Indium(I)/CuFe 2 O 4 Reagent for Allylation of Carbonyls and Epoxide Rearranged Carbonyls
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ndium(I)/CuFe2O4 Reagent for Allylation of Carbonyls and Epoxide Rearranged Carbonyls M. Kundua, S. P. Mandala, B. Mondala,b,*, and U. K. Roya a Department b Department
of Chemistry, Kazi Nazrul University, Asansol, 713340 India of Chemistry, National Institute of Technology Durgapur, Durgapur, 713209 India *e-mail: [email protected]
Received August 13, 2020; revised September 10, 2020; accepted October 2, 2020
Abstract—Indium(I)/CuFe2O4 reagent for carbonyl allylation and epoxide rearranged carbonyl allylation is proposed for formation of homoallylic alcohols. The In(I) reagent in combination with catalytic amount of CuFe2O4 support in situ formation of nucleophilic allylic indium from allyl halide in THF medium. Nucleophilic allylic indium species react with carbonyls to form homoallyl alcohols in good to excellent yields. Under the presented reaction conditions arylepoxides undergo smooth rearrangement into aldehydes that are also allylated with formation of homoallyl alcohols. The process is highly efficient and tolerates different functional groups. Keywords: indium(I)chloride, catalyst, copper ferrite, carbonyl allylation, arylepoxides, homoallylic alcohols
DOI: 10.1134/S1070363220110274 INTRODUCTION Allyl indium compounds bearing the C-In bond are the most widely used indium compounds in organic synthesis [1]. Among their unique properties is tolerance towards water. Allyl indium derivatives in situ were generated by reductive transmetallation of allyl transition metal complexes that could be accumulated from allyl bromide and transition metal catalysts in combination with In(0) and In(III) chloride. These are efficient nucleophilic partners in different multicomponent allylation reactions with a variety of electrophilic reagents [2, 3]. Such reactions lead to the new C–C bonds formation with the desired regio- and stereo-selectivity, that are of particular importance in synthesis of various natural compounds [4–7]. Allyl halides, their derivatives, as well as allenes and dienes are easily activated by a reactive Tm(0) catalyst (Tm = Pd, Ni) to give rise to the corresponding π-allylTm(II) intermediates. Allyl transfer from the latter to In(I) or In(0) generates reactive allylindium intermediates, that are utilized in situ for the subsequent C–C bond formation. The allylindium species react with carbonyl compounds to give the corresponding homoallyl alcohols. Oxidative addition of allyl halides, esters, carbonates, ethers, cyclic amines, and alcohols to Pd(0) leads to wellknown π-allylpalladium(II) intermediates (Scheme 1). Subsequent insertion of In(I) halides provides the corresponding π-allyl-Pd II–In III intermediates. The
follow-up reductive elimination affords allylindium(III) derivatives. The overall reaction may be interpreted as a redox transmetallation. It is noteworthy that indium(I) halide (In-Xʹ) may be used directly or generated in situ by mixing indium metal and an indium trihalide. The above strategy for the Barbier allylation of aldehydes using InI and catalytic amount of Pd(PPh3)4 in organ
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