S1 Organic Letters Supporting Information The First Cyclopropanation Reaction of Unmasked , -Unsaturated Carboxylic Acids: Direct and Complete Stereospecific Synthesis of Cyclopropanecarboxylic Acids Promoted by Sm/CHI 3 José M. Concellón,* Humberto Rodríguez-Solla and Carmen Simal Departamento de Química Orgánica e Inorgánica. Facultad de Química, Universidad de Oviedo, C/ Julián Clavería, 8, 33006, Oviedo, Spain. jmcg@uniovi.es General and General Procedure……...........…..................….......................................................S2 trans-2-Phenylcyclopropanecarboxylic acid 2a.…....……............……......................................S3 cis-2-Phenylcyclopropanecarboxylic acid 2b……..………………..…...……….…………S4 trans-2-(4-Methylphenyl)cyclopropanecarboxylic acid 2c………………….…….………....S5 trans-2-(3-Methylphenyl)cyclopropanecarboxylic acid 2d......…….....….……........….............S6 trans-2-(4-Bromo-3-methylphenyl)cyclopropanecarboxylic acid 2e...……………..…….........S7 trans-2-(4-Methoxyphenyl)cyclopropanecarboxylic acid 2f………….………...…...............S8 trans-2-(2-Methoxyphenyl)cyclopropanecarboxylic acid 2g……...............………....................S9 trans-2-(4-Fluorophenyl)cyclopropanecarboxylic acid 2h……………………........................S10 trans-2-(4-Chlorophenyl)cyclopropanecarboxylic acid 2i…………..…………...…................S11 trans-2-(4-Trifluoromethylphenyl)cyclopropanecarboxylic acid 2j……….…..….....………..S12 trans-2-(2-Trifluoromethylphenyl)cyclopropanecarboxylic acid 2k………...……..…………S13 trans-2-(3-Hydroxyphenyl)cyclopropanecarboxylic acid 2l….………..……….…...………..S14 trans-(E)-2-(Propen-1-yl)cyclopropanecarboxylic acid 2m…………..……………..………..S15