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Samarium(II) Iodide Mediated Sequential Reactions Roy Bowman January 16, 2004
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tarix | 05.03.2018 | ölçüsü | 487 b. | | #30027 |
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Roy Bowman January 16, 2004
Sequential Reactions Multiple bonds formed in a one pot process No need to collect and purify intermediates Access to elaborate products Although conceptually attractive, design of sequential reactions can be overwhelming Cationic, anionic, radical, pericyclic, carbenoid, and transition metal catalyzed sequential processes have been realized
Samarium(II) Iodide Totleben, M. J.; Curran, D. P.; Wipf, P. Journal of Organic Chemistry 1992, 57, 1740-4. Concellon, J. M.; Rodriguez-Solla, H.; Bardales, E.; Huerta, M. European Journal of Organic Chemistry 2003, 1775-1778
Samarium(II) Iodide
Samarium(II) Iodide Promotes several individual reactions important in synthesis: - Radical Cyclizations - Ketyl-Olefin Coupling - Pinacolic Coupling - Barbier Type Reactions - Aldol Type Reactions - Reformatsky Type Reactions - Conjugate Additions - Nucleophilic Acyl Substitutions -Cycloadditions
Samarium(II) Iodide Ability to promote both one and two electron processes Radical/Anionic Anionic/Radical Anionic/Anionic Radical/Radical
Reactivity Reactivity can be manipulated using: Co-solvents: HMPA, TMG, DBU Additives: Ni(II), Fe(III) Allows for highly selective and efficient sequential reactions to be effective
Radical Cyclization/Carbonyl Addition
Formation of Organosamarium
Formation of Organosamarium
Radical Cyclization/Carbonyl Addition
Radical Cyclization/Carbonyl Addition
Radical Cyclization/Carbonyl Addition
Radical Cyclization/Carbonyl Addition
Radical Cyclization/ Nucleophilic Addition
Radical Cyclization/ Nucleophilic Addition
Intramolecular Nucleophilic Acyl Substitution/Intramolecular Barbier Cyclization
Intramolecular Nucleophilic Acyl Substitution/Intramolecular Barbier Cyclization Ability to sequence formation of the organosamarium species so carbon-carbon bonds may be directed Alkyl halides are reduced in the order I > Br > Cl Sequences where order is unimportant are performed with diiodides Sequenced reactions in which side chain reaction order is significant are performed with alkyl iodide/alkyl chloride substrates
Intramolecular Nucleophilic Acyl Substitution/Intramolecular Barbier Cyclization
Nucleophilic Acyl Substitution/Ketyl Olefin Coupling for Preparation of Oxygen Heterocycles
Nucleophilic Acyl Substitution/Ketyl Olefin Coupling
Nucleophilic Acyl Substitution/Ketyl Olefin Coupling
Ketyl-Olefin Coupling/β-Elimination
Ketyl-Olefin Coupling/β-Elimination
Nucleophilic Acyl Substitution/Alkenyl Transfer Reactions
Nucleophilic Acyl Transfer/Alkenyl Transfer Reactions
Nucleophilic Acyl Transfer/Alkenyl Transfer Reactions
Nucleophilic Acyl Transfer/Alkenyl Transfer Reactions
Epoxide Ring Opening/Ketyl Olefin Coupling
Domino Epoxide Ring Opening/Ketyl Olefin Coupling Reactions
Domino Epoxide Ring Opening/Ketyl Olefin Coupling Reactions
Domino Epoxide Ring Opening/Ketyl Olefin Coupling Reactions
Epoxide Fragmentation/Tandem Radical Cyclizations
Epoxide Fragmentation/Tandem Radical Cyclizations
Epoxide Fragmentation/Tandem Radical Cyclizations
Intramolecular Barbier Cyclization/Grob Fragmentation
Ring Expansion by Grob Fragmentation Mediated by SmI2
Ring Expansion by Grob Fragmentation Mediated by SmI2
Reformatsky/Nucleophilic Acyl Substitution
Reformatsky/Nucleophilic Acyl Substitution
Reformatsky/Nucleophilic Acyl Substitution
Reformatsky/Nucleophilic Acyl Substitution
Transformation of Carbohydrate Derivatives into Cyclopentanols
Transformation of Carbohydrate Derivatives into Cyclopentanols
Insertion of Isocyanides into Organic Halides Preparation of -Hydroxy Ketones
Insertion of Isocyanides into Organic Halides Preparation of -Hydroxy Ketones
Insertion of Isocyanides into Organic Halides Preparation of -Hydroxy Ketones
Insertion of Isocyanides into Organic Halides Preparation of -Hydroxy Ketones
Insertion of Isocyanides into Organic Halides Preparation of -Hydroxy Ketones
Insertion of Isocyanides into Organic Halides Preparation of -Hydroxy Ketones
Synthesis of Vicinal Di- and Tri-Carbonyl Compounds
Synthesis of Vicinal Di- and Tri-Carbonyl Compounds
Synthesis of Vicinal Di- and Tri-Carbonyl Compounds
Cyclizations of Indole Derivatives
Cyclizations of Indole Derivatives
Cyclizations of Indole Derivatives
Cascade Radical Cyclizations: Synthesis of Paeonilactone B
Cascade Radical Cyclizations: Synthesis of Paeonilactone B
Synthesis of (±) Hypnophilin
Synthesis of (±) Hypnophilin
Synthesis of Phomoidrides
Synthesis of Phomoidrides
Synthesis of Phomoidrides
Synthesis of Phomoidrides
Synthesis of Phomoidrides
Synthesis of Phomoidrides
Synthesis of Phomoidrides
Summary Mild conditions, tolerant to functionality Reactivity can be manipulated allowing each step in the sequence to be tuned Capable of driving sequential reactions Highly diastereoselective resulting from highly organized transition states Sequential radical cyclization mediated by SmI2 have shown utility in natural product synthesis
Acknowledgements Dr. Jeff Johnson Johnson Group
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