C(C1C(C[C:15]2[CH:20]=[CH:19][C:18]([OH:21])=[CH:17][CH:16]=2)=C2N=C(C)C=C(C)N2N=1)C.C([Mg]Br)=C.CCOCC.[CH3:31][C@H:32]([NH2:39])[C:33]1[CH:38]=[CH:37][CH:36]=[CH:35][CH:34]=1>C1COCC1.O>[CH3:15][C@H:16]1[CH2:17][C:18](=[O:21])[CH2:19][CH2:20][N:39]1[C@H:32]([C:33]1[CH:38]=[CH:37][CH:36]=[CH:35][CH:34]=1)[CH3:31]
In a flame dried roundbottomflask (E)-but-2-enoic acid methoxy-methyl-amide (Einhorn et al., Synth. Commun. 20 (8), 1105-1112 (1990)) (8.0 g, 61.9 mmol) was dissolved in 150 ml of THF. A 1M solution of vinylmagnesium bromide in Et2O (68.1 ml, 68.1 mmol) was added at 0° C. and then the mixture was stirred for 1 h at rt. (S)-(−)-alpha-methylbenzylamin (15.8 ml, 124 mmol) was added at rt, followed by water (15 ml). The reaction was stirred at rt for 1 h. THF was evaporated and 150 ml of water was added. Then the mixture was extracted three times with CH2Cl2 The organic layer was washed with brine, dried over Na2 SO4 and evaporated. The crude product was purified by flash chromatography (silica gel, 20% EtOAc/cyclohexane) which furnished the (S,S) product as the first fraction (confirmed by x-ray).
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