Azlactones

Synthesis of dehydroamino acids and peptides by dehydrosulfenylation. Rate enhancement using sulfenic acid trapping agents

“…This temperature was chosen because the secondary sulfoxide 18 readily eliminates at 80 °C but the primary sulfoxide 12 does not appear to eliminate at this temperature. The reaction produced feri-butyloxycarbonyldehydromethylalanine 34 together with íerí-butyloxycarbonyl-3-S-benzylsulfinylalanine methyl ester 12, formed by the addition of benzylsulfenic acid to 29. No (V-methyl-(?-S-benzylsulfinyl derivative 18 remained, which showed that addition of sulfenic acid to the primary dehydroamino acid 29 was preferred over addition to the secondary dehydroamino acid 34. The crossover experiment established that sulfenic acids add readily to dehydroamino acids.…”

Prostaglandins and congeners. 11. Synthesis of dl-13-hydroxyprostanoic acids

“…The compound was pure by amino acid analysis, [a]22n -76.2°(c 1, 1 N HC1) [lit. 3 [ ] 25D -72.0°(c 1,1 N HC1)]. The disulfide desired for the preparation of derivatives was obtained by air oxidation of 7.0 g of 9 over a period of 4 days in 200 ml of aqueous ammonia at pH 8.6.…”

“…In a previous report we have described the synthesis and biological properties of prostaglandin analogues wherein the 15-hydroxy group is moved to the Cíe, C17, and C20 position or is replaced by a hydroxymethyl group.2 Another group has reported compounds wherein the hydroxy group is placed at C14. 3 We now describe a convenient synthesis of prostaglandin congeners wherein the hydroxy function has been shifted to the C13 position. After this work was completed, two reports appeared concerning the synthesis of 13-hydroxyprostanoic acids which do not contain the 11-hydroxy substituent.…”

“…Fractions 18-31 contained 2.01 g of a lower 7?/ isomer mixture; fractions 35-37 contained 0.5 g of a higher Rf isomer(s). For the lower Rf isomer mixture: NMR ¿Me4Si (CDCD 6.00 (bs, 3 , OH), 5.43 (m, 2 H, vinyl), 4.47 and 4.10-3.56 (m's, 2 H, CHOH), 3.00-1.10 (m's, 24 H, alkyl), 0.90 (m, 3 H, terminal CH3); IR (neat) 3370 (OH), 1720 cm-1 (C=0); high-resolution MS, 336.2309 [caled for C2oH34Oñ (M -H20), 336.2300], For the higher Rf isomer(s): NMR ¿Me4s¡ (CDCD 5.65 (bs, 3 , OH), 5.45 (m, 2 H, vinyl), 4.64 (m, 1 H, CHOH), 3.87 (m, 1 H, CHOH), 2.92-1.00 (m's, 24 H, alkyl), 0.90 (m, 3 H, terminal CH3); IR (neat) 3370 (OH), 1722cm-1 (C=0); high-resolution MS, 336.2306 [caled for C2oH3403 (M-H20), 336.2300].…”

Biologically oriented organic sulfur chemistry. 12. Principles of structure-activity relations for penicillamine analogs and derivatives

“…Chemistry. The preparation of the amino /3-thiolactone salt 14 followed a procedure of Sheehan and Poliak, in which IV-carbobenzoxy-DL-penicillamine (17) was allowed to react with dicyclohexylcarbodiimide to form 18, which then was decarbobenzoxylated with HBr to 14 (Scheme I).12•! Utilizing d-1, we were able to prepare the carbobenzoxy derivative d-17 but could not convert d-17 to the thiolactone d-18, evidently owing to sparing solubility of d-17 in suitable solvents.…”