The palladium catalyzed cross coupling and carbonylation trapped by enolates
Abstract
Based on the development of a novel and selective methodology of Zr-catalyzed carboalumination of alkynes and Pd-catalyzed homoallyl-alkenyl and homopropargyl-alkenyl cross coupling, we successfully synthesized the natural product of (all-E)-coenzyme Q10 in 9 linear steps with an overall 29% yield. The use of Pd(dppf)2Cl2 as a catalyst is a necessity to significantly increase the cross-coupling yields. The Pd-catalyzed α-substitution of α-iodoenones with aryl, alkyl, alkenyl and alkynylzinc derivatives promises to be a synthetic tool with widespread application. Conjugate reduction reactions provide the corresponding saturated carbonyl compounds in completely regiocontrolled manner. The reaction of alkenyl iodides with highly acidic ketones in the presence of high-pressure CO, one or two equivalent of NEt3 and 5% Pd(PPh3) 2Cl2 in DMF at 100°C provides the enol carboxylates formed via trapping of the putative acylpalladium intermediates with enolates. Some of the initially formed acyclic products can also be cyclized to give the corresponding lactones.
Degree
Ph.D.
Advisors
Negishi, Purdue University.
Subject Area
Organic chemistry|Chemistry
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