Photodimerisation und Adduktbildung von Xanthen‐Derivaten

Abstract

Photodimerisation von Xanthen-Derivaten73 5 I-(Chromonyl-3)-l-(4-hydroxycumarinyl-3)-2,2-diphenylathen (7a) 948 mg (2 mMol) 3a und 0.38 ml(2,4 mMol) Dimethylformamiddimethylacetal in 10 ml absol. Xylol wurden 3 h auf 130' und 30 min. auf 160' erhitzt Nach dem Abkiihlen wurde filtriert, 10 m l 9 0 proz. Photodimerisation and Adduct Formation Among Xanthene DerivativesFor the identification of photoproducts of xanthene-9-carboxylic esters of parasympatholytic activity the synthesis of model substances is necessary. In the course of preparing hydroxydixanthene by the method of Schonberg and Mustafa, the product of the photochemical reaction was proved to be an adduct of three components: 9,g'dixanthene and its 9-hydroxy-, and 9,9'-dihydroxy derivatives, which crystallize together in a ratio of 1 : 1 : 1. We give a modified photochemical synthesis for this adduct, furthermore methods (thin layer and column chromatography) for separation and qualitative investigation of the components.

Cycloketyl radical mediated living polymerization

“…Based on this hypothesis, the present work has involved the design and synthesis of a compound, i.e., 9,9 0 -bixanthene-9,9 0 -diol (BIX-ANDL) (I in Scheme 1; Chart S1, S2 and Fig. S1 †), 14 which could effectively dissociate to form cycloketyl xanthone (CX) radicals under thermal or photo stimuli. We found that the resulting CX radical could very effectively initiate and control the radical polymerization of typical monomers under thermal or photo stimuli, presenting good controlled/living features.…”