2,4-Dimethyl-3-pentyl a-diazopropionate

The cyclopropanation reaction of styrene with 2,4-dimethyl-3-pentyl a-diazopropionate by catalysis with 1 mol % of Rh2(5-TBPTTL)4 at —78 °C provides trans-cyclopropane in high yield with virtually complete diastereoselectivity and 86% ee (eq 5). The reaction can be carried out without slow addition of the diazo reagent, in which no signs of alkene product derived from a 1,2-hydride shift or dimeric products were observed. 

C-H insertion of Dienes. The reaction of 1,4-cyclohexadiene with 2,4-dimethyl-3-pentyl a-diazopropionate under catalysis by dirhodium(II) tetrakis[A-tetrafluorophthaloyl-(5)-fert-leucinate], Rh2(5-TFPTTL)4, in 2,2-dimethylbutane at room temperature gives the corresponding C-H insertion product in 66% yield and with 80% ee (eq 9). ... 

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