A concise, convergent total synthesis of monocerin

A concise and convergent eight-step synthesis of the antifungal metabolite monocerin 1 is reported. The key step involves an allylsilane metathesis/aldehyde condensation sequence to establish the core 2,3,5-trisubstituted tetrahydrofuran. End-game approaches based around intramolecular Heck chemistry revealed an interesting example of formal 6-endo cyclisation, the origin of which was probed using model substrates. The synthesis was ultimately completed by a strategy involving stepwise oxidative cleavage of the C3-ethenyl substituent.     

A concise and convergent (formal) total synthesis of huperzine A

The first convergent synthesis of the tricyclic skeleton of huperzine A is described and includes, as the key step, an efficient regioselective intramolecular Heck reaction of 2-(tert-butyldimethylsilyloxymethyl)-6-(2-methoxy-5-bromopyridin-6-yl)methylcyclohex-2-enol.     

抗结核候选药物PA-824的合成工艺优化

对抗结核候选药物PA-824的合成方法进行了优化。以4-硝基咪唑为原料,依次经亲核开环氧反应、氧烷基化反应和脱酯基反应制得(S)-3-(4-硝基-1H-咪唑-1-)-2-[(4-三氟甲氧基)苄氧基]丙烷-1-醇（3）;3在铜催化下发生分子内碳氢键活化烷氧化反应合成PA-824,总收率达到56.5%,其结构经¹H NMR,¹³C NMR和MS(ESI)确证。     

A concise synthesis of honokiol

Two approaches to the synthesis of the plant-derived biaryl neolignan honokiol are described. The second approach provided the natural product in either four steps with 34% overall yield or five steps and 55% overall yield.     

A concise synthesis of ent-Cholesterol

ent-Cholesterol was synthesized in 16 steps from commercially available (S)-citronellol. The overall yield for the synthesis was 2.0%. This route is amenable to gram-scale preparation of ent-cholesterol. Isotopic incorporation near the end of the synthesis was achieved using labeled methyl iodide. This synthesis is the most practical to date and will make ent-cholesterol more readily available to use as a probe of the function and metabolism of cholesterol.     

A concise synthesis of spirotryprostatin A

The preparation of two new synthons, 2,5- and 2,6-dibromotryptophan esters, and their use in diastereoselective intramolecular N-acyliminium ion spirocyclization methodology for the rapid construction of spirotryprostatin A and analogues are described.     

A concise synthesis of butylcycloheptylprodigiosin

A short and efficient total synthesis of the tripyrrole alkaloid butylcycloheptylprodigiosin is described. Key to the brevity of the approach is a two-step synthesis of macrocyclic formylpyrrole 4 from cyclononenone 6.     

A concise synthesis of honokiol

A simple synthesis of the natural product honokiol 1 has been developed which proceeds in four steps and provides a 32% overall yield. Suzuki coupling of 4-allyl-2-bromoanisole 3 with 4-hydroxyphenyl boronic acid, followed by allylation, gave 5-allyl-4′-allyloxy-2-methoxy-biphenyl 5. This compound 5 underwent Lewis acid-catalyzed Claisen rearrangement and demethylation in a one-pot reaction which yielded honokiol.     

A concise synthesis of denbinobin

A concise synthesis of denbinobin is described via an intramolecular free radical cyclization and Fremy’s salt mediated oxidation as a key reactions. A seven-step process starting from commercially available 3,5-dimethoxybenzyl bromide (6) and 2-bromoisovanillin (5) effectively constructs the natural product denbinobin (1).     

A concise synthesis of beta-asparaginyladenylate

Stable analogues of acyladenylate intermediates, such as N-acylphosphoramidates, are useful probes of tRNA aminoacylation and enzyme mechanism, and have potential application as enzyme inhibitors. We now report a concise, "one-pot" synthesis of beta-asparaginyladenylate using a novel coupling protocol that yields the target N-acylphosphoramidate in three reactions from readily available precursors. This simple synthetic procedure may represent a general approach for the preparation of functionalized N-acylphosphoramidates from amides that do not undergo coupling under the conditions of existing literature protocols.     

A concise and efficient synthesis of vildagliptin

An original synthesis of vildagliptin ((S)-1-[2-(3-hydroxyadamantan-1-ylamino)acetyl]pyrrolidine-2-carbonitrile), a powerful DPP-4 inhibitor, was developed. Vildagliptin was assembled from 3-amino-1-adamantanol, glyoxylic acid and l-prolinamide in a 4-step reaction sequence with the isolation of only two intermediates. The procedure is competitive with existing protocols, leading to vildagliptin in 63% overall yield.     

A concise and stereoselective synthesis of squalamine

[reaction: see text] A short and highly stereoselective synthesis of the novel steroid squalamine (1) was accomplished in nine steps from easily available methyl chenodeoxylcholanate 2. Our synthesis featured improved dehydrogenation of 4 followed by conjugate reduction to construct the trans AB-ring system and efficient asymmetric isopropylation of aldehyde 6 to introduce the C-24R-hydroxyl group.     

A concise and modular synthesis of pyranicin

A modular, 13-step synthesis of the tetrahydropyran-containing annonaceous acetogenin pyranicin is reported. Key features are the use of an Achmatowicz oxidation-Kishi reduction sequence for the assembly of a pyranone from a furan and the application of Fu's alkyl-alkyl Suzuki coupling for subunit union.     

A concise synthesis of polyhydroxydihydrochalcones and homoisoflavonoids

A general and single step synthesis of polyhydroxydihydrochalcones from the readily available phenols and dihydrocinnamic acids using BF₃·Et₂O is described. The method allows the synthesis of a wide range of compounds with multiple phenolic hydroxyls and other substituents. These dihydrochalcones are converted into homoisoflavonoids by DMF/PCl₅ and the methodology has been applied to the synthesis of naturally occurring phloretin and 5,7-dihydroxy-3-[(4-hydroxyphenyl)methyl]-4H-chromen-4-one. The antioxidant activity of dihydrochalcones and homoisoflavonoids was determined by superoxide free radical (NBT) and DPPH free radical scavenging methods. Polyhydroxydihydrochalcones 3c, 3f, 3g and homoisoflavonoids 4c, 4f, 4g displayed excellent antioxidant activity.     

A concise synthesis of (+)-cassiol

A synthesis of the anti-ulcerogenic compound (+)-cassiol 1b with 43% overall yield has been achieved. This short and efficient synthesis features the one-pot Julia olefination reaction of lactol (S)-2 with sulfone 3b through the key intermediate (−)-4b.     

A convergent synthesis of Hexahomotriazacalix

A new, convergent synthesis of hexahomotriazacalix[3]arenes 1a-e is described. The key transformation in this synthesis involves the coupling of the triamines 4a-d with 2, 6-bis(chloromethyl)-4-methylphenol 5 and results in the formation of the hexahomotriazacalix[3]arenes 1a-d in 90-95% yield. The triamines 4a-d were constructed by the one-pot reaction of monochloroaldehyde 3 and a primary amine followed by reduction to yield the triamines 4a-d in 50-55% yield. Deallylation of macrocycle 1d was accomplished by palladium catalysis to obtain the N-unsubstituted macrocycle 1e, which has the potential to be a precursor to a variety of N-substituted hexahomotriazacalix[3]arenes.     

A concise total synthesis of DL-histrionicotoxin

The synthesis of (+/-)-histrionicotoxin has been achieved in just nine steps using a two-directional synthesis strategy. Key reactions include a two-directional cross-metathesis, a tandem oxime formation/Michael addition/1,4-prototopic shift/[3 + 2]-cycloaddition cascade, a selective Z,Z-bisenyne formation, and a one-pot N-O and bischloroacetylene reduction.     

A concise synthesis of the octalactins

The total synthesis of octalactins A and B has been achieved in 15 steps (longest linear sequence) and 10% overall yield from commercially available materials. Key steps include the Paterson-Aldol reaction for the rapid assembly of the carbonate 46, methylenation of 46 and subsequent Claisen rearrangement of the corresponding alkenyl-substituted cyclic ketene acetal to provide the core unsaturated medium-ring lactone 47, and the use of enzyme-mediated acetate deprotection in the presence of a medium-ring lactone.