The first example of magnesium carbenoid 1,3-CH insertion reaction: a novel method for synthesis of cyclopropanes from 1-chloroalkyl phenyl sulfoxides in high yields

Treatment of 1-chloroalkyl phenyl sulfoxides having a geminal methyl group or a geminal benzyl group at the 2-position in THF at −78 °C with isopropylmagnesium chloride gave magnesium carbenoids. Carbenoid 1,3-CH insertion reaction of the magnesium carbenoids took place instantaneously to afford cyclopropanes in high to quantitative yields.