Total synthesis of (+)-anamarine

Total synthesis of (+)-anamarine a polyoxygenated δ-pyranone natural product was accomplished via cross-metathesis protocol starting from 3-butene-1-ol and glycidol. Other key features of this synthetic strategy include use of Sharpless asymmetric epoxidation, dihydroxylation, and deoxygenation-isomerization through allene rearrangement.     

Stereoselective total synthesis of (+)-anamarine via cross-metathesis protocol

A convergent stereoselective total synthesis of (+)-anamarine via cross-metathesis (CM) protocol starting from 2-butyn-1,4-diol and vinyl lactone is reported. Other key features of the strategy include the use of Sharpless asymmetric epoxidation, Sharpless dihydroxylation, and Red-Al reduction.     

Total synthesis of (+)-papulacandin D

A total synthesis of (+)-papulacandin D has been achieved in 31 steps, in a 9.2% overall yield from commercially available materials. The synthetic strategy divided the molecule into two nearly equal sized subunits, the spirocyclic C-arylglycopyranoside and the polyunsaturated fatty acid side-chain. The C-arylglycopyranoside was prepared in 11 steps in a 30% overall yield from triacetoxyglucal. The fatty acid side-chain was also prepared in 11 steps in a 30% overall yield from geraniol. The key strategic transformations in the synthesis are: (1) a palladium-catalyzed, organosilanolate-based cross-coupling reaction of a dimethylglucal-silanol with an electron-rich and sterically hindered aromatic iodide and (2) a Lewis-base catalyzed, enantioselective allylation reaction of a dienal and allyltrichlorosilane. A critical element in the successful execution of the synthesis was the development of a suitable protecting group strategy that satisfied a number of stringent criteria.     

Total synthesis of (+)-tanikolide, a toxic and antifungal δ-lactone, utilizing bromoalkene intermediates conveniently synthesized from vicinal dibromoalkane by regioselective elimination

Stereoselective total synthesis of (+)-tanikolide, a bioactive δ-lactone marine natural product, was successfully accomplished by using regioselective HBr elimination reaction of 3-acyloxy-1,2-dibromoalkanes, Pd-mediated coupling reaction, and the Sharpless asymmetric epoxidation as key steps.     

An efficient total synthesis of (−)-anamarine

An efficient synthesis of (−)-anamarine is described using d(+)-mannitol and (R)-epichlorohydrin. The synthesis is achieved starting from easily accessible d(+)-mannitol using a selective benzoylation, regioselective epoxide ring opening, a selective acetonide deprotection, tosylation and cross metathesis reaction.     

Total synthesis of (-)-anamarine

Total synthesis of polyhydroxy δ-pyranone natural product (-)-anamarine is accomplished from D-(-)-tartaric acid. The main feature of the synthesis is the utility of hitherto unexplored β-keto phosphonate derived from tartaric acid amide and further elaboration involving stereoselective reduction.     

Synthesis of gem-difluoromethylenated analogues of anamarine

Practical synthesis of two gem-difluoromethylenated analogues of anamarine was described. The important synthetic steps included the preparation of the key intermediates 20-21 through the indium-mediated gem-difluoropropargylation of aldehyde 18 with the fluorine-containing building block 19 and efficient construction of α,β-unsaturated-δ-lactone scaffold via BAIB/TEMPO procedure.     

Stereoselective total synthesis of (+)-boronolide, (+)-anamarine, 8-epi-spicegerolide

A stereoselective total synthesis of the naturally occurring cytotoxic lactones (+)-boronolide, (+)-anamarine, and 8-epi-spicigerolide is described. d-Xylose has been used as a chiral source to construct the four contiguous oxygenated stereogenic centers of target molecules. The diastereoselective allylation was performed using Brown’s protocol and the lactone moiety was prepared by ring closing metathesis.     

An efficient synthesis of (+)-prelactone B

An enantioselective synthesis of (+)-prelactone B 1 has been achieved on a multigram scale starting from a known bicyclic precursor 2. The key feature of the strategy is the generation of 3-stereogenic centres from a single bicyclic precursor, which has been utilized as a chiral building block for the synthesis of various natural products.     

An asymmetric synthesis of (+)-desoxoprosophylline

An efficient synthesis of (+)-desoxoprosophylline is described. The key steps in the reaction sequence include the preparation of an N-Cbz-sulfilimine from the corresponding sulfoxide using the Burgess reagent, regio- and stereoselective hetero-functionalization of an alkene using the pendant sulfilimine as the nucleophile and a stereoselective amidomercuration to form the cis-2,6-disubstituted piperidine ring.     

Reactions of 2- and 4-pyrones with secondary phosphine chalcogenides: a facile synthesis of functional phosphorylated pyrones

The oxidative cross-coupling between 4-hydroxy-6-methyl-2-pyrone or 3-hydroxy-2-methyl-4-pyrone and secondary phosphine chalcogenides proceeds in CCl₄/Et₃N under mild conditions (20–52 °С, 0.75–10 h) through the hydroxyl group to give O-(6-methyl-2-oxo-2H-pyran-4-yl) diorganylphosphinochalcogenoates or O-(2-methyl-4-oxo-4H-pyran-3-yl) diorganylphosphinochalcogenoates, in high yields.     

Total synthesis of (+)-massarinolin B and (+)-4-epi-massarinolin B, fungal metabolites from Massarina tunicata

The Cr(II)- and Ni(II)-mediated coupling of several tricyclic chiral aldehydes with (E)-β-iodomethacrylates (Nozaki-Hiyama-Kishi reaction) was successfully applied to the preparation of some valuable key intermediates of our synthetic strategy to the fungal metabolites (+)-massarinolin B, (+)-4-epi-massarinolin B and (+)-massarinolin C.     

First total synthesis of (+)-viroallosecurinine

The first diastereoselective chiral synthesis of (+)-viroallosecurinine, isolated from Securinega virosa as a cytotoxic alkaloid, was achieved by using a chelation-controlled addition of an alkyne moiety to the corresponding ketone, and a ring-closing metathesis, as key reactions.     

First total synthesis of (+)-crassalactone A

A simple and highly efficient first total synthesis of cytotoxic (+)-crassalactone A starting from (R)-mandelic acid is described. The strategy involves the osmium tetroxide-catalyzed cis-hydroxylation and the stereoselective addition of ethyl lithiopropiolate to a chiral aldehyde intermediate as key steps.     

Total synthesis and structure revision of deacetylravidomycin M

Total synthesis of the unnatural enantiomer of deacetylravidomycin M was accomplished. The key steps include, (1) aryl C-glycosidation of the azido-bearing fucosyl acetate 2 by using catalytic Sc(OTf)₃, (2) the [2+2] cycloaddition reaction of alkoxybenzyne bearing an azido sugar to ketene silyl acetal, and (3) the ring expansion reaction of alkoxybenzocyclobutenone. The synthesis revealed that the natural product is not the proposed amine, but the corresponding N-oxide.     

Sequential Baylis-Hillman/RCM protocol for the stereoselective synthesis of (+)-MK7607 and (+)-streptol

Sequential Baylis-Hillman/ring-closing metathesis (RCM) approach toward the total synthesis of (+)-MK7607 and (+)-streptol starting from (R,R)-tartaric acid is reported.     

A novel and stereospecific synthesis of (+)-exo-brevicomin

A novel and stereospecific synthesis of (+)-exo-brevicomin is disclosed. The key step of the reaction sequence employs the sulfinyl moiety as an intramolecular nucleophile to functionalize an alkene π-complexed to a bromonium ion.     

Total synthesis and structure revision of petrobactin

The total synthesis and the revised structural assignment of petrobactin, a siderophore isolated from the marine bacterium Marinobacter hydrocarbonoclasticus, is reported. The key step in the synthesis involved condensation of N¹-(2,3-dibenzoyloxybenzoyl)-N⁴-benzylspermidine with 1,3-di-(p-nitrophenyl)-2-tert-butyl citrate. Proton NMR spectra of the synthesized product compared with those reported for the natural product revealed that the compound did not contain 2,3-dihydroxybenzoyl moieties as published; instead, the splitting pattern suggested 3,4-dihydroxybenzoyl fragments. The 3,4-dihydroxybenzoyl analogue was accessed via a similar route; the proton and carbon-13 NMR spectra of this compound were consistent with those reported for natural petrobactin.     

Total synthesis of cimiracemate B and analogs

The synthesis of the biologically active cimiracemate B and some analogs is described. The key step of the synthesis is a coupling between a bromoketone and a cinnamic acid derivative.