Temporary Silicon Connection Strategies in Intramolecular Allylation of Aldehydes with Allylsilanes
作者:Julien Beignet、Peter J. Jervis、Liam R. Cox
DOI:10.1021/jo800824x
日期:2008.7.1
dimethylsilyl ether connection between the aldehyde and allylsilane, with a range of Lewis and Brønsted acid activators provides an (E)-diene product. The mechanism of formation of this undesired product is discussed. Systems containing a sterically more bulky diethylsilyl ether connection react differently: thus in the presence of TMSOTf and a Brønsted acid scavenger, intramolecular allylation proceeds
Stereoselective Synthesis of Allyl-<i>C</i>-mannosyl Compounds: Use of a Temporary Silicon Connection in Intramolecular Allylation Strategies with Allylsilanes
作者:Julien Beignet、James Tiernan、Chang H. Woo、Benson M. Kariuki、Liam R. Cox
DOI:10.1021/jo049061w
日期:2004.9.1
Methyl mannoside 16 containing an allyldimethylsilyl ether at C(2) was synthesized in nine steps from d-mannose. Reaction with TMSOTf in MeCN at room-temperature effected C-glycosylation to provide the α-allyl-C-mannosyl product 18 with excellent stereoselectivity. Crossover experiments over a range of reaction concentrations proved that reaction was proceeding via an intermolecular pathway rather