C(NC(C)C)(C)C.C([Li])CCC.CCCCCC.[C:19]([N:22]1[CH2:27][CH2:26][O:25][CH2:24][CH2:23]1)(=[O:21])[CH3:20].[C:28](OCC)(=[O:34])[C:29]([O:31][CH2:32][CH3:33])=[O:30]>C1COCC1>[N:22]1([C:19](=[O:21])[CH2:20][C:28](=[O:34])[C:29]([O:31][CH2:32][CH3:33])=[O:30])[CH2:27][CH2:26][O:25][CH2:24][CH2:23]110.2 g of diisopropylamine (0.1 mol) was placed in 100 ml dry THF under nitrogen and cooled in a freezing mixture. 40 ml n-butyllithium in hexane (2.5 M, 0.1 mol) was slowly added dropwise. When the addition was completed the mixture was allowed to stir for 60 minutes and then acetylmorpholine 12.9 g (0.1 mol) was added dropwise. The reaction mixture was stirred for 20 min in the freezing mixture. In a second flask, 43.7 g of diethyl oxalate (0.3 mol) in 50 ml of dry THF was cooled in a freezing mixture and the cooled reaction mixture was cannulated with stirring in small portions to it. It was left overnight under stirring to warm to room temperature. The THF was removed on a rotary evaporator and the residue was taken up in 80 ml half concentrated hydrochloric acid. The aqueous phase was extracted five times with 150 ml ethyl acetate, and the combined organic phases were dried over sodium sulfate and concentrated on a rotary evaporator to dryness. The excess diethyl oxalate was removed by distillation (2-3 mbar, 80° C.). 5.0 g of product were obtained in the form of white crystals with a melting point of 60° C. after crystallization from PE (petrol ether).
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