Reactivity of cyclic sulfamidates towards phosphonate-stabilised enolates: synthesis and applications of α-phosphono lactams
作者:John F. Bower、Andrew J. Williams、Hannah L. Woodward、Peter Szeto、Ron M. Lawrence、Timothy Gallagher
DOI:10.1039/b706315f
日期:——
Five and six ring α-phosphono lactams 14â20 are available by reaction of 1,2- and 1,3-cyclic sulfamidates respectively with enolates derived from ethyl dialkylphosphonoacetates 3 and 4. Subsequent WadsworthâEmmons olefination provides the enantiomerically pure exo-alkylidene variants e.g.25, which is efficiently converted to vinyl triflate 29 (>98% ee). Suzuki coupling of 29 to a range of aryl and vinyl boronic acids leads to a structurally diverse range of pyrrolidinones exemplified by 30 and 34. The degree of epimerisation at the base-sensitive C(5) stereocentre during the Suzuki coupling of 29 is shown to be dependent on both the nature of the aryl boronic acid and the reaction conditions used.
五环和六环α-磷酸内酯14–20可通过将1,2-和1,3-环状磺酰胺与源自乙基二烷基磷酸乙酸酯3和4的烯醇盐反应获得。随后进行Wadsworth-Emmons烯化反应,产生手性纯的exo-烯基变体,例如25,这可以高效地转化为乙烯基三氟甲磺酸酯29(>98%外消旋度)。将29与多种芳基和乙烯基硼酸进行Suzuki偶联,得到一系列结构多样的吡咯烷酮,以30和34为例。在29的Suzuki偶联过程中,基敏感C(5)立体中心的偏心化程度被证明依赖于芳基硼酸的性质和所用反应条件。