42842-40-0Relevant academic research and scientific papers
Radical reaction initiated and stereocontrolled by zinc chloride
Yamamoto, Yoshinori,Onuki, Setsuko,Yumoto, Masatoshi,Asao, Naoki
, p. 765 - 780 (2007/10/03)
The reaction of allyltributyltin with methyl 2-[N-((4S)-4-(1-methylethyl)-2-oxazolidinone-3-carbamoyl)amino]-2-bromoacetate (5 a) was accelerated at -50°C in the presence of AIBN and stopped in the presence of galvinoxyl, indicating that the reaction proceeds through a radical mechanism. The reaction was accelerated dramatically at -78°C in the presence of ZnCl2·OEt2, and the ZnCl2-mediated reaction was stopped in the presence of galvinoxyl. In the presence of 2 equiv ZnCl2·OEt2, the reaction afforded methyl (2R)-2-[N-((4SH-(1-methylethyl)-2-oxazolidinone-3-carbamoyl)amino]-4-pentenoate {6a(R)} with high diastereoselectivity (93:7). Taken together, ZnCl2·OEt2 works as a radical initiator as well as chelating agent.
Relative Reactivities of Alkyl-Substituted Alkenes and Cycloalkenes towards Diarylcarbenium Ions
Mayr, Herbert,Pock, Rudolf
, p. 2473 - 2496 (2007/10/02)
The relative reactivities of alkyl-substituted alkenes 4 towards diarylmethyl cations 2 generated in situ from diarylmethyl chlorides 1 and Lewis acids were determined by competition experiments.The relative reactivities were almost independent of the nature of the Lewis acid. Eventual differences of the solvation free enthalpies of various activated complexes are, therefore, independent of the nature of the gegen ions.The rate acceleration by methyl groups - 6-50 by CH3 at the attacked vinylic position and approximately 104 at the developing carbenium centre - indicates a scarcely bridged transition state.
