Process for the preparation of cyclopropane compounds using diazo-compounds

A process for the continuous production of a reaction product of a diazo compound and a substrate in a multi-stage continuous flow reactor comprising at least two connected reactors in fluid communication with each other, wherein a reaction product formed at each stage of the multistage sequence is continuously discharged from an upstream reactor in which it is formed, and is fed as a continuous fluid stream into a downstream reactor whereupon it can undergo further conversion, the process being characterized in that a precursor compound of the diazo compound that is continuously formed in an upstream reactor is continuously discharged into a downstream reactor under conditions conducive to convert it into the diazo-compound, and wherein said downstream reactor contains the substrate with which the diazo-compound reacts to form the reaction product of the diazo compound and the substrate.