title: Recent Advances in the Synthesis of Cyclobutanes by Olefin [2 + 2] Photocycloaddition Reactions.
abstract: The [2 + 2] photocycloaddition is undisputedly the most important and most frequently used photochemical reaction. In this review, it is attempted to cover all recent aspects of [2 + 2] photocycloaddition chemistry with an emphasis on synthetically relevant, regio-, and stereoselective reactions. The review aims to comprehensively discuss relevant work, which was done in the field in the last 20 years (i.e., from 1995 to 2015). Organization of the data follows a subdivision according to mechanism and substrate classes. Cu(I) and PET (photoinduced electron transfer) catalysis are treated separately in sections 2 and 4 , whereas the vast majority of photocycloaddition reactions which occur by direct excitation or sensitization are divided within section 3 into individual subsections according to the photochemically excited olefin.
authors.affiliation: Department Chemie and Catalysis Research Center (CRC), Technische Universität München , D-85747 Garching, Germany.
authors.forename: Saner
authors.initials: S
authors.lastname: Poplata
authors.affiliation: Department Chemie and Catalysis Research Center (CRC), Technische Universität München , D-85747 Garching, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Tröster
authors.affiliation: Department Chemie and Catalysis Research Center (CRC), Technische Universität München , D-85747 Garching, Germany.
authors.forename: You-Quan
authors.initials: YQ
authors.lastname: Zou
authors.affiliation: Department Chemie and Catalysis Research Center (CRC), Technische Universität München , D-85747 Garching, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Bach