ORGANIC CHEMISTRY Chapter 17 17.7 Lithium enolates Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 17.7 Lithium Enolates
ORGANIC CHEMISTRY Chapter 17 LDA Lithium diisopropylamide [(ch3)2 CH2N Li 二异丙氨基锂 THE [(CH3)2CH]2NH C4HOLi -[(CH3)2CI2NLI C4H1o o° CH3-C-CH3 +[(CH3)2 C]N Li-+CH2-C=CH Stronger acid Stronger base Weaker base pKa=20 +[(CH3)2CHINH Weaker acid pKa= 38 Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 LDA Lithium diisopropylamide [(CH3)2CH]2N −Li+ 二异丙氨基锂 [(CH3)2CH]2NH + C4H9Li THF [(CH3)2C]2N Li + C4H10 CH3 C O CH3 + [(CH3)2C]2N Li CH3 C O CH2 δ δ Li pKa = 20 [(CH3)2CH] + 2NH pKa = 38 Stronger acid Stronger base Weaker base Weaker acid
ORGANIC CHEMISTRY Chapter 17 17.7A Regioselective Formation of Enolate anions H H H weak base CH3 H CHS-CHSL H protic solvent H Kinetic Thermodynamic (less stable enolate) (more stable enolate H [(CH3)2C]N Li H H CH H CH Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 17.7A Regioselective Formation of Enolate Anions O CH3 H H H O CH3 H H O CH3 H H Kinetic (less stable enolate) Thermodynamic (more stable enolate) weak base protic solvent O CH3 H H H [(CH3)2C]2N Li O CH3 H H Li
ORGANIC CHEMISTRY Chapter 17 17. 7B Lithium Enolates in directed Aldol reactions LDA CH2-C-ChCh, TUE CH -C-CH,CH3+ CH,=C-CH,CH CH2CHCHO H2O CH2,-C-CHoCH OH CH2 CHbCH-CHo-C-CHoCH Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 17.7B Lithium Enolates in Directed Aldol Reactions CH3CH2CHO CH3 C O CH2CH3 70 LDA CH2 C O CH2CH3 CH3CH2CH O CH2 C O CH2CH3 CH2 C O CH2CH3 Li CH3CH2CH OH CH2 C O CH2CH3 H2O THF
ORGANIC CHEMISTRY Chapter 17 17.7c Direct Alkylation of Ketones via Lithium enolate CH CH CH LDA CH3-I CH DME C6HsCH2-Br CH CH2C6H5 Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 17.7C Direct Alkylation of Ketones via Lithium Enolate O CH3 LDA DME O CH3 Li CH3 I O CH3 CH3 C6H5CH2 Br O CH3 CH2C6H5
ORGANIC CHEMISTRY Chapter 17 17.8 a-Selenation: A Synthesis of a, B-Unsaturated Carbonyl Compounds Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 17.8 α-Selenation: A Synthesis of α,β-Unsaturated Carbonyl Compounds
ORGANIC CHEMISTRY Chapter 17 O LDA CeHs-C-CHCH C6H5s-C=CHCH3 CkHsSe- Br O HO CAHs-C-CHCH Secchi 25°C O C6H5-C-CH=CH2 CHs SeOh Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 C6H5 C CH2CH3 O LDA C6H5 C CHCH3 O C6H5Se Br C6H5 C CHCH3 O SeC6H5 H2O2 25°C C6H5 C CH O CH2 + C6H5SeOH
ORGANIC CHEMISTRY Chapter 17 17.9 Additions to a, B-Unsaturated Aldehydes and Ketones Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 17.9 Additions to α,β-Unsaturated Aldehydes and Ketones
ORGANIC CHEMISTRY Chapter 17 1.2-Addition C=C-C-O Nu N Simple addition C=C-C=O 1. 4-Addition -C-C=C-O Nu Conjugate addition Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 C C C O Nu 1,2-Addition 1,4-Addition C C C O Nu C C C O Nu Simple addition Conjugate addition
ORGANIC CHEMISTRY Chapter 17 I)C6H5MgBr_C6H5 CH=CHCH-C6H5 (2)H2O 100%OH CkHCHECHCHO 1.2-Addition (I)C2HsMgBr C6HsCH=CHCH-C2H5 (2)H2O 100%OH 1. 2-Addition 1. 4-Addition I)C6Hs MgBr 88% 120 (2)H2O CkHsCH-CHCCH (1)C2HS MgBr 409 60 (2)H2O Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 17 C6H5CH CHCHO 1,2-Addition C6H5CH CHCH C6H5 OH C6H5CH CHCH C2H5 OH (1)C6H5MgBr (2) H2O (1)C2H5MgBr (2) H2O 100% 100% C6H5CH CHCCH3 O (1)C2H5MgBr (2) H2O (1)C6H5MgBr (2) H2O 88% 12% 40% 60% 1,2-Addition 1,4-Addition