Stereoselective total synthesis of decarestrictine-J via Ring Closing Metathesis (RCM)

Stereoselective total synthesis of decarestrictine-J, a polyketide natural product is described. The synthesis involves the Prins cyclisation and Ring Closing Metathesis (RCM) as key steps.     

Total synthesis of naturally occurring 5,6,7- and 5,7,8-trioxygenated coumarins

The synthesis of five naturally occurring polyoxygenated coumarins is described. It concerns two 5,6,7-trioxygenated coumarins, i.e., 6-hydroxy-5,7-dimethoxycoumarin (fraxinol) 1 and 5,6,7-trimethoxycoumarin 2, and three 5,7,8-trioxygenated coumarins, i.e., 8-hydroxy-5,7-dimethoxycoumarin (leptodactylone) 3, 5,7,8-trimethoxycoumarin 4 and 8-(3-methyl-2-butenyloxy)-5,7-dimethoxycoumarin (artanin) 5. Key feature of the synthetic pathway is the synthesis of suitable tetraoxygenated benzaldehydes, which are then converted to the corresponding coumarins via a Wittig reaction.     

Protecting-group-free total synthesis of 4-epi-phomonol

A concise first total synthesis of 4-epi-phomonol has been accomplished in 6 steps and 33% overall yield from (R)-1,2-epoxypentane. The key features of the synthesis include an application of protecting-group-free strategy, a prins cyclization to install the tetrahydropyran ring, and a substrate-controlled dihydroxylation to fix the stereocenters at the C3 and C4 positions.     

Total synthesis of cryptophycin-24 (arenastatin A) via Prins cyclization

A stereoselective synthesis of fragment A of cryptophycin is achieved utilizing the versatile Prins cyclization. Subsequently, the total synthesis of cryptophycin-24 (arenastatin A) has been accomplished by coupling it with the depsipeptide subunit.     

Total syntheses via cyclopropanols

Cyclopropanols are readily available via the Kulinkovich cyclopropanation, the Simmons-Smith reaction, and other synthetic methods. Due to their intrinsic ring stains, cyclopropanols and their derivatives are highly reactive and can be converted to different structural scaffolds which are frequently found in many natural products. In this review, we highlight the applications of various cyclopropanol ring opening/expansion/fragmentation reactions in the total syntheses of natural products.     

Total synthesis of xanthanolides

The total synthesis and determination of the absolute configuration of (+)- and (−)-sundiversifolide have been achieved via intramolecular acylation and Wittig-lactonization as the key steps. The xanthanolide sesquiterpene lactones, 8-epi-xanthatin (1), dihydroxanthatin (2), and xanthatin (3) were also prepared, starting from a common intermediate derived from the synthesis of sundiversifolide.     

Total synthesis of farylhydrazones A and B

Herein we report a concise total synthesis of farylhydrazones A and B, naturally occurring phenylhydrazones recently isolated from cultures of the Cordyceps-colonizing fungus Isaria farinosa, completed in six and five steps respectively starting from 2-nitrobenzoic acid. The synthesis is completely scalable, and highly convergent—making it adaptable for the preparation of analogues and investigation into the biological activity of these unique natural products.     

Total synthesis of (+/−)-diospongin A via Prins reaction

A straightforward synthesis of (+/−)-diospongin A starting from benzaldehyde is described. A Prins cyclization reaction to control the relative configuration of the three stereogenic centers and a Mitsunobu inversion represent the key steps of the approach.     

Total Synthesis of Ciguatoxin

Something fishy : Ciguatoxin (see structure) is one of the principal toxins involved in ciguatera poisoning and the target of a total synthesis involving the coupling of three segments. The key transformations in this synthesis feature acetylene–dicobalthexacarbonyl complexation.

     

A novel strategy for the chiral 2,4,5-triol moiety and its application to the synthesis of seimatopolide A and (2S,3R,5S)-(−)-2,3-dihydroxytetradecan-5-olide

A highly stereoselective approach to the total synthesis of seimatopolide A and (2S,3R,5S)-(−)-2,3-dihydroxytetradecan-5-olide is described via a common polyketide precursor by means of Prins reaction and MacMillan aminoxylation sequence.     

Total synthesis of 3,5-O-dicaffeoylquinic acid and its derivatives

We report the first total synthesis of 3,5-O-dicaffeoylquinic acid and its derivatives, 3,5-O-diferuloylquinic acid and 3,5-(3,4-dimethoxycinnamyl)quinic acid, in a nine-step sequence. The key step involves Knoevenagel condensations between vanillin, 3,4-dimethoxybenzaldehyde or 4-hydroxy-3-methoxybenzaldehyde and the dimalonate ester of quinic acid.     

Total Synthesis of Leucosceptroids A and B

Leucosceptroids A and B are sesterterpenoids with potent antifeedant and antifungal activities. A more efficient gram‐scale total synthesis of leucosceptroid B and the first total synthesis of leucosceptroid A are presented. The key transformations include an aldol reaction between a substituted dihydrofuranone and an (S)‐citronellal‐derived aldehyde, a SmI₂‐mediated intramolecular ketyl–olefin radical cyclization, and final‐stage alcohol oxidation.     

Total synthesis of pteridic acids A and B

A convergent synthesis of pteridic acids A and B, epimeric spiroacetal polyketides with potent plant growth promoter properties, is described. The use of boron aldol methodology efficiently achieved the stereocontrolled construction of advanced C1-C11 and C12-C16 subunits, which were coupled to generate a linear (Z)-enone precursor that underwent spiroacetalization with HF·pyridine, providing pteridic acids A and B after saponification.     

Seven-step total synthesis of α-cyclopiazonic acid

A seven-step total synthesis of α-cyclopiazonic acid is reported from a commercially available 4-bromoindole.Salient feature of the work is the rapid formation of tetracyclic skeleton via a bioinspired [3+2] annulation to form the C/D rings.     

First enantioselective synthesis of methyl (+)-7-methoxyanodendroate, an antitubercular dihydrobenzofuran

An enantioselective synthesis of methyl (+)-7-methoxyanodendroate was achieved utilising a Claisen rearrangement, a Grubbs cross-metathesis, and a Shi epoxidation-cyclisation sequence, confirming the absolute configuration assigned to the natural product.