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).
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。
Enantioselective intramolecular Morita–Baylis–Hillman reaction using chiral bifunctional phosphinothiourea as an organocatalyst
Chiral cyclohexane-based phosphinothioureas were found to be efficient organocatalysts for the enantioselective intramolecular Morita–Baylis–Hillmanreaction of ω-formyl-enone. Among the solvents screened, t-BuOH was the best one which provided good yield and enantioselectivity. Moreover in the presence of 3 mol % of phosphinothiourea 2b, the desired products were obtained in good-to-excellent yields
available hydroxamic acids were leveraged to access challenging nitrones in the presence of H3PO4 as a Brønsted acid catalyst and engaged in an intramolecular (3+2) annulation reaction to make valuable cyclopentane-fused isoxazolidines with high yields and excellent diastereoselectivity. The products were further utilized in a unique base-promoted benzilic amide rearrangement to provide cyclopentane-fused
在 H 3 PO 4作为布朗斯台德酸催化剂存在下,利用容易获得的异羟肟酸来获得具有挑战性的硝酮,并进行分子内 (3+2) 成环反应,以高产率和优异的非对映选择性制备有价值的环戊烷稠合异恶唑烷。该产品进一步用于独特的碱促进的二苯乙醇酰胺重排,以提供带有三个连续立体中心的环戊烷稠合γ-内酰胺作为单一非对映体。