Tellurium and Iodine Promoted Cyclofunctionalization of Alkenyl Substituted β-Keto Esters

Abstract

This work describes the use of aryltellurium trichloride and iodine as suitable cyclization reagents for alkenyl substituted β-keto esters. The reaction takes place via the enolic form of the dicarbonyl compounds, giving the corresponding five-membered cyclic ethers in good yields.

Synthesis of Cyclic Enol Ethers from Alkenyl-β-dicarbonyl Compounds

“…b Different times (1−24 h) and temperatures (room temperature to reflux) were tried for these reactions. c Previously communicated in ref .…”

“…Nevertheless, the methodology herein presented provides access to cyclic ethers and tetrahydrobenzofuranones differently functionalized, in yields ranging from moderate to very good. Moreover, these products can be submitted to further elimination or reduction reactions, as described previously for the compounds 3a and 4a . Studies toward these kinds of reactions are in progress in our laboratory.…”

“…In all the conditions studied, the selenocyclic ethers II and IV were obtained in reasonable to good yields. In a preliminary communication, we reported the iodo- and tellurocyclization of some β-keto esters analogous to I or III , as will be discussed in the next section. The tellurocyclization of I (R 1 = Me, R 2 = OEt) has also been described by us…”

Studies on the dehydroiodination of cyclic beta-iodo-enol ethers

“…Three different reagents, namely iodine, p-methoxyphenyltellurium trichloride and phenylselenenyl bromide, were employed as the electrophilic species for promoting the cyclofunctionalization reactions. In such a work, as well as in a previous communication, 11 we reported the construction of a series of cyclic β-iodo-enol ethers containing an exocyclic double bond. We wish now to report the results of the dehydroiodination of these compounds.…”

Influence Halogen in Reaction Aryltellur Tryhalohenide Electrophilic Cyclization of N-Alkenyl of 2-Tioxobenzo (Thieno)pyrimidin-4-Ones

“…З літературних даних відомо, що для одержання телуровмісних поліконденсованих гетероциклічних систем широко застосовується електрофільна гетероциклізація ненасичених субстратів під дією арилтелуртрихлоридів [1][2][3][4][5][6][7][8][9][10][11], в той час використання в таких реакціях п-алкоксифенілтелуртрибромідів практично не описане.…”