Effect of Increase in Steric Bulk of Aryllithium on Stereoselectivity of Boronate Complexes

Abstract

(S)-4,4,5,5-Tetramethyl-2-(4-phenylbutan-2-yl)-1,3,2-dioxaborolane was reacted with 1-bromonaphthalene and ate-complex was synthesized and this resulted product acted as nucleophile. Stereoselectivity of ate-complex was determined by reacting with different electrophiles diisopropyl azodicarboxylate (DIAD), dibenzyl azodicarboxylate (DBAD) and tropylium tetrafluoroborate. Yields and enantiomeric ratios (e.r.) were measured at -78 ºC and room temperature. It was observed that the increase in steric bulk of aryl lithium (ArLi) resulted in the lower yields and enantiomeric ratios.