.0878 [M + H].
4,4ꢀDifluoroheptaꢀ5,6ꢀdienꢀ1ꢀyl benzoate (3b). Yield 474 mg
(94%). Colorless oil. Rf 0.22 (hexane—EtOAc, 12 : 1). 1H NMR
(300 MHz, CDCl3), δ: 1.94—2.08 (m, 2 H, CH2); 2.09—2.25
(m, 2 H, CH2CF2); 4.36 (t, 2 H, CH2O, J = 6.2 Hz); 5.09 (dt, 2 H,
=CH2, J = 7.2 Hz, J = 6.5 Hz); 5.44 (tt, 1 H, CH, J = 7.9 Hz,
J = 7.2 Hz); 7.39—7.48 (m, 2 H, CHmeta); 7.51—7.60 (m, 1 H,
CHpara); 8.04 (dd, 2 H, CHortho, J = 8.1 Hz, J = 1.1 Hz). 13C {1H}
NMR (75 MHz, CDCl3), δ: 22.2 (t, CH2, J = 4.2 Hz); 33.6
(t, CH2CF2, J = 26.3 Hz); 64.1 (CH2O); 80.2 (=CH2); 90.5 (t, CH,
J = 33.8 Hz); 121.1 (t, CF2, J = 238.5 Hz); 128.4 (CAr);
129.6 (CAr); 130.2 (С—CO2); 133.0 (CAr); 166.5 (CO); 208.3
(t, =CH2=, J = 10.1 Hz). 19F NMR (282 MHz, CDCl3), δ:
–90.1 (dtt, CF2, J = 7.9 Hz, J = 7.6 Hz, J = 6.5 Hz). HRMS
(ESI), found m/z: 275.0859. C14H14F2O2Na. Calculated, m/z:
275.0854 [M + Na].
(1,1ꢀDifluorobutaꢀ2,3ꢀdienꢀ1ꢀyl)(trimethyl)silane (5). DMF
(30.0 mmol, 4.65 mL), propargyl chloride (15.8 mmol, 1.15 mL),
and copper cyanide (0.75 mmol, 67.5 mg) were added to reagent 4
(15.0 mmol, 19.2 mL 0.78 M in diglyme) at 0 °C. The suspension
obtained was warmed to ~20 °C under stirring during next 2 h
followed by stirring at ~20 °C for additional 12 h. The product
was separated by recondensation in vacuo (7 Torr) using a liquid
nitrogen trap. The liquid obtained was dissolved in pentane
(10 mL), washed with water (5×10 mL), and filtered through
Na2SO4. Pentane was evaporated under atmospheric pressure
and the residue was distilled in vacuo, b.p. 80—82 °С (100 Torr).
Yield 1.63 g (67%). 1H NMR (300 MHz, CDCl3), δ: 0.20 (s, 9 H,
SiMe3); 5.05 (td, 2 H, CH2, J = 8.2 Hz, J = 6.9 Hz); 5.40 (tt,
1 H, CH, J = 12.7 Hz, J = 6.9 Hz). 13C {1H} NMR (75 MHz,
CDCl3), δ: 4.4 (t, SiMe3, J = 1.7 Hz); 79.4 (t, CH2, J = 2.2 Hz);
90.7 (t, CH, J = 26.6 Hz); 125.6 (t, CF2, J = 259.9 Hz); 208.5
(t, =С=, J = 12.9 Hz). 19F NMR (282 MHz, CDCl3), δ: –107.2
(td, CF2, J = 12.7 Hz, J = 8.2 Hz). Found (%): C, 52.04; H, 7.43.
C7H12F2Si (162.25). Calculated (%): C, 51.82; H, 7.45.
tuted allenes, hardly accessible by other methods, can be
readily obtained.
Experimental
All reactions were performed under dry argon. DMF was
purified by vacuum distillation from P2O5 and was kept under
MS 4Å. MeCN was purified by successive distillations from P2O5
1
and CaH2, and was kept under MS 3Å. H, 13C and 19F NMR
spectra were recorded on Bruker AM300 spectrometer. Highꢀ
resolution electrospray ionization (ESI) mass spectra were meaꢀ
sured on a Bruker micrOTOF II instrument.13 Starting comꢀ
pounds Me3SiCF2Br,14 1a,b,7a and 412 were prepared according
to the literature procedures.
Synthesis of allenes 3 (general procedure). Anhydrous sodiꢀ
um acetate (197 mg, 2.4 mmol) was placed in a flask and heated
at 150 °С for 15 min. Then the flask was cooled to room temperꢀ
ature and filled with argon. Organozinc reagent 1 (2.0 mmol in
THF) was added and the suspension formed was concentrated in
vacuo to get a viscous oil. The mixture was diluted with MeCN
(2.0 mL) and cooled to –25 °С. Me3SiCF2Br (487 mg, 2.4 mmol)
was added dropwise and the reaction mixture was stirred at
–25 °С for 18 h. After that DMF (0.31 mL, 4.0 mmol), propꢀ
argyl bromide (4.8 mmol, 0.53 mL, 80% solution in toluene)
and copper cyanide (0.2 mmol, 18 mg) were added. The coolꢀ
ing bath was replaced by a cold water bath (3—5 °С) and
the mixture was allowed to warm up to room temperature during
next 2 h and then stirred at ∼20 °C for additional 12 h. The
reaction was quenched with HCl (8 mL, 0.5 M water soluꢀ
tion) and the product was extracted with ethyl acetate (3×5 mL).
The organic phase was dried over Na2SO4 and concentrated in
vacuo. Product was purified by column chromatography on
silica gel.
This study was financially supported by the Ministry of
Education and Science of the Russian Federation (Project
MKꢀ6724.2016.3) and the Russian Foundation for Basic
Research (Project No. 14ꢀ03ꢀ00293).
References
1. D. J. Burton, Z.ꢀY. Yang, Tetrahedron, 1992, 48, 189.
2. V. P. Ananikov, L. L. Khemchyan, Y. V. Ivanova, V. I.
Bukhtiyarov, A. M. Sorokin, I. P. Prosvirin, S. Z. Vatsadze,
A. V. Medved´ko, V. N. Nuriev, A. D. Dilman, V. V. Levin,
I. V. Koptyug, K. V. Kovtunov, V. V. Zhivonitko, V. A.
Likholobov, A. V. Romanenko, P. A. Simonov, V. G. Nenajꢀ
denko, O. I. Shmatova, V. M. Muzalevskiy, M. S. Nechaev,
A. F. Asachenko, O. S. Morozov, P. B. Dzhevakov, S. N.
Osipov, D. V. Vorobyeva, M. A. Topchiy, M. A. Zotova,
S. A. Ponomarenko, O. V. Borshchev, Y. N. Luponosov, A. A.
Rempel, A. A. Valeeva, A. Y. Stakheev, O. V. Turova, I. S.
Mashkovsky, S. V. Sysolyatin, V. V. Malykhin, G. A. Bukhtiꢀ
Methyl 4ꢀ(2,2ꢀdifluoropentaꢀ3,4ꢀdienꢀ1ꢀyl)benzoate (3a).
Yield 438 mg (92%). Colorless oil. Rf 0.23 (hexane—EtOAc,
12 : 1). 1H NMR (300 MHz, CDCl3), δ: 3.32 (t, 2 H, CH2,
J = 15.3 Hz); 3.91 (s, 3 H, CH3); 5.05 (td, 2 H, =CH2, J = 6.5 Hz,
J = 6.3 Hz); 5.38 (tt, 1 H, CH, J = 8.7 Hz, J = 6.3 Hz); 7.36 (d, 2 H,
CHAr, J = 8.2 Hz); 7.99 (d, 2 H, CHAr, J = 8.2 Hz). 13C {1H}
NMR (75 MHz, CDCl3), δ: 43.5 (t, CH2, J = 26.9 Hz); 52.2