Derek discovered and extensively documented a number of examples of the "Mason Efffect." When allenylstannannes are treated with organolithium reagents (Li/Sn exchange) different ratios of allenyl and propargyl products products are formed depending on the conditions under which they are trapped - in situ or sequential.
This project was later taken up by John Holladay, who did extensive studies of the solution structure of allenyl lithium reagents to clarify the mechanism, and Bill Sikorski who helped put the finishing touches on the full paper.
"Lithium-Metalloid Exchange: Reactivity Studies of an Allenyl Lithium Reagent Using an Isomeric Pair of Allenyl and Prop-2-ynyl Stannanes," Hans J. Reich and J. Derek Mason, and Jonathan E. Holladay, J. Chem. Soc., Chem. Commun. 1993, 1481-3. (Communication).|
"The Origin of Regioselectivity in an Allenyllithium Reagent," Hans J. Reich, Johnathan E. Holladay, J. Derek Mason, William H. Sikorski, J. Am. Chem. Soc. 1995, 117, 12137-12150. (Article) PDF
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