1 SM2 (1r)-1-(2-thienylacetylamino)-1-(3-carboxyphenyl)methylboronic acid 1.000 2 SM3 (1r)-1-(2-thienylacetylamino)-1-phenylmethylboronic acid 0.864 3 SM4 (1r)-1-(2-thiophen-2-yl-acetylamino)-1-(3-(2-carboxyvinyl)-phenyl) methylboronic acid 0.769