[NH2:1][C:2]1[CH2:6][CH2:5][C@@H:4]([CH3:7])[C:3]=1[C:8]([O:10]CC)=O.C([O-])=O.[NH4+].[CH:17]([NH2:19])=O>C1(C)C=CC=CC=1>[CH3:7][C@H:4]1[C:3]2[C:8]([OH:10])=[N:19][CH:17]=[N:1][C:2]=2[CH2:6][CH2:5]1A 2 L 3-neck round bottom flask equipped with a condenser, internal temperature probe, was charged with (R)-ethyl 2-amino-5-methylcyclopent-1-enecarboxylate (185 g, 1093 mmol) and ammonium formate (103.4 g, 1640 mmol) in formamide (400 mL) and toluene (200 mL). The reaction was heated to an internal temperature of 150° C. and stirred for 36 hours. The reaction was cooled and transferred to a 2 L single next flask and excess formamide was removed by high vacuum distillation. The resulting oil was dissolved in CH2Cl2 and washed with brine. The combined aqueous layers were extracted with CH2Cl2. The combined organic layers were dried over sodium sulfate, filtered and concentrated to give the crude product as a brown semi solid which was taken into the next step without any further purification.
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