Enantiospecific syntheses of leukotrienes C4, D4, and E4, and [14,15-3H2]leukotriene E4 dimethyl ester

Total Synthesis of Leukotrienes from Butadiene

“…Scheme 5. Synthesis of [ 2 H 2 ]-LTA 4 methyl ester (28) The conversion of LTA 4 methyl ester (4) to the peptidoleukotrienes 1, 2 and 3 was carried out following established protocols [21,49] as described in Scheme 6. Leukotriene C 4 (1), D 4 (2) and E 4 (3) could be prepared from LTA 4 methyl ester (4) by reaction with the free thiopeptides as described earlier [15] or with N-trifluoroacetyl--cysteinylglycine methyl ester or -cysteine methyl ester in the case of 2 and 3 respectively.…”

“…The same chiral key intermediate was used in all later reported total syntheses. [20] Cohan and coworkers obtained this key intermediate from -araboascorbic acid, [21] whereas Rokach et al, [22] and Bantik et al, [23] used different approaches from 2-deoxy--ribose for their chiral-pool synthesis. Baker et al used -glucose as the chiral starting material.…”

Deoxyhydantocidin: Synthesis by Base-Catalyzed Spiro Cyclization and Interconversion with the 1′-Epimer

“…Ϫ Elemental analysis were performed by the ''Service central de microanalyse du CNRS''. The compounds 5, [16] 6, [4c] 15 [17] and 16 [19] were prepared according to known procedures.…”

“…This precursor was thus prepared from ascorbic acid by successive H 2 O 2 oxidation into erythronolactone, in situ protection of the secondary hydroxyls by acetonide, and DIBAL reduction. [17] However, the hemiacetal 15 failed to react with the protected hydantoin 6 in the conditions that were successful for condensation of aldehyde 5. We thus turned to different condensation strategies making use of the WittigϪHorner reaction.…”

Synthesis of the Kedarcidin Core Structure by a Transannular Cyclization Pathway

“…homologative alkynylation sequence [7] was developed to transform the lactone 9 into the acetylene 10. Reduction of 9 with diisobutylaluminum hydride (DIBAL, 1.15 equiv) [8] in toluene (À 78 8C), followed by addition of a solution of the resultant lactols in tetrahydrofuran (THF) to a mixture of lithium diisopropylamide (LDA, 1.2 equiv) and (trimethylsilyl)diazomethyllithium [9] (1.2 equiv, formed from LDA and TMSCHN 2 ) in THF (À 78 3 23 8C), provided 10 in 77 % yield. Iterative silylation of the hydroxyl and alkynyl groups of 10, respectively, followed by selective cleavage of the SiÀO bond with Et 3 N´3 HF afforded the C-protected product 11 (82 % overall).…”