The total synthesis of alkaloids (-)-histrionicotoxin 259A, 285C and 285E

The first total syntheses of three "unsymmetrical" (i.e. different terminal groups in the side chains) members of the histrionicotoxin family of alkaloids have been accomplished via stepwise introduction of the two side chain moieties onto a common tricyclic core.     

Total synthesis of (-)-histrionicotoxin

A total synthesis of (-)-histrionicotoxin was achieved. Our synthesis features preparation of a pseudosymmetrical dienyne through chirality transfer from an allenylsilane, a dienyne metathesis to produce the bicyclo [5.4.0] system in optically active form, selective functionalization of a diene via a 5-exo-trig iodoetherification, and an asymmetric propargylation.     

A total synthesis of OSW-1

A new and practical method was developed to synthesize OSW-1, a natural saponin with potent antitumor activities, from (+)-dehydroisoandrosterone, l-arabinose, and D-xylose on gram scale. The synthesis was achieved in 10 linear steps with an overall yield of 6.4% starting from (+)-dehydroisoandrosterone.     

Total synthesis of (-)-histrionicotoxin 285A and (-)-perhydrohistrionicotoxin

Starting from commercially available ( S)-glycidol, and via a common intermediate, the total synthesis of (-)-histrionicotoxin 285A and (-)-perhydrohistrionicotoxin has been achieved. Key to this synthesis was the efficient construction of a six-membered, chiral, cyclic nitrone.     

The first total synthesis of dragmacidin d

The first total synthesis of the biologically significant bis-indole alkaloid dragmacidin D (5) has been achieved. Thermal and electronic modulation provides the key for a series of palladium-catalyzed Suzuki cross-coupling reactions that furnished the core structure of the complex guanidine- and aminoimidazole-containing dragmacidins. Following this crucial sequence, a succession of meticulously controlled final events was developed leading to the completion of the natural product.     

Enantioselective total synthesis of 1-epi-pathylactone A

[structure: see text]. The first enantioselective total synthesis of 1-epi-pathylactone A, 3, has been accomplished using a PhI(OAc)2-mediated domino reaction as a key step. No diastereomeric separation was required throughout the whole synthetic scheme presented in this paper. Comparison of 1H and 13C NMR spectral data of the synthetic product with the reported spectral data of natural pathylactone A, coupled with an X-ray crystallographic analysis, led to the conclusion that the C1 configuration in the original paper was erroneously ascribed to (R).     

Stereoselective total synthesis of cryptopyranmoscatone A1

The first total synthesis of cryptopyranmoscatone A1 isolated from Cryptocarya moschata has been accomplished from 3,4,6-tri-O-acetyl-d-glucal. In addition to the RCM and cross-metathesis (CM) reactions, the synthesis features a highly diastereoselective Brown’s allylation reaction and sets the absolute stereochemistry of the natural product.     

Macrolide closure via fluorodesilylation a total synthesis of d, 1-17-o-methyllythridine

A synthesis of the macrolide 17-O-methyllythridine is reported in which cyclization is initiated by fluorodesilylation of a trimethlsilylacetate.     

Total synthesis of d,1-occidentalol by photoannelation

A nine step synthesis of an intermediate previously used in the synthesis of the sesquiterpene occidentalol is reported which incorporates a 2+2 photocycloaddition reaction as the key carbon carbon bond forming step.     

A total synthesis of d1-coriolin

A total synthesis of d1-coriolin has been accomplished starting from 1,3-cyclooctadiene, in which a rational and efficient introduction of various functional groups to the synthetic intermediate, 7-endo-t-butyldimethylsilyloxybicyclo[3.3.0]-oct-8-en-2-one, is involved.     

Solid-phase total synthesis of trunkamide A(1).

Marine organisms are a rich source of novel, biologically active compounds. Herein, the solid-phase total synthesis of trunkamide A, currently in preclinical trials, is presented. Trunkamide A contains a thiazoline heterocycle and two residues of Ser and Thr with the hydroxy function modified as reverse prenyl (rPr). Cornerstones of the synthesis are as follows: (i) solid-phase peptide chain elongation using a quasi-orthogonal protecting scheme with tert-butyl and fluorenyl based groups, on a chlorotrityl resin; (ii) concourse of HOAt-based coupling reagents; and (iii) cyclizations in solution. Furthermore, the following synthetic steps are discussed: (i) preparation of the reverse prenyl derivatives of Ser and Thr; (ii) introduction of precursor of thiazoline as a protected amino thionoacid derivative; and (iii) formation of the thiazoline ring with DAST. All these features make this strategy particularly suitable for the large-scale synthesis of trunkamide A and other peptides containing the same motifs.     

A concise total synthesis of arizonins B1 and C1

A concise and efficient total synthesis of arizonins B1 and C1 is reported. A key building block alkyne is synthesized from d-glucono-δ-lactone and used in the Dötz benzannulation reaction to construct the naphthalene unit. An oxa-Pictet–Spengler reaction gave the pyran ring while an H₂SO₄ mediated isomerization set the correct stereochemistry of the target molecules. Alternatively, a direct anti-pyran stereochemistry was prepared in a TFA solvent. The synthesis is competitive to previous reports and marks the first enantioselective synthesis of arizonin B1.     

A concise, stereocontrolled total synthesis of rippertenol

The first total synthesis of the unique terpene rippertenol, a molecule with dense stereochemical complexity arrayed on a compact framework largely devoid of functional groups, is described. Key elements include orchestrated and unique applications of aldol condensations, Diels-Alder chemistry, and a ring expansion to advance a chiral starting material containing a single chiral center into the final target in a concise and diastereocontrolled manner.     

Asymmetric, stereocontrolled total synthesis of paraherquamide A

The first total synthesis of paraherquamide A, a potent anthelmintic agent isolated from various Penicillium sp. with promising activity against drug-resistant intestinal parasites, is reported. Key steps in this asymmetric, stereocontrolled total synthesis include a new enantioselective synthesis of alpha-alkylated-beta-hydroxyproline derivatives to access the substituted proline nucleus and a highly diastereoselective intramolecular S(N)2' cyclization to generate the core bicyclo[2.2.2]diazaoctane ring system.     

Concise, asymmetric total synthesis of spirotryprostatin A

The structurally intriguing cell-cycle inhibitor spirotryprostatin A has been synthesized utilizing an azomethine ylide dipolar cycloaddition reaction as the key step. This pentacyclic alkaloid contains a prenylated tryptophan-derived oxindole moiety that has been created in a regiocontrolled and stereocontrolled manner in a single step.     

Concise,asymmetric total synthesis of spirotryprostatin A

[structure: see text] The structurally intriguing cell-cycle inhibitor spirotryprostatin A has been synthesized utilizing an azomethine ylide dipolar cycloaddition reaction as the key step. This pentacyclic alkaloid contains a prenylated tryptophan-derived oxindole moiety that has been created in a regiocontrolled and stereocontrolled manner in a single step.