Lecture 9 given Sp 09

Lecture 9 given Sp 09 - Lecture 9 Organic Chemistry II for...

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Lecture 9 Chemistry 310N Chemistry 310N       Organic Chemistry II for Prehealth Professionals Unique number: 53185 Tu,Th 12:30-2:00 pm, Welch 2.224   Professor:  Jonathan Sessler, Ph.D. [email protected] Note: Office Hours will end at 3:10 pm today and Tuesday; sorry! Good seminar tomorrow; 3:30 pm in Convocation Center. Dr. D. Johnson
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Chapter 15 Introduction to Organometallic Chemistry --Continued
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Carbenes and Carbenoids Carbene, R Carbene, R C: C: A neutral molecule in which a carbon atom is surrounded by only six valence electrons. Methylene, the simplest carbene Prepared by photolysis or thermolysis of diazomethane. : H 2 C H 2 C N N + h ν Ν Ν + Μετηψλενε (τηε σιμ πλεστχαρβενε29
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Carbene In its lowest electronic state, carbon is sp 2 hybridized with the unshared pair of electrons occupying the third sp 2 orbital.
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Carbenes and Carbenoids Dichlorocarbene Prepared by treating chloroform with potassium tert- butoxide. CHCl 3 ( CH 3 ) 3 CO - K + Cl 2 C: ( CH 3 ) 3 COH K + Cl - + + Trichloromethane (Chloroform) Potassium tert- butoxide Dichloro- carbene tert- Butyl alcohol +
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Carbenes and Carbenoids Dichlorocarbene :CCl 2 Reacts with alkenes to give dichlorocyclopropanes. Cl 2 C: Dichloro- carbene + A dichloro- cyclopropane CCl 2 H H HCCl 3 ( CH 3 ) 3 CO - K + H Cl Cl H cis- 3-Hexene + cis- 1,1-Dichloro- 2,3-diethylcyclopropane
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Carbenes and Carbenoids Simmons-Smith reaction A way to add methylene to an alkene to form a cyclopropane. Generation of the Simmons-Smith reagent This organozinc compound reacts with a wide variety of alkenes to give cyclopropanes. CH 2 I 2 Zn( Cu) ICH 2 ZnI + diethyl ether Diiodo- methane Iodomethylzinc iodide (Simmons-Smith reagent) Zinc-copper couple
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Carbenes and Carbenoids Simmons-Smith reagent O CH 2 I 2 Zn( Cu) O CH 2 H H ZnI 2 + diethyl ether + 2-Cyclohexenone Bicyclo[4.1.0]heptan-2-one (racemic) CH 2 I 2 Zn( Cu) ZnI 2 + diethyl ether + Methylene- cyclopentane Spiro[4.2]heptane
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Carbenes and Carbenoids Simmons-Smith reaction The organozinc compound reacts with an alkene by a concerted mechanism. CH 2 I Zn I ZnI 2 H 2 C +
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RCM R 1 R 2 R 1 R 2 CM A New Development: Olefin Metathesis Reactions Ring Closing Metathesis (RCM ) Cross Metathesis (CM) Example O OAc OAc O OAc OAc RCM Ru PCy 3 Cl Cl N N Mes Mes N Mo O O F 3 C F 3 C CF 3 CF 3 Schrock Grubbs
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  "for the development of the metathesis method in organic synthesis" Yves Chauvin   Robert H. Grubbs   Richard R. Schrock   France  USA  USA  Institut Français du Pétrole  Rueil-Malmaison, France  California Institute of  Technology (Caltech) 
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This note was uploaded on 06/15/2009 for the course CH 53185 taught by Professor Sessler during the Spring '09 term at University of Texas.

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Lecture 9 given Sp 09 - Lecture 9 Organic Chemistry II for...

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