Total synthesis

About: Total synthesis is a research topic. Over the lifetime, 25578 publications have been published within this topic receiving 489319 citations.

Short, Enantioselective Total Synthesis of Okaramine N

Abstract: The first enantioselective total synthesis of a member of the okaramine family of bis-indole alkaloids, okaramine N (1), has been accomplished via intermediates 2-7, as outlined. The N-prenylated derivative of (S)-tryptophan methyl ester (2) was coupled with Fmoc-protected N-tert-prenylated tryptophan (3) to form the amide 4 in 70% yield. Pd(II)-mediated cyclization/rearrangement, a key step in the synthesis, transformed 4 into the indoloazacine 5 (44%), which was deprotected and cyclized in a single step to give the hexacyclic diketopiperazine 6 (95%). In the following novel and key sequence, 6 was transformed into 1: (1) selective ene reaction with N-methyltriazolinedione, (2) photooxidation of the remaining tert-prenylated indole subunit to provide 7, and (3) thermal retroene reaction of 7 to afford okaramine N (70% from 6).

Total synthesis of (±)-pancratistatin

Abstract: La synthese de l'octahydro pentahydroxy-1,2,3,4,7 dioxolo-1,3 [4,5-j] phenanthridinone-6 a ete effectuee; le controle stereochimique de la synthese est realise par une serie de reactions de fonctionalisations cis vicinales

Total Synthesis of Rubriflordilactone B

Abstract: The first and asymmetric total synthesis of rubriflordilactone A, a bisnortriterpenoid isolated from Schisandra rubriflora, has been accomplished in a convergent manner. Two enantioenriched fragments were forged together to give a functionalized cis-triene. A 6π-electrocyclization/aromatization sequence assembled the penta-substituted arene, and a formal vinylogous Mukaiyama aldol reaction introduced the butenolide side chain.

Combined C-H activation/cope rearrangement as a strategic reaction in organic synthesis: total synthesis of (-)-colombiasin a and (-)-elisapterosin B.

Abstract: The total synthesis of (−)-colombiasin A (2) and (−)-elisapterosin B (3) has been achieved The key step is a C−H functionalization process, the combined C−H activation/Cope rearrangement, between methyl (E)-2-diazo-3-pentenoate and 1-methyl-1,2-dihydronaphthalenes When the reaction is catalyzed by dirhodium tetrakis((R)-(N-dodecylbenzenesulfonyl)prolinate), Rh2(R-DOSP)4, an enantiomer differentiation step occurs where one enantiomer of the dihydronaphthalene undergoes the combined C−H activation/Cope rearrangement while the other undergoes cyclopropanation This sequence controls the three key stereocenters in the natural products such that the remainder of the synthesis is feasible using standard chemistry

Synthesis of chiral chromans by the Pd-catalyzed asymmetric allylic alkylation (AAA): scope, mechanism, and applications.

Abstract: The Pd-catalyzed asymmetric allylic alkylation (AAA) of phenol allyl carbonates serves as an efficient strategy to construct the allylic C−O bond allowing access to chiral chromans in up to 98% ee. The effect of pH and the influence of olefin geometry, as well as substitution pattern on the ee and the absolute configuration of the chiral chromans were explored in detail. These observations suggest a mechanism involving the cyclization of the more reactive π-allyl palladium diastereomeric intermediate as the enantiodiscriminating step (Curtin−Hammett conditions). This methodology led to the enantioselective synthesis of the vitamin E core, the first enantioselective total synthesis of (+)-clusifoliol and (−)-siccanin, and the synthesis of an advanced intermediate toward (+)-rhododaurichromanic acid A.