A rhodium/chiral diene catalytic system is reported for the reaction of enone-diones and arylboronic acids that allows the switchable synthesis of chiral bicyclic products and acyclic products in a controlled manner. The production of bicyclic products containing four contiguousstereocenters is assumed to proceed through the enantioselective arylrhodation of enone-diones with Cs2CO3, forming a rhodium-enolate
据报道,一种铑/手性二烯催化体系可用于烯酮二酮和芳基硼酸的反应,该体系允许以受控方式可转换地合成手性双环产物和无环产物。假设通过烯酮-二酮与 Cs 2 CO 3的对映选择性芳基罗德化生成含有四个连续立体中心的双环产物,形成铑-烯醇化物中间体,然后通过醛醇环化和定量非对映体选择和出色的对映体过量使非对映体二酮去对称化。假设无环产物的生产通过烯酮二酮的对映选择性加氢芳基化进行,具有优异的对映体过量,其中通过选择 Et 3 N 作为碱可显着抑制醛醇环化。所提出的模型使双环产物(通过串联芳基化-醛醇环化)和无环产物(通过加氢芳基化)的选择性合理化。
Enantioselective synthesis of bicyclo[3.n.1]alkanes by chiral phosphoric acid-catalyzed desymmetrizing Michael cyclizations
作者:Alan R. Burns、Amaël G. E. Madec、Darryl W. Low、Iain D. Roy、Hon Wai Lam
DOI:10.1039/c5sc00753d
日期:——
2,2-Disubstituted cyclic 1,3-diketones containing a tethered electron-deficient alkene undergo chiral phosphoric acid-catalyzed desymmetrizing Michael cyclizations to give bridged bicyclic products in high enantioselectivities.
A one-pot procedure involving radical conjugate addition of B-alkylcatecholboranes to enones followed by intramolecular aldol reaction is reported. Application to the stereoselective synthesis of monocyclic and bicyclic products with up to four contiguous stereogenic centers is presented.