The Dimerization of Cinnamic Acid Derivatives

Abstract

For Abstract see ChemInform Abstract in Full Text.

Recent Advances in the Synthesis of Cyclobutanes by Olefin [2 + 2] Photocycloaddition Reactions

“… 3 α-Truxillic acid ( 2 ) 4 − 6 represents another centrosymmetric photodimer, which was a few years later obtained by [2 + 2] photodimerization of cinnamic acid. 7 An array of similar [2 + 2] photodimerization reactions were performed at the end of the 19th century and at the turn to the 20th century, the history of which has been summarized in an instructive review by Roth on the beginnings of organic photochemistry. 8 The year 1908 marks the discovery of what we call today an intramolecular enone [2 + 2] photocycloaddition reaction.…”

A DFT Study of the Photochemical Dimerization of Methyl 3-(2-Furyl)acrylate and Allyl Urocanate

“…The dimerization of cinnamic acid derivatives has been recently reviewed [3]. Cinnamic acid ( 1 ), irradiated in the solid state, gave the corresponding dimers depending on the crystal form of the starting material: the metastable β-form was reported to yield β-truxinic acid ( 2 ), while the stable α-form gave α-truxillic acid ( 3 ) (Scheme 1) [4,5,6,7,8,9,10].…”

Template-Directed Photochemical Homodimerization and Heterodimerization Reactions of Cinnamic Acids

“…1 One particular type of [2 + 2] cycloadditions that attracted significant attention is the photodimerization of cinnamic acid derivatives due to the challenges associated with this transformation in terms of regio-and stereoselectivity as well as reactivity. 2 In addition, [2 + 2] cycloadducts of cinnamic acids are attractive synthetic targets because of their diverse and promising biological activity profiles and their presence in various natural products. 3 Irradiation of cinnamic acid derivatives in solution leads predominantly to E/Z photoisomerization, and therefore, efforts to achieve these transformations were focused primarily on solid-state photochemistry.…”

“…The crystal structures of certain olefins fulfill these criteria so that irradiation of such compounds in solid state directly affords the corresponding cycloaddition products. For instance, irradiation of the α-polymorph of trans-cinnamic acid (1) with UV light gives selectively the head-to-tail homodimerization product α-truxillic acid (2), whereas the photocycloaddition of the metastable β-polymorph leads to the formation of the head-to-head dimer β-truxinic acid (3a) (Scheme 1). 5b,6 On the other hand, the γ-polymorph does not undergo a [2 + 2] cycloaddition upon irradiation since the distance between the olefin centers is greater than 4.2 Å.…”