Synthesis of an Isomer‐Free Tetravaline Derivative by Stereoselective Four‐Component Condensation and Exponential Multiplication of Selectivity

Abstract

the study of this kind of ring-chain tautomerism than other conventional methodsf2]. Thus, compounds ( 3 a ) , X = C 0 2 C 2 H 5 and (3 a ) , X = CO,-tert-B~[~l were found to occur in the chain form ( 4 ) , whereas the reaction products obtained from ( 2 b ) and ( 2 c ) are y-hydroxy lactams (3). Accordingly, cleavage of the tert-butyl group from ( 4 ) , 151 (6 I / 7 A Z + E )

Bioorganometallic Chemistry of Ferrocene

“…Chiral R-ferrocenylalkylamines, in particular compound 117 shown in Scheme 38, have found widespread application in these stereoselective four-component condensations. [241][242][243][244][245][246][247][248] This is because (1) they were shown to have strong asymmetric inducing power and (2) they were cleaved easily under acidolytic conditions. In fact, the chiral primary amine 117 can be regenerated from the peptide 118 by a series of steps, as shown in Scheme 39.…”

“…As a proof of concept, stereoselective 4-CC employing chiral ferrocenylalkylamines has been used to synthesize tetravaline and glutathione 103 of high enantiomeric purity. 243,244,248 In two related patents, it was reported that stereoselective 3-CC with isobutyraldehyde-N-R-ferrocenylethylamine as one of the components yields N-acyl-R-amino acid amides and peptides after TFA cleavage. 251,252 These compounds were claimed to be useful as paint and varnish thickeners and as plastisizers for poly(vinyl chloride).…”

Isocyanoacetate Derivatives: Synthesis, Reactivity, and Application

“…The minor isomer was cleaved some 230 times faster and the thus obtained enriched peptide 710b was deprotected easily to afford diastereopure tetravaline 711 in 92% yield (Scheme 173). 354 Diastereopure glutathione also was synthesized in this manner by Urban in 1979. 355 Glucopyranosyl amine 708a has been used to prepare protected tripeptides 712 and dipeptides 713 in high diastereopurity (Scheme 174).…”

“…Preparation of pure tetrapeptide 710b can be accomplished by selective acidolysis and removal of the ferrocenyl group from of the mixture. The minor isomer was cleaved some 230 times faster and the thus obtained enriched peptide 710b was deprotected easily to afford diastereopure tetravaline 711 in 92% yield (Scheme ) . Diastereopure glutathione also was synthesized in this manner by Urban in 1979 …”