Cyclopropanation of alkenes, N-H and S-H insertion of ethyl diazoacetate catalysed by ruthenium porphyrin complexes

Product yields, stereoselectivities and regioselectivities for cyclopropanation reactions of ethyl diazoacetate with styrene derivatives and alpha-heteroatom alkenes, catalysed by ruthenium porphyrins, are reported and compared with observed stereoselectivities for cyclopropanation reactions catalysed with other metalloporphyrin catalysts. Linear correlations are observed when the rates for competitive cyclopropanation or product stereoisomer ratio are plotted against Hammet constants of various ring-substituted groups on styrenes. Isomeric distribution for the cyclopropanation of isoprene and 1,3-pentadiene with ethyl diazoacetate and competition studies of the cyclopropanation and diazo insertion into heteroatom-hydrogen bonds are also reported. Ail these results agree with a major electronic and steric influence on both the regiochemical and stereochemical control in the catalytic cyclopropanation and diazo insertion reactions. (C) 2000 Elsevier Science Ltd. All rights reserved.