Ethyl Acetate → (E)-(7S,10S,13S)-13-tert-Butoxycarbonylamino-10-isopropyl-9,12-dioxo-2-oxa-8,11-diazabicyclo[13.2.2]nonadeca-1(18),4,15(19),16-tetraene-7-carboxylic acid methyl ester

Beteiligte Stoffe

Reaktionsschritte

Diene 44 (1.80 g, 3.39 mmol) was dissolved in anhydrous 1,1,2-trichloroethane (0.01M) under an atmosphere of argon. GSGC (0.10 equiv) was added. The mixture was heated at reflux for one hour. Two further additions of GSGC (0.10 equiv) were added and after each the reaction mixture was subjected to one h and eighteen h of reflux respectively. This was then cooled and concentrated in vacuo. The crude material was purified by flash chromatography on silica using a gradient of EtOAc and (50/70) petroleum ether to yield a brown solid, 0.205 g, 12%. Rf=0.24 (1/1 EtOAc/(50/70) petroleum ether). m.p. 105-107° C.

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