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

Product yields, stereoselectivities and regioselectivities for cyclopropana tion reactions of ethyl diazoacetate with styrene derivatives and alpha-het eroatom alkenes, catalysed by ruthenium porphyrins, are reported and compar ed with observed stereoselectivities for cyclopropanation reactions catalys ed with other metalloporphyrin catalysts. Linear correlations are observed when the rates for competitive cyclopropanation or product stereoisomer rat io 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 cycl opropanation and diazo insertion into heteroatom-hydrogen bonds are also re ported. Ail these results agree with a major electronic and steric influenc e on both the regiochemical and stereochemical control in the catalytic cyc lopropanation and diazo insertion reactions. (C) 2000 Elsevier Science Ltd. All rights reserved.