A comparative study of thallium(iii) and iodine(iii)-mediated ring contraction reactions for the synthesis of indane†
Reported herein is a comparative study of the synthesis of indane via ring contraction reaction, mediated by iodine(III) and thallium(III). A series of protected 1,2-dihydronaphthalenes were synthesized and subjected to hydroxy(tosyloxy)iodobenzene (HTIB) and thallium(III) nitrate trihydrate (TTN) in trimethyl orthoformate (TMOF) to compare the percent yields provided by both oxidizing agents. The yields of the ring contracted products (indanes) were in the range of 61–88% for reactions performed with TTN·3H2O in TMOF. However, the yields were found to be significantly lower (e.g., 18–34%) when using HTIB in TMOF with some addition products. This study provides an important development related to the efficacy of the two oxidizing agents for ring contraction reaction.