Correlations Between Nucleophilicities and Selectivities in the Substitutions of Tetrahydropyran Acetals

Citations Over TimeTop 10% of 2009 papers

Abstract

Selectivities that deviate from SN1 stereoelectronic models in the nucleophilic substitutions of tetrahydropyran acetals were investigated. When weak nucleophiles were employed, stereoselectivities conformed to known SN1 stereoelectronic models. In contrast, stereoselectivities in the substitutions of acetals with strong nucleophiles depended on reaction conditions. Erosions in selectivities were observed when strong nucleophiles were employed in the absence of coordinating counterions. These erosions in selectivities are attributed to rates of nucleophilic additions to oxocarbenium ion intermediates that approach the diffusion limit. When triflate counterions were present, however, SN2-like pathways became accessible with strong nucleophiles. In most cases examined, the major stereoisomers formed from reactions that proceeded through SN2-like pathways were opposite to the major stereoisomers formed from the analogous reactions that proceeded through SN1 pathways.

Related Papers

• A GEOMETRIC MEAN IN THE FURUTA INEQUALITY(2002)
• Susquehanna Chorale Spring Concert "Roots and Wings"(2017)
• Коммуникaтивно- прaгмaтический aнaлиз дипломaтических бумaг (нa основе вербaльных нот)(2018)
• → ФОРМИРОВAНИЕ ГОТОВНОСТИ БУДУЩИХ ПЕДAГОГОВ К ОРГAНИЗAЦИИ РAБОТЫ ПО РAЗВИТИЮ ВAЛЕОЛОГИЧЕСКОЙ КУЛЬТУРЫ ШКОЛЬНИКОВ(2023)