Cyclopropanations trimethylsilyldiazomethane

Aryldiazomethane can also be used for iron porphyrin-catalyzed alkene cyclopropanation [55]. For example, the treatment of p-tolyldiazomethane with styrene in the presence of [Fe(TTP)] afforded the corresponding arylcyclopropapane in 79% yield with a high transicis ratio of 14 1 (eq. 1 in Scheme 11). Interestingly, when bulkier mesityldiazomethane was used as carbene source, ds-selectivity was observed (cisitrans = 2.0 1). Additionally, mesityldiazomethane was found to react with frans-p-styrene, the latter was found not to react with EDA or trimethyl-silyldiazomethane under the similar reaction conditions, to give l-mesityl-2-methyl-3-phenylcyclopropane in 35% yield. Trimethylsilyldiazomethane is also an active carbene source for [Fe(TTP)]-catalyzed cyclopropanation of styrene, affording l-phenyl-2-trimethylsilylcyclopropane in 89% yield with transicis ratio of 10 1 (eq. 2 in Scheme 11). 

The same complex is a suitable catalyst for the cyclopropanation of 1,1- and 1,2-disubstituted alkenes with trimethylsilyldiazomethane (Eq. 9) [18]. High exo selectivity was obtained when cyclohexene was used as an olefin. 

Cyclopropane-substituted BOX ligand complex 221 was used for the asymmetric cyclopropanation of diazoacetate (Scheme 1.102) [155]. Nitrodiazoacetate [156] and trimethylsilyldiazomethane [157] underwent asymmetric cyclopropanation catalyzed by chiral copper BOX complex 222 (Scheme 1.103). Stereocontrol was primarily controlled by BOX ligand 227 if an extra stereogenic... 

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