D. H. Ripin, D A. Evans The Eschenmoser Coupling Reaction Chem 20 Key Bond Construction Needed for the B12 Synthesis: cH2)2CO 2 M (CH2l2 M E. Knott J. Chem. Soc. 916(1955) () The General Reaction: Acylation of an Amide C=O (CH2)2CO2Me (CH2)2CO2 Me Base, Thiophile Review. Trost Comp. Org. Synth. Vol. 2, Ch 3.7(1991) Me Meo2CCH H The Thioamide component R" Reagents p-MeOP -PhOMe A Eschenmoser Science 196, 1410(1977) JoC463558(1981). Synthesis149(1973) Lawesson ' s R Bull. Chim. Soc. Belg. 87, 229& 293(1978) lan J. Chem., Sect. B 14, 999, (1976) JAcs102,2392(1980) RCS2R'+ R2NH Imidate +H2s 一 Thioamidehem. Ind (London)803(1974) H23-06-Eschenmoser-1 11/5/008: 27 PME. Knott J. Chem. Soc. 916 (1955) The Thioamide component: Reagents P4S10 JOC 46, 3558 (1981), Synthesis 149 (1973) Lawesson's Reagent Bull. Chim. Soc. Belg. 87, 229 & 293 (1978) P4S10, Et3N or NaHCO3 Indian J. Chem., Sect. B 14, 999, (1976) JACS 102, 2392 (1980) RCS2R' + R2NH Thioamide Imidate +H2S Thioamide Chem. Ind. (London) 803 (1974) Angew. Chem. 79, 865 (1967) R R3P=S 3P The Solution: ? (+) (–) The Problem: ?? (–) (+) (–) (+) (–) (+) ?? A. Eschenmoser Science 196, 1410 (1977) Key Bond Construction Needed for the B12 Synthesis: ? Key papers: Review: Trost Comp. Org. Synth. Vol. 2, Ch. 3.7 (1991) A. Eschenmoser Helv. Chim. Acta. 54, 710 (1971) A. Eschenmoser Angew. Chem., Int. Ed. Engl. 6, 866 (1967) A. Eschenmoser Angew. Chem., Int. Ed. Engl. 8, 343 (1969) Base, Thiophile The General Reaction: Acylation of an Amide C=O D. H. Ripin, D. A. Evans The Eschenmoser Coupling Reaction Chem 206 R N X R3 S R’ R” O N R” R’ R R3 O N N H N O O Me Me (CH2)2CO2Me O Me N H N H O N H (CH2)2CO2Me Me Me O O N H O R N O R’ R” N R” R’ S (CH2)2CO2Me R P S P Me Me O N Me H (CH2)2CO2Me (CH2)2CO2Me Me Me O N R Me Me O N O H N H N O O Me Me R3 Me Me R3 Me R2 Me R3 O R2 Me R2 N NH N H O N N H N H N N H S NH N Me MeO2CCH2 Me MeO2CCH2 O (CH2)2CO2Me Me MeO2CCH2 C S N Me N H N S N X S S S p-MeOPh PhOMe H H23-06-Eschenmoser-1 11/5/00 8:27 PM