Fluorine-Induced Pseudo-Anomeric Effects in Methoxycyclohexanes through Electrostatic 1,3-Diaxial Interactions

Autor(es)

Piscelli, Bruno A. ^[1] ; Sanders, William ^[2] ; Yu, Cihang ^[2] ; Al Maharik, Nawaf ^{[2, 3]} ; Lebl, Thomas ^[2] ; Cormanich, Rodrigo A. ^[1] ; O'Hagan, David ^[2]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Chem Inst, Monteiro Lobato St, BR-13083862 Campinas, SP - Brazil

^[2] Univ St Andrews, Sch Chem, St Andrews KY16 9ST, Fife - Scotland

^[3] An Najah Natl Univ, Fac Sci, Dept Chem, POB 7, Nabulus, West Bank - Palestine

• Tipo de documento: Artigo Científico
• Fonte: CHEMISTRY-A EUROPEAN JOURNAL; v. 26, n. 52 AUG 2020.
• Citações Web of Science: 0

Resumo

We report counter-intuitive axial preferences in non-stereochemically biased, selectively fluorinated methoxycyclohexanes. These pseudo-anomeric effects are apparent when electronegative CF2 groups are placed at the C-2, C-4 and C-6 positions of the cyclohexane ring to render the C-3/5 axial hydrogen atoms electropositive. The electrostatic interaction between these axial hydrogen atoms and the -OMe oxygen is stabilising. The effect is explored using high-level ab initio and DFT calculations in the framework of NBO, QTAIM and NCI analysis across a range of derivatives, and experimentally (F-19[H-1]-NMR at -80 degrees C) for some illustrative examples. The effect is significant in energy terms for a weak interaction, and illustrates a new stereoelectronic aspect attributed to selective fluorine substitution in organic chemistry. (AU)

• Processo FAPESP: 18/03910-1 - Estudos físico-químicos de compostos orgânicos fluorados: abordagens experimental e teórica
• Beneficiário: Rodrigo Antonio Cormanich
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 19/05028-7 - Estudos físico-químicos de compostos orgânicos fluorados: abordagem experimental e teórica
• Beneficiário: Rodrigo Antonio Cormanich
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• Processo FAPESP: 19/03855-3 - Síntese de derivados fluorados do timol e do carvacrol e estudo de suas propriedades físico-químicas
• Beneficiário: Bruno de Almeida Piscelli
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica