Trimethylsilyl Trifluoromethanesulfonate Catalyzed One-Pot Method for the Conversion of Aldehydes to Homoallyl Ethers in an Ionic Liquid
作者:Ram Mohan、Peter Anzalone
DOI:10.1055/s-2005-872112
日期:——
A mild method for the trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed one-pot synthesis of homoallyl ethers from aldehydes has been developed in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim] [OTf]). The advantages of this method include the use of a recyclable ionic liquid, facile product isolation without employing excess organic solvent, elimination of an aqueous waste stream, and mild reaction conditions.
作者:Viresh H. Rawal、Surendra P. Singh、Claire Dufour、Christophe Michoud
DOI:10.1021/jo00079a016
日期:1993.12
We have explored different aspects of the cyclization capability of alkoxymethyl radicals and report here a full account of our investigations. The required radicals were generated from (phenylseleno)methyl ethers (e.g., 6), which were prepared from homoallylic or bis-homoallylic alcohols by a two-step process. The alcohols were alkylated with (iodomethyl)tributylstannane. The stannanes were reacted with n-BuLi, and the resulting alpha-alkoxyanions were trapped with diphenyldiselenide to give the (phenylseleno)methyl ethers, which were stable to chromatography. When treated with tributyltin hydride, in the presence of a radical initiator, these precursors undergo a smooth cyclization to substituted tetrahydrofurans and tetrahydropyrans. Formation of the cyclization product was found to be the primary pathway even at relatively high tin hydride concentration. The diastereoselectivity of this cyclization was comparable to that observed in other radical cyclizations. The cis selectivity in cyclization of 6 increased gradually (up to 11:1) as the reaction temperature was lowered. The cyclization can be used for the synthesis of bicyclic and tricyclic compounds and can be incorporated in systems capable of tandem cyclizations.
Bismuth Compounds in Organic Synthesis. A One-Pot Synthesis of Homoallyl Ethers and Homoallyl Acetates from Aldehydes Catalyzed by Bismuth Triflate
作者:Peter W. Anzalone、Ashvin R. Baru、Eric M. Danielson、Patrick D. Hayes、Mai P. Nguyen、Ambrose F. Panico、Russell C. Smith、Ram S. Mohan
DOI:10.1021/jo048475m
日期:2005.3.1
[GRAPHICS]Three one-pot methods for the conversion of aldehydes to homoallyl ethers catalyzed by Bi(OTf)(3)center dot xH(2)O (1 < x < 4) have been developed. The one-pot synthesis of homoallyl ethers can be achieved either by in situ generation of the acetal followed by its reaction with allyltrialkylsilane or by a three-component synthesis in which the aldehyde, trimethylorthoformate or an alkoxytrimethylsilane and allyltrimethylsilane are mixed together in the presence of bismuth triflate (0.1-1.0 mol %). In addition, a three-component synthesis of homoallyl acetates, which is achieved by reacting the aldehyde, acetic anhydride, and allyltrimethylsilane in the presence of bismuth triflate (3.0-5.0 mol %), has been developed. The use of a relatively nontoxic, easy to handle, and inexpensive catalyst adds to the versatility of these methods.
Action d'organoaluminiques α-insatures sur les acetals et les cetals
作者:F. Barbot、Ph. Miginlac
DOI:10.1016/s0022-328x(00)83185-x
日期:1979.4
Cyclization of alkoxymethyl radicals
作者:Viresh H. Rawal、Surendra P. Singh、Claire Dufour、Christophe Michoud
DOI:10.1021/jo00018a005
日期:1991.8
Alkoxymethyl radicals, generated conveniently from phenylseleno precursors, cyclize to afford substituted tetrahydrofurans and tetrahydropyrans in excellent yield and with good stereoselectivity.