Reaktion #2005519

Reaktionsgleichung

azodicarboxylic acid dipotassium salt

(1R,2S)-1-tert-Butoxycarbonylamino-2-vinyl-cyclopropanecarboxylic acid ethyl ester

Azodicarboxylic acid dipotassium salt

acetic acid

Acetic acid

→

title compound

(1R,2R)-1-Amino-2-ethyl-cyclopropanecarboxylic acid ethyl ester

Lösungsmittel

methanol

methanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGthe mixture stirred for 1 h
2. 2
   SonstigeThe volatiles were evaporated
3. 3
   Sonstigethe residue was partitioned between EA
4. 4
   Trocknena saturated sodium hydrogencarbonate solution, and the combined organic extracts were dried over sodium chloride
5. 5
   Sonstigedecanted over a small plug of silica gel
6. 6
   Sonstigeevaporated to dryness
7. 7
   workup.DISSOLUTIONThe obtained intermediate was dissolved in a mixture of DCM (5 ml) and TFA (1 ml)
8. 8
   workup.STIRRINGstirred for 1 h at room temperature
9. 9
   SonstigeThe volatiles were evaporated
10. 10
    Sonstigethe residue was partitioned between diethyl ether and saturated sodium hydrogencarbonate solution
11. 11
    TrocknenThe combined organic extracts were dried over sodium chloride
12. 12
    Sonstigedecanted
13. 13
    Sonstigeevaporated to dryness

Vorschrift

(1R,2S)-1-tert-Butoxycarbonylamino-2-vinyl-cyclopropanecarboxylic acid ethyl ester (400 mg, 1.57 mmol) was dissolved in methanol (5 ml) and added to a suspension of azodicarboxylic acid dipotassium salt (1.46 g, 7.5 mmol; cf. D. J. Pasto et al., Organic Reactions 40 (1991), 91-155) in methanol (10 ml). Acetic acid (1.12 g, 18.8 mmol) was added in the course of 10 min and the mixture was stirred for 1 h at room temperature. Azodicarboxylic acid dipotassium salt (1.46 g) and acetic acid (1.12 g) were added once again and the mixture stirred for 1 h. LC/MS analysis then indicated complete conversion. The volatiles were evaporated, the residue was partitioned between EA and a saturated sodium hydrogencarbonate solution, and the combined organic extracts were dried over sodium chloride, decanted over a small plug of silica gel and evaporated to dryness. The obtained intermediate was dissolved in a mixture of DCM (5 ml) and TFA (1 ml) and stirred for 1 h at room temperature. The volatiles were evaporated, and the residue was partitioned between diethyl ether and saturated sodium hydrogencarbonate solution. The combined organic extracts were dried over sodium chloride, decanted and evaporated to dryness to yield the title compound.

Quelle