Approaches Towards the Synthesis of Bradyoxetin
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Recyclization Reactions of 8,10-Dibromocamphor with Grignard and Organolithium Compounds Ihor S
FRENCH-UKRAINIAN JOURNAL OF CHEMISTRY (2021, VOLUME 09, ISSUE 01) Recyclization reactions of 8,10-dibromocamphor with Grignard and organolithium compounds Ihor S. Verenka, Marian V. Gorichko* Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska Street, 64/13, Kyiv 01601, Ukraine [email protected] Keywords: camphor, recyclization, Grob fragmentation, intramolecular alkylation, bicyclo[3.2.0]heptane. Grignard reagents and organolithium compounds react with 8,10-dibromocamphor to afford substituted 1-methyl-2-methylenebicyclo[3.2.0]heptanes. Recyclization proceeds via intramolecular enolate alkylation and Grob fragmentation of the reaction intermediates. All compounds have been characterized by 1H, 13C and 19F NMR spectroscopy and their chemical composition proved by HRMS analyses. The relative spatial arrangement of substituents in the molecule of (1-methyl-2- methylenebicyclo[3.2.0]heptan-6-yl)diphenylmethanol was studied by NOESY experiments. ________________________________________________________________________________ Introduction Even nowadays, comparing to other Camphor is known as the naturally relatively simple natural molecules, the available starting material in a number of chemistry of camphor has many uncharted syntheses of more complex compounds from the domains. middle of the XIX century. Nowadays many Electrophilic bromination is the very syntheses of steroids [1-3], terpenoids [4-12], important approach in the preparation of bromo- vitamins [13-15] and other natural products [16- functionalized terpenoid derivatives, which are 19] that involve camphor or its derivatives are common as intermediates in organic synthesis described in the literature. because of the ease of further modifications via Camphor derived chiral auxiliaries can nucleophilic substitutions or various skeletal be prepared in both enantiomeric forms since rearrangements and cyclizations [26–30]. -
1 the Principle of Conservation of Structural Aspect: Facilitating Visual Communication and Learning in Organic Chemistry Instr
1 The Principle of Conservation of Structural Aspect: Facilitating Visual Communication and Learning in Organic Chemistry Instruction John Andraos CareerChem 504-1129 Don Mills Road Toronto, ON M3B 2W4 Canada [email protected] Abstract An effective pedagogical method is presented for the visual communication of chemical reactions learned in organic chemistry undergraduate courses. The basis for the method is the preservation of the visual aspect of reactant and product structures so that the tracking of cleaved and formed chemical bonds is made self-evident. This consequently leads to improved clarity of presentation and a better understanding and grasp of proposed reaction mechanisms to explain product outcomes. The method is demonstrated for a variety of individual reaction types and synthesis plans. Various visual training exercises are also presented using ChemDraw Ultra 7.0 software and literature table of contents (TOC) graphics appearing in journal articles. Keywords: upper-division undergraduate, curriculum, organic chemistry pedagogy, problem solving, organic synthesis Introduction It is well known that when students encounter organic chemistry for the first time in undergraduate courses, they perceive the subject as “hard”. From their point of view their complaint stems from two major issues: (a) the apparent overwhelming volume of material that needs to be digested and learned in a relatively short period of time 2 (typically a three-month course session); and (b) the material is presented in a visual manner that is not always “easy” or evident to understand what is going in any given chemical reaction that is presented to them. The inevitable outcome is increased frustration and ultimately a dislike for the subject for the majority of students, particularly those that take organic chemistry as a standard mandatory requirement for other disciplines such as pre-medical studies and life sciences. -