Regio- and Stereoselective Synthesis of Alkyl Allylic Ethers via Gold(I)-Catalyzed Intermolecular Hydroalkoxylation of Allenes with Alcohols
作者:Zhibin Zhang、Ross A. Widenhoefer
DOI:10.1021/ol800646h
日期:2008.5.1
carbene complex and AgOTf at roomtemperature for 1 h led to isolation of (E)-(3-phenethoxy-1-butenyl)benzene in 96% yield as a single regio- and stereoisomer. Gold(I)-catalyzed intermolecular allene hydroalkoxylation was effective for monosubsituted, 1,1- and 1,3-disubstituted, trisubstituted, and tetrasubstituted allenes and for a range of primary and secondary alcohols, methanol, phenol, and propionic
Highly Regio- and Stereoselective Cyclic Iodoetherification of 4,5-Alkadienols. An Efficient Preparation of 2-(1′(<i>Z</i>)-Iodoalkenyl)tetrahydrofurans
作者:Bo Lü、Xinpeng Jiang、Chunling Fu、Shengming Ma
DOI:10.1021/jo802079b
日期:2009.1.2
In this paper, an efficient way to synthesize 2-(1'(Z)-iodoalkenyl)tetrahydrofurans from 4,5-alkadienols and 12 was developed. The reaction of the 4,5-allenols with a substituent in the 3-position afforded the trans-2,3-disubstituted tetrahydrofurans with very high diastereoselectivity. However, when the axially optically active 4,5-allenol was treated with 12 in n-hexane, the efficiency for chirality transfer was low. This problem was circumvented by conducting the reaction in CH2Cl2 at room temperature and applying N-iodosuccinimide as the electrophilic reagent; however, the Z/E ratio for the products is much lower. Highly optically active Z-products may be prepared via the kinetic resolution via a Sonogashira coupling reaction with propargyl alcohol.