有机合成剑桥版.pptVIP

 5.1 Carbon Radical Reactions The stages in radical reactions 1 initiation step Typical initiators :dibenzoyl peroxide The Cadiot-Chodkiewicz oxidative coupling of terminal alkynes using ammoniacal氨的 copper (1) chloride 5.2 Radical Addition Reactions tributylstannane as the provider of radical 5.3 Carbenes 2 Losing nitrogen from diazomethane 3 Losing CO from ketene Synthesis the following compound Arndt-Eistert reaction based on diazomethane 5.4 Alkene Metathesis (易位) Outcome: coupling of two chains via an alkene. No intermediate exist in this process Cis-formed ring junction Endo form is the main product The Ene Reaction The ene reaction is a sigmatropic(σ移位的) rearrangement The Cope rearrangement is a 3,3-sigmatropic reaction Sigmatropic rearrangement involving the cleavage of a σ bond at an oxygen atom are called Claisen rearrangement . 5.7 The Cope and Claisen Rearrangements C-H ?-HOMO Diene л-LUMO * * Free Radical and Pericyclic Reactions in the Formation of Carbon-carbon Bonds 5.1carbon radical reaction 5.2 radical addition reaction 5.3 carbene 5.4 alkene metathesis 5.5 the Diels-Alder reaction 5.6 the ene reaction 5.7 the cope and claisen rearrangements A carbon radical is a trivalent species Containing an unpaired electron in a p orbital azobisisobutyronitrile (AIBN)偶氮二异丁腈 propagation step termination step: Two radical combining with each other to form a covalent bond by losing a hydrogen atom. Synthetically useful radical reactions coupling, addition and substitution Kolbe electrolysis of carboxylic acids. The Ullmann coupling of aryl iodides to give diphenyls the Pschorr synthesis of phenanthrenes菲 Reductive free radical coupling processes The reducing of ketones by Magnesium The acyloin酮醇 condensation of esters with sodium Addition of TMSCl favor Acyloin condensation , Prevent Dieckmann reaction The McMurry coupling of aldehydes and ketones using low oxidation titanium