Synthetic studies on nemorosone via enantioselective intramolecular cyclopropanation

Catalytic radical cascade cyclization of alkene-tethered enones to fused bicyclic cyclopropanols

Fused bicyclic cyclopropanols were achieved via an unprecedented HAT-triggered radical cascade reaction of alkene-tethered enones in the presence of an iron catalyst.

Research Progress of Polycyclic Polyprenylated Acylphloroglucinols

Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of hybrid natural products sharing the mevalonate/methylerythritol phosphate and polyketide biosynthetic pathways and showing considerable structure and bioactivity diversity. This review discusses the progress of research into the chemistry and biological activity of 421 natural PPAPs in the past 11 years as well as in-depth studies of biological activities and total synthesis of some PPAPs isolated before 2006. We created an online database of all PPAPs known to date at http://www.chem.uky.edu/research/grossman/PPAPs . Two subclasses of biosynthetically related metabolites, spirocyclic PPAPs with octahydrospiro[cyclohexan-1,5'-indene]-2,4,6-trione core and complicated PPAPs produced by intramolecular [4 + 2] cycloadditions of MPAPs, are brought into the PPAP family. Some PPAPs' relative or absolute configurations are reassigned or critically discussed, and the confusing trivial names in PPAPs investigations are clarified. Pharmacologic studies have revealed a new molecular mechanism whereby hyperforin and its derivatives regulate neurotransmitter levels by activating TRPC6 as well as the antitumor mechanism of garcinol and its analogues. The antineoplastic potential of some type B PPAPs such as oblongifolin C and guttiferone K has increased significantly. As a result of the recent appearances of innovative synthetic methods and strategies, the total syntheses of 22 natural PPAPs including hyperforin, garcinol, and plukenetione A have been accomplished.

Collective Total Synthesis of PPAPs: Total Synthesis of Clusianone via Intramolecular Cyclopropanation

The total synthesis of clusianone was accomplished through the stereoselective construction of a bicyclo[3.3.1]nonane derivative via a three-step sequence which has been utilized for the total syntheses of nemorosone garsubellin A and hyperforin: intramolecular cyclopropanation formation of a geminal dimethyl group and regioselective ring opening of cyclopropane. Further elaboration including chemo- and stereoselective hydrogenation to generate the C7 stereogenic center and cross-metathesis to construct prenyl groups in the side-chains was employed to complete the total synthesis of clusianone.

Adventures in bridgehead substitution chemistry: synthesis of polycyclic polyprenylated acylphloroglucinols (PPAPs)

The polycyclic polyprenylated acylphloroglucinol (PPAP) family of natural products includes important compounds with notable biological activities, such as garsubellin A, hyperforin and clusianone. The synthesis of these complex, bridged, highly oxidized and substituted systems presents a formidable challenge to synthetic chemists. This feature article describes how the use of unconventional bridgehead substitution chemistry has enabled the synthesis of these natural products and their analogues.

Stereoselective total synthesis of nemorosone

The highly stereoselective total synthesis of nemorosone via a new approach to the bicyclo[3.3.1]nonane-2,4,9-trione core which features intramolecular cyclopropanation of an α-diazo ketone, stereoselective alkylation at the C8 position, and regioselective ring-opening of cyclopropane is described. The total synthesis of nemorosone includes chemo- and stereoselective hydrogenation directed by the internal alkene.

The chemistry of the polycyclic polyprenylated acylphloroglucinols

With their fascinating biological profiles and stunningly complex molecular architectures, the polycyclic polyprenylated acylphloroglucinols (PPAPs) have long provided a fertile playing field for synthetic organic chemists. In particular, the recent advent of innovative synthetic methods and strategies together with C-C bond-forming reactions and asymmetric catalysis have revitalized this field tremendously. Consequently, PPAP targets which once seemed beyond reach have now been synthesized. This Review aims to highlight the recent achievements in the total synthesis of PPAPs, as well as notable methods developed for the construction of the bicyclo[3.3.1] core of these chemically and biologically intriguing molecules.

Total synthesis of plukenetione A

We describe an alkylative dearomatization/acid-mediated adamantane annulation sequence that allows facile access to type A polyprenylated acylphloroglucinol natural products including plukenetione A. Introduction of the 2-methyl-1-propenyl moiety was achieved via stereodivergent S(N)2 and S(N)1 cyclizations of allylic alcohol substrates.