Reaction #50023

Reaction equation

trimethyl orthoformate

L-Proline

sulfuryl chloride

→

product

L-Proline Methyl Ester Hydrochloride

Solvents

methanol

Conditions

Workup

1. 1
   workup.WAITAfter 16 hours at room temperature
2. 2
   Temperatureanother 4 hours at reflux
3. 3
   Temperatureheating
4. 4
   Temperatureat reflux
5. 5
   workup.WAITcontinued for another 24 hr
6. 6
   ConcentrationThe reaction mixture was then concentrated
7. 7
   workup.WAITthe resultant oil was placed under high vacuum for several days

Procedure

To a solution of L-Proline (115 g,1 mol) in methanol (1.2 L) at 0° C. was added sulfuryl chloride (45 mL, 0.55 mol) slowly during ~15-20 min, then the reaction mixture stirred overnight at room temperature. After 16 hours at room temperature and another 4 hours at reflux, trimethyl orthoformate (120 mL, 1.1 mol) was added and heating at reflux continued for another 24 hr. The reaction mixture was then concentrated and the resultant oil was placed under high vacuum for several days to afford the product as a clear oil (205 g).

Source