Analogs of D(+)-pantothenic acid. V. Synthesis and investigation of the structure of N-pantoyl derivatives of proline

Toward Diels−Alder Reactions on a Solid Support Using Polymer Bound N‐Substituted 3‐Hydroxy‐4,4‐dimethyl‐2‐pyrrolidinone Acrylate Derivatives

“…The racemic 1-(4-carboxyphenyl)-3-hydroxy-4,4-dimethyl-2-pyrrolidinone (24) was prepared in moderate yield, as described previously, [20] by fusion of a mixture of an excess of the lactone 17 with the sodium salt of 4-aminobenzoic acid at 190°C (Scheme 3). The corresponding racemic benzyl ester 25a was obtained in high yield upon reaction with (benzotriazolyloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and diisopropylethylamine (DIEA).…”

“…The mixture was then stirred for 5 h at room temperature under H 2 (the reaction was monitored by TLC). After filtration through celite, concentration of the filtrate yielded the expected compound 23 as a colourless oil ( [20] Commercially available pantolactone (25 g, 192.0 mmol, 2.9 equiv.) was melted at 190°C and then sodium 4-aminobenzoate (10.5 g, 65.9 mmol) was added in one go.…”

(R)- or (S)-4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoic acid as a new chiral auxiliary for solid phase asymmetric Diels–Alder reactions

“…As part of our programme directed towards the development of asymmetric reactions on solid support, 14 we decided to convert the racemic 4- (3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoic acid acrylate derivative into the corresponding enantiopure compound and to evaluate its possible use as a supported chiral auxiliary in asymmetric DielsAlder reactions. benzoic acid (±)-1 was prepared as previously described 15 in moderate yield under severe conditions by fusion of an excess of pantolactone 2 and the sodium salt of the 4-aminobenzoic acid at 190°C (Scheme 1). The corresponding racemic benzyl ester 3 was obtained in high yield using benzyl alcohol, benzotriazolyloxytris-(dimethylamino)phosphonium hexafluorophosphate (BOP) and N,N-diisopropylethylamine (DIEA).…”