Synthesis and reactions of polymer-bound Ph₃PCCO: a quick route to tenuazonic acid and other optically pure 5-substituted tetramates

Abstract

Polystyrene-bound cumulated ylide Ph3PCCO was prepared on a large scale in two steps. It reacts with Grignard compounds, amines and alcohols to give immobilized acyl, amide and ester ylides, respectively. Their Wittig reactions lead to alkenes free of phosphane oxide. Optically pure 5-substituted tetramates were obtained from reactions of resin-bound Ph3PCCO with alpha-ammonium esters in one step. The mycotoxin (-)-tenuazonic acid was accordingly prepared in just three steps.

An expedient synthesis of 3-acyltetramic acids of the melophlin family from α-aminoesters and immobilized Ph3PCCO

“…PS-3 is a yellow air-stable freerunning powder which is easy to prepare, dose and handle, and which furnishes olefins not contaminated with otherwise difficult to remove triphenylphosphane oxide. 30 Cleavage of 4a with TFA quantitatively yielded N-methylpyrrolidine-2,4-dione 5a. 31,32 Although Jones 23 reported that 5-unsubstituted tetramic acids may not be acylated at C-3 with acetyl chloride/BF 3 -diethyl etherate due to side reactions such as rearrangements and condensations, we were able to attach myristoyl and palmitoyl residues to 5a under these conditions.…”

Stereoselective Synthesis of (2E,4Z)‐Dienamides Employing (Triphenylphosphoranylidene)ketene

“…For this purpose, we intended to use the Bestmann ylide (triphenylphosphoranylidene)ketene [18] (Ph 3 P=C=C=O, 9) for preparing (2E,4Z)-dienamides 11 on the basis of our previous syntheses of (E)-α,β-unsaturated amides from aldehydes and amines (Scheme 2). [19,20] The results are reported below. Scheme 2.…”

Domino syntheses of bioactive tetronic and tetramic acids

“…A congener of the CO 2 t-Bu ylide attached to a polystyrene (PS) resin support (1.4 mmol/g resin) was prepared in two steps from a commercially available PS-bound triphenylphosphane, benzyl bromoacetate and lithium hexamethyldisilazanide, LiHMDS (Schobert et al 2004). PS-Ph 3 PCCO undergoes the same reactions as the parent ylide Ph 3 PCCO in solution under almost identical conditions.…”

“…(−)-Tenuazonic acid, a mycotoxin first isolated in 1957 from the culture filtrates of Alternaria tenuis and later also from other Alternaria and Pyricularia species (Rosett et al 1957;Stickings 1959), which shows a broad spectrum of bioactivity (Gitterman 1965;Miller et al 1963), was prepared in three steps from L-isoleucine benzyl ester hydrochloride and a twofold excess of PS-Ph 3 PCCO (Fig. 6) (Schobert et al 2004). Debenzylation of the intermediate tetramate with hydrogen gas at palladium on charcoal furnished 5-sec-butyl-pyrrolidine-2,4-dione, which was acylated with an excess of acetyl chloride and boron trifluoride-diethyl etherate.…”