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.
Chiral phosphine-squaramides as enantioselective catalysts for the intramolecular Morita–Baylis–Hillman reaction
作者:Hong-Liang Song、Kui Yuan、Xin-Yan Wu
DOI:10.1039/c0cc03187a
日期:——
squaramides containing tertiary phosphine were developed as chiral bifunctional organic catalysts to promote the asymmetric intramolecularMorita-Baylis-Hillmanreaction of omega-formyl-enones. The adducts were obtained in high yields with good-to-excellent enantioselectivity (up to 93% ee).
catalysis, ferrocene could be an excellent scaffold for organocatalysts. The simple and easily accessible bifunctional ferrocene-based squaramide-phosphine shows high enantioselectivity in the intramolecularMorita–Baylis–Hillmanreaction of 7-aryl-7-oxo-5-heptenals, giving a variety of 2-aroyl-2-cyclohexenols in up to 96% ee.
A series of chiral bifunctional phosphinothioureas derived from l-amino acids have been developed to promote the enantioselectiveintramolecularMorita–Baylis–Hillmanreaction. The process afforded the cyclic hydroxyl enones with up to 84% ee and good yields under mild conditions.
Rh(<scp>iii</scp>)-catalyzed diastereoselective C–H bond addition/cyclization cascade of enone tethered aldehydes
作者:Jeffrey A. Boerth、Jonathan A. Ellman
DOI:10.1039/c5sc04138d
日期:——
The Rh(III)-catalyzed cascade addition of a C–H bond across alkene and carbonyl π-bonds is reported. The reaction proceeds under mild reaction conditions with low catalyst loading. A range of directing groups were shown to be effective as was the functionalization of alkenyl in addition to aromatic C(sp2)–H bonds. When the enone and aldehyde electrophile were tethered together, cyclic β-hydroxy ketones
报道了Rh( III ) 催化的 C-H 键在烯烃和羰基 π-键上的级联加成。该反应在温和的反应条件和低催化剂负载下进行。一系列导向基团被证明是有效的,除了芳香族 C(sp 2 )–H 键之外,烯基的官能化也是如此。当烯酮和醛亲电体连接在一起时,得到具有三个连续立体中心的环状β-羟基酮,具有高非对映选择性。醛和亚胺亲电子试剂都证明了分子间三组分级联反应。此外,报告了第一个阳离子 Cp*Rh( III ) 烯醇化物的 X 射线结构,其原子间距离与 η 3结合烯醇化物一致。