Synthesis
GENERAL STEPS: L-alanyl-L-alanine (1 mmol) was slowly added to a solution of ethanol (1 mL) containing guanidine hydrochloride (15 mmol) and di-tert-butyl dicarbonate (2.5-3 mmol) under stirring conditions, maintaining the reaction temperature at 35-40°C. The reaction mixture was stirred continuously until a clarified solution was formed. Subsequently, the ethanol was removed by evaporation under reduced pressure. The residue was washed sequentially with distilled water (2 mL) and hexane or petroleum ether (2 mL) to obtain nearly pure N-tert-butoxycarbonyl-alanylalanine. If further product purity is required, the crude product can be purified by recrystallization.
References
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[2] Journal of the American Chemical Society, 2000, vol. 122, # 12, p. 2687 - 2697
[3] Journal of Organic Chemistry, 1994, vol. 59, # 19, p. 5784 - 5793
[4] Tetrahedron Letters, 2011, vol. 52, # 12, p. 1260 - 1264
[5] Journal of Medicinal Chemistry, 2005, vol. 48, # 16, p. 5305 - 5320
