Sulfuryl fluoride

To each of
the two duplicate Parr autoclave reactors fitted with Teflon inlays
(30 mL total volume) were added Ru/C (5 wt % Ru, 75 mg), Birch sawdust
(500 mg), and MeOH (10 mL). The reactors were closed, evacuated five
times with H₂, and subjected to a H₂ pressure
of 30 bar at room temperature. The autoclaves were then stirred at
250 °C for 16 h and thereafter filtered through celite into a
round-bottom flask, rinsed with EtOAc, and concentrated in
vacuo. EtOAc (25 mL) was added to the concentrate followed
by sonification for 5 min. Pentane (25 mL) was then introduced, whereafter
the mixture was passed through a short silica dry column (5 cm silica),
rinsing with EtOAc/pentane (1:1, 50 mL) into a cone-shaped flask (100
mL). The concentrate was used in the subsequent step without further
purification. Quantification via GC-MS using dodecane
as an internal standard was carried out for the monomer products,
2-methoxy-4-propylphenol 1 (13.9 mg) and 2,6-dimethoxy-4-propylphenol 2 (51.3 mg). This provides a reaction scale of 0.345 mmol
for the subsequent fluorosulfation and cyanation reaction steps.
To chamber A of a two-chamber reactor (20 mL total volume) were added
K₂CO₃ (143 mg, 1.03 mmol, 3.0 equiv) and the
concentrate from the prior hydrogenolysis reaction (Step I), which
was transferred with MeCN (4 mL × 1 mL). The chamber was sealed
with a screwcap fitted with a Teflon-coated silicone seal. 1,1′-Sulfonylbis(1H-imidazole) (205 mg, 1.03 mmol, 3.0 equiv) and KF (160
mg, 2.76 mmol, 8.0 equiv) were added to chamber B of the two-chamber
reactor. The chamber was sealed with a screwcap fitted with a pierceable
Teflon-coated silicone seal. Trifluoroacetic acid (0.5 mL) was then
added to the closed chamber B via the Teflon-coated
silicone seal and sulfuryl fluoride release was observed within a
minute. The reactor was stirred at room temperature for 16 h, after
which the reaction mixture was passed through celite into a cone-shaped
flask and concentrated in vacuo. Qualitative GC-MS
analysis showed a full conversion of 1 and 2 to aryl fluorosulfates 3 and 4 (see the
SI, Figure S4). The concentrate was used
in the subsequent step without further purification.
In an argon-filled
glovebox, Pd–XPhos–G4 (14.8 mg,
0.017 mmol, 5 mol %), K₂CO₃ (143 mg, 1.03 mmol,
3.0 equiv.), and KCN (33.7 mg, 0.517 mmol, 1.5 equiv) were added to
a pressure tube (9 mL total volume). The concentrate from the prior
fluorosulfation reaction (Step II) was also transferred to the tube
with MeCN (2 mL × 1 mL) and 2-MeTHF (2 mL × 1 mL). The chamber
was sealed with a screwcap fitted with a Teflon-coated silicone seal
and stirred at 70 °C for 16 h. The reaction mixture was then
evaporated onto celite and purified by flash column chromatography
to yield aryl nitrile products 5 (13.6 mg, 5.4 wt %)
as a colorless liquid (eluted with pentane to pentane/EtOAc 95:5)
and 6 (44.4 mg, 18 wt %) as a colorless crystalline solid
(eluted with Pentane/EtOAc 80:20).