Methanol → methyl L-prolinate hydrochloride

反応式

S(Cl)([Cl:3])=O.[NH:5]1[CH2:12][CH2:11][CH2:10][C@H:6]1[C:7]([OH:9])=[O:8].[CH3:13]O>>[ClH:3].[NH:5]1[CH2:12][CH2:11][CH2:10][C@H:6]1[C:7]([O:9][CH3:13])=[O:8]

参加物

反応物 3

HCID 887Methanol

HCID 24386Thionyl Chloride

HCID 145742L-Proline

生成物 1

HCID 2733200methyl L-prolinate hydrochloride収率 99.6%

実験手順

Thionyl chloride (65 ml, 0.89 mol) was added dropwise at ice-cooling for 45 min to a solution of L-proline (57.6 g, 0.50 mol) in 500 ml MeOH. The temperature was raised to reflux and after 4 h the solvent was evaporated in vacuo. MeOH was added to the residue and then evaporated repeatedly to give 86 g crude methyl (S)-2-pyrrolidinecarboxylate hydrochloride (99.6% purity by GLC) as a thick syrup. The ester (16.5 g, 0.10 mol) was transferred to a flask containing propionaldehyde (36 ml, 50 mol), 10% Pd/C (1.5 g) and 100 ml MeOH. The mixture was shaken in a Parr apparatus overnight at a hydrogen pressure of 55 psi at room temperature. Filtration and evaporation in vacuo gave 22.0 g of the crude title ester (94% purity by GLC) as a hydrochloride salt, which was used in the aminolysis in Example 11B.