Brønsted Acid Catalyzed Asymmetric Reduction of 2- and 2,9-Substituted 1,10-Phenanthrolines<b />
作者:Costa Metallinos、Fred Barrett、Shufen Xu
DOI:10.1055/s-2008-1032103
日期:——
Several 2- and 2,9-substituted1,10-phenanthrolines are reduced asymmetrically for the first time using a Hantzsch dihydropyridine in the presence of BINOL-derived phosphoric acid catalysts. The best results are obtained with phenanthrolines bearing unbranched or nitrogen-containing alkyl groups in the 2- or 2,9-positions, which afford chiral octahydrophenanthrolines in a range of yields (40-88%) and
An Experimental and Theoretical Study of the Asymmetric Lithiation of 1,2,3,5,6,7-Hexahydro-3a,4a-diazacyclopenta[<i>def</i>]phenanthren-4-one
作者:Costa Metallinos、Travis Dudding、Josh Zaifman、Jennifer L. Chaytor、Nicholas J. Taylor
DOI:10.1021/jo062244t
日期:2007.2.1
ne to undergo asymmetric lithiation with (−)-sparteine is circumvented by use of a urea functionality as the directing group. Asymmetric lithiation followed by electrophile quench gives products substituted α to nitrogen in better yield (17−30%) but slightly lower enantiomeric ratio (er 84:16) than analogous lithiation of N-Boc-piperidine (er 87:13). Computational studies at the MP2/6-316(d)//B3LYP/6-316(d)