1: (+/-)-2-hydroxy-2,3-dimethylbutanoic acid With thionyl chloride; N,N-dimethyl-formamide T=23°C; 2 h; 2: 1-((1S,2S,4R)-bicyclo[2.2.1]heptan-2-yl)thiourea With N-ethyl-N,N-diisopropylamine in N,N-dimethyl-formamide T=23°C; 12 h; optical yield given as percent de;