A free radical route to syn lactones and other prostanoid intermediates in isoprostaglandin synthesis.

New Bioactive Oxylipins Formed by Non‐Enzymatic Free‐Radical‐Catalyzed Pathways: the Phytoprostanes

“…At the beginning of the 1990s, the Durand/ Rossi group along with Rokach's team reported the synthesis of key intermediate 6, a diastereomer of Corey's formyl-lactone, via an acyclic thionocarbonate [36]. Durand and Rossi developed subsequently radical carbocyclizations of functionalized iodo precursors 8 and 9 (Scheme 2) [37], which replace the thionocarbonate precursors initially proposed advantageously.…”

Design and Synthesis of Hydroxyethylene-Based BACE-1 Inhibitors Incorporating Extended P1 Substituents

“…1,2:5,6-Di- O -isopropylidene-a-D-glucofuranose was used as a precursor from which compound 5 was synthesized in 49% yield over five steps using a method described in the literature [12-15]. Treatment of 5 with MeI and Ag 2 O in DMF furnished the methyl ether 6 in 89% yield.…”

“…Compound 5 was synthesized in 49% total yield over five steps according to references [12-15]. Analytical data was in accordance with reference [13].…”

Recent advances in the stereoselective synthesis of isoprostanes and neuroprostanes

“…Rokach and co-workers (Hwang et al, 1994), along with the Durand-Rossi group (Rondot et al, 1993;Roland et al, 2000), reported an innovative solution to the pivotal stereocontrol of the ring-forming step to distereoselectively produce both cis-dialkyl substituted cyclopentanes from a common substrate (Scheme 4). Cyclization of diol 20, which was prepared in seven steps from l-glucose, under typical radical-generating conditions, produced lactone 23 as the major product in 40% yield, whereas cyclization of the corresponding bis-silyl derivative 21 resulted in predominant formation of 25 in comparable yield.…”

“…In contrast, deployment of bulky protecting groups, as in the case of 21, would prefer the conformer 24 to afford the alternate cis-disubstituted product 25, as predicted by the Beckwith-Houk model of hex-5-enyl cyclizations. The factors controlling the diastereoselectivity of the cyclization reactions of these polyhydroxyated hex-5-enyl radicals have been carefully examined by the Durand-Rossi group (Rondot et al, 1993;Roland et al, 2000). By standard methods, 25 and 23 were then converted to enantiomerically pure 2a (Hwang et al, 1994) and 1a (Hwang et al, 1996),…”