Reaktion #161908

Reaktionsgleichung

#12

Nα-(tert-butoxycarbonyl)-L-phenylalaninamide

2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-dithione

→

#13

Ausbeute 130.6%

tert-butyl [(2S)-1-amino-3-phenyl-1-thioxopropan-2-yl]carbamate

Ausbeute 130.6%

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturthe reaction was refluxed for 90 minutes
2. 2
   Sonstigequenched by addition of saturated aqueous sodium bicarbonate solution
3. 3
   ExtraktionThe mixture was extracted twice with ethyl acetate
4. 4
   Trocknenthe combined organic layers were dried over sodium sulfate
5. 5
   Filtrationfiltered
6. 6
   Einengenconcentrated in vacuo
7. 7
   workup.DISSOLUTIONThe residue was dissolved in ethyl acetate
8. 8
   Einengenconcentrated in vacuo onto silica
9. 9
   Sonstigepurified by silica gel chromatography (Gradient: 0% to 100% ethyl acetate in heptane)

Vorschrift

To a solution of #12 (14.060 g, 53.192 mmol, 1 eq.) in tetrahydrofuran (180 mL, 0.296 M), was added 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-dithione (Lawesson's reagent) (12.70 g, 31.40 mmol, 0.59 eq.) and the reaction was refluxed for 90 minutes. The reaction was cooled to room temperature and quenched by addition of saturated aqueous sodium bicarbonate solution. The mixture was extracted twice with ethyl acetate and the combined organic layers were dried over sodium sulfate, filtered, and concentrated in vacuo. The residue was dissolved in ethyl acetate, concentrated in vacuo onto silica and purified by silica gel chromatography (Gradient: 0% to 100% ethyl acetate in heptane), affording #13 (11.50 g, 77%) as a white solid. LC-MS: m/z 279.4 [M−H+], 225.2 [(M−2-methylprop-1-ene)+H+], 181.2 [(M−Boc)+H+]; 1H NMR (400 MHz, DMSO-d6), presumed to be a mixture of rotamers, major rotamer: δ 9.60 (br s, 1H), 9.19 (br s, 1H), 7.23-7.32 (m, 5H), 6.82 (d, J=8.8 Hz, 1H), 4.44 (ddd, J=9.4, 9.1, 4.4 Hz, 1H), 3.00 (dd, J=13.7, 4.5 Hz, 1H), 2.79 (dd, J=13.6, 9.9 Hz, 1H), 1.29 (s, 9H).

Quelle