Reacción #2195513

Ecuación de reacción

Isocyanate

( 2 )

3-Fluoro-2-trimethylsilylbenzoic acid

NaN3

oxalylchloride

→

3-Fluoro-2-trimethylsilylphenyl isocyanate

Disolventes

CH2Cl2

H2O

acetone

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroThe residue obtained
2. 2
   Otroafter evaporation of the solvent
3. 3
   workup.ADDITIONwas diluted with THF (10 mL)
4. 4
   workup.STIRRINGwith vigorous stirring to a ice-
5. 5
   workup.WAITAfter 15 min at 0° C.
6. 6
   Extracción1 min at room temperature, the solution was extracted with Et2O (4×50 mL)
7. 7
   Secadodried (Na2SO4)
8. 8
   OtroThe residue obtained
9. 9
   Otroafter evaporation of solvents
10. 10
    Temperaturawas refluxed in toluene for 1 h 30
11. 11
    Otroto provide, upon solvent removal, 2.85 g (79%) of a slightly yellow oil

Procedimiento

Preparation of the Intermediate Isocyanate was carried out via a Curtius rearrangement. See Capson, T. L. et al., Tetrahedron Lett., 25, 3515 (1984) and references herein. To a solution of the compound prepared in (2) (3.03 g, 14.3 mmol) in CH2Cl2 (20 mL) was added oxalylchloride (1.30 mL, 15.0 mmol) and the resulting mixture was stirred 3 h at room temperature. The residue obtained after evaporation of the solvent was diluted with THF (10 mL) and injected with vigorous stirring to a ice-cooled solution of NaN3 (3.70 g, 57 mmol) in H2O (20 mL) and acetone (50 mL). After 15 min at 0° C. and 1 min at room temperature, the solution was extracted with Et2O (4×50 mL) and dried (Na2SO4). The residue obtained after evaporation of solvents was refluxed in toluene for 1 h 30 to provide, upon solvent removal, 2.85 g (79%) of a slightly yellow oil: IR (neat, cm−1) 2269, 1598, 1433, 1252, 1228, 846, 788; 1H NMR (300 MHz, CDCl3) δ 0.38 (d, J=1.9 Hz, 9 H), 6.82 (br t, J=8.3 Hz, 1 H), 6.90 (br d, J=8.2 Hz, 1 H), 7.25 (ddd, J1=J2=8.1 Hz, J3=6.6 Hz, 1 H); 13C NMR (75 MHz, CDCl3) δ 0.4, 112.6 (d, JCF=26 Hz), 120.5, 122.5, 131.5, 139.2, 167.4 (d, JCF=241 Hz).

Fuente