A CONVENIENT AND MILD PROCEDURE FOR THE PREPARATION OF α-KETO PHOSPHONATES OF 1-HYDROXYPHOSPHONATES UNDER SOLVENT-FREE CONDITIONS USING MICROWAVE
摘要:
The Reactions of 1-hydroxyphosphonates on the alumina-supported CrO3 are accelerated by microwave irradiation under solvent-free conditions to afford a high yielding synthesis of alpha -keto phosphonates.
Cu(II)-catalyzed enantioselective 1,3-dipolar cycloaddition of nitrones with α, β-unsaturated acyl phosphonates
作者:Lei Xie、Hui Bai、Jiaqi Li、Xuan Yu、Zhenhua Zhang、Bin Fu
DOI:10.1016/j.tet.2017.03.086
日期:2017.5
A highly enantioselective 1, 3-dipolar cycloaddition of nitrone with α, β-unsaturated acyl phosphonate was developed for the first time by using a chiral indane-bis(oxazoline)-copper(II) complex. The reaction proceeded smoothly under mild conditions to provide isoxazolidines with multi-stereocenters in good yields with high to excellent diastereo- (>20:1 dr) and enantioselectivities (up to 99% ee)
in a Michael addition promoted oxidative domino three‐component reaction under heterogeneous conditions. This multicomponentreaction sequence led to the development of a general synthesis of highlyfunctionalized pyridines (see scheme), allowing selective and simultaneous incorporation of a substituent at the 4‐position and a synthetically useful functionality at the strategic 2‐position.
A highly stereoselective vinylogousMukaiyamaMichael reaction (VMMR) leading to α‐keto phosphonate‐containing γ‐butenolides with two stereogenic centers is described. The presented transformation is catalyzed by a combination of a commercially available C2‐symmetric bisoxazoline (BOX) ligand and a copper salt and tolerates a variety of nucleophiles and electrophiles. The stereoselectivities of the
Enantioselective Copper(II)-Catalyzed Conjugate Addition of Indoles to β<i>-</i>Substituted Unsaturated Acyl Phosphonates
作者:Hong-Li Ma、Lei Xie、ZhenHua Zhang、Jia-Qi Li、Zhao-Hai Qin、Bin Fu
DOI:10.1002/adsc.201500923
日期:2016.3.31
The first copper‐catalyzedenantioselective conjugate addition of indoles to β‐substituted unsaturated acyl phosphonates was successfully realized by using a heteroarylidene‐tethered bis(oxazoline) ligand. The reaction features high efficiency, cheap catalyst and broad generality. In the case of either β‐alkyl‐ or β‐aryl‐substituted unsaturated acyl phosphonates, the 3‐indolyl adducts were achieved
rocks! Proline and (2S,3aS,7aS)‐octahydro‐1H‐indole‐2‐carboxylic acid are both poor catalysts for the inverse‐electron‐demand hetero‐Diels–Alder reactions between aldehydes and electron‐deficient enones. However, forming modularly designed organocatalysts (MDOs) through their self‐assembly with cinchona alkaloid‐derived thioureas can dramatically improve the efficiency of these catalysts (see scheme;