Conformationally Locked Pyramidality Explains the Diastereoselectivity in the Methylation of trans-Fused Butyrolactones
Csókás, Dániel; Siitonen, Juha H.; Pihko, Petri M.; Pápai, Imre (2020). Conformationally Locked Pyramidality Explains the Diastereoselectivity in the Methylation of trans-Fused Butyrolactones. Organic Letters, 22 (12), 4597-4601. DOI: 10.1021/acs.orglett.0c01008
Published inOrganic Letters
© 2020 American Chemical Society
A stereoselectivity model inspired by the total synthesis of stemona alkaloids is developed to explain why enolate-derived 3,4-fused butyrolactones are methylated with a preference for syn alkylation. The model shows how conformational locking present in nonplanar enolate structures favors syn over anti methylation, due to less significant structural distortions in the syn pathway. The developed model was also successfully used to rationalize selectivities of previously documented methylation reactions.