Double Diastereoselective, Nucleophile-Catalyzed Aldol Lactonizations (NCAL) Leading to β-Lactone Fused Carbocycles and Extensions to β-Lactone Fused Tetrahydrofurans
摘要:
A double diastereoselective variant of the nucleophile-catalyzed aldol lactonization (NCAL) process is described. This strategy delivers beta-lactone-fused carbocycles with good to excellent diastereoselectivities using cinchona alkaloid catalysts with enantioenriched aldehyde acids, which gave low diastereoselectivity based on substrate control alone. beta-Lactone-fused tetrahydrofurans are also prepared for the first time via the NCAL process; however, diastereoselectivity was only modestly improved when applying double diastereodifferentiation to these systems.
已经研究了苄胺和硼酸酯之间的偶联反应。邻-Lithiated苄胺与硼酸酯反应,并且一个Ñ -activator,得到邻位与正规1,1'-亚苄基取代的插入苄硼酸酯到C-B键。该反应通过S N 2'的消除和N活化的硼酸酯络合物的1,2-金属化物重排而得到脱芳香化的中间体,该中间体经过路易斯酸催化的1,3-硼向转变以得到硼酸酯产物。高收率和优异的对映体特异性。使用富含对映体的α-取代的苄胺得到相应的具有高ee的仲硼酸酯。
Copper-Catalyzed Coupling of Alkyl Vicinal Bis(boronic Esters) to an Array of Electrophiles
作者:Ningxin Xu、Ziyin Kong、Johnny Z. Wang、Gabriel J. Lovinger、James P. Morken
DOI:10.1021/jacs.2c02817
日期:2022.10.5
between vicinal bis(boronic esters) and allyl, alkynyl, and propargyl electrophiles as well as a simple proton. Because the reactive substrates are vicinal bis(boronic esters), the cross-coupling described herein provides an expedient new method for the construction of boron-containing reaction products from alkenes. Mechanistic experiments suggest that chelated cyclic ate complexes may play a role in