Focus of this diploma thesis is photochemical dearomative cyclopropanation of electron-rich arenes. Dearomatizations of benzene derivatives allows design of synthetic pathway, which includes transformation of cheap and readily avalilable aromatic π-systems into structurally complex molecules in several convergent synthetic steps. 1,2-dimethoxybenzene was used as a substrate for the cyclopropanation. Cyclopropanation of 1,2-dimethoxybenzene via carbene transfer of photochemically in situ generated carbenes from aryldiazoesters under blue light resulted with a number of meso norcaradiens. Resulting meso norcaradiens were subjected to desymmetrizations via secondary photochemical cyclopropanation. Transformation potential of produced norcaradiens and σ-bishomobenzenes has been confirmed by [4+2] cycloadition of in situ generated benzyne onto norcaradiene, as well as by a reaction of σ-bishomobenzene with BBr3 that caused cyclopropane ring opening resulting in an α-methoxyketone that is also a Michael acceptor allowing further transformations. Prepared starting materials, as well as resulting compunds were characterized by analytical techniques such as nuclear magnetic resonance spectroscopy, mass spectrometry and x-ray diffraction on a monocrystal.