Executing and Rationalizing the Synthesis of a Difluorinated Analogue of a Ring-Expanded Calystegine B2

• Published in: Journal of organic chemistry Vol. 77; no. 2; pp. 991 - 998
• Main Authors: Kyne, Sara H, Miles, Jonathan A. L, Percy, Jonathan M, Singh, Kuldip
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 20.01.2012; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Organic; Exact sciences and technology; Fluorine Compounds - chemical synthesis; Fluorine Compounds - chemistry; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Magnetic Resonance Spectroscopy; methodology; Models, Molecular; Molecular Structure; Nortropanes - chemical synthesis; Nortropanes - chemistry; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; Solanaceous Alkaloids - chemical synthesis; Solanaceous Alkaloids - chemistry; stereochemistry; Stereoisomerism; Thermodynamics; TRANSITION; ENERGY; MECHANISM; DIOXIRANE; ASYMMETRIC EPOXIDATION; FLUORINE; DIMETHYLDIOXIRANE; Regioselectivity; Microwave; Selectivity; Ring cleavage; Stereoselectivity; Alkaloid; Thermodynamic control; Cyclization; Steric effect; Epoxidation; Density functional method; Transannular reaction; Chemical synthesis; Protection
• ISSN: 0022-3263; 1520-6904; 1520-6904
• DOI: 10.1021/jo2022845

A difluorinated analogue of a ring-expanded calystegine B2 and some N-protected species were prepared via microwave-mediated transannular ring-opening of an epoxyketone. The diastereofacial selectivity of the epoxidation reaction, which delivers the key intermediate, and the regioselectivity of the transannular reactions were analyzed by density functional theory (DFT) methods. The epoxidation stereoselectivity arises from simple steric control, whereas the ring-closure reactions are subject to thermodynamic control.