Total synthesis of muconin

Total Synthesis, Stereochemical Assignment, and Biological Activity of Chamuvarinin and Structural Analogues

“…Disconnection of the central C20-C23 THF ring system in 6 gives the C9-C20 aldehyde 7 and the C21-C34 alkyne 8, [18] in which www.chemeurj.org control over the C20 stereocenter would be reliant upon Felkin-Anh induction from the carbonyl component to enable 5-exo cyclization of the C23-hydroxyl to furnish the 2,5-syn-configured THF ring system. [13,20] Synthesis of the C1-C8 subunit: The synthesis of the C1-C8 subunit 5 was performed in four steps from lactone 9 through an adaptation of the Marshall butenolide synthesis, as outlined in Scheme 3. [14j] The synthesis began with alkylation of iodide 10 [21] with the lithium enolate of (S)-lactone 9…”

“…Activation of the C20-hydroxyl in 43 as its me- www.chemeurj.org sylate (MsCl/Et 3 N) was followed by deprotection of the C15-and C23-TBS ethers with 3 n HCl in MeOH and exposure of the crude reaction products to pyridine at reflux provided (+)-chamuvarinin in 57 % yield over three steps. [13,40] This three-step sequence only required a single chromatographic purification of the final product, which was identical to an authentic sample in all respects. [8,19] By implementation of this revised coupling strategy, we were able to improve the overall step efficiency (the longest linear sequence being 17 steps from 13, compare with 20 steps in our initial approach), although the overall yield was only slightly improved (2.2 % overall yield), in part due to the challenging C20-C21 bond construction.…”

“…These approaches are dominated by the application of intramolecular Williamson etherification reactions, as depicted in Scheme 1. [11][12][13][14] The cyclization of activated 1,4-hydroxysulfonate precursors of type A or 1,4-epoxyalcohols of type B provides efficient access to the corresponding isolated monoTHF compounds of type C and D, respectively. [12] The former approach has been readily applied in the installation of additional THF motifs in preconstructed systems.…”

“…[12] The former approach has been readily applied in the installation of additional THF motifs in preconstructed systems. [13] Further extension of this tactic has led to the implementation of two-directional cyclization of pseudo-C2-symmetric activated precursors of type E and F, to assemble the characteristic anti-threo-anti-configured bisTHF array of type G, [14,15] the predominant structural motif of the adjacent bisTHF acetogenin subclass, typified by squamocin (4). [4,16] Abstract: A highly stereocontrolled synthesis of (+)-chamuvarinin has been completed in 1.5 % overall yield over 20 steps.…”

Efficient synthesis of multiply substituted furans using BF@Propyl/dopamine/Pd as a green catalyst

“…[11][12][13] Furan and its end product, obtained from synthetic in addition to natural resources, have attracted much attention with extensive varieties of medicine usages. [14,15] These skeletons display several biological activities such as antimicrobial, [16][17][18][19] antifungal, [20] anti-inflammatory, [21,22] anticancer [23,24] and anti-viral HIV-1 [25] activities.…”