A Stereospecific Access to Allylic Systems Using Rhodium(II)−Vinyl Carbenoid Insertion into Si−H, O−H, and N−H Bonds
作者:Priyadarshanie Bulugahapitiya、Yannick Landais、Liliana Parra-Rapado、Denis Planchenault、Valéry Weber
DOI:10.1021/jo961952j
日期:1997.3.1
Rhodium-catalyzed decomposition of alpha-vinyldiazoesters in the presence of silanes, alcohols, ethers, amines, and thiols have been shown to produce the corresponding alpha-silyl, alpha-hydroxy, alpha-alkoxy, alpha-amino, and alpha-thioalkoxy esters in generally good yield with a complete retention of the stereochemistry of the double bond of the diazo precursor. An extension of the process in homochiral series has also been devised using either a chiral auxiliary attached to the ester function or achiral alpha-vinyldiazoesters and Doyle's chiral catalyst Rh-2(MEPY)(4). In the former approach, pantolactone as chiral auxiliary gave diastereoselectivities of up to 70%, while the second approach produced the desired allylsilane with ee as high as 72%. On the other hand, Rh-2(MEPY)(4)-catalyzed insertion into the O-H bond of water led to poor or no enantioselectivity in good agreement with recent literature reports.