Ah ighly efficient copper-catalyzed protocolf or the synthesis of bis-and tris-selenide alkenes from alkynyl carboxylic acids and diselenides has been developed. The reaction of alkynyl carboxylic acids and diselenides in the presence of CuI/Cs 2 CO 3 /toluene under white light LEDs only gave bis-selenide alkenes, whereas tris-selenide alkenes were obtained in the presence of aC uI/Cs 2 CO 3 /NMP system. This method provides ar apid access to bis-and tris-selenide alkenes derivatives.

A simple and efficient methodology has been developed for the regioselective synthesis of fused 1,2,3-triazole and isoindoline derivatives under catalyst free conditions.

We report herein our synthetic efforts towards the divergent syntheses of (À)-huperzine Q( 1), (+ +)-lycopladine B (2), (+ +)-lycopladine C( 3), and (À)-lycopladine D( 4). The 10-step total synthesis of (À)-huperzine Q( 1)a nd the first total syntheses of (+ +)-lycopladines B( 2)a nd C( 3)w ere accomplished through as eries of cascade reactions. Our approach involved aM ichael addition/aldol/intramolecular C-alkylation sequence to forge the 6/9 spirocycle ring, and this was followed by an ethylene-accelerated carbonyl-olefin metathesis to construct the common 6/5/9 ring system.F inally,l atestage enamine bromofunctionalization enabled us to access (À)-huperzine Q( 1), (+ +)-lycopladine B( 2), and (+ +)-lycopladine C( 3), and at andem C4-epimerization/retro-Claisenc ondensation furnished (À)-4-epi-lycopladine D( 63). IntroductionThe Lycopodium alkaloids are al arge family of complex natural products.N early 300 compounds have been isolated so far. [1] Owing to their intricate polycyclic skeletons andd iverse bioactivities, the total syntheses of these alkaloids have attracted broad attention from the synthetic community in recent years. [2] Among these compounds, (À)-huperzine Q( 1), (+ +)-lycopladine B( 2), (+ +)-lycopladine C( 3), and (À)-lycopladine D( 4) are four structurally relatedf awcettimine-type alkaloids (Figure 1). HuperzineQ (1)w as isolatedf rom Huperzia serrata by Zhu and co-workersi n2 002, and it possessesa nu nprecedented pentacyclic ring system and an aminal moiety. [3] The Takayama group [4] and the Zhao group [5] reported the total syntheseso f1 in 2011a nd 2015, respectively.( + +)-Lycopladine B (2), (+ +)-lycopladine C( 3), and (À)-lycopladine D( 4)w ere isolated from Lycopodium complanatum by Kobayashi and co-workers in 2006. [6] Whereasb oth (+ +)-lycopladines B( 2)a nd C( 3) contain au nique tetracyclic skeleton with ad ienamine moiety, (À)-lycopladine D( 4)c onsists of ap entacyclic core structure with ac arbinolamine lactone core. In 2013, Zhao and co-workers achievedt he first total synthesis of (À)-lycopladine D( 4). [7] Herein, we describe af ull account of our divergents yntheses of (À)-huperzine Q( 1), (+ +)-lycopladine B( 2), and (+ +)-lycopladine C( 3) [8] as wella so ur synthetic efforts towards (À)-lycopladine D( 4). Retrosynthetic analysisOur retrosynthetic analysisf or (À)-huperzine Q( 1), (+ +)-lycopladine B( 2), (+ +)-lycopladine C( 3), and (À)-lycopladine D( 4)i s outlined in Scheme 1. We envisioned that the aminal moietyi n 1 and the dienamine moieties in 2 and 3 could be derived from enamine intermediates 5 and 6,r espectively.W hereas both 5 and 6 could arise from 7 by aC 4-epimerization/cyclization sequence, diketone 7 could also potentially serve as ac ommon synthetic intermediate for the synthesis of (À)-lycopladine D( 4)t hrough aldehyde 10.T he cyclopentanone ring in 7 could be constructedf rom spirocyclic diketone 8,w hich could be readily accessed from enone 9 through our previously developed Michael addition/aldol/C-alkylation method.Initial synthe...

The Yu’s Rh-catalyzed [3+2+1] cycloaddition followed by a Pd-mediated 5-endo cycloalkenylation is shown to be a general and powerful approach for efficient construction of the tetracyclic core structure of ent-kaurane diterpenoids. The utility of this strategy was further demonstrated by concise and protecting-group-free total syntheses of ent-1α-hydroxy­kauran-12-one, 12-oxo-9,11-dehydro­kaurene, and 12α-hydroxy-9,11-dehydro­kaurene.