第三章c-c双键五的形成.pptx

Chapter 3 Formation of Carbon-Carbon Doule Bonds;1. ?-Elemination reactions （?-消去反应）;2. Pyrolytic syn eliminations（顺式热消去反应）;Cope reaction;3. Wittig and related reactions （Wittig 及有关反应）; General Scheme; Representative Examples ;Example 3; Mechanism ; Influence of solvent on the selectivity; Schl?sser modification: allows the preparation of trans vs. cis olefins.; Stabilized Ylides; Influence of solvent on the selectivity; Wadsworth–Horner–Emmons Reaction; Preparation of Phosphonate Esters;- But can use variation on Claisen conditions:; Modifications and Scope;-Hindered phosphonates and hindered aldehydes increase E-selectivity ( trans).;- Additional Z-selective stabilized phosphonates.; Peterson Reaction;- The elimination is stereospecific:; Stabilized Peterson Reagents;- Additional examples:;4. The Tebbe Reaction and Related Titanium-stabilized Methylenations (Tebbe反应及与有关稳定化钛试剂的亚甲基化反应）;- Tolerates ketal and alkene derivatives. Scope defined by Evans and Grubbs J. Am. Chem. Soc. 1980, 102, 3270. Extended to tertiary amides by Pine J. Org. Chem. 1985, 50, 1212.;5. Sulphoxide-sulphenate rearragement: Synthesis of allyl alcohols (亚砜-次磺酸酯重排：烯丙醇类化合物的合成);?-alkylation of allylic alcohlos;6. Alkenes from sulphones (由砜制备烯烃）; Julia developed a more recent, single-step variant that avoids the reductive elimination;- Ramberg–Backlund reaction;7. Decarboxylation of ?-lactones (?-内酯的脱羧反应）;Fehr C. et al. Tetrahedron Lett., 1992, 33, 2465 ;Mulzer J., et al., J. Chem. Soc. Chem. Commun., 1979, 52 ;8. Stereoselective synthesis of tri- and tetra- substituted alkenes ( 三、四取代烯烃的立体选择性合成）; Development;Example;Method 2;Zweifel, G. et al., J. Am. Chem. Soc., 1967, 89, 5085. ;9. Oxidative decarboxylation of carboxylic acids ( 羧酸的氧化脱羧反应）;Tanzawa T. et al. Tetrahedron Lett., 1992, 33, 6783 ;10. Alkenes from arylsulphonylhydrazones (由芳基磺酰腙制备烯烃）;Less substituted alkene;11. Fragmentation Reactions (裂解反应） ;12. Olefin Inversion Rea