Reaktion #50039

Reaktionsgleichung

NaBr

carbobenzyloxy-L-prolinol

Na2CO3

NaOCl

TEMPO

→

CBZ-L-prolinal

Lösungsmittel

toluene

water

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeat 0° C.
2. 2
   workup.ADDITIONTo this vigorously-stirred mixture was added
3. 3
   Extraktionwas extracted with ethyl acetate (2×250 mL)
4. 4
   WaschenThe combined organics were washed with Kl 5% KHSO4 (1×50 mL)
5. 5
   Trocknenaqueous Na2S2O3 (1×100 mL), then pH 7 phosphate buffer (1×100 mL), then brine (1×100 mL) and dried (Na2SO4)
6. 6
   FiltrationFiltration and evaporation of solvents
7. 7
   workup.WAITleft carbobenzyloxy-L-prolinal (5.55 g) as an oil

Vorschrift

Following the method of Leanna et al. (M. Robert Leanna, Thomas J. Sowin, Howard E. Morton, Tetrahedron Lett., 1992, 33(35), 5029-5032), carbobenzyloxy-L-prolinol (9.23 g, 39 mmole) in toluene (100 mL) at 0° C. was added NaBr (Aldrich, 4.01 g, 40 mmole) in water (45 mL) followed by 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO reagent, Aldrich, 0.05 g, 0.32 mmole). To this vigorously-stirred mixture was added a mixture of Na2CO3 (11.16 g, 132 mmole)in water (50 mL) and aqueous NaOCl (0.7M, 65 mL, 46 mmole) dropwise over 30 minutes. After stirring 30 minutes at 0° C. the mixture was extracted with ethyl acetate (2×250 mL). The combined organics were washed with Kl 5% KHSO4 (1×50 mL), then aqueous Na2S2O3 (1×100 mL), then pH 7 phosphate buffer (1×100 mL), then brine (1×100 mL) and dried (Na2SO4). Filtration and evaporation of solvents left carbobenzyloxy-L-prolinal (5.55 g) as an oil.

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