Reaction #51981

Reaction equation

2-{2-chloro-1-[(triisopropylsilyl)oxy]ethenyl}pyridine

NaHCO3

CH2Cl2

→

title compound

Yield 85.0%

2-chloro-1-pyridin-2-ylethanone

Yield 85.0%

Solvents

acetonitrile

Conditions

Workup

1. 1
   workup.ADDITIONTo the stirring solution is added 48% aqueous HF (170 mL, 0.45 mL/mmol)
2. 2
   Other2 hours
3. 3
   workup.ADDITIONThe mixture is poured into a separatory funnel
4. 4
   OtherThe organic phase is removed
5. 5
   Extractionthe aq. layer is extracted with CH2Cl2 (2×1.0 L)
6. 6
   OtherThe combined organic layers are dried
7. 7
   Concentration(Na2SO4), and concentration in vacuo

Procedure

Crude 2-{2-chloro-1-[(triisopropylsilyl)oxy]ethenyl}pyridine (117.3 g, 0.376 mol) is placed in a 4 L plastic bottle and is dissolved in acetonitrile (0.4 L). To the stirring solution is added 48% aqueous HF (170 mL, 0.45 mL/mmol) and the progress of the reaction is monitored by reverse phase analytical HPLC. After. Ca. 2 hours the reaction is judged to be complete, and the pH of the solution is carefully adjusted to ca. 8 with saturated aq. NaHCO3. The mixture is poured into a separatory funnel containing CH2Cl2 (1.5 L). The organic phase is removed and the aq. layer is extracted with CH2Cl2 (2×1.0 L). The combined organic layers are dried (Na2SO4), and concentration in vacuo affords the title compound (49.5 g, 85%) as a tan solid (after cooling). The crude material is judged to be quite pure by 1H-NMR and HPLC and is used as is in the Noyori asymmetric reduction.

Source