Enantiospecific syntheses of .gamma.-substituted enones: organometallic SN2' conjugate-addition reactions of epoxy vinyl sulfones

Multicomponent Strategy for the Synthesis of Prostaglandin E2 Methyl Ester under Anion Relay Chelation Control

“…Final deprotection of the silyl ether with HF·pyridine in acetonitrile at 0 °C afforded PGE 2 methyl ester 12 in 42% overall yield from (−)- 14 . The stereochemistry was confirmed by NOESY as shown in 40a , and the specific rotation of PGE 2 methyl ester 12 ([α] D 24 , 65.9 ( c 0.30, MeOH)) was in agreement with literature report ([α] D 24 , 71.7 ( c 1.04, MeOH)) …”

“…Prostanoids are biosynthesized in the body from arachidonic acid by the action of COX enzymes − and play various physiological roles including smooth muscle constriction or dilation, regulating inflammation, and platelet aggregation or disaggregation . Since the 1960s, many efforts on the chemical synthesis of prostaglandins have been reported, including the elegant strategies designed by Corey, Woodward, Stork, Fuchs, Noyori, Aggarwal, Hayashi, Nicolaou, and others. Because of the high demand of prostaglandins as drugs, there is still a necessity for the development of more efficient routes toward this class of compounds, based on new reactions and strategies.…”

Multiply convergent syntheses via conjugate-addition reactions to cycloalkenyl sulfones

“…Chiral epoxy vinyl sulfone l-57 can be further functionalized by treatment with nucleophilic methylating agents. 34 Reaction of l-57 under conditions favoring association of the methylating agent with the epoxide "Via transmetalation from tetraallyltin. bVia transmetalation from vinyltributyltin.…”

Total Syntheses of (±)-Cyclophellitol and (1R*,6S*)-Cyclophellitol

“…On the other hand, the use of non-nucleophilic bases gave rise to the isomerization with concomitant elimination of the β‘-benzyloxy group. Thus, the reaction of 4c with LDA or t -BuOK yielded the diene 10 . It should be noted that related dienyl systems have been previously prepared from dienes or by SO 2 extrusion of (arylsulfonyl)sulfolenes and used as synthetic intermediates on the basis of their dienic properties 17a.…”