L-Alanine → tert-Butyl alaninate hydrochloride

In a 2 L one-neck flask, L-alanine (6.23 g) is stirred for 4 days with 1.1 L of t-butylacetate at room temperature and perchloric acid (70%, 6.65 mL, 7.7. g). The mixture is concentrated to 1/4 of its original volume, and the residue extracted at 0°-5° C. with 0.5N HCl (4×60 mL). The aqueous phase is immediately neutralized with KHCO3 (solid). The pH is adjusted to 13 with 4N NaOH, and the solution extracted with Et2O (4×100 mL). The combined organic layers are washed with bicarbonate solution (2×50 mL), dried (MgSO4), and evaporated. The oily residue is dissolved in 10 mL of Et2O (anh.) and treated with HCl:Et2O under cooling. The precipitated salt is filtered and dried to yield 4 g of L-alanine-t-butyl ester hydrochloride having a m.p. 167° C.; [α]20 =+177 (c=2 in EtOH).

1. concentrationThe mixture is concentrated to 1/4 of its original volume
2. extractionthe residue extracted at 0°-5° C. with 0.5N HCl (4×60 mL)
3. extractionthe solution extracted with Et2O (4×100 mL)
4. washThe combined organic layers are washed with bicarbonate solution (2×50 mL)
5. dry with materialdried (MgSO4)
6. customevaporated
7. dissolutionThe oily residue is dissolved in 10 mL of Et2O (anh.)
8. additiontreated with HCl
9. temperatureEt2O under cooling
10. filtrationThe precipitated salt is filtered
11. customdried

ORD record

ord-e72684306c674e5db1d393acac668b95

Source dataset

uspto-grants-1988_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04730006